Reg Watson’s Publication List

1. Food for All: Designing Sustainable and Secure Future Seafood Systems

A. K. Farmery, K. Karen Alexander, K. Anderson, J. L. Blanchard, C. Carter, K. Evans, M. Fischer, A. Fleming, S. Frusher, E. A. Fulton, B. Haas, C. K. MacLeod, L. Murray, K. L. Nash, G. Pecl, Y. Rousseau, R. Trebilco, I. E. van Putten, S. Mauli, L. Dutra, G. D., J. Kaltavara, R. Watson, B. Nowak, (2021). Reviews in Fish Biology and Fisheries,

food and nutrition security; equity; mariculture; wild capture fisheries; blue food; food system; seafood

Food from the sea can make a larger contribution to healthy and sustainable diets, and to addressing hunger and malnutrition, through improvements in production, distribution and equitable access to wild harvesting and mariculture resources and products. The supply and consumption of seafood is influenced by `drivers’

including ecosystem change and ocean regulation, the influence of corporations and evolving consumer demand, as well as the growing focus on the importance of seafood for meeting nutritional needs. These changes need to be examined in a holistic way to develop an informed understanding of the needs, potential impacts and solutions that align seafood production and consumption with relevant 2030 Sustainable Development Goals (SDGs). This paper uses an evidence-based narrative approach to examine how the anticipated global trends for seafood might be experienced by people in different social, geographical and economic situations over the next ten years. Key drivers influencing seafood within the global food system are identified and used to construct a future scenario based on our current trajectory (Business-as-usual 2030). Descriptive pathways and actions are then presented for a more sustainable future scenario that strives towards achieving the SDGs as far as technically possible (More sustainable 2030). Prioritising actions that not only sustainably produce more seafood, but consider aspects of access and utilisation for all, particularly those who are foodand nutrition insecure, is an essential part of designing sustainable and secure future seafood systems.

2. Poleward Bound: Adapting to Climate-Driven Species Redistribution

J. Melbourne-Thomas, A. Audzijonyte, M. J. Brasier, K. Cresswell, H. E. Fogarty, M. Haward, A. J. Hobday, H. L. Hunt, S. C. Ling, P. C. McCormack, T. Mustonen, K. Mustonen, J. Nye, M. Oellermann, R. Trebilco, I. van Putten, C. Villanueva, R. A. Watson, G. T. Pecl, (2021). Reviews in Fish Biology and Fisheries,

Climate change; range shifts; species redistribution, global, future seas,

One of the most pronounced effects of climate change on the world’s oceans is the (generally) poleward movement of species and fishery stocks in response to increasing water temperatures. In some regions, such redistributions are already causing dramatic shifts in marine socioecological systems, profoundly altering ecosystem structure and function, challenging domestic and international fisheries, and impacting on human communities. Such effects are expected to become increasingly widespread as waters continue to warm and species ranges continue to shift. Actions taken over the coming decade (2021–2030) can help us adapt to species redistributions and minimise negative impacts on ecosystems and human communities, achieving a more sustainable future in the face of ecosystem change.We describe key drivers related to climate-driven species redistributions that are likely to have a high impact and influence on whether a sustainable future is achievable by 2030. We posit two different futures—a ‘business as usual’ future and a technically achievable and more sustainable future, aligned with the Sustainable Development Goals. We then identify concrete actions that provide a pathway towards the more sustainable 2030 and that acknowledge and include Indigenous perspectives. Achieving this sustainable future will depend on improved monitoring and detection, and on adaptive, cooperative management to proactively respond to the challenge of species redistribution. We synthesise examples of such actions as the basis of a strategic approach to tackle this global-scale challenge for the benefit of humanity and ecosystems.

3. Advancing Global Ecological Modeling Capabilities to Simulate Future Trajectories of Change in Marine Ecosystem

M. Coll, J. Steenbeek, M. G. Pennion, J. Buszowski, K. Kashner, H. K. Lotze, Y. Rousseau, D. P. Tittensor, C. Walters, R. Watson, V. Christensen, (2020). Frontiers in Marine Science 7, 567877.

marine ecosystems; climate change; fishing; future trajectories; projections


Considerable effort is being deployed to predict the impacts of climate change and anthropogenic activities on the ocean’s biophysical environment, biodiversity, and natural resources to better understand how marine ecosystems and provided services to humans are likely to change and explore alternative pathways and options. We present an updated version of EcoOcean (v2), a spatial-temporal ecosystem modeling complex of the global ocean that spans food-web dynamics from primary producers to top predators. Advancements include an enhanced ability to reproduce spatial-temporal ecosystem dynamics by linking species productivity, distributions, and trophic interactions to the impacts of climate change and worldwide fisheries. The updated modeling platform is used to simulate past and future scenarios of change, where we quantify the impacts of alternative configurations of the ecological model, responses to climate-change scenarios, and the additional impacts of fishing. Climate-change scenarios are obtained from two Earth-System Models (ESMs, GFDL-ESM2M, and IPSL-CMA5-LR) and two contrasting emission pathways (RCPs 2.6 and 8.5) for historical (1950–2005) and future (2006–2100) periods. Standardized ecological indicators and biomasses of selected species groups are used to compare simulations. Results show how future ecological trajectories are sensitive to alternative configurations of EcoOcean, and yield moderate differences when looking at ecological indicators and larger differences for biomasses of species groups. Ecological trajectories are also sensitive to environmental drivers from alternative ESM outputs and RCPs, and show spatial variability and more severe changes when IPSL and RCP 8.5 are used. Under a non-fishing configuration, larger organisms show decreasing trends, while smaller organisms show mixed or increasing results. Fishing intensifies the negative effects predicted by climate change, again stronger under IPSL and RCP 8.5, which results in stronger biomass declines for species already losing under climate change, or dampened positive impacts for those increasing. Several species groups that win under climate change become losers under combined impacts, while only a few (small benthopelagic fish and cephalopods) species are projected to show positive biomass changes under cumulative impacts. EcoOcean v2 can contribute to the quantification of cumulative impact assessments of multiple stressors and of plausible ocean-based solutions to prevent, mitigate and adapt to global change.

4. Revisiting ‘Reinventing Residual Reserves in the Sea: Are We Favouring Ease of Establishment over Need for Protection?’

R. Devillers, R. L. Pressey, A. Grech, J. N. Kittinger, G. J. Edgar, T. Ward, R. Watson, (2020). Aquatic Conservation 30, 1758–1764.

marine protected areas, mpa, residual reserves, global


As systems of marine protected areas (MPAs) expand globally, there is a risk that new MPAs will be biased toward places that are remote or unpromising for extractive activities, and hence follow the trend of terrestrial protected areas in being ‘residual’ to commercial uses. Such locations typically provide little protection to the species and ecosystems that are most exposed to threatening processes. 2. There are strong political motivations to establish residual reserves that minimize costs and conflicts with users of natural resources. These motivations will likely remain in place as long as success continues to be measured in terms of area (km2) protected. 3. The global pattern of MPAs was reviewed and appears to be residual, supported by a rapid growth of large, remote MPAs. The extent to which MPAs in Australia are residual nationally and also regionally within the Great Barrier Reef (GBR) Marine Park was also examined. 4. Nationally, the recently announced Australian Commonwealth marine reserves were found to be strongly residual, making almost no difference to ‘business as usual’ for most ocean uses. Underlying this result was the imperative to minimize costs, but without the spatial constraints of explicit quantitative objectives for representing bioregions or the range of ecological features in highly protected zones. 5. In contrast, the 2004 rezoning of the GBR was exemplary, and the potential for residual protection was limited by applying a systematic set of planning principles, such as representing a minimum percentage of finely subdivided bioregions. Nonetheless, even at this scale, protection was uneven between bioregions. Within bioregion heterogeneity might have led to no-take zones being established in areas unsuitable for trawling with a risk that species assemblages differ between areas protected and areas left available for trawling. 6. A simple four-step framework of questions for planners and policy makers is proposed to help reverse the emerging residual tendency of MPAs and maximize their effectiveness for conservation. This involves checks on the least-cost approach to establishing MPAs in order to avoid perverse outcomes.

5. Energy Flow through Marine Ecosystems: Confronting Transfer Efficiency

T. D. Eddy, J. Bernhardt, J. Blanchard, W. W. L. Cheung, M. Colléter, H. D. Pontavice, E. A. Fulton, D. Gascuel, K. Kearney, P. C.M., T. Roy, R. R. Rykaczewski, R. Selden, C. A. Stock, C. C. C. Wabnitz, R. A. Watson, (2020). Trends in Ecology and Evolution,

trophic ecology; food web; trophic efficiency; energy transfer; climate change; fishing impacts,

Transfer efficiency is the proportion of energy passed between nodes in food webs. It is an emergent, unitless property that is difficult to measure and responds dynamically to environmental and ecosystem changes. Because the consequences of changes in transfer efficiency compound through ecosystems, slight variations can have large effects on food availability for top predators. We review processes controlling transfer efficiency, approaches to estimate it, and known variations across ocean biomes. Both process-level analysis and observed macroscale variations suggest that ecosystemscale transfer efficiency is highly variable, impacted by fishing, and will decline with climate change. It is important that we more fully resolve the processes controlling transfer efficiency in models to effectively anticipate changes in marine ecosystems and fisheries resources.

6. Changes in Higher Trophic Level Productivity, Diversity and Niche Space in a Rapidly Warming Continental Shelf Ecosystem

K. D. Friedland, J. A. Langan, S. I. Large, R. L. Selden, R. A. Watson, J. S. Link, (2020). Science of the Total Environment 704,

Species interactions; Niche overlap; Biodiversity; Habitat; Species distribution model,

There is long-standing ecological and socioeconomic interest in what controls the diversity and productivity of ecosystems. That focus has intensified with shifting environmental conditions associated with accelerating climate change. The U.S. Northeast Shelf (NES) is a well-studied continental shelf marine ecosystem that is among the more rapidly warming marine systems worldwide. Furthermore, many constituent species have experienced significant distributional shifts. However, the system response of the NES to climate change goes beyond simple shifts in species distribution. The fish and macroinvertebrate communities of the NES have increased in species diversity and overall productivity in recent decades, despite no significant decline in fishing pressure. Species distribution models constructed using random forest classification and regression trees were fit for the dominant species in the system. Over time, the areal distribution of occupancy habitat has increased for approximately 80% of the modeled taxa, suggesting most species have significantly increased their range and niche space. These niche spaces were analyzed to determine the area of niche overlap between species pairs. For the vast majority of species pairs, interaction has increased over time suggesting greater niche overlap and the increased probability for more intense species interactions, such as between competitors or predators and prey. Furthermore, the species taxonomic composition and size structure indicate a potential tropicalization of the fish.

7. Comparative Production of Fisheries Yields and Ecosystem Overfishing in African Large Marine Ecosystems

J. Link, R. A. Watson, F. Pranovi, S. Libralato, (2020). Environmental Development,

fisheries ecosystem, thresholds, systemic overfishing, comparative analysis, integrative metrics, food security, Atlantic Ocean, Indian Ocean


Marine capture fisheries in African Large Marine Ecosystems (LMEs) are important from economic, cultural, social, and food provision perspectives. These African fisheries have a long history of high exploitation in the context of datalimited situations. There is a growing, global movement (both in terms of management requirements and scientific efforts) to develop measures of ecosystem overfishing (EOF) that detect overfishing of an entire ecosystem using readily available data and based on widely repeatable patterns. These EOF indicators extend the thinking beyond single stock overfishing to an entire ecosystem and are largely based on well-established trophic theory. Moreover,

they need to be germane for data limited situations, easily interpretable, and simple to calculate. Here we introduce and present the results of several of these indicators—the Ryther index, Fogarty index, and Friedland index—as well as indices based on cumulative biomass-Trophic Level curve parameters for eight African LMEs. Significantly, all these EOF indicators also have thresholds beyond which EOF is indicated, particularly when coupled with other evidence. These thresholds were applied to the African LME EOF indicators to determine the degree to which EOF may be occurring. Five out of eight African LMEs exhibited symptoms of EOF, one with significant EOF, with at least one LME still currently experiencing EOF, and three more that may be close to EOF thresholds. One LME exhibited evidence of recovering trends. Additionally, EOF indicators detected changes in the LMEs five-ten years prior to major impacts that would be identified by piecing together fishing impacts on a stock-by-stock basis. We conclude that if EOF is detected, at the very least these relative simple measures should be monitored and means to mitigate total fishing pressure in an ecosystem should be explored.

8. Prioritization of the Sustainable Development Goals Drives Opportunities and Risks for a Blue Future

K. L. Nash, J. L. Blythe, C. Cvitanovic, E. A. Fulton, B. S. Halpern, E. J. Milner-Gulland, P. F. E. Addison, G. T. Pecl, R. A. Watson, J. L. Blanchard, (2020). One Earth ONE-EARTH-D-19-00108, 1-13.

Sustainable Development Goals; marine ecosystems; environmental change; human well-being; trade-offs, synergies; blue economy; blue futures


The Sustainable Development Goals (SDGs) were designed to recognize the fundamental role the biosphere plays in our sustainable future. However, decision-making bodies, from local to international levels, have assigned lowest priority towards Goal 14 (Life Below Water). Here, we analyze policy reports and indicators to explore risks associated with low attainment of Goal 14 for other targets. We show that limited progress towards Goal 14 is likely to affect long-term attainment of social and economic targets. This is particularly the case for countries highly dependent on fisheries or for those developing a blue economy, due to the reliance of the social and economic goals on a healthy ocean in these contexts. To help ensure sustainability is not compromised by environmental degradation we suggest an extension to existing indicator assessments. This approach would provide greater transparency and specificity to decision-makers as they direct actions to attain SDGs.

9. Sixty Endangered Marine Species Are Legally Caught in Industrial Fisheries

L. Roberson, R. A. Watson, C. Klein, (2020). Nature communications 11, 4764.

endangered; global fisheries, sustainability


Industrial-scale harvest of species at risk of extinction is controversial and usually highly regulated on land and for charismatic marine animals (e.g. whales). In contrast, threatened marine fish species can be legally caught in industrial fisheries. To determine the magnitude and extent of this problem, we analyze global fisheries catch and import data and find reported catch records of 91 globally threatened species. Thirteen of the species are traded internationally and predominantly consumed in European nations. Targeted industrial fishing for 73 of the threatened species accounts for nearly all (99%) of the threatened species catch volume and value. Our results are a conservative estimate of threatened species catch and trade because we only consider species-level data, excluding group records such as ‘sharks and rays.’ Given the development of new fisheries monitoring technologies and the current push for stronger international mechanisms for biodiversity management, industrial fishing of threatened fish and invertebrates should no longer be neglected in conservation and sustainability commitments.

10. Rethinking Spatial Costs and Benefits of Fisheries in Marine Conservation

M. Baker-Médard, T. F. Allnutt, M. L. Baskett, R. A. Watson, E. Lagabrielle, C. Kremen, (2019). Ocean and Coastal Management 178, 104824.

Marine conservation, Fisheries, Marxan, Spatial planning, Marine reserves, Madagascar


Fishing catch is often used as a cost in marine conservation planning to avoid areas of high fishing activity when identifying potential marine reserve locations. However, the theory of marine reserves indicates that reserves are more likely to benefit fisheries in areas of heavy fishing activity that would otherwise be overfished. Whether or not fishing catch is calculated as a cost depends on the balance of conservation and fisheries goals for a reserve, and thus is critical for policymakers to consider when designing marine reserve networks. This research shows the utility of running an inverted cost model of fishery catches during marine reserve spatial prioritization as a first step in a marine planning process oriented towards stabilizing local fisheries. This technique serves as a heuristic tool that may help conservation planners explore regions that would otherwise be overlooked if fisheries data were absent or integrated purely as a cost in the planning process. Drawing on data from Madagascar to illustrate our approach, this research demonstrates that the regions most frequently selected using the inverted cost model not only meet conservation targets, but are also those most accessible to community-based resource managers, the dominant management paradigm in Madagascar as well as in many developing countries.

11. Food Production Shocks across Land and Sea

R. S. Cottrell, K. L. Nash, B. S. Halpern, T. A. Remenyi, S. P. Corney, A. Fleming, E. A. Fulton, S. Hornborg, A. Johne, R. A. Watson, J. L. Blanchard, (2019). Nature Sustainability,

Food security; Food production; trade-offs; shock; fisheries; agriculture


Sudden losses to food production (that is, shocks) and their consequences across land and sea pose cumulative threats to global sustainability. We conducted an integrated assessment of global production data from crop, livestock, aquaculture and fisheries sectors over 53 years to understand how shocks occurring in one food sector can create diverse and linked challenges among others. We show that some regions are shock hotspots, exposed frequently to shocks across multiple sectors. Critically, shock frequency has increased through time on land and sea at a global scale. Geopolitical and extreme-weather events were the main shock drivers identified, but with considerable differences across sectors. We illustrate how social and ecological drivers,influenced by the dynamics of the food system, can spill over multiple food sectors and create synchronous challenges or trade-offs among terrestrial and aquatic systems. In a more shock-prone and interconnected world, bold food policy and socialprotection mechanisms that help people anticipate, cope with and recover from losses will be central to sustainability.

12. Global Ecosystem Overfishing: Clear Delineation within Real Limits to Production

J. S. Link, R. A. Watson, (2019). Science Advances 5, eaav0474.

ecological indicators, ecosystem, overfishing


The well-documented value of marine fisheries is threatened by overfishing. Management typically focuses on target populations but lacks effective tools to document or restrain overexploitation of marine ecosystems. Here, we present three indices and accompanying thresholds to detect and delineate ecosystem overfishing (EOF): the Fogarty, Friedland, and Ryther indices. These are based on widely available and readily interpreted catch and satellite data that link fisheries landings to primary production using known limits of trophic transfer efficiency. We propose theoretically and empirically based thresholds for each of those indices; with these criteria, several ecosystems are fished sustainably, but nearly 40 to 50% of tropical and temperate ecosystems exceed even extreme thresholds. Applying these criteria to global fisheries data results in strong evidence for two specific instances of EOF, increases in both pressure on tropical fish and a climate-mediated polar shift. Here, we show that these two patterns represent evidence for global EOF.

13. Evolution of Global Marine Fishing Fleets and the Response of Fished Resources

Y. Rousseau, R. A. Watson , J. Blanchard, E. Fulton, (2019). PNAS,

fishing capacity; effort; cpue; artisanal; industrial


Previous reconstructions of marine fishing fleets have aggregated data without regard to the artisanal and industrial sectors. Engine power has often been estimated from subsets of the developed world, leading to inflated results. We disaggregated data into three sectors, artisanal (unpowered/powered) and industrial, and reconstructed the evolution of the fleet and its fishing effort. We found that the global fishing fleet doubled between 1950 and 2015—from 1.7 to 3.7 million vessels. This has been driven by substantial expansion of the motorized fleet, particularly, of the powered-artisanal fleet. By 2015, 68% of the global fishing fleet was motorized. Although the global fleet is dominated by small powered vessels under 50 kW, they contribute only 27% of the global engine power, which has increased from 25 to 145 GW (combined powered-artisanal and industrial fleets). Alongside an expansion of the fleets, the effective catch per unit of effort (CPUE) has consistently decreased since 1950, showing the increasing pressure of fisheries on ocean resources. The effective CPUE of most countries in 2015 was a fifth of its 1950s value,which was compared with a global decline in abundance. There are signs, however, of stabilization and more effective management in recent years, with a reduction in fleet sizes in developed countries. Based on historical patterns and allowing for the slowing rate of expansion, 1 million more motorized vessels could join the global fleet by midcentury as developing countries continue to transition away from subsistence fisheries, challenging sustainable use of fisheries’ resources.

14. Defining Global Artisanal Fisheries

Y. Rousseau, R. A. Watson , J. Blanchard, B. Fulton, (2019). Marine Policy 108, 103634.

artisanal; small-scale; global Fisheries


While small-scale and artisanal fisheries are undeniably important globally, there is no global consensus on how to define the sectors, hindering comparative studies and international agreements. We focused on the usage of the words in both the scientific literature and legal documents and show that the confusion stems from a misuse of the terms artisanal, small-scale, coastal and subsistence, and is further propagated by language barriers. Accepting the complexity and subtleties of each term, we developed a simple method based on rhetoric and within a transdisciplinary background, which allows the ‘level’ of artisanal fisheries between nations to be parameterised and compared.

15. Progress in Integrating Natural and Social Science in Marine Ecosystem-Based Management Research

K. A. Alexander, A. J. Hobday, C. Cvitanovic, E. Ogier, K. L. Nash, R. Cottrell, A. Fleming, M. Fudge, E. Fulton, S. Frusher, R. Kelly, C. McLeod, G. Pecl, I. van Putten, J. Vince, R. Watson, (2018). Marine and Freshwater Research,

transdisciplinary, social science, marine ecosystem,

Climate change, in combination with population growth, is placing increasing pressure on the world’s oceans and their resources. This is threatening sustainability and societal well-being. Responding to these complex and synergistic challenges requires holistic management arrangements. To this end, ecosystem based management (EBM) promises much by recognising the need to manage the ecosystem in its entirety including the human dimensions. Operationalisation of EBM in the marine environment, however, has been slow. One reason may be a lack of the inter-disciplinary science required to address complex social-ecological marine systems. In this paper, we synthesise the collective experience of the authors to explore progress in integrating natural and social sciences in marine EBM research, illustrating actual and potential contributions. We identify informal barriers to and incentives for this type of research. We find that the integration of natural and social science has progressed at most stages of the marine EBM cycle; however, practitioners do not yet have the capacity to address all of the problems that have led to the call for inter-disciplinary research. In addition, we assess how we can support the next generation of researchers to undertake the effective inter-disciplinary research required to assist with operationalising marine EBM, particularly in a changing climate.

16. Fuel Use and Greenhouse Gas Emissions of World Fisheries

R. W. R. Parker, J. L. Blanchard, C. Gardner, B. S. Green, K. Hartmann, P. H. Tyedmers, R. A. Watson, (2018). Nature Climate Change 8, 333-337.

food production, greenhouse gas, global fishing,

Food production is responsible for a quarter of anthropogenic greenhouse gas (GHG) emissions globally. Marine fisheries are typically excluded from global assessments of GHGs or are generalized based on a limited number of case studies. Here we quantify fuel inputs and GHG emissions for the global fishing fleet from 1990–2011 and compare emissions from fisheries to those from agriculture and livestock production. We estimate that fisheries consumed 40 billion litres of fuel in 2011 and generated a total of 179 million tonnes of CO2-equivalent GHGs (4% of global food production). Emissions from the global fishing industry grew by 28% between 1990 and 2011, with little coinciding increase in production (average emissions per tonne landed grew by 21%). Growth in emissions was driven primarily by increased harvests from fuel-intensive crustacean fisheries. The environmental benefit of low-carbon fisheries could be further realized if a greater proportion of landings were directed to human consumption.

17. Predicting Global Tuna Vulnerabilities with Spatial, Economic, Biological and Climatic Considerations.

A. N. Tidd, J. L. Blanchard, L. T. Kell, R. A. Watson, (2018). Scientific Reports 8,

tuna, global, economics, sustainability


Overfishing impacts the three pillars of sustainability: social, ecological and economic. Tuna represent a significant part of the global seafood market with an annual value exceeding USD$42B and are vulnerable to overfishing. Our understanding of how social and economic drivers contribute to overexploitation is not well developed. We address this problem by integrating social, ecological and economic indicators to help predict changes in exploitation status, namely fishing mortality relative to the level that would support the maximum sustainable yield (F/FMSY). To do this we examined F/FMSY for 23 stocks exploited by more than 80 states across the world’s oceans. Low-HDI countries were most at risk of overexploitation of the tuna stocks we examined and increases in economic and social development were not always associated with improved stock status. In the short-term frozen price was a dominant predictor of F/FMSY providing a positive link between the market dynamics and the quantity of fish landed. Given the dependence on seafood in low-income regions, improved measures to safeguard against fisheries overexploitation in the face of global change and uncertainty are needed.

18. From Tuna to Cod – Global Patterns in Marine Predatory Fish

P. D. van Denderen, M. Lindegren, B. R. Mackenzie, R. A. Watson, K. H. Andersen, (2018). Nature Ecology and Evolution 2, 65-70.

pelagic, global, fishes, climate change, energy, food chain, ecology


Large teleost (bony) fish are a dominant group of predators in the oceans and constitute a major source of food and livelihood for humans. These species differ markedly in morphology and feeding habits across oceanic regions; large pelagic species such as tunas and billfish typically occur in the tropics, whereas demersal species of gadoids and flatfish dominate boreal and temperate regions. Despite their importance for fisheries and the structuring of marine ecosystems, the underlying factors determining the global distribution and productivity of these two groups of teleost predators are poorly known. Here, we show how latitudinal differences in predatory fish can essentially be explained by the inflow of energy at the base of the pelagic and benthic food chain. A low productive benthic energy pathway favours large pelagic species, whereas equal productivities support large demersal generalists that outcompete the pelagic specialists. Our findings demonstrate the vulnerability of large teleost predators to ecosystem-wide changes in energy flows and hence provide key insight to predict the responses of these important marine resources under global change.

19. Mapping Nearly a Century and a Half of Global Marine Fishing: 1869 to 2015

R. A. Watson, A. N. Tidd, (2018). Marine Policy 93, 171-177.

global fisheries, mapping, artisanal, small-scale, IUU, discards, history,

Understanding global fisheries patterns contributes significantly to their management. By combining harmonized unmapped data sources with maps from satellite tracking data, regional tuna management organisations, the ranges of fished taxa, the access of fleets and the logistics of associated fishing gears the expansion and intensification of marine fisheries for nearly a century and half (1869-2015) is illustrated. Estimates of industrial, non-industrial reported, illegal/unreported (IUU) and discards reveal changes in country dominance, catch composition and fishing gear use. Catch of industrial and non-industrial marine fishing by year, fishing country, taxa and gear by 30-min spatial cell broken to reported, IUU and discards is available. Results show a historical increase in bottom trawl with corresponding reduction in the landings from seines. Though diverse, global landings are now dominated by demersal and small pelagic species. .

20. Global Fishing Capacity and Fishing Effort from 1950–2012

J. D. Bell, R. A. Watson, Y. Ye, (2017). Fish and Fisheries 18, 489–505.

Fisheries management, fishing power, fishing energy use, fishing efficiency, global


Global marine wild capture landings have remained relatively stable for >20 years, however there is a lack of credible fishing capacity and effort information required to assess the likely sustainability and efficiency of the global fleet. As such, we estimated global fishing capacity and effort from 1950-2012 using a relatively comprehensive database developed by the FAO, supplemented by other data sources. Using random sampling techniques, we estimated the uncertainty surrounding many of our estimates enabling the identification of deficiencies and limitations. Global fishing capacity and effort increased rapidly from the late 1970’s through to around 2010 before stabilising. The Asian fleet is more than an order of magnitude larger than any other region in both capacity and effort and continues to increase. Most other regions have stabilised and there have been considerable declines in Europe and to a lesser extent North America. Developed nations, as a whole, have decreased in both measures in recent years and are responsible for the stabilisation of the global trend. Developing and undeveloped countries are still increasing with the former having the largest fleet and showing the greatest relative increase and the socio-economic impacts of reversing these trends are likely to be high. The efficiency of the global fleet, in terms of watt days of fishing effort per tonnage of wild marine catch, is now less than in 1950 despite the considerable technological advances, and expansion throughout the world’s oceans, that has occurred during this period of time.

21. Global Fishing Capacity and Fishing Effort from 1950–2012 Corrigendum

J. D. Bell, R. A. Watson, Y. Ye, (2017). Fish and Fisheries 18, 792-793.

Fisheries management, fishing power, fishing energy use, fishing efficiency, global


Global marine wild capture landings have remained relatively stable for >20 years, however there is a lack of credible fishing capacity and effort information required to assess the likely sustainability and efficiency of the global fleet. As such, we estimated global fishing capacity and effort from 1950-2012 using a relatively comprehensive database developed by the FAO, supplemented by other data sources. Using random sampling techniques, we estimated the uncertainty surrounding many of our estimates enabling the identification of deficiencies and limitations. Global fishing capacity and effort increased rapidly from the late 1970’s through to around 2010 before stabilising. The Asian fleet is more than an order of magnitude larger than any other region in both capacity and effort and continues to increase. Most other regions have stabilised and there have been considerable declines in Europe and to a lesser extent North America. Developed nations, as a whole, have decreased in both measures in recent years and are responsible for the stabilisation of the global trend. Developing and undeveloped countries are still increasing with the former having the largest fleet and showing the greatest relative increase and the socio-economic impacts of reversing these trends are likely to be high. The efficiency of the global fleet, in terms of watt days of fishing effort per tonnage of wild marine catch, is now less than in 1950 despite the considerable technological advances, and expansion throughout the world’s oceans, that has occurred during this period of time.

22. Linked Sustainability Challenges and Trade-Offs among Fisheries, Aquaculture and Agriculture

J. L. Blanchard, R. A. Watson, E. A. Fulton, R. S. Cottrell, K. L. Nash, A. Bryndum-Buchholz, M. Büchner, D. A. Carozza, W. Cheung, J. Elliott, L. N. K. Davidson, N. K. Dulvy, J. P. Dunne, T. D. Eddy, E. Galbraith, H. K. Lotze, O. Maury, C. Müller, D. P. Tittensor, S. Jennings, (2017). Nature Ecology and Evolution 1, 1240–1249.

fisheries, sustainability, Food security, global, agriculture


Fisheries and aquaculture make a crucial contribution to global food security, nutrition and livelihoods. However, the UN Sustainable Development Goals separate marine and terrestrial food production sectors and ecosystems. To sustainably meet increasing global demands for fish, the interlinkages among goals within and across fisheries, aquaculture and agriculture sectors must be recognized and addressed along with their changing nature. Here, we assess and highlight development challenges for fisheries-dependent countries based on analyses of interactions and trade-offs between goals focusing on food, biodiversity and climate change. We demonstrate that some countries are likely to face double jeopardies in both fisheries and agriculture sectors under climate change. The strategies to mitigate these risks will be context-dependent, and will need to directly address the trade-offs among Sustainable Development Goals, such as halting biodiversity loss and reducing poverty. Countries with low adaptive capacity but increasing demand for food require greater support and capacity building to transition towards reconciling trade-offs. Necessary actions are context-dependent and include effective governance, improved management and conservation, maximizing societal and environmental benefits from trade, increased equitability of distribution and innovation in food production, including continued development of low input and low impact aquaculture.

23. Continental-Scale Hotspots of Pelagic Fish Abundance Inferred from Commercial Catch Records

P. Bouchet, J. Meeuwig, Z. Huang, T. Letessier, S. Nichol, R. A. Watson, (2017). Global Ecology and Biogeography, 1-14.

submarine canyon, marine protected areas, pelagic fish, hotspot, topography, geomorphometrics, spatial modelling, random forest, catch standardisation


We compiled ten years of commercial fishing records from the Sea Around Us Project and derived relative abundance indices from standardised catch rates while accounting for confounding effects of effort, year, gear type and body mass. We used these indices to map pelagic “hotspots” over a 0.5°-resolution grid, and we built random forests to estimate the importance of 29 geophysical, oceanographic and anthropogenic predictors in explaining their locations. We additionally examined the spatial congruence between inferred hotspots and an extensive network of marine reserves, and determined whether patterns of co-occurrence deviated from random expectations using null model simulations. We identify three regional pelagic hotspots off the coast of Western Australia. (2) Geomorphometrics alone explained more than 50% of the variance in relative abundance of pelagic fish, and submarine canyon presence ranked as the most influential variable in the North bioregion. Seafloor rugosity and fractal dimension, salinity, ocean energy, current strength and human impacts were also identified as important predictors. (3) The spatial overlap between hotspots and marine reserves was limited, with most high-abundance areas primarily found in zones where anthropogenic activities are subject to few regulations. This study reveals that geomorphometrics are potentially valuable indicators of the distribution of mobile fish species and highlights the relevance of harnessing static topography as a blueprint for ocean zoning and spatial management.

24. Considering Land-Sea Interactions and Trade-Offs for Food and Biodiversity

R. S. Cottrell, A. Fleming, E. A. Fulton, K. L. Nash, R. A. Watson, J. L. Blanchard, (2017). Global Change Biology, 1-17.

Land-sea, interactions, trade-offs, food production, food security, biodiversity, sustainable development


With the human population expected to near 10 billion by 2050, and diets shifting towards greater per-capita consumption of animal protein, meeting future food demands will place ever-growing burdens on natural resources and those dependent on them. Solutions proposed to increase the sustainability of agriculture, aquaculture, and capture fisheries have typically approached development from single sector perspectives. Recent work highlights the importance of recognising links among food sectors, and the challenge cross-sector dependencies create for sustainable food production. Yet without understanding the full suite of interactions between food systems on land and sea, development in one sector may result in unanticipated trade-offs in another. We review the interactions between terrestrial and aquatic food systems. We show that most of the studied land-sea interactions fall into at least one of four categories: ecosystem connectivity, feed interdependencies, livelihood interactions, and climate feedback. Critically, these interactions modify nutrient flows, and the partitioning of natural resource use between land and sea, amid a backdrop of climate variability and change that reaches across all sectors. Addressing counter-productive trade-offs resulting from land-sea links will require simultaneous improvements in food production and consumption efficiency, while creating more sustainable feed products for fish and livestock. Food security research and policy also needs to better integrate aquatic and terrestrial production to anticipate how cross-sector interactions could transmit change across ecosystem and governance boundaries into the future.

25. Assessing the Environmental Impacts of Seafood as Part of a Sustainable Diet

A. Farmery, S. Jennings, C. Gardner, R. A. Watson, B. Green, (2017). Fish and Fisheries 18, 607–618.

aquaculture, food, greenhouse gas emissions, life cycle assessment, nutrition, wild-capture


The literature on sustainable diets is broad in its scope, and application yet is consist-ently supportive of a move away from animal- based diets towards more plant- based diets. The positioning of seafood within the sustainable diet literature is less clear. A literature review was conducted to examine how the environmental impacts of seafood consumption are assessed and what conclusions are being drawn about the inclusion of seafood in a sustainable diet. Seafood is an essential part of the global food system but is not adequately addressed in most of the sustainable diet literature. Aquaculture, the world’s fastest growing food sector, was considered by very few papers. Seafood con-sumption was commonly presented as a dilemma due to the perceived trade- offs be-tween positive health outcomes from eating seafood and concerns of overfishing. A number of studies included seafood as part of their sustainable diet scenario, or as part of a diet that had lower impacts than current consumption. Most of the indicators used were biophysical, with a strong focus on greenhouse gas emissions, and very few stud-ies addressed biological or ecological impacts. The assessment of seafood was limited in many studies due to relevant data sets not being incorporated into the models used. Where they were used, data sources and methodological choices were often not stated thereby limiting the transparency of many studies. Both farmed and wild- capture pro-duction methods need to be integrated into research on the impacts of diets and future food scenarios to better understand and promote the benefits of sustainable diets.

26. Naturalness as a Basis for Incorporating Marine Biodiversity into Life Cycle Assessment of Seafood.

A. K. Farmery, S. Jennings, C. Gardner, R. A. Watson, B. Green, (2017). The International Journal of Life Cycle Assessment,

Life cycle assessment, biodiversity, land use, sea floor, seawater column, seafood, hemeroby, naturalness,

Methods to quantify biodiversity impacts through LCA are evolving for both land- and marine-based production systems, although typically independently from each other. An indicator for terrestrial food production systems that may be suitable to assess marine biodiversity, and is applicable across all food production systems, is a measure of hemeroby, or distance from the natural state. We explore the possibility of adapting this approach to marine systems to assess the impact of fishing on seawater column and seafloor systems.

The terrestrial hemeroby concept is adapted here for marine ecosystems. Two commercial fishery case studies are used to test the effectiveness of hemeroby in measuring the influence exerted by fishing practices on marine biodiversity. Available inventory data are used to score areas to a hemeroby class, following a semi-quantitative scoring matrix and seven-point scale, to determine how far the seafloor and seawater column are from their natural state. This assessment process may progress to the impact assessment stage involving characterisation of the hemeroby score, to determine the Naturalness Degradation Potential (NDP) for use in calculating the Naturalness Degradation Indicator (NDI). The method builds on well-established processes for assessing fisheries within the Ecosystem-Based Fisheries Management framework, and is designed to enhance assessment of fishing impacts within LCA.


27. Farming and the Geography of Nutrient Production for Human Use

M. Herrero, P. K. Thornton, B. Power, J. Bogard, R. Remans, S. Fritz, J. Gerber, G. C. Nelson, L. See, K. Waha, R. A. Watson, P. West, L. Samberg, J. van de Steeg, E. Stephenson, M. van Wijk, P. Havlik, (2017). Lancet Planetary Health 1, e33–42.

Global Fisheries, nutrition, biodiversity,

Globally, small and medium farms (≤50 ha) produce 51–77% of nearly all commodities and nutrients examined here. However, important regional differences exist. Large farms (>50 ha) dominate production in North America, South America, and Australia and New Zealand. In these regions, large farms contribute between 75% and 100% of all cereal, livestock, and fruit production, and the pattern is similar for other commodity groups. By contrast, small farms (≤20 ha) produce more than 75% of most food commodities in Sub-Saharan Africa, Southeast Asia, South Asia, and China. In Europe, West Asia and North Africa, and Central America, medium-size farms (20–50 ha) also contribute substantially to the production of most food commodities. Very small farms (≤2 ha) are important and have local significance in Sub-Saharan Africa, Southeast Asia, and South Asia, where they contribute to about 30% of most food. The majority of vegetables (81%), roots and tubers (72%), pulses (67%), fruits (66%), fish and livestock products (60%), and cereals (56%) are produced in diverse landscapes (H>1·5). Similarly, the majority of global micronutrients (53–81%) and protein (57%) are also produced in more diverse agricultural landscapes (H>1·5). By contrast, the majority of sugar (73%) and oil crops (57%) are produced in less diverse ones (H≤1·5), which also account for the majority of global calorie production (56%). The diversity of agricultural and nutrient production diminishes as farm size increases. However, areas of the world with higher agricultural diversity produce more nutrients, irrespective of farm size.

28. Widely Used Marine Seismic Survey Air Gun Operations Negatively Impact Zooplankton

R. D. McCauley, R. D. Day, K. M. Swadling, Q. P. Fitzgibbon, R. A. Watson, J. M. Semmens, (2017). Nature Ecology and Evolution 1,

seismic, zooplankton, marine, ecosystems, impacts


Zooplankton underpin the health and productivity of global marine ecosystems. Here we present evidence that suggests seismic surveys cause significant mortality to zooplankton populations. Seismic surveys are used extensively to explore for petroleum resources using intense, low-frequency, acoustic impulse signals. Experimental air gun signal exposure decreased zooplankton abundance when compared with controls, as measured by sonar (~3–4 dB drop within 15–30 min) and net tows (median 64% decrease within 1 h), and caused a two- to threefold increase in dead adult and larval zooplankton. Impacts were observed out to the maximum 1.2 km range sampled, which was more than two orders of magnitude greater than the previously assumed impact range of 10 m. Although no adult krill were present, all larval krill were killed after air gun passage. There is a significant and unacknowledged potential for ocean ecosystem function and productivity to be negatively impacted by present seismic technology.

29. Planetary Boundaries for a Blue Planet

K. L. Nash, C. Cvitanovic, E. A. Fulton, B. S. Halpern, E. J. Milner-Gulland, R. A. Watson, J. L. Blanchard, (2017). Nature Ecology and Evolution 1, 1625-1634.

Global Fisheries, marine ecology, functional traits, ecosystems, resilience, database


Concepts underpinning the planetary boundaries framework are being incorporated into multilateral discussions on sustainability, influencing international environmental policy development. Research underlying the boundaries has primarily focused on terrestrial systems, despite the fundamental role of marine biomes for Earth system function and societal wellbeing, seriously hindering the efficacy of the boundary approach. We explore boundaries from a marine perspective. For each boundary, we show how improved integration of marine systems influences our understanding of the risk of crossing these limits. Better integration of marine systems is essential if planetary boundaries are to inform Earth system governance.

30. Improving Understanding of Fisheries Functional Diversity by Exploring the Influence of Global Catch Reconstruction

K. L. Nash, R. A. Watson, B. S. Halpern, E. A. Fulton, J. L. Blanchard, (2017). Nature Scientific Reports 7,

Global Fisheries, sustainability, planetary boundaries, marine ecology, policy


Functional diversity is thought to enhance ecosystem resilience, driving research focused on trends in the functional composition of fisheries, most recently with new reconstructions of global catch data. However, there is currently little understanding of how accounting for unreported catches (e.g. small-scale and illegal fisheries, bycatch and discards) influences functional diversity trends in global fisheries. We explored how diversity estimates varied among reported and unreported components of catch in 2010, and found these components had distinct functional fingerprints. Incorporating unreported catches had little impact on global-scale functional diversity patterns. However, at smaller, management-relevant scales, the effects of incorporating unreported catches were large (changes in functional diversity of up to 46%). Our results suggest there is greater uncertainty about the risks to ecosystem integrity and resilience from current fishing patterns than previously recognized. We provide recommendations and suggest a research agenda to improve future assessments of functional diversity of global fisheries.

31. Drivers of Fuel Use in Rock Lobster Fisheries

R. Parker, C. Gardner, B. S. Green, K. Hartmann, R. A. Watson, (2017). ICES Journal of Marine Science,

energy, fisheries, fuel, greenhouse gas emissions, lobster.


Fuel consumption is a leading cost to fishers and the primary source of greenhouse gas emissions from the global fishing industry. Fuel performance varies substantially between and within fisheries, but the drivers behind this variation are unclear and inconsistent across studies. We surveyed rock lobster fishers in Australia and New Zealand to measure rates of fuel use and assess the influence of technological (e.g. vessel size, engine power), behavioural (e.g. distance travelled, speed), and managerial (e.g. catch per unit effort, fishery capacity) factors. Weighted fuel use intensity across the region was 1,890 l/t. Managerial factors were the most influential drivers of fuel use in single day trips while technological factors heavily influenced multi-day trips. Catch per unit effort was the only significant driver present across both types of fishing trips. The vast majority of surveyed fishers identified fuel use as an important aspect of fishing operations, and nearly half had already implemented changes to try to reduce consumption. Our results suggest that efforts to reduce fuel consumption, costs, and emissions in fisheries need to be tailored to the nature of individual fisheries, as the relative roles of technology, behaviour, and management vary.

32. Reconciling Fisheries Catch and Ocean Productivity

C. A. Stock, J. G. John, R. R. Rykaczewski, R. G. Asch, W. W. L. Cheung, J. P. Dunne, K. D. Friedland, V. W. Y. Lam, J. L. Sarmiento, R. A. Watson, (2017). PNAS 114, E1441-E1449.

production, global fishing, marine ecosystems


Photosynthesis fuels marine food webs, yet differences in fish catch across globally distributed marine ecosystems far exceed differences in net primary production (NPP). We consider the hypothesis that ecosystem-level variations in pelagic and benthic energy flows from phytoplankton to fish, trophic transfer efficiencies, and fishing effort can quantitatively reconcile this contrast in an energetically consistent manner. To test this hypothesis, we enlist global fish catch data that include previously neglected contributions from small-scale fisheries, a synthesis of global fishing effort, and plankton food web energy flux estimates from a prototype high-resolution global earth system model (ESM). After removing a small number of lightly fished ecosystems, stark interregional differences in fish catch per unit area can be explained (r = 0.79) with an energy-based model that (i) considers dynamic interregional differences in benthic and pelagic energy pathways connecting phytoplankton and fish, (ii) depresses trophic transfer efficiencies in the tropics and, less critically, (iii) associates elevated trophic transfer efficiencies with benthic-predominant systems. Model catch estimates are generally within a factor of 2 of values spanning two orders of magnitude. Climate change projections show that the same macroecological patterns explaining dramatic regional catch differences in the contemporary ocean amplify catch trends, producing changes that may exceed 50% in some regions by the end of the 21st century under high emissions scenarios. Models failing to resolve these trophodynamic patterns may significantly underestimate regional fisheries catch trends and hinder adaptation to climate change.

33. A Database of Global Marine Commercial, Small-Scale, Illegal and Unreported Fisheries Catch 1950-2014.

R. Watson, (2017). Nature Scientific Data 4,

global fisheries, catch, landings, historical, IUU, discards


Global fisheries landings data from a range of public sources was harmonised and mapped to 30-min spatial cells based on the distribution of the reported taxa and the fishing fleets involved. This data was extended to include the associated fishing gear used, as well as estimates of illegal, unregulated and unreported catch (IUU) and discards at sea. Expressed as catch rates, these results also separated small-scale fisheries from other fishing operations. The dataset covers 1950 to 2014 inclusive. Mapped catch allows study of the impacts of fisheries on habitats and fauna, on overlap with the diets of marine birds and mammals, and on the related use of fuels and release of greenhouse gases. The fine-scale spatial data can be aggregated to the exclusive economic zone claims of countries and will allow study of the value of landed marine products to their economies and food security, and to those of their trading partners.

34. Global Seafood Trade Flows and Developing Economies: Insights from Linking Trade to Production.

R. A. Watson, R. Nichols, V. W. Y. Lam, U. R. Sumaila, (2017). Marine Policy 82, 41-49.

global seafood trade, global fisheries, seafood valued, eveloping nations, access agreements,

Knowing the patterns of marine resource exploitation and seafood trade may help countries to design their future strategic plans and development policies. To fully understand these patterns, it is necessary to identify where the benefits accumulate, how balanced the arrangements are, and how the pattern is evolving over time. Here the flow of global seafood was traced from locations of capture or production to their countries of consumption using novel approaches and databases. Results indicate an increasing dominance of Asian fleets by the volume of catch from the 1950s to the 2010s, including fishing in the high seas. The majority of landings were by high-income countries’ fishing fleets in their own waters in the 1950s but this pattern was greatly altered by the 2010s, with more equality in landings volume and value by fleets representing different income levels. Results also show that the higher the income of a country, the more valuable seafood it imports compared to its exports and vice versa. In theory, this implies that the lower income countries are exporting high value seafood in part to achieve the broader goal of ending poverty, while achieving the food security goal by retaining and importing lower value seafood. In the context of access arrangements between developed and developing countries, the results allow insights into the consequences of these shifting sources of income may have for goals such as poverty reduction and food security.

35. Plenty More Fish in the Sea?

R. A. Watson, T. J. Pitcher, S. Jennings, (2017). Fish and Fisheries 18, 105-113.

Conservation, global abundance, historical fishing, reconstruction, stock assessment


Only in the last century did humans overwhelmingly accept that fisheries resources are finite. Consequently, ‘there are more fish still in the sea than ever came out of it’ served as a popular metaphor for unbounded expectations for half a millennium, expectations that also extended to use of the planet in general. By reconstructing historical fishing back 1200 years, we identify when this metaphor actually ceased to be true. For some of our most important stocks, it has not been true for centuries, although surprisingly, for fishes globally, it applied until the last century. We demonstrate, however, that there can still be ‘plenty more fish in the sea’ and that with effective management they provide a continuous flow of benefits for our future.

36. Provenance of Global Seafood

R. A. Watson, B. S. Green, S. Tracey, A. Farmery, T. J. Pitcher, (2016). Fish and Fisheries 17, 585-595.

Export, import, mapping, Seafood consumption, provenance, seafood


Knowing where and how seafood is caught or farmed is central to empowering consumers, and the importers that supply them, with informed choices. Given the wide-ranging, complex and at times commercially sensitive nature of global seafood trade, it can prove very challenging to link imported seafood with information about its provenance. The databases involved are incomplete, at times vague and not harmonized. Here, we present a first attempt to link all global seafood imports through a virtual marketplace to exports and map their origins. Considerable work remains to ground-truth the specific origins of all seafood commodities. We illustrate the flow of seafood and its evolution since the 1970s when supporting records began. This work allows the impact of fishing or marine farming to be associated with seafood imports.

37. The Global Ocean Is an Ecosystem: Simulating Marine Life and Fisheries

V. Christensen, M. Coll, J. Buszowski, W. W. L. Cheung , T. L. Frölicher, J. Steenbeek, C. A. Stock, R. A. Watson, C. J. Walters, (2015). Global Ecology and Biogeography 24, 507–517.

Ecosystem model, end-to-end model, fish biomass trends, fish catches, food security, model tuning, seafood production, world ocean


There has been considerable effort allocated to understanding the impact of climate change on our physical environment, but comparatively little to how life on

Earth and ecosystem services will be affected. Therefore, we have developed a spatial–temporal food web model of the global ocean, spanning from primary producers through to top predators and fisheries. Through this, we aim to evaluate how alternative management actions may impact the supply of seafood for future generations.

38. Reinventing Residual Reserves in the Sea: Are We Favouring Ease of Establishment over Need for Protection?

R. Devillers, R. L. Pressey, A. Grech, J. N. Kittinger, G. J. Edgar, T. Ward, R. Watson, (2015). Aquatic Conservation 25, 480-504.

marine protected areas, mpa, residual reserves, global


1. As systems of marine protected areas (MPAs) expand globally, there is a risk that new MPAs will be biased toward places that are remote or unpromising for extractive activities, and hence follow the trend of terrestrial protected areas in being ‘residual’ to commercial uses. Such locations typically provide little protection to the species and ecosystems that are most exposed to threatening processes. 2. There are strong political motivations to establish residual reserves that minimize costs and conflicts with users of natural resources. These motivations will likely remain in place as long as success continues to be measured in terms of area (km2) protected. 3. The global pattern of MPAs was reviewed and appears to be residual, supported by a rapid growth of large, remote MPAs. The extent to which MPAs in Australia are residual nationally and also regionally within the Great Barrier Reef (GBR) Marine Park was also examined. 4. Nationally, the recently announced Australian Commonwealth marine reserves were found to be strongly residual, making almost no difference to ‘business as usual’ for most ocean uses. Underlying this result was the imperative to minimize costs, but without the spatial constraints of explicit quantitative objectives for representing bioregions or the range of ecological features in highly protected zones. 5. In contrast, the 2004 rezoning of the GBR was exemplary, and the potential for residual protection was limited by applying a systematic set of planning principles, such as representing a minimum percentage of finely subdivided bioregions. Nonetheless, even at this scale, protection was uneven between bioregions. Within bioregion heterogeneity might have led to no-take zones being established in areas unsuitable for trawling with a risk that species assemblages differ between areas protected and areas left available for trawling. 6. A simple four-step framework of questions for planners and policy makers is proposed to help reverse the emerging residual tendency of MPAs and maximize their effectiveness for conservation. This involves checks on the least-cost approach to establishing MPAs in order to avoid perverse outcomes.

39. Life Cycle Assessment of Wild Capture Prawns: Expanding Sustainability Considerations in the Australian Northern Prawn Fishery.

A. Farmery, C. Gardner, B. Green, S. Jennings, R. Watson, (2015). Journal of Cleaner Production 87, 96-104.

Northern prawn fishery, Banana and tiger prawn, Shrimp trawling, Greenhouse gas emissions, Sustainable seafood, LCA, prawn, shrimp, trawling


Prawns and shrimp are among the most popular seafood consumed globally and their production is responsible for a range of environmental impacts in wild capture fisheries and associated supply chains. Management of the Australian Northern Prawn Fishery has been promoted as a sustainable model for other countries to emulate, although broader environmental impacts, such as those relating to energy and water use or greenhouse gas emissions are not currently monitored under sustainability assessments. We use life cycle assessment (LCA) to assess the environmental impacts of the white banana prawn (Fenneropenaeus merguiensis). Fishing operations were the main source of impacts for the supply chain examined, contributing 4.3 kg CO2e kg- 1 prawn or 63% of the overall global warming potential. This result was lower than emissions reported for other prawn species, including tiger prawns from the same fishery. Processing and storage were key contributors to ecotoxicity while transport made a negligible contribution to any impact category. We discuss how LCA can complement existing fisheries management, and broaden current seafood sustainability assessments including the potential for emerging fishery-specific indicators to improve the efficacy of seafood LCAs.

40. Domestic or Imported? An Assessment of Carbon Footprints and Sustainability of Seafood Consumed in Australia

A. K. Farmery, B. G. Green, S. Jennings, R. A. Watson, C. Gardner, (2015). Environmental Science & Policy 54, 35-43.

imports, seafood trade, supply chain, life cycle assessment, food miles, sustainable seafood, Australia,

The distance between where food is produced and consumed is increasing, and is often taken as evidence of an unsustainable global food system. Seafood is a highly traded commodity yet seafood sustainability assessments do not typically consider the impacts of the movement of products beyond the fishery or farm. Here we use life cycle assessment to examine the carbon footprint of the production and distribution of select seafood products that are consumed in Australia and determine differences in the sustainability of imports and their domestically produced counterparts. We found that the distance food is transported is not the main determinant of food sustainability. Despite the increased distance between production and consumption, carbon footprints of meals from imported seafood are similar to meals consisting of domestically produced seafood, and sometimes lower, depending on the seafood consumed. In combining LCA with existing seafood sustainability criteria the trade-offs between sustainability targets become more apparent. Carbon ‘footprinting’ is one metric that can be incorporated into in assessments of sustainability, thereby demonstrating a broader perspective of the environmental cost of food production and consumption.

41. When Is a Fishery Sustainable?

R. Hilborn, E. A. Fulton, B. S. Green, K. Hartmann, S. R. Tracey, R. A. Watson, (2015). Canadian Journal Fisheries and Aquatic Sciences 72, 1433-1441.

sustainability, Global Fisheries, Fisheries management, stock assessment


Despite the many scientific and public discussions on the sustainability of fisheries, there are still great differences in both perception and definition of the concept. Most authors now suggest that sustainability is best defined as the ability to sustain goods and services to human society, with social and economic factors to be considered along with environmental impacts. The result has been that each group (scientists, economists, NGOs etc.) defines “sustainable seafood” using whatever criteria it considers most important, and the same fish product may be deemed sustainable by one group and totally unsustainable by another one. We contend, however, that there is now extensive evidence that an ecological focus alone does not guarantee long-term sustainability of any form and that seafood sustainability must consistently take on a socio-ecological perspective if it is to be effective across cultures and in the future. The sustainability of seafood production depends not on the abundance of a fish stock, but on the ability of the fishery management system to adjust fishing pressure to appropriate levels. While there are scientific standards to judge the sustainability of food production, once we examine ecological, social and economic aspects of sustainability there is no unique scientific standard.

42. Is Fisheries Production within Large Marine Ecosystems Determined by Bottom-up or Top-Down Forcing?

C. J. McOwen, W. W. L. Cheung, R. R. Rykaczewski, R. A. Watson, L. J. Wood, (2015). Fish and Fisheries 16, 623-632.

bottom-up, climate forcing, fishing effort, Large Marine Ecosystem, LME, top-down, fisheries production, primary production


Understanding the mechanisms driving fisheries production is essential if we are to accurately predict changes under climate change and exploit fish stocks in a sustainable manner. Traditionally studies have sought to distinguish between the two most prominent drivers, ‘bottom-up’ (resource driven) and ‘top-down’ (consumer driven), however, this dichotomy is increasingly proving to be artificial; as the relative importance of each mechanism has been shown to vary through space and time. Nevertheless, the reason why one predominates over another within a region remains largely unknown. To address this gap in understanding we identified the dominant driver of commercial landings within 47 ecosystems, encompassing a wide range of biogeochemical conditions and fishing practices in order to elucidate general patterns. We show that bottom-up and top-down effects vary consistently with past fishing pressure and oceanographic conditions; bottom-up control predominates within productive, overfished regions and top-down in relatively unproductive and under-exploited areas. We attribute these findings to differences in the species composition and oceanographic properties of regions, together with variation in fishing practices and (indicative) management effectiveness. Collectively, our analyses suggest that despite the complexity of ecological systems it is possible to elucidate a number of generalities. Such knowledge could be used to increase the parsimony of ecosystem models and to move a step forward in predicting how the global ocean, particularly fisheries productivity, will respond to climate change.

43. Fishing Access Agreements and Harvesting Decisions of Host and Distant Water Fishing Nations

R. Nichols, S. Yamazaki, S. Jennings, R. A. Watson, (2015). Marine Policy 54, 77–85.

Fisheries, Access agreements, Tuna, Pacific island nations, Distant water fishing nations


The declaration of exclusive economic zones (EEZs) granted coastal states sovereign rights over the marine resources in their EEZs and enabled developing coastal states to legally charge access fees to distant water fishing (DWF) nations for access to the resources in these waters. Despite the potential for economic gains, however, the ability of coastal states to benefit from the granting of sovereign rights and to ensure the sustainable use of their fisheries resources depends on how domestic fishing effort responds to the harvesting decisions of the DWF nations. We develop a stylized bioeconomic model to explore the change in fishing behavior of host and DWF nations when the two nations enter into an access agreement with varying levels of access fee. We further conduct an econometric analysis of changes in Pacific island nations’ harvesting behavior in response to the harvest decisions of DWF nations using data from the Western and Central Pacific tuna fishery. Our model results show that there is a range of variable access payment levels over which the host nation substitutes benefits from its domestic fishing activity with access payments from the DWF nation and that setting fees in this range can create a trap whereby host nations are forced to trade-off receiving a fair return to their fishery resources through access fees and retaining their own active fleet capacity. Our empirical analysis further shows a gradual shift in the way in which Pacific island host nations responded to the harvest decision of DWF nations as a result of the creation of the 200-nautical-mile EEZ.

44. Environmental and Economic Dimensions of Fuel Use in Australian Fisheries

R. W. R. Parker, K. Hartmann, B. S. Green, C. Gardner, R. A. Watson, (2015). Journal of Cleaner Production 87, 78-86.

Fuel, australia, Fisheries, Fisheries, Fuel, Fuel consumption, Carbon footprint, Life cycle assessment, Oil prices


Fisheries globally are facing multiple sustainability challenges, including low fish stocks, overcapacity, unintended bycatch and habitat alteration. Recently, fuel consumption has joined this list of challenges, with increasing consumer demand for low-carbon food production and the implementation of carbon pricing mechanisms. The environmental impetus for improving fishery fuel performance is coupled with economic benefits of decreasing fuel expenditures as oil prices rise. Management options to improve the fuel performance of fisheries could satisfy multiple objectives by providing low-carbon fish products, improving economic viability of the industry, and alleviating pressure on overfished stocks. We explored the association of fuel consumption and fuel costs in a wide range of Australian fisheries, tracking trends in consumption and expenditure over two decades, to determine if there is an economic impetus for improving the fuel efficiency e and therefore carbon footprint e of the industry. In the years studied, Australian fisheries, particularly energy-intensive crustacean fisheries, consumed large quantities of fuel per kilogram of seafood product relative to global fisheries. Many fisheries improved their fuel consumption, particularly in response to increases in biomass and decreases in overcapacity. Those fisheries that improved their fuel consumption also saw a decrease in their relative fuel expenditure, partially counteracted by rising oil prices. Reduction in fuel use in some Australian fisheries has been substantial and this has resulted not from technological or operational changes but indirectly through fisheries management. These changes have mainly resulted from management decisions targeting ecological and economic objectives, so more explicit consideration of fuel use may help in extending these improvements.

45. Winners and Losers in a World Where the High Seas Is Closed to Fishing.

U. R. Sumaila, W. Y. Lam, D. D. Miller, L. Teh, R. A. Watson, D. Pauly, D. Zeller, W. W. L. Cheung , I. M. Côté, A. D. Rogers, C. M. Roberts, E. Sala, (2015). Nature Scientific Reports 5,

Global Fisheries, high seas, Exclusive Economic Zones, tuna


Fishing takes place in the high seas and Exclusive Economic Zones (EEZs) of maritime countries. Closing the former to fishing has recently been proposed in the literature and is currently an issue of debate in various international fora. We determine the degree of overlap between fish caught in these two areas of the ocean, examine how global catch might change if catches of straddling species or taxon groups increase within EEZs as a result of protection of adjacent high seas; and identify countries that are likely to gain or lose in total catch quantity and value following high-seas closure. We find that ,0.01% of commercial fish taxa are caught exclusively in the high seas, and if the catch of straddling taxa increases by 18% on average following closure because of spillover, there would be no loss in global catch. The Gini coefficient, which measures income inequality, would decrease from 0.66 to 0.33. Thus, closing the high seas could be catch-neutral while inequality in the distribution of fisheries benefits among the world’s maritime countries could be reduced by 50%.

46. Species Traits and Climate Velocity Explain Geographic Range Shifts in an Ocean Warming Hotspot

J. M. Sunday, G. T. Pecl, S. Frusher, A. J. Hobday, N. Hill, N. J. Holbrook, G. J. Edgar, R. Stuart-Smith, N. Barrett, T. Wernberg, R. A. Watson, D. A. Smale, E. A. Fulton, D. Slawinski, M. Feng, B. T. Radford, P. A. Thompson, A. E. Bates, (2015). Ecology Letters,

range shifts, climate change, species traits, range extension, climate velocity, functional traits, climate response


Species’ ranges are shifting globally in response to climate warming, with substantial variability among taxa, even within regions. Relationships between range dynamics and intrinsic species traits may be particularly tractable in the ocean, where temperature more directly shapes species distributions. Here we test the possible role of species traits and climate velocity in driving the rate of range extensions in a region of rapid ocean warming. Climate expectation explained some variation in range shifts. However, including species traits more than doubled the variation explained. Swimming ability, omnivory, and latitudinal range size all have positive relationships with range extension rates, supporting hypotheses that increased dispersal capacity and ecological generalism promote range extensions. We find independent support for the hypothesis that species with narrow marine latitudinal ranges are out of equilibrium with climate. These findings suggest that small-ranging species are in double jeopardy, with a limited ability to escape warming and greater intrinsic vulnerability to stochastic threats.

47. Marine Foods Sourced from Farther as Their Use of Global Ocean Primary Production Increases.

R. A. Watson, G. Nowara, K. Hartmann, B. S. Green, S. Tracey, C. G. Carter, (2015). Nature communications 6,

Seafood consumption, seafood production, Food security, Global Fisheries, Aquaculture


The growing human population must be fed, but historic land-based systems struggle to meet expanding demand. Marine production supports some of the world’s poorest people but increasingly provides for the needs of the affluent, either directly by fishing or via fodderbased feeds for marine and terrestrial farming. Here we show the expanding footprint of humans to utilize global ocean productivity to feed themselves. Our results illustrate how incrementally each year, marine foods are sourced farther from where they are consumed and moreover, requires an increasing proportion of the ocean’s primary productivity that underpins all marine life. Though mariculture supports increased consumption of seafood, it continues to require feeds based on fully exploited wild stocks. Here we examine the ocean’s ability to meet our future demands to 2100 and find that even with mariculture supplementing near-static wild catches our growing needs are unlikely to be met without significant changes.

48. Defining and Observing Stages of Climate-Mediated Range Shifts in Marine Systems.

A. E. Bates, G. Pecl, S. Frusher, A. J. Hobday, T. Wernberg, D. A. Smale, J. M. Sunday, R. K. Colewell, N. Dulvy, G. J. Edgar, M. Feng, E. A. Fulton, N. Hill, N. Holbrook, B. T. Radford, D. Slawinski, P. A. Thompson, R. A. Watson, (2014). Global Environmental Change 26, 27-38.

species, redistribution, range, attribution, prediction, biogeography, warming, climate change, abundance–occupancy relationship


Climate change is transforming the structure of biological communities through the geographic extension and contraction of species’ ranges. Range edges are naturally dynamic, and shifts in the location of range edges occur at different rates and are driven by different mechanisms. This leads to challenges when seeking to generalize responses among taxa and across systems. We focus on warming-related range shifts in marine systems to describe extensions and contractions as stages. Range extensions occur as a sequence of (1) arrival, (2) population increase, and (3) persistence. By contrast, range contractions occur progressively as (1) performance decline, (2) population decrease and (3) local extinction. This stage-based framework can be broadly applied to geographic shifts in any species, life-history stage, or population subset. Ideally the probability of transitioning through progressive range shift stages could be estimated from empirical understanding of the various factors influencing range shift rates. Nevertheless, abundance and occupancy data at the spatial resolution required to quantify range shifts are often unavailable and we suggest the pragmatic solution of considering observations of range shifts within a confidence framework incorporating the type, amount and quality of data. We use case studies to illustrate how diverse evidence sources can be used to stage range extensions and contractions and assign confidence that an observed range shift stage has been reached. We then evaluate the utility of trait-based risk (invasion) and vulnerability (extinction) frameworks for application in a range shift context and find inadequacies, indicating an important area for development. We further consider factors that influence rates of extension and contraction of range edges in marine habitats. Finally, we suggest approaches required to increase our capacity to observe and predict geographic range shifts under climate change.

49. Where the Waters Meet: Sharing Ideas and Experiences between Inland and Marine Realms to Promote Sustainable Fisheries Management.

S. J. Cooke, R. Arlinghaus, D. M. Bartley, T. D. Beard, I. G. Cowx, T. E. Essington, O. P. Jensen, A. Lynch, W. W. Taylor, R. Watson, (2014). Canadian Journal of Fisheries and Aquatic Sciences 71, 1593-1601.

fisheries management,freshwater,inland fisheries,global fisheries,marine fisheries,sustainability


Although inland and marine environments, their fisheries, fishery managers, and the realm-specific management approaches are often different, there are a surprising number of similarities that frequently go unrecognized. We contend that there is much to be gained by greater cross-fertilization and exchange of ideas and strategies between realms and the people who manage them. The purpose of this paper is to provide examples of the potential or demonstrated benefits of working across aquatic boundaries for enhanced sustainable management of the world’s fisheries resources. Examples include the need to: (1) engage in habitat management and protection as the foundation for fisheries, (2) rethink institutional arrangements and management for open access fisheries systems, (3) establish ‘reference points’ and harvest control rules, (4) engage in integrated management approaches, (5) reap conservation benefits from the link to fish as food, and (6) reframe conservation and management of fish to better engage the public and industry. Cross-fertilization and knowledge transfer between realms could be realized using environment-independent curricula and symposia, joint scientific advisory councils for management, integrated development projects, and cross-realm policy dialogue. Given the interdependence of marine and inland fisheries, promoting discussion between the realms has the potential to promote meaningful advances in managing global fisheries.

50. Tropical Marginal Seas: Priority Regions for Managing Marine Biodiversity and Ecosystem Function

A. D. McKinnon, A. Williams, J. Young, D. Ceccarelli, P. Dunstan, R. J. W. Brewin, R. Watson, R. Brinkman, M. Cappo, S. Duggan, R. Kelley, K. Ridgway, D. Lindsay, D. Gledhill, T. Hutton, A. Richardson, J., (2014). Annual Review of Marine Science 6, 1-23.

coral reef, fisheries, pelagic, deep sea, transboundary management


Tropical marginal seas (TMSs) are natural subregions of tropical oceans containing biodiverse ecosystems with conspicuous, valued, and vulnerable biodiversity assets. They are focal points for global marine conservation because they occur in regions where human populations are rapidly expanding. Our review of 11 TMSs focuses on three key ecosystems—coral reefs and emergent atolls, deep benthic systems, and pelagic biomes—and synthesizes, illustrates, and contrasts knowledge of biodiversity, ecosystem function, interaction between adjacent habitats, and anthropogenic pressures. TMSs vary in the extent that they have been subject to human influence—from the nearly pristine Coral Sea to the heavily exploited South China and Caribbean Seas—but we predict that they will all be similarly complex to manage because most span multiple national jurisdictions.We conclude that developing a structured process to identify ecologically and biologically significant areas that uses a set of globally agreed criteria is a tractable first step toward effective multinational and transboundary ecosystem management of TMSs.

51. Energy Prices and (Sea)Food Security

N. Pellitier, J. André, A. Charef, D. Damalas, B. Green, R. Parker, R. Sumaila, G. Thomas, R. Tobin, R. Watson, (2014). Global Environmental Change 24, 30-41.

food security, energy price, fuel, fisheries, aquaculture, adaptive capacity, vulnerability


Fish resources are critical to the food security of many nations. Similar to most contemporary food systems, much of fisheries and aquaculture resource supply chains are heavily dependent on fossil fuels. Energy price increases and volatility may hence undermine food security in some contexts. Here, we explore the relationships between energy price changes, fish resource supply chain viability, seafood availability and food security outcomes – both for producers and consumers of fish resources. We begin by characterizing the energy intensities of fish resource supply chains, which are shown to be highly variable. We subsequently assess the comparative magnitude and distribution of potential food security impacts of energy price increases for nation states by scoring and ranking countries against a set of vulnerability criteria including metrics of national exposure, sensitivity and adaptive capacity. Considerable variability in the vulnerability of populations and high levels of exposure for already food-insecure populations are apparent. Developed countries are likely to be most exposed to the effects of energy price increases due to their high rates of fleet motorization and preference for energy-intensive seafood products. However, heavy reliance on seafood as a source of food and income, as well as limited national adaptive capacity, translates into greater overall vulnerability in developing countries. At the level of individual producers, a variety of adaptation options are available that may serve to reduce vulnerability to energy price changes and hence contribute to increased food security for producers and consumers, but uptake capacity depends on numerous situational factors.

52. The Global Contribution of Forage Fish to Marine Fisheries and Ecosystems

E. K. Pikitch, J. R. Konstantine, T. E. Essington, C. Santora, D. Pauly, R. Watson, U. R. Sumaila, P. D. Boersma, I. L. Boyd, D. O. Conover, P. Cury, S. S. Heppell, E. D. Houde, M. Mangel, E. Plaganyi-Lloyd, K. Sainsbury, R. S. Steneck, T. M. Geers, N. Gownaris, S. P. Munch, (2014). Fish and Fisheries 15, 43-64.

ecosystem-based management, ecosystem service, fisheries value, forage fish, supportive values, trade-offs


Forage fish play a pivotal role in marine ecosystems and economies worldwide by sustaining many predators and fisheries directly and indirectly. We estimate global forage fish contributions to marine ecosystems through a synthesis of 72 published Ecopath models from around the world. Three distinct contributions of forage fish were examined: 1) the ecological support service of forage fish to predators in marine ecosystems, 2) the total catch and value of forage fisheries, and 3) the support service of forage fish to the catch and value of other commercially targeted predators. Forage fish use and value varied by latitude and ecosystem type, and exhibited patterns across these groups. Forage fish supported many kinds of predators, including fish, seabirds, marine mammals and squid. Overall, forage fish contribute a total of about $16.9 billion USD to global fisheries values annually, i.e. 20% of the global ex-vessel catch values of all marine fisheries combined. While the global catch value of forage fisheries was $5.6 billion, fisheries supported by forage fish were more than twice as valuable ($11.3 billion). These estimates provide important information for evaluating the trade-offs of various uses of forage fish across ecosystem types, latitudes, and globally. We did not estimate a monetary value for supportive contributions of forage fish to recreational fisheries or to uses unrelated to fisheries, thus the estimates of economic value reported herein understate the global value of forage fishes.

53. Primary Productivity Demands of Global Fishing Fleets

R. Watson, D. Zeller, D. Pauly, (2014). Fish and Fisheries 15, 231-241.

primary production, Large Marine Ecosystem, LME, global fishing fleets, marine fishing


To be sustainable the extractive process of fishing requires biomass renewal via primary production driven by solar energy. Primary production required (PPR) estimates how much primary production is needed to replace the biomass of fisheries landings removed from marine ecosystems. Here we examine the historical fishing behavior of global fishing fleets, which parts of the food web they rely on, which ecosystems they fish and how intensively. Highly mobile European and Asian fleets have moved to ever more distant productive waters since the 1970s, especially once they are faced with the costs of access agreements for Exclusive Economic Zones (EEZs) declared by host countries. We examine fleet PPR demands in the context of Large Marine Ecosystems (LME) which are frequently fished with PPR demands well above their average primary productivity (PP). In some cases this was mitigated by subsequent emigration of fleets or by management intervention. Fleet movements, however, have stressed additional marine areas, including the EEZs of developing countries. This suggests the potential for spatial serial depletion, if fishing capacity is not reduced to more sustainable PP removal levels. Fundamentally, fishing is limited by solar-powered PP limits. Fishing beyond solar production has occurred but in the future, marine systems may not be as forgiving, especially if overfishing and climate change compromise their resilience.

54. Signature of Ocean Warming in Global Fisheries Catch.

W. W. L. Cheung , R. Watson, D. Pauly, (2013). Nature 497, 365-368.

climate change, ocean warming, global, fisheries


Marine fishes and invertebrates respond to ocean warming through distribution shifts, generally to higher latitudes and deeper waters. Consequently, fisheries should be affected by ‘tropicalization’ of catch (increasing dominance of warm-water species). However, a signature of such climate-change effects on global fisheries catch has so far not been detected. Here we report such an index, the mean temperature of the catch (MTC), that is calculated from the average inferred temperature preference of exploited species weighted by their annual catch. Our results show that, after accounting for the effects of fishing and large-scale oceanographic variability, global MTC increased at a rate of 0.19 degrees Celsius per decade between 1970 and 2006, and non-tropical MTC increased at a rate of 0.23 degrees Celsius per decade. In tropical areas, MTC increased initially because of the reduction in the proportion of subtropical species catches, but subsequently stabilized as scope for further tropicalization of communities became limited. Changes in MTC in 52 large marine ecosystems, covering the majority of the world’s coastal and shelf areas, are significantly and positively related to regional changes in sea surface temperature. This study shows that ocean warming has already affected global fisheries in the past four decades, highlighting the immediate need to develop adaptation plans to minimize the effect of such warming on the economy and food security of coastal communities, particularly in tropical regions.

55. Global Reductions in Seafloor Biomass in Response to Climate Change

D. O. B. Jones, A. Yool, C. Wei, S. A. Henson, H. A. Ruhl, R. A. Watson, M. Gehlen, (2013). Global Change Biology 20, 1861–1872.

benthic, climate change, seafloor


Seafloor organisms are vital for healthy marine ecosystems, contributing to elemental cycling, benthic remineralization, and ultimately sequestration of carbon. Deep-sea life is primarily reliant on the export flux of particulate organic carbon from the surface ocean for food, but most ocean biogeochemistry models predict global decreases in export flux resulting from 21st century anthropogenically induced warming. Here we show that decadal-to-century scale changes in carbon export associated with climate change lead to an estimated 5.2% decrease in future (2091–2100) global open ocean benthic biomass under RCP8.5 (reduction of 5.2 Mt C) compared with contemporary conditions (2006–2015). Our projections use multi-model mean export flux estimates from eight fully coupled earth system models, which contributed to the Coupled Model Intercomparison Project Phase 5, that have been forced by high and low representative concentration pathways (RCP8.5 and 4.5, respectively). These export flux estimates are used in conjunction with published empirical relationships to predict changes in benthic biomass. The polar oceans and some upwelling areas may experience increases in benthic biomass, but most other regions show decreases, with up to 38% reductions in parts of the northeast Atlantic. Our analysis projects a future ocean with smaller sized infaunal benthos, potentially reducing energy transfer rates though benthic multicellular food webs. More than 80% of potential deep-water biodiversity hotspots known around the world, including canyons, seamounts, and cold-water coral reefs, are projected to experience negative changes in biomass. These major reductions in biomass may lead to widespread change in benthic ecosystems and the functions and services they provide.

56. Exploring Patterns of Seafood Provision Revealed in the Global Ocean Health Index.

K. M. Kleisner, C. Longo, M. Coll, B. S. Halpern, D. Hardy, S. K. Katona, F. Le Manach, D. Pauly, A. A. Rosenberg, S. F. Samhouri, C. Scarborough, U. R. Sumaila, R. Watson, D. Zeller, (2013). AMBIO: a Journal of the Human Environment 42, 910-992.

indicator, status, assessment, ocean health, global


Sustainable provision of seafood is a fundamental component of healthy marine ecosystems. As such, the Ocean Health Index includes a model for sustainable seafood provision. Here we critically review this model, and explore the implications of knowledge gaps, scale of analysis, choice of reference points, measures of sustainability, and quality of input data. Global patterns for fisheries are positively related to human development and latitude, whereas patterns for mariculture are most closely associated with economic importance of seafood. Sensitivity analyses show that scores are robust to several model assumptions, but highly sensitive to choice of reference points and, for fisheries, extent of time series available to estimate landings. We show how results for Food Provision may be interpreted and used, and we evaluate which modifications show the greatest potential for improvements.

57. China’s Distant Water Fisheries in the 21st Century.

D. Pauly, D. Belhabib, R. Blomeyer, W. Cheung, A. Cisneros-Montemayor, D. Copeland, S. Harper, V. Lam, Y. Mai, F. Le Manach, H. Österblom, K. Mok, L. van der Meer, A. Sanz, S. Shon, U. Sumaila, W. Swartz, R. Watson, Y. Zhai, D. Zeller, (2013). Fish and Fisheries 15, 474-488.

China, distant water, fishing, history


We conservatively estimate the distant-water fleet catch of the People’s Republic of China for 2000–2011, using a newly assembled database of reported occurrence of Chinese fishing vessels in various parts of the world and information on the annual catch by vessel type. Given the unreliability of official statistics, uncertainty of results was estimated through a regionally stratified Monte Carlo approach, which documents the presence and number of Chinese vessels in Exclusive Economic Zones and then multiplies these by the expected annual catch per vessel. We find that China, which over-reports its domestic catch, substantially under-reports the catch of its distant-water fleets. This catch, estimated at 4.6 million t year-1 (95% central distribution, 3.4–6.1 million t year-1) from 2000 to 2011 (compared with an average of 368 000 t year-1 reported by China to FAO), corresponds to an exvessel landed value of 8.93 billion € year-1 (95% central distribution, 6.3–12.3 billion). Chinese distant-water fleets extract the largest catch in African waters (3.1 million t year-1, 95% central distribution, 2.0–4.4 million t), followed by Asia (1.0 million t year-1, 0.56–1.5 million t), Oceania (198 000 t year-1, 144 000–262 000 t), Central and South America (182 000 t year-1, 94 000–299 000 t) and Antarctica (48 000 t year-1, 8 000–129 000 t). The uncertainty of these estimates is relatively high, but several sources of inaccuracy could not be fully resolved given the constraints inherent in the underlying data and method, which also prevented us from distinguishing between legal and illegal catch.

58. Response to Removing Biases in Forecasts of Fishery Status

U. T. Srinivasan, W. W. L. Cheung, R. Watson, U. R. Sumaila, (2013). Journal of Bioeconomics 16, 221-222.

overfishing, fisheries management, depletion, sustainability


Previously in this journal, we demonstrated an empirical relationship between maximum sustainable yield (MSY) and historical maximum catch (Cmax) for fishery stocks off the Northeast U.S.—a relationship we then applied to estimate the potential catch losses from unsustainable fishing worldwide (Srinivasan et al. 2010). Two studies have since found similar relationships between MSY and maximum catch using larger regional datasets (Froese et al. 2012; Halpern et al. 2012). In a third paper in this issue of the Journal of Bioeconomics, Costello et al. (in press) update the MSY- Cmax relationship in two ways. First, they correct for the “retransformation bias” (Duan 1983) omitted in our earlier analysis, and second, they reparametrize the model using data for 109 stocks from the RAM II global database of stock assessments (Ricard et al. 2011). Their updated model is arguably more representative of global fisheries than the one we used (Srinivasan et al. 2010), and when we apply it to re-estimate global catch losses to overfishing over 1950-2004, we find that our original conclusions are strengthened.

59. Ecosystem Model of Tasmanian Waters Explores Impacts of Climate-Change Induced Changes in Primary Productivity

R. Watson, G. Nowara, S. Tracey, B. Fulton, C. Bulman, G. Edgar, N. Barrett, J. Lyle, S. Frusher, C. Buxton, (2013). Ecological Modelling,

climate-induced changes, climate change, marine, ecosystem model, primary productivity


An Ecopath with Ecosim (EwE) model was developed that represents the marine shelf environment surrounding the island state of Tasmania (south of mainland Australia). Climate change scenarios representing a range of potential impacts (30% increase or decrease over a century) on marine primary productivity were investigated. Temperature changes and other impacts were not investigated. This analysis uncovered an asymmetric set of system responses. Modeled increases in primary productivity predict increases in the biomass of most groups, especially shallow filter-feeders (which includes oysters), fished macrozoobenthos which includes rock lobsters (Jasus edwardsii) and octopus. In contrast the group of unfished macrozoobenthos (sea stars, whelks) decreased their relative biomass as primary productivity increased. All modeled fisheries responded to varying primary production levels. The most responsive modeled fisheries were for flathead (Platycephalidae) and for those offshore. Of the groups of special conservation interest (marine mammals and seabirds) the most responsive was the dolphin group – though all responded.

60. Coastal Catch Transects as a Tool for Studying Global Fisheries

R. Watson, D. Pauly, (2013). Fish and Fisheries 15, 445-455.

cross-sectional, transects, global fisheries, coastal, Large Marine Ecosystems, LME, Exclusive Economic Zones, EEZ


We present a new, intuitive approach for the representation of fisheries catches within profiles perpendicular to coast of the Exclusive Economic Zones (EEZ) of countries, or of Large Marine Ecosystems (LME). These ‘catch transects’ show where catch is extracted in the water column and near the sea bottom on plots of log-bathymetry versus log-distance offshore, and thus allow for representation of the catch density of pelagic and benthic fisheries. Hence, they also allow direct visual comparison of the intensity of fishing through time and space. The California Current, North Sea and the South China Sea LMEs and the EEZs of Australia, Canada, Chile, China, India and Thailand are presented as examples, revealing the general intensification and extension of fishing offshore and into the depths over the decades from the 1950s. Catch transects reveal how these trends have accelerated in some areas, but surprisingly, have reversed themselves in some others. It is proposed that these catch transects will be particularly useful for communicating the results of large scale fisheries studies to a wide spectrum of groups ranging from the fishing industry to the general public.

61. The Changing Face of Global Fisheries – the 1950s Vs. The 2000s

R. Watson, D. Pauly, (2013). Marine Policy 42, 1-4.

global fisheries, marine, change, history


Spatialized catch and effort data, representing the world’s marine fisheries in the 1950s and the 2000s are presented in form of cartograms, i.e., global maps in which the surface areas of continents are made proportional to the magnitude of the annual catches and fishing effort by their fleets. This is complemented by an analysis of the flows of seafood between the continents in whose waters the fish were captured, in the 1950s and 2000s, and the continents where fleets originated. Such broad-brush analyses of temporal changes and trade patterns are helpful to understand major trends of fisheries, which, we argue, are increasingly dominated by scarcity of fish, and competition, notably off the coast of West Africa, and in newly accessed polar waters.

62. Global Marine Yield Halved as Fishing Intensity Redoubles

R. A. Watson, W. W. L. Cheung, J. A. Anticamara, R. U. Sumaila, D. Zeller, D. Pauly, (2013). Fish and Fisheries 14, 493–503.

fishing effort, fishing intensity, spatial expansion, yield


There is widespread concern and debate about the state of global marine resources and the ecosystems supporting them, notably global fisheries, as catches now generally stagnate or decline. Many fisheries are not assessed by standard stock assessment methods including many in the world’s most biodiverse areas. Though simpler methods using widely available catch data are available, these are often discounted largely because data on fishing effort that contributed to the changes in catches are mostly not considered. We analyse spatial and temporal patterns of global fishing effort and its relationship with catch to assess the status of the world’s fisheries. The study reveals that fleets now fish all of the world’s oceans and have increased in power by an average of 10-fold (25-fold for Asia) since the 1950s. Significantly, for the equivalent fishing power expended, landings from global fisheries are now half what they were a half-century ago, indicating profound changes to supporting marine environments. This study provides another dimension to understand the global status of fisheries.

63. Fishing Down the Deep: Accounting for within-Species Changes in Depth of Fishing.

R. A. Watson, T. Morato, (2013). Fisheries Research 140, 63-65.

deep-sea, deep-water fisheries, depth of fishing, fishing deeper, global fisheries, coastal


New estimates of the global mean depth of fishing, which consider both the between and within species changes over time, showed a stronger shift to deeper water than estimated previously based only on between-species changes. The new estimates show a linear increase in the mean depth of fishing of 62.5m decade-1, corresponding to an increase of about 350m for the period since 1950. These values are about 5 times higher than those obtained by using between-species change in catch composition over time, suggesting that deep water species and habitats are under a more serious threat from fishing than hitherto assumed.

64. Comparison of Marine Spatial Planning Methods in Madagascar Demonstrates Value of Alternative Approaches

T. F. Allnutt, T. R. McClanahan, S. Andréfouët, M. Baker, E. Lagabrielle, C. McClennen, A. J. M. Rakotomanjaka, T. F. Tianarisoa, R. Watson, C. Kremen, (2012). PloS one 7, e28969.

marine spatial planning, Madagascar, MPA


The Government of Madagascar plans to increase marine protected area coverage by over one million hectares. To assist this process, we compare four methods for marine spatial planning of Madagascar’s west coast. Input data for each method was drawn from the same variables: fishing pressure, exposure to climate change, and biodiversity (habitats, species distributions, biological richness, and biodiversity value). The first method compares visual color classifications of primary variables, the second uses binary combinations of these variables to produce a categorical classification of management actions, the third is a target-based optimization using Marxan, and the fourth is conservation ranking with Zonation. We present results from each method, and compare the latter three approaches for spatial coverage, biodiversity representation, fishing cost and persistence probability. All results included large areas in the north, central, and southern parts of western Madagascar. Achieving 30% representation targets with Marxan required twice the fish catch loss than the categorical method. The categorical classification and Zonation do not consider targets for conservation features. However, when we reduced Marxan targets to 16.3%, matching the representation level of the “strict protection” class of the categorical result, the methods show similar catch losses. The management category portfolio has complete coverage, and presents several management recommendations including strict protection. Zonation produces rapid conservation rankings across large, diverse datasets. Marxan is useful for identifying strict protected areas that meet representation targets, and minimize exposure probabilities for conservation features at low economic cost. We show that methods based on Zonation and a simple combination of variables can produce results comparable to Marxan for species representation and catch losses, demonstrating the value of comparing alternative approaches during initial stages of the planning process. Choosing an appropriate approach ultimately depends on scientific and political factors including representation targets, likelihood of adoption, and persistence goals.

65. Shrinking of Fishes Exacerbates Impacts of Global Ocean Changes on Marine Ecosystems

W. W. L. Cheung, J. L. Sarmiento, J. Dunne, T. L. Frölicher, V. W. Y. Lam, M. L. D. Palomares, R. Watson, D. Pauly, (2012). Nature Climate Change,

shrinkage, growth, climate change, global, marine ecosystems, ocean


Changes in temperature, oxygen content and other ocean biogeochemical properties directly affect the ecophysiology of marine water-breathing organisms. Previous studies suggest that the most prominent biological responses are changes in distribution, phenology and productivity. Both theory and empirical observations also support the hypothesis that warming and reduced oxygen will reduce body size of marine fishes. However, the extent to which such changes would exacerbate the impacts of climate and ocean changes on global marine ecosystems remains unexplored. Here,we employ a model to examine the integrated biological responses of over 600 species of marine fishes due to changes in distribution, abundance and body size. The model has an explicit representation of ecophysiology, dispersal, distribution, and population dynamics. We show that assemblage-averaged maximum body weight is expected to shrink by 14–24% globally from 2000 to 2050 under a high-emission scenario. About half of this shrinkage is due to change in distribution and abundance, the remainder to changes in physiology. The tropical and intermediate latitudinal areas will be heavily impacted, with an average reduction of more than 20%. Our results provide a new dimension to understanding the integrated impacts of climate change on marine ecosystems.

66. The Mediterranean Sea under Siege: Spatial Overlap between Marine Biodiversity, Cumulative Threats and Marine Reserves

M. Coll, C. Piroddi, C. Albouy, F. Ben Rais Lasram, W. W. L. Cheung, V. Christensen, V. S. Karpouzi, F. Guilhaumon, D. Mouillot, M. Paleczny, M. L. Palomares, J. Steenbeek, P. Trujillo, R. Watson, D. Pauly, (2012). Global Ecology and Biogeography 21, 465-480.

cumulative impacts, human threats, marine biodiversity, marine conservation, marine protected areas, MPA, Mediterranean Sea


Our results show that areas with high marine biodiversity in the Mediterranean Sea are mainly located along the central and north shores, with lower values in the south-eastern regions. Areas of potential high cumulative threats are widespread in both the western and eastern basins, with fewer areas located in the south-eastern region. The interaction between areas of high biodiversity and threats for invertebrates, fishes and large animals in general (including large fishes, marine mammals, marine turtles and seabirds) is concentrated in the coastal areas of Spain, Gulf of Lions, north-eastern Ligurian Sea, Adriatic Sea, Aegean Sea, south-eastern Turkey and regions surrounding the Nile Delta and north-west African coasts. Areas of concern are larger for marine mammal and seabird species.

67. Sustainability of Deep-Sea Fisheries

E. A. Norse, S. Brooke, W. W. L. Cheung, M. R. Clark, I. Ekeland, R. Froese, K. M. Gjerde, R. L. Haedrich, S. S. Heppell, T. Morato, L. E. Morgan, D. Pauly, R. Sumaila, R. Watson, (2012). Marine Policy 36, 307-320.

sustainability, deep-sea fisheries, fisheries collapse, fisheries economics, high seas, global fisheries


As coastal fisheries around the world have collapsed, industrial fishing has spread seaward and deeper in pursuit of the last economically attractive concentrations of fishable biomass. For a seafood-hungry world depending on the oceans’ ecosystem services, it is crucial to know whether deep-sea fisheries can be sustainable. The deepsea is by far the largest but least productive part of the oceans, although in very limited places fish biomass can be very high. Most deep-sea fishes have life histories giving them far less population resilience/productivity than shallow-water fishes, and could be fished sustainably only at very low catch rates if population resilience were the sole consideration. But like old-growth trees and great whales, their biomass makes them tempting targets while their low productivity creates strong economic incentive to liquidate their populations rather than exploiting them sustainably (Clark’sLaw). Many deep-sea fisheries use bottom trawls, which often have high impacts on nontarget fishes (e.g., sharks) and invertebrates (e.g.,corals), and can often proceed only because they receive massive government subsidies. The combination of very low target population productivity, nonselectivefishing gear, economics that favor population liquidation and a very weak regulatory regime makes deep-sea fisheries unsustainable with very few exceptions. Rather, deep-sea fisheries more closely resemble mining operations that serially eliminate fishable populations and moveon. Instead of mining fish from the least-suitable places on Earth, an ecologically and economically preferable strategy would be rebuilding and sustainably fishing resilient populations in the most suitable places, namely shallower and more productive marine ecosystems that are closer to markets.

68. Global Fisheries Losses at the Exclusive Economic Zone Level, 1950 to Present

U. T. Srinivasan, R. Watson, U. R. Sumaila, (2012). Marine Policy 36, 544-549.

overfishing, fisheries management, depletion, sustainability


Up to one-third of commercial fishery stocks maybe overfished at present. By analyzing catch trends and applying an empirical relationship derived from stock assessments, this article tracks the geographic spread of overfishing at the country level in terms of lost catch and lost revenue, from the start of industrialized fishing in 1950–2004The results tell a cautionary tale of serial depletion to meet the ever-rising demand for fish. Examining country losses with respect to fishery management reveals that overcapacity and excess fishing effort are widespread, but also that recent trends towards sustainability can stabilize or reverse losses(e.g. for Norway, Iceland, the US, Canada, Australia, and New Zealand). Global trade effectively masks the successive depletion of stocks, so that without decisive action to reduce fishing effort, many more stocks will suffer and undernourishment impacts for the major exporting, food-deficit nations will only magnify.

69. Benefits of Rebuilding Global Marine Fisheries Outweigh Costs.

U. R. Sumaila, W. Cheung, A. Dyck, K. Gueye, L. Huang, V. Lam, D. Pauly, U. Srinivasan, W. Swartz, R. Watson, D. Zeller, (2012). PLoS One 7,

global fisheries, marine, rebuilding, costs


Global marine fisheries are currently underperforming, largely due to overfishing. An analysis of global databases finds that resource rent net of subsidies from rebuilt world fisheries could increase from the current negative US$13 billion to positive US$54 billion per year, resulting in a net gain of US$600 to US$1,400 billion in present value over fifty years after rebuilding. To realize this gain, governments need to implement a rebuilding program at a cost of about US$203 (US$130–US$292) billion in present value. We estimate that it would take just 12 years after rebuilding begins for the benefits to surpass the cost. Even without accounting for the potential boost to recreational fisheries, and ignoring ancillary and non-market values that would likely increase, the potential benefits of rebuilding global fisheries far outweigh the costs.

70. Impact of the Deepwater Horizon Well Blowout on the Economics of U.S. Gulf Fisheries

U. R. Sumaila, A. Cisneros-Montemayor, A. Dyck, L. Huang, W. Cheung, J. Jacquet, K. Kleisner, V. Lam, A. McCrea-Strub, W. Swartz, R. Watson, D. Zeller, D. Pauly, (2012). Canadian Journal Fisheries and Aquatic Sciences 69, 499-510.

oil spill, marine ecosystems, ecological impact, profit, wages


Marine oil spills usually harm organisms at two interfaces, near the water surface and on shore. However, due to the depth of the April 2010 Deepwater Horizon well blowout, deeper parts of the Gulf of Mexico are likely impacted. We estimate the potential negative economic effects of this blow out and oil spill on commercial and recreational fishing, as well as mariculture (marine aquaculture) in the U.S. Gulf area, by computing potential losses throughout the fish value chain. We find that the spill could, in the next seven years, result in (midpoint) present value losses of total revenues, total profits, wages, and economic impact of US$3.7, $1.9, $1.2, and $8.7 billion, respectively. Commercial and recreational fisheries would likely suffer most losses, with an estimated US$1.6 and US$1.9 billion of total revenue loss, US$0.8 and 1.1 billion in total profit, and US$4.9 and US$3.5 billion of total economic impact for commercial and recreational fisheries, respectively.

71. Global Ex-Vessel Fish Price Database Revisited: A New Approach for Estimating ‘Missing’prices

W. Swartz, R. Sumaila, R. Watson, (2012). Environmental and Resource Economics, 1-14.

price, value, global marine fisheries


The Global Ex-vessel Fish Price Database (Ex-vessel DB) reported in Sumaila et al. (J Bioecon 9(1):39–51, 2007) was the first comprehensive database that presents average annual ex-vessel prices for all commercially exploited marine fish stocks by nationality of the fishing fleet. It contained over 30,000 reported price items, covering the period from 1950 to the present, and supplemented missing prices with estimates based on prices from a different year, species group or fleet nationality. This paper describes a revised missing price estimation approach, focused on the computation of annual average international prices for each species group, adjusted to domestic prices using the real exchange rate based on national purchasing power parity. Key advantages of the new approach are that it allows a larger number of reported prices to be used in the price estimation, and accounts for relative price level differences that exist between countries. Our new approach should improve the estimates in regions where reported prices are scarce or non-existent by linking domestic prices to the trends in international prices. Our analysis, based on the revised ex-vessel price estimates (in real 2005 USD), shows that the global marine fisheries landings have generated total value of USD 4.2 trillion since 1950, including USD 100 billion in 2005.

72. Rapid Global Expansion of Invertebrate Fisheries: Trends, Drivers, and Ecosystem Effects

S. C. Anderson, J. M. Flemming, R. Watson, H. K. Lotze, (2011). PloS one 6, e14735.

invertebrate, fisheries, global, ecosystem


Worldwide, finfish fisheries are receiving increasing assessment and regulation, slowly leading to more sustainable exploitation and rebuilding. In their wake, invertebrate fisheries are rapidly expanding with little scientific scrutiny despite increasing socio-economic importance.

73. Serial Exploitation of Global Sea Cucumber Fisheries

S. C. Anderson, J. M. Flemming, R. Watson, H. K. Lotze, (2011). Fish and Fisheries 12, 317-339.

beche-de-mer, seacucumber, echinoderms, global market, invertebrate fisheries, global fisheries


In recent decades, invertebrate fisheries have expanded in catch and value worldwide. One increasingly harvested group is sea cucumbers (class Holothuroidea), which are highly valued in Asia and sold as trepang or beˆche-de-mer. We compiled global landings, economic data, and country-specific assessment and management reports to synthesize global trends in sea cucumber fisheries, evaluate potential drivers, and test for local and global serial exploitation patterns. Although some sea cucumber fisheries have existed for centuries, catch trends of most individual fisheries followed boom-and-bust patterns since the 1950s, declining nearly as quickly as they expanded. New fisheries expanded five to six times faster in 1990 compared to 1960 and at an increasing distance from Asia, encompassing a global fishery by the 1990s. Global sea cucumber production was correlated to the Japanese yen at a leading lag. Regional assessments revealed that population declines from overfishing occurred in 81% of sea cucumber fisheries, average harvested body size declined in 35%, harvesters moved from near- to off-shore regions in 51% and from high- to low-value species in 76%. Thirty-eight per cent of sea cucumber fisheries remained unregulated, and illegal catches were of concern in half. Our results suggest that development patterns of sea cucumber fisheries are largely predictable, often unsustainable and frequently too rapid for effective management responses. We discuss potential ecosystem and human community consequences and urge for better monitoring and reporting of catch and abundance, proper scientific stock assessment and consideration of international trade regulations to ensure long-term and sustainable harvesting of sea cucumbers worldwide.

74. Global Fishing Effort (1950–2010): Trends, Gaps, and Implications

J. Anticamara, R. Watson, A. Gelchu, D. Pauly, (2011). Fisheries Research 107, 131-136.

fishing effort, global fishing, database, FAO, EU, CCAMLR


According to a recent World Bank report, the intensification of global fishing effort and the ensuing depletion of marine fish stocks causes economic losses of 50 billion US dollars annually. Data deficiencies, however, currently hamper analysis of global fishing effort. We analyzed data from the Food and Agricultural Organization of the United Nations (FAO), the EUROPA fishing fleet registry, and peer-reviewed and other publications, to determine the global trends in fishing effort from 1950 to 2006. Our results show that global fishing effort, expressed as total engine power and the number of fishing days in a year (kilowatt · days), was roughly constant from 1950 to 1970, and then steadily increased up to the present. Europe dominated global fishing effort, followed by Asia. Projecting current trends suggests that Asia will soon surpass Europe. Trawlers contribute a major fraction of global fishing effort, as do vessels greater than 100 gross registered tons. Current estimates of global fishing effort, the number of vessels, and total vessel tonnage are, however, underestimates given the data gaps that we have identified. Our results are useful in the following ways: (1) they encourage researchers in academia and government to improve global fishing effort databases; (2) they allow deeper global analyses of the impact of fishing on marine ecosystems; (3) they induce caution in accepting current underestimates of economic losses of global fisheries; and (4) they reinforce calls for a reduction in global fishing effort.

75. High Value and Long Life—Double Jeopardy for Tunas and Billfishes

B. B. Collette, K. E. Carpenter, B. A. Polidoro, M. J. Juan-Jordá, A. Boustany, D. J. Die, C. Elfes, W. Fox, J. Graves, L. Harrison, R. McManus, C. V. Minte-Vera, R. Nelson, V. Restrepo, J. Schratwieser, C. Sun, A. Amorim, M. B. Peres, C. Canale, G. Cardenas, S. Chang, W. Chiang, N. Leite, H. Harwell, R. Lessa, F. L. Fredou, H. A. Oxenford, R. Serra, K. Shao, R. Sumaila, S. Wang, R. Watson, E. Yáñez, (2011). Science 333, 291-292.

tuna, billfish, threat, global


We present here the first standardized data on the global distribution, abundance, population trends, and impact of major threats for all known species of scombrids and billfishes [see supporting online material (SOM) for details].

76. Construction and First Applications of a Global Cost of Fishing Database

V. W. Y. Lam, U. R. Sumaila, A. Dyck, D. Pauly, R. Watson, (2011). ICES Journal of Marine Science: Journal du Conseil 68, 1996-2004.

catch, database, fisheries, fishing cost, fixed cost, fuel cost, global cost, sustainability, variable cost


The development of a new global database of fishing cost is described, and an overview of fishing cost patterns at national, regional, and global scales is provided. This fishing cost database provides economic information required for assessing the economics of fisheries at various scales. It covers variable and fixed costs of maritime countries, representing 98% of global landings in 2005. Linked to country and gear-type combinations, cost estimates can be mapped to a database of spatially allocated fisheries catches for future analysis in both spatial and temporal dimensions. The global average variable cost per tonne of catch in 2005 is estimated to range between US$639 and $1217, and the total cost per tonne from $763 to $1477, with mean values of $928 and $1120, respectively. The total global variable fishing cost is estimated to be in the range US$50–96 billion per year, with a mean of $73 billion per annum in 2005 dollar equivalents.

77. Protected and Threatened Components of Fish Biodiversity in the Mediterranean Sea.

D. Mouillot, C. Albouy, F. Guilhaumon, F. Ben Rais Lasram, M. Coll, V. DeVictor, E. Douzery, C. Meynard, D. Pauly, J. A. Tomasini, M. Troussellier, L. Velez, R. Watson, N. Mouquet, (2011). Current Biology 21, 1044-1050.

Mediterranean, biodiversity, hot spots


The Mediterranean Sea (0.82% of the global oceanic surface) holds 4%–18% of all known marine species (w17,000), with a high proportion of endemism [1, 2]. This exceptional biodiversity is under severe threats [1] but benefits from a system of 100 marine protected areas (MPAs). Surprisingly, the spatial congruence of fish biodiversity hot spots with this MPA system and the areas of high fishing pressure has not been assessed. Moreover, evolutionary and functional breadth of species assemblages [3] has been largely overlooked in marine systems. Here we adopted a multifaceted approach to biodiversity by considering the species richness of total, endemic, and threatened coastal fish assemblages as well as their functional and phylogenetic diversity. We show that these fish biodiversity components are spatially mismatched. The MPA system covers a small surface of the Mediterranean (0.4%) and is spatially congruent with the hot spots of all taxonomic components of fish diversity. However, it misses hot spots of functional and phylogenetic diversity. In addition, hot spots of endemic species richness and phylogenetic diversity are spatially congruent with hot spots of fishery impact. Our results highlight that future conservation strategies and assessment efficiency of current reserve systems will need to be revisited after deconstructing the different components of biodiversity.

78. Potential Impact of the Deepwater Horizon Oil Spill on Commercial Fisheries in the Gulf of Mexico

A. Scrub-McCrea, D. Zeller, U. R. Sumaila, W. Swartz, K. Kleisner, R. Watson, D. Pauly, (2011). Fisheries 36, 332-336.

oil spill, Gulf of Mexico, shrimp, closures,

Given the economic and social importance of fisheries in the Gulf of Mexico large marine ecosystem (LME), it is imperative to quantify the potential impacts of the Deepwater Horizon oil spill. To provide a preliminary perspective of the consequences of this disaster, spatial databases of annual reported commercial catch and landed value prior to the spill were investigated relative to the location of the fisheries closures during July 2010. Recent trends illustrated by this study suggest that more than 20% of the average annual U.S. commercial catch in the Gulf has been affected by postspill fisheries closures, indicating a potential minimum loss in annual landed value of US$247 million. Lucrative shrimp, blue crab, menhaden, and oyster fisheries may be at greatest risk of economic losses. Overall, it is evident that the oil spill has impacted a highly productive area of crucial economic significance within the Gulf of Mexico LME. This study draws attention to the need for ongoing and thorough investigations into the economic impacts of the oil spill on Gulf fisheries.

79. Modelling the Effects of Fishing on the Biomass of the World’s Oceans from 1950 to 2006

L. Tremblay-Boyer, D. Gascuel, R. Watson, V. Christensen, D. Pauly, (2011). Marine Ecology Progress Series 442, 169-185.

ecosystem modelling, biomass, fisheries, marine predators, trophic level, global


Marine fisheries have endured for centuries but the last 50 years have seen a drastic increase in their reach and intensity. We generate global estimates of biomass for marine ecosystems and evaluate the effects that fisheries have had on ocean biomass since the 1950s. A simple but versatile ecosystem model was used to represent ecosystems as a function of energy fluxes through trophic levels. Using primary production data, sea surface temperature, transfer efficiency, fisheries catch and trophic level of species, the model was applied on a half-degree spatial grid covering all oceans. Estimates of biomass by trophic levels were derived for marine ecosystems in an unexploited state, as well as for all decades since the 1950s. Trends in the decline of marine biomass from the unexploited state were analyzed with a special emphasis on predator species since they are highly vulnerable to overexploitation. This study highlights three main trends about the global effects of fishing: (1) predators are more affected than organisms at lower trophic levels; (2) declines in ecosystem biomass are stronger along coastlines than in the High Seas; (3) the extent of fishing and its impacts have expanded from north temperate to equatorial and southern waters in the last 50 years. More specfically, this modelling work shows that many oceans historically exploited by humans have seen a drastic decline in their predator biomass, with about half of the coastal areas of the North Atlantic and North Pacific showing a decline in predator biomass of more than 90%.

80. Aggregate Performance in Managing Marine Ecosystems of 53 Maritime Countries

J. Alder, S. Cullis-Suzuki, V. Karpouzi, K. Kaschner, S. Mondoux, W. Swartz, P. Trujillo, R. Watson, D. Pauly, (2010). Marine Policy 34, 468-476.

environmental indicator, fisheries, sustainability, mariculture, aquculture, marine mammal, seabird


Fourteen indicators of marine living resource management performance by country, reflecting both their intention to sustainably use the resource within their Exclusive Economic Zones and the effectiveness of their policies, were developed and the performances of 53 maritime countries were assessed. Four rankings of the countries, which jointly account for over 95 percent of the world’s marine fisheries landings, are presented here as aggregated scores of the fourteen indicators, using differentschemes for weighting the indicators, each reflective of the management preferences identified by the Global Environment Outlook 4 (GEO4) future development scenarios: Market First; Policy First; Security First; and Sustainability First. The resulting rankings differed substantially between the weighting schemes for the top performing countries but less so for the countries performing poorly.

81. The Trophic Fingerprint of Marine Fisheries

T. A. Branch, R. Watson, E. A. Fulton, S. Jennings, C. R. McGilliard, G. T. Pablico, D. Ricard, S. R. Tracey, (2010). Nature 468, 431-435.

Marine Trophic Index, trophic level, global marine, catch, ecosystems


Biodiversity indicators provide a vital window on the state of the planet, guiding policy development and management. The most widely adopted marine indicator is mean trophic level (MTL) from catches, intended to detect shifts from high-trophic-level predators to low-trophic-level invertebrates and plankton-feeders. This indicator underpins reported trends in human impacts, declining when predators collapse (“fishing down marine food webs”) and when low-trophic-level fisheries expand (“fishing through marine food webs”). The assumption is that catch MTL measures changes in ecosystem MTL and biodiversity. Here we combine model predictions with global assessments of MTL from catches, trawl surveys and fisheries stock assessments and find that catch MTL does not reliably predict changes in marine ecosystems. Instead, catch MTL trends often diverge from ecosystem MTL trends obtained from surveys and assessments. In contrast to previous findings of rapid declines in catch MTL, we observe recent increases in catch, survey and assessment MTL. However, catches from most trophic levels are rising, which can intensify fishery collapses even when MTL trends are stable or increasing. To detect fishing impacts on marine biodiversity, we recommend greater efforts to measure true abundance trends for marine species, especially those most vulnerable to fishing.

82. Effects of Climate‐Driven Primary Production Change on Marine Food Webs: Implications for Fisheries and Conservation

C. J. Brown, E. A. Fulton, A. J. Hobday, R. Matear, H. Possingham, C. Bulman, V. Christensen, R. Forrest, P. Gehrke, N. Gribble, S. Griffiths, S. H. Lozano-Montes, J. Martin, S. Metcalf, T. Okey, R. Watson, A. J. Richardson, (2010). Global Change Biology 16, 1194-1212.

climate change, marine, ecosystem modelling, Ecopath


Climate change is altering the rate and distribution of primary productivity in the world’s oceans. Predicting effects of changes in primary production on marine ecosystems and fisheries will assist the conservation of marine biodiversity and the sustainable management of fisheries. However, predicting the response of populations to primary production change is difficult, because inter-specific interactions can influence outcomes. We simulated the effects of change in primary production on Australian marine ecosystems across a wide latitudinal range using the marine food web model called ‘Ecosim’. We link models of primary production under climate change with Ecosim to predict changes in fishery catch, fishery value, abundance of animals of conservation interest, and indicators of community composition. Under a plausible climate change scenario, primary production will increase around Australia and generally this benefits fisheries catch and value and abundance of threatened marine animals such as turtles and sharks, but surprisingly, community composition was not strongly affected. However, ecological interactions reverse the expected responses for some populations, resulting in loss of value for some specific fisheries and localised declines for two threatened marine animal populations. We conclude that climate-driven primary production change should be considered by marine ecosystem managers and production increases can simultaneously benefit fisheries and conservation of biodiversity. Greater focus on incorporating biological interactions into management will significantly improve the ability to identify species and industries most at risk from climate change.

83. Global Biodiversity: Indicators of Recent Declines

S. H. M. Butchart, W. Walpole, B. Collen, A. van Strien, R. E. A. Almond, J. E. M. Baillie, B. Bomhard, C. Brown, J. Bruno, G. M. Carr, A. Chenery, J. Csirke, N. C. Davidson, M. Foster, A. Galli, J. N. Galloway, P. Genovesi, R. Gregory, M. Hockings, V. Kapos, J. Lamarque, F. Leverington, J. Loh, M. A. McGeoch, L. McRae, A. Minasyan, M. H. Morcillo, T. Oldfield, D. Pauly, S. Quader, C. Revenga, J. Sauer, J. P. W. Scharlemann, B. Skolnik, D. Spear, D. Stanwell-Smith, A. Symes, M. Tierney, T. R. Tyrrell, J. Vié, R. Watson, (2010). Science 328, 1164-1168.

global, biodiversity, marine


In 2002, world leaders committed through the Convention on Biological Diversity (CBD) to achieve a significant reduction in the rate of biodiversity loss by 2010. We compiled 31 indicators to report on progress toward this target. Most indicators of the state of biodiversity (covering species’ population trends, extinction risk, habitat extent/condition, and community composition) showed declines, with no significant recent reductions inrate, whereas indicators of pressures on biodiversity (including resource consumption, invasive alien species, nitrogen pollution, over-exploitation, and climate change impacts) showed increases. Despite some local successes and increasing responses (including extent and biodiversity coverage of protected areas, sustainable forest management, policy responses to invasive alien species, and biodiversity-related aid), the rate of biodiversity loss does not appear to be slowing.

84. Global Marine Primary Production Constrains Fisheries Catches

E. Chassot, S. Bonhommeau, N. K. Dulvy, F. Mélin, R. Watson, D. Gascuel, O. Le Pape, (2010). Ecology Letters 13, 495-505.

fisheries, bottom-up, Large Marine Ecosystem, LME, transfer efficiency


Primary production must constrain the amount of fish and invertebrates available to expanding fisheries; however the degree of limitation has only been demonstrated at regional scales to date. Here we show that phytoplanktonic primary production, estimated from an ocean-color satellite (SeaWiFS), is related to global fisheries catches at the scale of Large Marine Ecosystems, while accounting for temperature and ecological factors such as ecosystem size and type, species richness, animal body size, and the degree and nature of fisheries exploitation. Indeed we show that global fisheries catch since 1950 have been increasingly constrained by the amount of primary production. The primary production appropriated by current global fisheries is 17 to 112% higher than that appropriated by sustainable fisheries. Global primary production appears to be declining, in some part due to climate variability and change, with consequences for the near future fisheries catches.

85. Large‐Scale Redistribution of Maximum Fisheries Catch Potential in the Global Ocean under Climate Change

W. W. L. Cheung, V. W. Y. Lam, J. L. Sarmiento, K. Kearney, R. Watson, D. Zeller, D. Pauly, (2010). Global Change Biology 16, 24-35.

climate change, global, marine, fisheries, catch redistribution, potential


Previous projection of climate change impacts on global food supply focuses solely on production from terrestrial biomes, ignoring the large contribution of animal protein from marine capture fisheries. Here, we project changes in global catch potential for 1,066 species of exploited marine fish and invertebrates from 2005 to 2055 under climate change scenarios. We show that climate change may lead to large scale re-distribution of global catch potential, with an average of 30 – 70% increase in high latitude regions and a drop of up to 40% in the tropics. Moreover, maximum catch potential declines considerably in the southward margins of semi-enclosed seas while it increases in poleward tips of continental shelf margins. Such changes are most apparent in the Pacific Ocean. Among the 20 most important fishing Exclusive Economic Zone (EEZ) regions in terms of their total landings, EEZ regions with the highest increase in catch potential by 2055 include Norway, Greenland, US (Alaska) and Russia (Asia). On the contrary, EEZ regions with the biggest loss in maximum catch potential include Indonesia, USA (excluding Alaska and Hawaii), Chile, and China. Many highly impacted regions, particularly those in the tropics, are socio-economically vulnerable to these changes. 36 Thus, our results indicate the need to develop adaptation policy that could minimize climate change impacts through fisheries. The study also provides information which may be useful to evaluate fisheries management options under climate change.

86. The Contribution of Cephalopods to Global Marine Fisheries: Can We Have Our Squid and Eat Them Too?

M. E. Hunsicker, T. E. Essington, R. Watson, U. R. Sumaila, (2010). Fish and fisheries 11, 421-438.

cephalopod, invertebrates, global, marine, fisheries


Cephalopods are a key component of marine food webs, providing sustenance for myriad marine species. Cephalopods are also of increasing economic importance as evidenced by the rapid rise in their global landings over recent decades. If fisheries continue on this trajectory, conflicts may transpire among cephalopod and finfish fisheries, particularly in ecosystems where cephalopods are highly valuable both directly as a landed commodity and indirectly as prey for other harvested species. We provide the first measure of the ecosystem services that cephalopods contribute to fisheries in 28 marine ecosystems, both as a commodity and an ecological support service. We also evaluate how current demands on cephalopods compare to mid-20th century conditions. We find that cephalopod contributions to fisheries vary widely, but are substantial in many ecosystems. Commodity and supportive services provided by cephalopods contributed as much as 55% of fishery landings (tonnes) and 70% of landed values ($USD). The contribution of cephalopods as a commodity was generally greatest in the coastal ecosystems, whereas their contribution as a supportive service was highest in open ocean systems. Further, the commodity and supportive services provided by cephalopods to fisheries landings increased in most of the coastal ecosystems between the mid-20th century (years 1960–70) and contemporary periods (years 1990–2004), indicating the rising demand for cephalopods. Current demands have no historical precedent and ecosystems in which cephalopods are highly exploited as a targeted resource and as an ecological support service should be further evaluated to prevent the unsustainable development of marine fisheries within them.

87. Seamount Fisheries: Do They Have a Future?

T. N. J. Pitcher, M. R. Clark, T. Morato, R. Watson, (2010). Oceanography 23, 134.

seamount, fisheries, trawling


Today, seamount fish populations are in trouble following a 30-year history of overexploitation, depletion, and collapse, with untold consequences for global biodiversity and the complex, delicate, but poorly understood, open-ocean food webs. Seamount fishes are especially vulnerable to fishing because their “boomand-bust” life history characteristics can be exploited by heavy, high-technology fisheries. We estimate present global seamount catches to be about 3 million tonnes per annum and increasing—vastly in excess of estimated sustainable levels. Unfortunately, most seamount fisheries are unmanaged. In a few developed countries, precautionary management regimes have recently been introduced, including protection from bottom trawling. Small-scale artisanal fisheries using less-harmful fishing gear, patial closures, and low catch levels provide an attractive model for improved seamount fishery management that could foster the reconstruction of previously damaged seamount ecosystems. Such restored systems might one day support a substantial global sustainable fishery, although, like many other fisheries, the prognosis is poor.

88. Global Fishery Development Patterns Are Driven by Profit but Not Trophic Level

S. A. Sethi, T. A. Branch, R. Watson, (2010). Proceedings of the National Academy of Sciences 107, 12163-12167.

fishing, harvest, management, business, trophic level


Successful ocean management need consider not only fishing impacts, but drivers of harvest. Consolidating post-1950 global catch and economic data, we assess which attributes of fisheries are good indicators for fishery development. Surprisingly, year of development and economic value are not correlated with fishery trophic levels. Instead, patterns emerge of profit-driven fishing for attributes related to costs and revenues. Fisheries initially developed on shallow ranging species with large catch, high price, and big body size, and then expanded to less desirable species. Revenues expected from developed fisheries declined 95% during 1951-1999, and few high catch or valuable fishing opportunities remain. These results highlight the importance of economic attributes of species as leading indicators for harvest-related impacts in ocean ecosystems.

89. Food Security Implications of Global Marine Catch Losses Due to Overfishing

U. T. Srinivasan, W. W. L. Cheung, R. Watson, U. R. Sumaila, (2010). Journal of Bioeconomics 12, 183-200.

value loss, protein, nourishment, global


Excess fishing capacity and the growth in global demand for fishery products have made overfishing ubiquitous in the world’s oceans. Here we describe the potential catch losses due to unsustainable fishing in all countries’ exclusive economic zones (EEZs) and on the high seas over 1950-2004. To do so, we relied upon catch and price statistics from the Sea Around Us Project as well as an empirical relationship we derived from species stock assessments by the U.S. National Oceanic and Atmospheric Administration. In 2000 alone, estimated global catch losses amounted to 7-36% of the actual tonnage landed that year, resulting in a landed value loss of between $6.4 and 36 billion (in 2004 constant US$). From 1950-2004, 36-53% of commercial species in 55-66% of EEZs may have been overfished. Referring to a species-level database of intrinsic vulnerability (V) based on life-history traits, it appears that susceptible species were depleted quickly and serially, with the average V of potential catch losses declining at a similar rate to that of actual landings. The three continental regions to incur greatest losses by mass were Europe, North America, and Asia—forming a geographic progression in time. But low-income and small island nations, heavily dependent on marine resources for protein, were impacted most profoundly. Our analysis shows that without the inexorable march of overfishing, ~20 million people worldwide could have averted undernourishment in 2000. For the same year, total catch in the waters of low-income food deficit nations might have been up to 17% greater than the tonnage actually landed there. The situation may be worst for Africa, which in our analysis registered losses of about 9-49% of its actual catches by mass in year 2000, thus seriously threatening progress towards the UN Millennium Development Goals.

90. Subsidies to High Seas Bottom Trawl Fleets and the Sustainability of Deep-Sea Demersal Fish Stocks

U. R. Sumaila, A. Khan, L. Teh, R. Watson, P. Tyedmers, D. Pauly, (2010). Marine Policy 34, 495-497.

subsidies, high seas, deep-sea fisheries, sustainability


The life spans of demersal species of fishes occurring in deepwaters are much longer and their potential growth rates much lower than those of related shallow water species. As a result, deep-sea demersal fish species are more vulnerable to exploitation. This is because low growth rates relative to the available market discount rate for capital makes it desirable for fishing firms to mine, rather than sustainably exploit, these resources even in the absence of fisheries subsidies. However, it is common knowledge that governments around the world do provide subsidies to their fishing industries. The objective of this contribution is to estimate the global amount of subsidies paid to bottom trawl fleets operating in the highseas, i.e., outside of the Exclusive Economic Zones of maritime countries. Our study suggests that fisheries subsidies to these fleets stand at about US$ 152million per year, which constitutes 25%of the total landed value of the fleet. Economic data for bottom trawlers suggest that the profit achieved by this vessel group is normally not more than 10%of landed value. The implication of this finding is that without subsidies, the bulk of the world’s bottom trawl fleet operating in the high seas will be operating at a loss, and unable to fish, thereby reducing the current threat to deep-sea and high seas fish stocks.

91. A Bottom-up Re-Estimation of Global Fisheries Subsidies

U. R. Sumaila, A. S. Khan, A. J. Dyck, R. Watson, G. Munro, P. Tydemers, D. Pauly, (2010). Journal of Bioeconomics 12, 201-225.

subsidies, global fisheries, value


Using a recently developed database of fisheries subsidies for 148 maritime countries spanning 1989 to the present, total fisheries subsidies for the year 2003 is computed. A key feature of our estimation approach is that it explicitly deals with missing data from official sources, and includes estimates of subsidies to developing country fisheries. Our analysis suggests that global fisheries subsidies for 2003 are between US$ 25 and 29 billion, which is higher than an earlier World Bank estimate of between US$ 14–20 billion. This new estimate is lower than our 2000 global subsidies estimate of US$ 30–34 billion.We find that fuel subsidies compose about 15–30% of total global fishing subsidies, and that capacity enhancing subsidies sum to US$ 16 billion or about 60% of the total. These results imply that the global community is paying.

92. Sourcing Seafood for the Three Major Markets: The Eu, Japan and the USA

W. Swartz, U. Rashid Sumaila, R. Watson, D. Pauly, (2010). Marine Policy 34, 1366-1373.

seafood consumption; global fisheries; international trade; sustainability; Japan; USA; EU; markets


This paper describes the marine fish and invertebrate consumption in three of the world’s major seafood markets (the EU, Japan and the USA)using a series of global maps indicating the likely origin of the seafood consumed by each market. These maps display a high level of dependence by these markets on foreign sources as the serial depletion of local fisheries resources forced the fleets in search for new seafood supplies well beyond their domestic waters. The acquisition of foreign(and highseas) seafood by these markets is conducted through two channels: by dispatching distant water fishing fleets that directly exploit foreign stocks; and by importing catch landed elsewhere by local fleets. The results also demonstrate that each of the three major markets occupies a zone of influence within which it is dominant.

93. The Spatial Expansion and Ecological Footprint of Fisheries (1950 to Present)

W. Swartz, E. Sala, S. Tracey, R. Watson, D. Pauly, (2010). PloS one 5, e15143.

global fisheries, marine fisheries, primary production, sustainability, human footprint


Using estimates of the primary production required (PPR) to support fisheries catches (a measure of the footprint of fishing), we analyzed the geographical expansion of the global marine fisheries from 1950 to 2005. We used multiple threshold levels of PPR as percentage of local primary production to define ‘fisheries exploitation’ and applied them to the global dataset of spatially-explicit marine fisheries catches. This approach enabled us to assign exploitation status across a 0.5 latitude/longitude ocean grid system and trace the change in their status over the 56-year time period. This result highlights the global scale expansion in marine fisheries, from the coastal waters off North Atlantic and West Pacific to the waters in the Southern Hemisphere and into the high seas. The southward expansion of fisheries occurred at a rate of almost one degree latitude per year, with the greatest period of expansion occurring in the 1980s and early 1990s. By the mid 1990s, a third of the world’s ocean, and two-third of continental shelves, were exploited at a level where PPR of fisheries exceed 10% of PP, leaving only unproductive waters of high seas, and relatively inaccessible waters in the Arctic and Antarctic as the last remaining ‘frontiers.’ The growth in marine fisheries catches for more than half a century was only made possible through exploitation of new fishing grounds. Their rapidly diminishing number indicates a global limit to growth and highlights the urgent need for a transition to sustainable fishing through reduction of PPR.

94. Estimating the Worldwide Extent of Illegal Fishing

D. J. Agnew, J. Pearce, G. Pramod, T. Peatman, R. Watson, J. R. Beddington, T. J. Pitcher, (2009). PLoS One 4, e4570.

Illegal catch, IUU, global catch


Illegal and unreported fishing contributes to overexploitation of fish stocks and is a hindrance to the recovery of fish populations and ecosystems. This study is the first to undertake a world-wide analysis of illegal and unreported fishing. Reviewing the situation in 54 countries and on the high seas, we estimate that lower and upper estimates of the total value of current illegal and unreported fishing losses worldwide are between $10bn and $23.5bn annually, representing between 11 and 26 million tonnes. Our data are of sufficient resolution to detect regional differences in the level and trend of illegal fishing over the last 20 years, and we can report a significant correlation between governance and the level of illegal fishing. Developing countries are most at risk from illegal fishing, with total estimated catches in West Africa being 40% higher than reported catches. Such levels of exploitation severely hamper the sustainable management of marine ecosystems. Although there have been some successes in reducing the level of illegal fishing in some areas, these developments are relatively recent and follow growing international focus on the problem. This paper provides the baseline against which successful action to curb illegal fishing can be judged.

95. Projecting Global Marine Biodiversity Impacts under Climate Change Scenarios

W. W. L. Cheung, V. W. Y. Lam, J. L. Sarmiento, K. Kearney, R. Watson, D. Pauly, (2009). Fish and Fisheries 10, 235-251.

bioclimate envelope, climate change impact, global marine biodiversity, niche-based model, species turnover


Climate change can impact the pattern of marine biodiversity through changes in species’ distributions. However, global studies on climate change impacts on ocean biodiversity have not been performed so far. Our paper aims to investigate the global patterns of such impacts by projecting the distributional ranges of a sample of 1066 exploited marine fish and invertebrates for 2050 using a newly developed dynamic bioclimate envelope model. Our projections show that climate change may lead to numerous local extinction in the sub-polar regions, the tropics and semi-enclosed seas. Simultaneously, species invasion is projected to be most intense in the Arctic and the Southern Ocean. Together, they result in dramatic species turnovers of over 60% of the present biodiversity, implying ecological disturbances that potentially disrupt ecosystem services. Our projections can be viewed as a set of hypothesis for future analytical and empirical studies.

96. Database-Driven Models of the World’s Large Marine Ecosystems.

V. Christensen, C. Walters, R. Ahrens, J. Alder, J. Buszowski, L. B. Christensen, W. Cheung, J. Dunne, R. Froese, V. Karpouzi, K. Kaschner, K. Kearney, S. Lai, V. Lam, M. L. D. Palomares, A. Peters-Mason, C. Piroddi, J. L. Sarmiento, J. Steenbeek, R. Sumaila, R. Watson, D. Zeller, D. Pauly, (2009). Ecological Modelling 220, 1984-1996.

Ecopath, Ecosim, Ecosytem model, global model, LME, biomass


We present a newmethodology for database-driven ecosystem model generation and apply the methodology to the world’s 66 currently defined Large Marine Ecosystems. Themethod relies on a largenumber of spatial and temporal databases, including FishBase, SeaLifeBase, as well as several other databases developed notably as part of the Sea Around Us project. The models are formulated using the freely available Ecopath with Ecosim (EwE) modeling approach and software. We tune the models by fitting to available time series data, but recognize that the models represent only a first-generation of database-driven ecosystem models.We use the models to obtain a first estimate of fish biomass in the world’s LMEs. The biggest hurdles at present to further model development and validation are insufficient time series trend information, and data on spatial fishing effort.

97. Management Effectiveness of the World’s Marine Fisheries.

C. Mora, R. A. Myers, T. J. Pitcher, C. De Young, R. Sumaila, D. Zeller, R. Watson, F. J. Gaston, B. Worm, (2009). PLoS Biology 7, e1000131.

fisheries, global, management, sustainability


Ongoing declines in production of the world’s fisheries may have serious ecological and socioeconomic consequences. As a result, a number of international efforts have sought to improve management and prevent overexploitation, while helping to maintain biodiversity and a sustainable food supply. Although these initiatives have received broad acceptance, the extent to which corrective measures have been implemented and are effective remains largely unknown. We used a survey approach, validated with empirical data, and enquiries to over 13,000 fisheries experts to assess the current effectiveness of fisheries management regimes worldwide; for each of those regimes we also calculated the probable sustainability of reported catches to determine how management affects fisheries sustainability. Our survey shows that 7% of all coastal states undergo rigorous scientific assessment for the generation of management policies, 1.4% also have a participatory and transparent processes to convert scientific recommendations into policy and 0.95% also provide for robust mechanisms to ensure the compliance with regulations; none is also free of the effects of excess fishing capacity, subsidies or access to foreign fishing. A comparison of 2 fisheries management attributes with the sustainability of reported fisheries catches indicated that the conversion of scientific advice into policy, through a participatory and transparent process, is at the core of achieving fisheries sustainability, regardless of other attributes of the fisheries. Our results illustrate the great vulnerability of the world’s fisheries and the urgent need to meet wellidentified guidelines for sustainable management; they also provide a baseline against which future changes can be quantified.

98. Rebuilding Global Fisheries

B. Worm, R. Hilborn, J. K. Baum, T. A. Branch, J. S. Collie, C. Costello, M. J. Fogarty, E. A. Fulton, J. A. Hutchings, S. Jennings, O. P. Jensen, H. J. Lotze, P. M. Mace, T. A. McClanahan, C. Minto, S. R. Palumbi, A. M. Parma, D. Ricard, A. A. Rosenberg, R. Watson, D. Zeller, (2009). Science 325, 578-585.

fisheries, global, management, recovery, collapse, LME


After a long history of overexploitation, increasing efforts to restore marine ecosystems and rebuild fisheries are under way. Here, we analyze current trends from a fisheries and conservation perspective. In 5 of 10 well-studied ecosystems, the average exploitation rate has recently declined and is now at or below the rate predicted to achieve maximum sustainable yield for seven systems. Yet 63% of assessed fish stocks worldwide still require rebuilding, and even lower exploitation rates are needed to reverse the collapse of vulnerable species. Combined fisheries and conservation objectives can be achieved by merging diverse management actions, including catch restrictions, gear modification, and closed areas, depending on local context. Impacts of international fleets and the lack of alternatives to fishing complicate prospects for rebuilding fisheries in many poorer regions, highlighting the need for a global perspective on rebuilding marine resources.

99. Application of Macroecological Theory to Predict Effects of Climate Change on Global Fisheries Potential

W. W. L. Cheung, C. Close, V. Lam, R. Watson, D. Pauly, (2008). Marine Ecology Progress Series 365, 187-197.

global warming, climate change, global fisheries, macroecology, range


Global changes are shaping the life history and biogeography of marine species, which then affects their fisheries. Macroecology theories, which deal with large scale relationships between life history and biogeography, can be used to develop models to predict effects of global changes on marine species and hence on their fisheries. Firstly, based on theories of allometric scaling of metabolism and trophic energetic, we develop a theoretical model that relates maximum catch potential from a species with its trophic level, geographic range, mean primary production within the species’ range, and the fraction that is exploited at the geographic range. Secondly, using this theoretical model and data from 1,000 species of exploited marine fishes and invertebrates, we analyze the empirical relationship between species’ approximated maximum catch potential, their life history, and biogeography variables. The empirical model has high explanatory power and agrees with expectations from theory. Although problems in the original data and the imprecision of model parameters result in high variance between the empirical model and the data, predictions of relative changes in catch potential under climate change-induced changes in biogeography should be robust to uncertainties. In the future, this empirical model can be combined with bioclimate envelope model to predict the socio-economic impacts of climate change on marine fisheries, and this is illustrated here with an example pertaining to the small yellow croaker (Larimichthys polyactis, Sciaendae) from the East China Sea.

100. Diminishing Sea Ice

B. S. Halpern, C. V. Kappel, F. Micheli, K. A. Selkoe, C. D’Agrosa, J. Bruno, K. Casey, C. Ebert, H. Fox, Fujita.R., D. Heinemann, H. S. Lenihan, E. M. P. Madin, M. Perry, E. Selig, M. Spalding, R. Steneck, S. Walbridge, R. Watson, (2008). Science 321,

mapping, global marine, ecosystems, human threats, impacts.

101. A Global Map of Human Impact on Marine Ecosystems

B. S. Halpern, S. Walbridge, K. A. Selkoe, C. V. Kappel, F. Micheli, C. D’Agrosa, J. Bruno, K. Casey, C. Ebert, H. Fox, Fujita.R., D. Heinemann, H. S. Lenihan, E. M. P. Madin, M. Perry, E. Selig, M. Spalding, R. Steneck, R. Watson, (2008). Science 319, 948-952.

mapping, global marine, ecosystems, human threats, impacts


Conservation prioritization and management of the oceans require spatially explicit information on how all types of human activities impact marine ecosystems, but methods for globally assessing such impacts and mapping their distribution have not previously existed. Using a novel ecosystem-specific and scale-independent model, we synthesized 17 global datasets on anthropogenic threats to 20 marine ecosystems. Results show that every part of the oceans is affected by humans and that a large fraction (34%) is heavily impacted, including both nearshore and offshore ecosystems in nearly every corner of the world. Although human impact on marine ecosystems is pervasive, areas of little impact remain, particularly near the poles. Our quantitative approach provides important guidelines for where conservation action and threat mitigation are most needed for achieving global management and conservation goals.

102. Response to Comment on” a Global Map of Human Impact on Marine Ecosystems”

K. Selkoe, C. Kappel, B. Halpern, F. Micheli, C. D’Agrosa, J. Bruno, K. Casey, C. Ebert, H. Fox, R. Fujita, D. Heinemann, H. S. Lenihan, E. M. P. Madin, M. Perry, E. Selig, M. Spalding, R. Steneck, S. Walbridge, R. Watson, (2008). Science 321, 1446c.

global, human threats, impacts, marine, mapping.

103. The Debt of Nations and the Distribution of Ecological Impacts from Human Activities

U. T. Srinivasan, S. P. Carey, E. Hallstein, P. A. T. Higgins, A. C. Kerr, L. E. Koteen, A. B. Smith, R. Watson, J. Harte, R. B. Norgaard, (2008). Proceedings of the National Academy of Sciences 105, 1768-1773.

global impacts, debt, biological impacts, over-fishing

10.1073 pnas.0709562104,

As human impacts to the environment accelerate, disparities in the distribution of damages between rich and poor nations mount. Globally, environmental change is dramatically affecting the flow of ecosystem services, but the distribution of ecological damages and their driving forces have not been estimated previously. Here we give conservative, considerably partial estimates of the environmental costs of human activities over 1961-2000 in six major categories: climate change, stratospheric ozone depletion, agricultural intensification and expansion, deforestation, overfishing, and mangrove conversion. We calculate total costs ranging up to $47 trillion (net present value, 2005 international $), 92% of the year 2000 world GDP, purchasing power parity-adjusted. By quantitatively connecting the costs borne by rich, middle-income, and poor nations to activities by the three groups, we find striking imbalances. Up to 87% of the impacts of climate change and ozone depletion that are predicted to be borne by low-income nations have been directly driven by emissions from the middle- and high-income groups. Indeed, due to rich countries’ disproportionate emissions of greenhouse gases, poor nations may bear climate impacts 68% more than their year 2000 foreign debt. In a world increasingly connected ecologically and economically, our analysis is an early step towards reframing issues of development, globalization, and international debt in accordance with true ecological costs.

104. Fuel Price Increase, Subsidies, Overcapacity, and Resource Sustainability

U. R. Sumaila, L. Teh, R. Watson, P. Tyedmers, D. Pauly, (2008). ICES Journal of Marine Science: Journal du Conseil 65, 832-840.

subsidy, global fishing, fuel, price


Global fisheries are currently overcapitalized, resulting in overfishing in many of the world’s fisheries. Given that fuel constitutes a significant component of fishing costs, we expect recent increases in fuel prices to reduce overcapacity and overfishing. However, government fuel subsidies to the fishing sector reduce, if not completely negate, this positive aspect of increasing fuel costs. Here, we explore the theoretical basis for the expectation that the increasing fuel prices faced by fishing enterprises will reduce fishing pressure. Next, we estimate the amount of fuel subsidies to the fishing sector by governments globally to be in the range of US$4.2–8.5 billion per year. Hence, depending on how much of this subsidy existed before the recent fuel price increases, fishing enterprises, as a group, can absorb as much as this amount of increase in their fuel budget before any conservation benefits occur as a result of fuel price increases.

105. Intrinsic Vulnerability in the Global Fish Catch

W. W. L. Cheung, R. Watson, T. Morato, T. J. Pitcher, D. Pauly, (2007). Marine Ecology Progress Series 333, 1-12.

global catch, threat, vulnerability


We identify marine fishes most vulnerable to exploitation in different environments by comparing life history traits, represented by an index of intrinsic vulnerability. We then evaluate global changes in the mean vulnerability of catches comprising different species assemblages. Over the past 50 years, declines in mean vulnerability reveal increasing domination by low intrinsic vulnerability species. Coral reef fishes show the strongest decline, followed by seamount and estuarine assemblages: declines are most likely a result of rapid over-exploitation of highly vulnerable species. This is supported by a correlation between the spatial distributions of fishes listed under the IUCN Red List of Threatened Species and the rates of decline of mean vulnerability of catches. Fishes on the Red List are generally highly vulnerable. Deep water demersal and benthopelagic fishes, particularly those aggregated around seamounts, also have higher intrinsic vulnerability. These findings suggest that coral reef and seamount ecosystems potentially suffer high conservation risks from fishing. Moreover, concentrations of threatened fishes and strong declines in the mean vulnerability of catches in the Indo-Pacific and Caribbean highlight these regions for conservation attention.

106. Modelling and Mapping Resource Overlap between Seabirds and Fisheries on a Global Scale: A Preliminary Assessment

V. S. Karpouzi, R. Watson, D. Pauly, (2007). CM-International Council for the Exploration of the Sea 343, 87-99.

seabird – fisheries interactions, resource overlap, foraging distribution, seabird food consumption, seabird


Coexistence of foraging seabirds and operating fisheries may result in interactions such as competition for the same prey resources. We used GIS-based modelling at a scale of 30-min spatial cells to: (a) map the foraging distribution of seabirds; (b) predict their annual food consumption rates in a spatially-explicit manner; and (c) estimate a spatially-explicit seabird – fisheries overlap index. Information on population size, diet composition, and foraging attributes of 351 seabird species was compiled into a Microsoft Access database. Global annual food consumption by seabirds was estimated to be 96.4 million tonnes (95% CI: 78.0 to 114.7 million tonnes), compared to a total catch of nearly 120 million tonnes by all marine fisheries. Krill and cephalopods comprised over 58% of the overall food consumed and fishes most of the remainder. The families Procellariidae (albatrosses, petrels, shearwaters, etc.) and Spheniscidae (penguins) were responsible for over 54% of the overall food consumption. Seabird foraging distribution maps revealed that areas around New Zealand, the eastern Australian coast, and the sub-Antarctic islands had high species richness. However, temperate and polar regions supported high seabird densities, and most food extracted by seabirds originated there. Furthermore, maps of food consumption rates revealed that most food consumed by seabirds was extracted from offshore rather than nearshore waters, and from areas where seabird – fisheries overlap was low. The resource overlap maps identified ‘hotspots’ of highest potential for conflict between fisheries and seabirds. Thus, this study may provide useful insight when developing management approaches for designing offshore marine conservation areas.

107. The World Trade Organization and Global Fisheries Sustainability

U. R. Sumaila, A. Khan, R. Watson, G. Munro, D. Zeller, N. Baron, D. Pauly, (2007). Fisheries Research 88, 1-4.

subsidy, global fisheries, WTO


The World Trade Organization (WTO) is in a unique position to move global fisheries towards sustainability. The current Doha Trade Round of Negotiations offers an important opportunity to improve the future prospects of fish as a main source of animal protein for one fifth of the world’s population. Countries are wrestling with the issue of government fisheries subsidies, which keep too many commercial fishing boats in operation and drive the unsustainable exploitation of the world’s depleted fish populations. Removal of subsidies is challenging as it cannot be resolved without international cooperation because unilateral action has trade implications, and may not work because fish and fishing vessels do not respect national exclusive economic zones. This is why the WTO, which has in place mechanisms to enforce its agreements, is the only institution that can tackle the global problem of overfishing subsidies. We identify the opportunities and challenges that WTO members face, and provide suggestions on how to address these challenges.

108. A Global Ex-Vessel Fish Price Database: Construction and Applications

U. R. Sumaila, A. D. Marsden, R. Watson, D. Pauly, (2007). Journal of Bioeconomics 9, 39-51.

landed values, catches, price, mapping, temporal applications


We describe the first effort at creating a global ex-vessel fish price database, which is required for understanding the economic behaviour of participants in the world’s fisheries. We demonstrate potential applications of the database by linking it to a spatially defined catch database, which makes it possible to attach landed values to species in both time and space. This is the first database available publicly where interested members of the public, researchers and managers can easily find and access ex-vessel prices of the world’s major commercial fish species. Preliminary results indicate that the average real price of a number of species have declined between 1950 and 2002. The estimated landed value of fish globally, in year 2000 dollars, was about US$24 billion in 1950. It increased steadily to about US$90 billion in the early 1970s, reached a peak of US$100 billion at the end of the 1980s, and declined to about US$80 billion in 2000. The top 15 fishing countries cumulatively account for 79% of total real landed value, with Japan leading, even though the value of its landings has been declining.

109. Potential Costs and Benefits of Marine Reserves in the High Seas

U. R. Sumaila, D. Zeller, R. Watson, J. Alder, D. Pauly, (2007). Marine Ecology Progress Series 345, 305-310.

marine protected area, MPA, high seas, global, marine reserve


The issue of conservation and sustainable use of high seas resources is increasingly becoming significant, as is reflected in the number of planned international activities in ocean science and management, e.g. the United Nations General Assembly Working Group on marine biodiversity beyond national jurisdiction. Essentially, the increasing exploitation pressure on high and deep sea resources makes discussion of viable policy options for international waters an important topic. To our knowledge, this paper provides the first global, economically supported assessment of the impact on fisheries of potentially protecting a portion of the high seas in no-take marine protected areas. Such closures are likely to result in relatively little global annual profit loss. For example, closure of 20% of the high seas may lead to the loss of only 1.8% of the current global reported marine fisheries catch, and a decrease in profits to the high seas fleet of about US$270 million per year. Thus, at globally minimal costs, the international community could benefit substantially by securing insurance against extinctions and the loss of the spectacular marine diversity in the high and deep seas, while protecting many market and non-market values for the benefit of both current and future generations.

110. Mapping World-Wide Distributions of Marine Mammal Species Using a Relative Environmental Suitability (Res) Model

K. Kaschner, R. Watson, A. Trites, D. Pauly, (2006). Marine Ecology Progress Series 316, 285-310.

spatial modeling, habitat prediction, RES, habitat suitability,

We developed a large-scale habitat suitability modeling approach to map global distributions of 115 species of marine mammals. Predictions were generated by first assigning each species to broad-scale categories of habitat preferences with respect to depth, sea surface temperature and ice edge association based on synopses of published qualitative and quantitative habitat preference information. Using a global grid with 0.5 degree lat/long cell dimensions, we generated an index of the relative environmental suitability (RES) of each cell for a given species by relating quantified habitat preferences to locally averaged environmental conditions in a GIS modeling framework. RES predictions closely matched published maximum range extents for most species, suggesting that our model-based approach for identifying habitat represents a useful, more objective alternative to existing sketched distributional outlines. In addition, raster-based predictions provided more detailed information about heterogeneous patterns of potentially suitable habitat for species throughout their range. We validated RES model outputs for eleven species (northern fur seal, harbor porpoise, sperm whale, killer whale, hourglass dolphin, fin whale, humpback whale, blue whale and Antarctic minke whale) from a broad taxonomic and geographic range using at-sea sightings from dedicated surveys. Observed relative encounter rates and species-specific predicted environmental suitability were significantly and positively correlated for all, but one species. In comparison, observed encounter rates were correlated with < 1 % of 1000 simulated random data sets for all but two species. Mapping of suitable habitat for marine mammals using this environmental envelope model is helpful for evaluating current assumptions and knowledge about species? occurrences, especially for data-poor species. Moreover, RES modeling may help to focus research efforts on smaller geographic scales and usefully supplement other, statistical, habitat suitability models.

111. Fishing Down the Deep

T. Morato, R. Watson, T. J. Pitcher, D. Pauly, (2006). Fish and Fisheries 7, 24-34.

deep-sea, deep-water fisheries, threat, global trends, global


Global landings of demersal marine fishes are demonstrated to have shifted to deeper water species over the last 50 years. Our analysis suggests deep-water fish stocks may be at serious risk of depletion, as their life histories render them highly vulnerable to overfishing with little resilience to over-exploitation. Deep-sea fisheries are exploiting the last refuges for commercial fish species and should not be seen as a eplacement for declining resources in shallower waters. Instead, deep-water habitats are new candidates for conservation.

112. Fishing Gear Associated with Global Marine Catches: I Database Development.

R. Watson, C. Revenga, Y. Kura, (2006). Fisheries Research 79, 97-102.

fishing gear, database, catch, trawl, dredge, purse seine,

Fishing gears, instrumental to the fishing process, can exert direct impacts on marine communities and habitats. The database described here allows for the analysis of global fishing patterns, by associating all reported global catch with fishing gear types. The fine spatial detail of the Sea Around Us project?s catch database allows for the construction of maps showing subtle changes in the use of fishing gears annually since 1950. Maps included in this report chronicle the expansion of these and other gears in ways that will inform the current debate over their impacts, and provide critical information to shape policy development and management choices.

113. Fishing Gear Associated with Global Marine Catches. Ii. Trends in Trawling and Dredging

R. Watson, C. Revenga, Y. Kura, (2006). Fisheries Research 79, 103-111.

fishing gear, database, catch, trawl, dredge,

Fishing gears, instrumental to the fishing process, exert direct but often poorly documented impacts on marine communities and habitats. Analysis of global fishing patterns is now possible using a database that associates all global catch with fishing gear types. Maps prepared from this database are particularly useful to help assess the impact of fishing gears such as bottom trawls and dredges, which have been shown to have significant impacts on marine communities.

114. Impacts of Biodiversity Loss on Ocean Ecosystem Services

B. Worm, E. B. Barbier, N. Beaumont, J. E. Duffy, C. Folke, B. S. Halpern, J. B. C. Jackson, H. K. Lotze, F. Micheli, S. R. Palumbi, E. Sala, K. A. Selkoe, J. J. Stachowicz, R. Watson, (2006). Science 314, 787-790.

marine biodiversity, value, biodiversity, services, global


Human-dominated marine ecosystems are experiencing accelerating loss of populations and species, with largely unknown consequences. We analyzed local experiments, longterm regional time series, and global fisheries data to test how biodiversity loss affects marine ecosystem services across temporal and spatial scales. Overall, rates of resource collapse increased, and recovery potential, stability, and water quality decreased exponentially with declining diversity. Restoration of iodiversity, in contrast, increased productivity four-fold and decreased variability by 21%, on average. We conclude that marine biodiversity loss is increasingly impairing the ocean’s capacity to provide food, maintain water quality, and recover from perturbations. Yet, available data suggest that at this point these trends are still reversible.

115. Background and Interpretation of the ‘Marine Trophic Index’as a Measure of Biodiversity

D. Pauly, R. Watson, (2005). Philosophical Transactions of the Royal Society B: Biological Sciences 360, 415-423.

global, trophic level, biodiversity


Since the demonstration, in 1998, of the phenomenon now widely known as ?fishing down marine food webs?, and the publication of a critical rejoinder by FAO staff, a number of studies have been conducted in different parts of the world, based on more detailed data than the global FAO fisheries statistics originally used, which established the validity and ubiquity of this phenomenon. In this contribution, we briefly review how, rather than being an artifact of biased data, this phenomenon was in fact largely masked by such data, and is, indeed, more widespread than was initially anticipated. This is here made visible by comparing two global maps of trophic level (TL) changes from the early 1950s to the present. The first presents the 50 year difference of the grand mean TL values originally used to demonstrate the fishing down effect, while the second is based on means above a cutoff TL (here set at 3.25), thus eliminating the highly variable and abundant small pelagic fishes caught throughout the world. Based on this, we suggest that using mean TL as ?Marine Trophic Index? (MTI), as endorsed by the Convention on Biological Diversity always be done with an explicitly stated cutoff TL (i.e., cutMTI), chosen (as is the case with our proposed value of 3.25) such as to emphasize changes in the relative abundance of the more threatened, high-TL fishes. We also point out the need to improve the taxonomic resolution, completeness and accuracy of the national and international fisheries catch data series upon which the cutMTI is to be based.

116. Global Trends in World Fisheries: Impacts on Marine Ecosystems and Food Security

D. Pauly, R. Watson, J. Alder, (2005). Philosophical Transactions of the Royal Society B: Biological Sciences 360, 5-12.

global, fisheries, impacts, trends


This contribution, which reviews broad trends in the history of fisheries, argues that sustainability, however defined, rarely if ever occurred as a result of an explicit policy, but as result of our inability to access a major part of exploited stocks. With the development of industrial fishing, and the resulting invasion of the refuges previously provided by distance and depth, our interactions with fisheries resources have come to resemble the wars of extermination that newly arrived hunters conducted 40-50,00 years ago in Australia, and 11-12,000 years ago against large terrestrial mammals. These broad trends are documented here through maps of change in trophic levels and fish sizes, which displays characteristic declines, first in the nearshore waters of industrialized countries of the Northern Hemisphere, then spread offshore and to the Southern Hemisphere. This geographical extension met its natural limit in the late 1980s, when the catches from newly accessed stocks ceased to compensate for the collapsed in areas accessed earlier, hence leading to a gradual decline of global landing. These trends affect developing countries stronger than the developed world, which have been able to meet the shortfall by increasing imports from developing countries. These trends, however, along with the rapid growth of farming of carnivorous fish, which consumes other fish suited for human consumption, has led to serious food security issue. This gives urgency to the implementation of the remedies traditionally proposed to alleviate overfishing (reduction of overcapacity, enforcement of conservative TACs, etc.), and to the implementation of non-conventional approaches, notably the re-establishment of the refuges (a.k.a. marine reserve), which made possible the apparent sustainability of pre-industrial fisheries.

117. Fueling Global Fishing Fleets

P. H. Tyedmers, R. Watson, D. Pauly, (2005). AMBIO: a Journal of the Human Environment 34, 635-638.

fuel, energy, global fleets


Marine fisheries are the most diverse of the major global food-producing sectors, both in terms of their outputs (species landed1) and the technology used2. One characteristic, however, common to nearly all contemporary fisheries is their dependence on fossil fuels. While numerous analyses have been undertaken to quantify fuel inputs to a wide range of fisheries3,4,5,6,7,8, to date, no attempt has been made to determine the fossil fuel consumption of the world’s fishing fleets. Here, we calculate that for 2000, they burned approximately 56.7 billion litres of fuel in the process of landing just over 85 million tonnes of marine fish and invertebrates. Consequently, contemporary fisheries yield approximately 1.77 tonnes of fish per tonne of fuel burned. Moreover, total fuel inputs to the world’s fishing fleets account for about 1.4% of total global oil consumption.

118. Catching Some Needed Attention

R. Watson, J. Alder, A. Kitchingman, D. Pauly, (2005). Marine Policy 29, 281-284.

internet, catch, global


Globally, the most basic need of policy makers and fisheries managers is to know what catch was taken within their jurisdictional boundaries, and which countries took it. Surprisingly, for many countries this has not been possible. We introduce a web site devoted to making this and related information available to everyone via the internet.

119. Bioeconomic Modelling and Risk Assessment of Tiger Prawn (Penaeus Esculentus) Stock Enhancement in Exmouth Gulf, Australia

Y. Ye, N. Loneragan, D. Die, R. Watson, B. Harch, (2005). Fisheries research 73, 231-249.

bioeconomic modelling, risk assessment, stock enhancement, tiger prawn, Penaeus esculentus, Australia


A bioeconomic model was developed to evaluate the potential performance of brown tiger prawn stock enhancement in Exmouth Gulf, Australia. This paper presents the framework for the bioeconomic model and risk assessment for all components of a stock enhancement operation, i.e. hatchery, grow-out, releasing, population dynamics, fishery, and monitoring, for a commercial scale enhancement of about 100 metric tonnes, a 25% increase in average annual catch in Exmouth Gulf. The model incorporates uncertainty in estimates of parameters by using a distribution for the parameter over a certain range, based on experiments, published data, or similar studies. Monte Carlo simulation was then used to quantify the effects of these uncertainties on the model-output and on the economic potential of a particular production target. The model incorporates density-dependent effects in the nursery grounds of brown tiger prawns. The results predict that a release of 21 million 1 g prawns would produce an estimated enhanced prawn catch of about 100 t. This scale of enhancement has a 66.5% chance of making a profit. The largest contributor to the overall uncertainty of the enhanced prawn catch was the post-release mortality, followed by the densitydependent mortality caused by released prawns. These two mortality rates are most difficult to estimate in practice and are much under-researched in stock enhancement.

120. Mapping Global Fisheries: Sharpening Our Focus

R. Watson, A. Kitchingman, A. Gelchu, D. Pauly, (2004). Fish and Fisheries 5, 168-177.

fisheries landings, fisheries statistics, global fisheries, mapping


Mapping global landings is an important prerequisite for examining causal relationships between fishing and ecological change. Landing statistics, typically provided with poor spatial precision, can be disaggregated into a grid system of spatialcells (30 min x 30 min) using a rule-based approach and ancillary data about distributions of fished taxa and fishing access of reporting countries. Presentation of time series catch composition is then possible for many types of marine areas including biogeochemical provinces, large marine ecosystems and exclusive economic zones.

121. Hundred‐Year Decline of North Atlantic Predatory Fishes

V. Christensen, S. Guenette, J. J. Heymans, C. J. Walters, R. Watson, D. Zeller, D. Pauly, (2003). Fish and fisheries 4, 1-24.

Ecopath, saup, biomass decline, ecosystem modelling, Atlantic, predatory fish


We estimate the biomass of high-trophic level fishes in the North Atlantic at a spatial scale of 0.5º latitude by 0.5º longitude based on 23 spatialized ecosystem models, each constructed to represent a given year or short period from 1880 to 1998. We extract over 7 800 data points that describe the abundance of high-trophic level fishes as a function of year, primary production, depth, temperature, latitude, ice cover and catch composition. We then use a multiple linear regression to predict the spatial abundance for all North Atlantic spatial cells for 1900 and for each year from 1950 to 1999. The results indicate that the biomass of high-trophic level fishes has declined by two-thirds during the last 50-year period, and with a factor of nine over the century. Catches of high-trophic level fishes increased from 2.4 to 4.7 million tonnes annually in the late 1960s, and subsequently declined to below 2 million tonnes annually in the late 1990s. The fishing intensity for high-trophic level fishes tripled during the first half of the time period and remained high during the last half of the time period. Comparing the fishing intensity to similar measures from 35 assessments of high-trophic level fish populations from the North Atlantic, we conclude that the trends in the two data series are similar. Our results raise serious concern for the future of the North Atlantic as a diverse, healthy ecosystem; we may soon be left with only low-trophic level species in the sea.

122. The Future for Fisheries

D. Pauly, J. Alder, E. Bennett, V. Christensen, P. Tyedmers, R. Watson, (2003). Science 302, 1359-1361.

global, biodiversity, catch scenario, energy, fuel


Formal analyses of long- term global marine fisheries prospects have yet to be performed, as fisheries research focuses on local, species-specific management issues. Extrapolation of present trends implies expansion of bottom fisheries into deeper waters, serious impact on biodiversity, and declining global catches, the last possibly aggravated by fuel cost increases. Examination of four scenarios, covering various societal development choices suggests that the negative trends now besetting fisheries can be turned around, and their supporting ecosystems rebuilt, at least partly.

123. Towards Sustainability in World Fisheries

D. Pauly, V. Christensen, S. Guénette, T. J. Pitcher, U. R. Sumaila, C. J. Walters, R. Watson, D. Zeller, (2002). Nature 418, 689-695.

sustainability, fisheries, global


Fisheries have rarely been ‘sustainable’. Rather, fishing has induced serial depletions, long masked by improved technology, geographic expansion and exploitation of previously spurned species lower in the food web. With global catches declining since the late 1980s, continuation of present trends will lead to supply shortfall, for which aquaculture cannot be expected to compensate, and may well exacerbate. Reducing fishing capacity to appropriate levels will require strong reductions of subsidies. Zoning the oceans into unfished marine reserves and areas with limited levels of fishing effort would allow sustainable fisheries, based on resources embedded in functional, diverse ecosystems.

124. Estimating Illegal and Unreported Catches from Marine Ecosystems: A Basis for Change

T. J. Pitcher, R. Watson, R. Forrest, H. Þ. Valtýsson, S. Guénette, (2002). Fish and Fisheries 3, 317-339.

bycatch, IUU, illegal, catch


To evaluate the impacts of fishing on marine ecosystems, the total extraction of fish must be known. Putting a figure on total extraction entails the difficult task of estimating, in addition to reported landings, discards, illegal and unmandated catches. Unreported catches cast various types of shadow, which may be tracked and estimated quantitatively. Some shadows of unreported catches are reviewed, for example, an innovative, well-funded NGO publicizes illegal catch inthe Southern Ocean. For various reasons, official figures often have the implicit but unacceptable assumption that such categories are null.We present an estimation procedure based on adjustment factors taken from observer reports, correspondents and published information that track changes in a regulatory regime, and hence reflect incentives and disincentives to misreport. Monte Carlo simulations address uncertainty using multiple sources of information to provide upper and lower estimates. Once in place, this method provides preliminary estimates that may be refined without disruption. The method is demonstrated for fisheries in Iceland and Morocco. We use a ?by-species? approach for Icelandic cod and haddock, while the Moroccan catch is divided into demersal and pelagic categories. Results suggest that Icelandic cod catches may have been underestimated by between 1 and 14% at different times, and haddock by between 1 and 28%. Underestimation of Moroccan catches appears to have been as much as by 50%. These case studies show that it is possible to obtain estimates of misreporting, even when direct data are lacking. Our method encourages transparency because sources of information are presented so that uncertain values are easily identifed, offering a basis for comment, collaboration and refinement in estimating illegal and unreported fishing.

125. Systematic Distortions in World Fisheries Catch Trends

R. Watson, D. Pauly, (2001). Nature 414, 534-536.

landings, saup, China, global, bias


Over 75% of the world marine fisheries catch (over 80 million tonnes per year) is sold on international markets, in contrast to other food commodities (such as rice). At present, only one institution, the Food and Agriculture Organization of the United Nations (FAO) maintains global fisheries statistics. As an intergovernmental organization, however, FAO must generally rely on the statistics provided by member countries, even if it is doubtful that these correspond to reality. Here we show that misreporting by countries with large fisheries, combined with the large and widely fluctuating catch of species such as the Peruvian anchoveta, can cause globally spurious trends. Such trends influence unwise investment decisions by firms in the fishing sector and by banks, and prevent the effective management of international fisheries.

126. A Dynamic Mass-Balance Model for Marine Protected Areas

R. Watson, J. Alder, C. J. Walters, (2000.). Fish and Fisheries 1, 94-98.

marine protected areas, ecological models, Ecosim, Ecopath, marine reserves, MPA


A modified EcoSim model was used to investigate the impact of establishing marine protected areas (MPAs) in ecosystems defined by existing EcoPath models. The impacts of MPAs of various sizes was stimulated, and changes in biomass and catch over a range of years observed. The response of biomass and catch to MPA size depended on the time period examined. For some ecosystem groups, the initial was negative, but for all groups there were increases after 10 years. The greater the biomass exchange across the MPA boundary, the larger the MPA required to increase biomass levels. Within the range of exchange rates simulated, the maximum increase in catch and overall biomass levels were reached when 20% of the system was protected.

127. Marine Reserves and the Restoration of Fisheries and Marine Ecosystems in the South China Sea

T. J. Pitcher, R. Watson, N. Haggan, S. Guénette, R. Kennish, U. R. Sumaila, D. Cook, K. Wilson, A. Leung, (2000). Bulletin of Marine Science 66, 543-566.

MPA, China, Hong Kong, ecosystem


The South China Sea has been devastated by human fishing. This paper reports an initiative to restore Hong Kong’s marine ecosystems and fisheries through the deployment of artificial reefs (ARs) within marine protected areas (MPAs). Current catch and biomass data by species and fishery sector were available. Quasi-spatial ecosystem simulations, using a modified ECOSIM method, have been employed to forecast benefits from a successful MPA/ AR system. Results indicate that, despite increasing fishing power in the Hong Kong fleet, a 10-20% MPA/AR system could provide significant benefits within 10 yrs, and shifts to low-value pelagic fish could be reversed. Approximate scores, expressing how species benefit from protectedARs, suggest that results are not biased by changes in species composition. The design of MPA/ ARs balances island biogeographic theory with the needs of monitoring and compliance: minimizing perimeter losses and establishing colonizing corridors are trade-offs with statistical replication and monitoring, whereas sacrifice of some ARs to fishing encourages compliance and learning. In Hong Kong, workshops with fishing communities encouraged support. Bioeconomic analysis shows an MPA/ AR system increasing fishery value, but noncompliance rapidly erodes benefits. The benefits of this approach are assessed together with problems and difficulties that have arisen.

128. Uncertainty and Risk Associated with Optimised Fishing Patterns in a Tropical Penaeid Fishery

R. A. Watson, N. R. Sumner, (1999). Environment international 25, 735-744.

shrimp, prawn, model, optimisation, fisheries


Simulation was used to improve the management of prawn fisheries by indicating patterns of fishing effort which favour the harvest of more highly valued, larger animals. Attempts to use conventional local optimisation methods to find the optimum pattern ofweekly fishing efforts were ineffective. Simulating annealing, a global optimisation method, was used effectively to find fishing effort patterns which maximised catch values. Sensitivity of the maximum catch value to the parameters used to model fishing and biological behaviour was also investigated. The optimum catch value was not sensitive to variations in trawl net selectivity or catchability parameters, although the optimum fishing season to obtain these maxima altered. In contrast, changes to biological parameters had a notable effect on the maximum catch value, despite compensatory changes to the optimum weekly pattern of fishing effort. The risk associated with achieving management goals using a range of fishing strategies was also assessed when recruitment timing and growth rates were modelled as partly stochastic. With uncertainty in recruitment timing, it was found that the optimum fishing pattern did not change. Uncertainty in growth rates made fishing earlier the best strategy , and increased harvest values in 43% of simulations.

129. Performance of Transect and Point Count Underwater Visual Census Methods.

R. A. Watson, T. J. Quinn II, (1997). Ecological Modelling 104, 103-112.

visual census, transect, dive, census, model, simulation, coral reef,

A simulation approach was used to study bias and variability of density estimates of fish using the transect and point count underwater visual census methods. Three experiments were conducted to examine the effects of fish density, sampling effort, and the speed of fish in relation to the observer. Fish density and sampling effort did not significantly bias estimates of fish density using either census method, and variation was a function of the area sampled with both methods. The speed at which fish approached the diver caused appreciable bias with the transect method but not with the point count method, because of underlying assumptions about how the two methods were implemented. Performance of methods was quantified with the root mean squared error RMSE (combined measure of bias and variability) and was dependent on the ratio of sampling times per dive for each method. From assumed sampling times for the point count and transect methods, the point count method performed better than the transect method, but different results could be obtained under different sampling protocols. Nevertheless, the simulation approach offers an efficient means to evaluate sampling methods in conjunction with actual field experiments.

130. Identifying Tropical Penaeid Recruitment Patterns

R. Watson, C. T. Turnbull, K. J. Derbyshire, (1996). Marine and freshwater research 47, 77-85.

shrimp, recruitment, model, Australia


Knowledge of recruitment patterns is a requisite for modern fisheries management. These patterns can range in complexity from a single pulse of identically sized and aged prawns, which is often assumed in fisheries models, to continuous recruitment by prawns of several ages. Existing techniques used to identify recruitment patterns range from the ad hoc use of size limits to more complex methods that examine changes in length-frequency modes through time. A model that allowed variable growth of individuals was used to simulate monthly length-frequency fisheries data from a range of recruitment patterns of varying complexity. The effectiveness of a range of methods to identify these underlying recruitment patterns was examined. Length-frequency survey data from tropical penaeid fisheries for Penaeus esculentus, the brown tiger prawn, in two locations off north-eastern Australia (Torres Strait and Turtle Island Group) were also subjected to these methods. Methods that employed simple truncation by length successfully identified simple recruitment patterns but were not effective for multi-age recruitment patterns. Only the length-cohort and age-cohort methods could identify the presence of older recruits in multi-age patterns. All methods were sensitive to estimates of growth parameters, particularly the cohort-based methods. Results suggest that P. esculentus from the two fisheries examined had different recruitment patterns requiring different management approaches.

131. Bias Introduced by the Non-Random Movement of Fish in Visual Transect Surveys

R. Watson, G. M. Carlos, M. A. Samoilys, (1995). Ecological Modelling 77, 205-214.

transect, diver, survey, model, simulation, coral reef


Non-random movement has been observed in a number of reef fish species but its effect on visual counts has not been previously examined. A simulation program Reefex was used to examine the relationship between speed and approach angle of fish, and the degree of bias introduced in estimates of fish numbers from visual transects. Fish approaching at right-angles to the direction of the direction of the transect did not introduce a bias regardless of their speed. Fish approachIng against the diver introduced a positive bias which increased linearly with fish speed. Fish moving in direction of the diver created a negative bias, fish counts decreased linearly until fish speed matched that of diver. This minimum value reflected the immediately visible portion of the entire transect that could be surveyed instantaneously by the diver when the survey began. Changes in the effective area surveyed determine bias. An equation is presented which relates bias to fish speed, angle of approach, diver speed, transect length and visibility.

132. Evaluating Closed Season Options with Simulation for a Tropical Shrimp Fishery

R. A. Watson, V. R. Restrepo, (1995). ICES Marine Science Symposia 199, 391-398.

shrimp, model, optimisation, closures, prawn


We used simulation modelling to find seasonal closures which maximized either yield per recruit (Y/R) or relative value per recruit (V/R) for several tropical shrimp fisheries. Each case examined represented a choice of (1) a single versus a multicohort population, (2) the reduction of annual fishing effort levels through closures versus its redistribution to the fishing season, and (3) a range of fishing mortality levels. Under most conditions, seasonal closures which maximized Y/R also maximized V/R, though simulated gains in the latter were smaller. Timing of seasonal closures was more critical for fisheries of single-cohort populations than multicohort populations. Multicohort-based fisheries required shorter seasonal closures to maximize V/R than did those based on single-cohort populations. Assumptions about the disposition of fishing effort normally expended during the period of a seasonal closure greatly affected the best closure choice. Predicted best closures were of a longer duration when annual fishing effort was simply redistributed rather than reduced by closures. Greatest improvements in Y/R (30 to 40% ) were obtained for fisheries based on singlecohort populations when closure effort was redistributed. Predicted increases in Y/R for multicohort-based fisheries never exceeded 7%. The duration of best closures increased with increasing values of fishing mortality when the annual fishing effort was reduced by closures. This trend was reversed when annual fishing effort was conserved. As fishing mortality increased, potential gains in Y/R or V/R improved at the cost of equilibrium egg production.

133. Distribution of Seagrasses, and Their Fish and Penaeid Prawn Communities, in Cairns Harbour, a Tropical Estuary, Northern Queensland, Australia

R. G. Coles, W. J. L. Long, R. A. Watson, K. Derbyshire, (1993). Marine and Freshwater Research 44, 193-210.

seagrass, shrimp, habitat prediction, Australia


From aerial photography (July 1987) and diving surveys (February 1988), 876 ha of seagrasses (eight species) were mapped in Cairns Harbour, tropical north-eastern Queensland. Zosteru cupricorni was the most common seagrass species and had the greatest biomass at 79 9 m-2 dry weight of stems and leaves and 180 9 m-2 dry weight of roots and rhizomes. The maximum shoot density found was 4798 shoots m-2 of Hulodule pinijoliu, the second most common species. Seagrasses were found only between 0.5 and 5.0 m below mean sea level. Zosteru cupricorni was found at the shallowest depths, Hulodule pinifoliu at the deepest depths. Twenty species of penaeid prawns, nine of which are marketed commercially, were sampled from the seagrass beds. Abundances of prawns of commercial species were significantly greater on seagrass-covered substrata than on nonvegetated substrata. Overall, 5614 mostly small or juvenile fish, representing 134 taxa, were sampled from seagrasses in Cairns Harbour. The most numerous fish species were a goby, Yongeichthys criniger, and a pony fish, Leiognuthus splendens. Only 15 species were highly valued as recreational fish, and only 11 species were highly valued as commercial fish. Of the fish species, five (4%) were highly valued species of both groups. The density of fish on the seagrass beds was estimated to be 8809 fish ha-1.

134. Migration and Growth of Two Tropical Penaeid Shrimps within Torres Strait, Northern Australia

R. Watson, C. T. Turnbull, (1993). Fisheries Research 17, 353-368.

prawn, shrimp, Torres Strait, Australia, migration, growth, tiger prawn, endeavour prawn


In total 9259 brown tiger shrimp, Penaeus esculentus and 4705 endeavour shrimp, Metapenaeus endeavouri, were tagged and relaeased in Torres Strait. Within 4 months 8% of tagged P. esculentus and 2% of tagged M. endeavouri were recaptured by commercial shrimp trawlers. Return rates were three to six times greater for shrimp released within the commercial fishery to the east of Warrior Reefs, than those released to the west. Shrimp released to the west of the Warrior Reefs, which is permanently closed to fishing, averaged 7–10 weeks at liberty and travelled an average of 55 km before recapture, compared with a 3–4 week, 5-km journey for those released in the east. We established that the growth parameter K should be estimated separately for males and females of the two species. In contrast to P. esculentus, a common estimate of the growth parameter L∞ was indicated for both sexes of M. endeavouri. Although female M. endeavouri generally did not grow as large as female P. esculentus the males of the two species grew to a similar size. Net migration speeds, distance and direction were estimated. After correction for the spatial-temporal distribution of fishing effort there was still evidence of an eastward and southward movement of all tagged shrimp indicating that P. esculentus and M. endeavouri migrated from the unfished West into the East and contributed to commercial catches in the fishery.

135. Simulation Estimates of Annual Yield and Landed Value for Commercial Penaeid Prawns from a Tropical Seagrass Habitat, Northern Queensland, Australia

R. A. Watson, R. G. Coles, W. J. L. Long, (1993). Marine and Freshwater Research 44, 211-219.

shrimp, value, yield, seagrass, Australia, model, simulation, prawn


Concern over the loss of seagrass habitat has prompted examination of the value of the production of commercial prawns from such habitat. Cairns Harbour in tropical northern Queensland has 876 ha of mixed seagrasses, dominated by Zostera capricorni and Halodule pinijolia, that support a multispecies commercial penaeid prawn fishery offshore. Densities of juvenile commercial prawns estimated from seagrass surveys were used to project estimates of annual yield and landed value, using a deterministic simulation model employing lunar-period time steps. Estimates of the potential total annual yield from Cairns Harbour seagrasses for the three major commercial prawn species (Penaeus esculentus, P. semisulcatus and Metapenaeus endeavouri) were 178 t (range 81-316 t) year-1 with a landed value of .2 million (range $0.6 million to $2.2 million) year-l.

136. Closed Seasons and Tropical Penaeid Fisheries: A Simulation Including Fleet Dynamics and Uncertainty

R. A. Watson, D. J. Die, V. R. Restrepo, (1993). North American Journal of Fisheries Management 13, 326-336.

model, shrimp, simulation, optimisation, fleet, model, prawn, Australia, Torres Strait


Seasonal fishery closures are commonly used in fisheries management for various purposes, including limitation of effort, protection of spawners, and maximization of the yield or value that can be obtained from a cohort. The effectiveness of a proposed closure can be evaluated through yield-per-recruit analysis, which can be carried out analytically for some simple situations. For other fisheries, such as the penaeid shrimp fishery of Torres Strait, Australia, investigated here, the analyses are more complex because recruitment occurs in pulses throughout the year and the intensity of fishing is itself unevenly distributed in time, being patterned after these recruitment pulses. Furthermore, the imposition of closures of different durations has been documented to alter the pattern and intensity of fishing after the fishery reopens. In this study, a simulation approach is used to identify the timing and duration of closures that are likely to increase the yield or the value per recruit of the fishery. The simulation allows for changes in the distribution and magnitude of effort directly caused by the closures. All input parameters are assumed to be known precisely, except those controlling fishing and natural mortality, which are drawn from empirically derived ranges. The simulation results indicate that a 6-month closure starting in December or January could increase the value of the fishery by 5-10%, compared with a fishery with the same fishing pattern and no closure.

137. Dissipation of Spatial Closure Benefits as a Result of Non-Compliance

D. J. Die, R. A. Watson, (1992). Mathematics and computers in simulation 33, 451-456.

value, compliance, closure, model, simulation, Australia


Spatial closures are imposed by resource managers to prevent the operation of fishing fleets in certain areas of a stock’s distribution. In Queensland, east coast trawl closures are usually located in shallow waters to prevent fishing of prawns before they reach an optimum marketable size and migrate offshore. The success of such fishery controls should be measured by careful analysis of the benefits to fishery production, and the costs and practicality of enforcing the regulation. The potential of simulation models to investigate optimising fishery production by adjusting the starting date, length and extent of a fishing closure has been established in the Torres Straits tiger prawn fishery. It was predicted that by modifying the length and starting dates of seasonal closures that gains of up to 15% in yield-per-recruit and value-per-recruit could be achieved. By comparison, the best gains predicted by adjusting the boundaries of permanent spatial closures were less than 10% of value-per-recruit and negligible for yield-per-recruit. Enforcing fisheries regulations is expensive and especially difficult in the case of spatial closures. Most fishers are aware of this difficulty and some fish in closed areas because of the competitive advantage and the short-term benefits this practice provides. Therefore, it is important to evaluate the level of non-compliance which would dissipate the benefits gained from any closure regulations. In this paper the effect of cheating is evaluated by value-per-recruit and egg-per recruit analysis.

138. A Per-Recruit Simulation Model for Evaluating Spatial Closures in an Australian Penaeid Fishery

D. J. Die, R. A. Watson, (1992). Aquatic Living Resources 5, 145-153.

simulation, shrimp, prawn, Australia, closure, model


Spatial closures are commonly used by Australian fisheries managers to alter fishing patterns. To evaluate different fishing closures, however, fishery scientists have to understand and model the spatiotemporal interactions between fish stocks and fishing fleets. We develop a deterministic, stationary, per-recuit, age-structured simulation model to assess different spatial closure strategies, and use date from the Torres Strait tiger prawn fishery, Penaeus esculentus, as a working example. Our results show that selection of an optimum spatial closure largely depends on the relative importance given to changes of the different utility functions evaluated (yield, value, egg production). We show that, on average, with a spatial closure yield-per-recruit would decrease, but also show that value-per-recruit may increase 10% with the appropriate closure. Our results suggest that egg-per-recruit would always increase in the presence of a closure. By incorporating parameter uncertainty within the simulation model we predict the uncertainty associated with alternative closure strategies, and thus provide valuable information for the decision-making process.

139. Sledges for Daytime Sampling of Juvenile Penaeid Shrimp

C. T. Turnbull, R. A. Watson, (1992). Fisheries research 14, 31-40.

shrimp, prawn, sampling, juvenille, seagrass


Daytime catches ofjuvenile penaeid shrimp from two modified sledges (providing stimulation by water-jet or electric current) were compared with catches from a conventional sledge ( or beam trawl ) used at night. The results indicate that the daytime use of a water-jet sledge is a suitable alternative when night-time sampling is precluded. Mean catch rate of the Brown tiger prawn (Penaeus esculentus) in the daytime water-jet sledges was not significantly different from the night-time conventional sledges. but catches in the daytime electric trawls were significantly less. In contrast, the catches of the Endeavour shrimp (Metapenaeus endeavouri) and the Greentail shrimp (Metapenaeus bennettae), in both the daytime water-jet and daytime electric sledges, were significantly lower (approximately one-quarter) than in the night-time trawls. There was no significant difference between the length frequency distributions of P. esculentus, M. endeavouri or M. bennettae caught in the conventional night-time and in the daytime water-jet sledges.

140. An Approach to Modelling Crustacea in Egg-Bearing Fractions as a Function of Size and Season

V. R. Restrepo, R. A. Watson, (1991). Canadian Journal of Fisheries and Aquatic Sciences 48, 1431-1436.

shrimp, reproduction, model, prawn, crustacean,

We present an approach to the analysis of crustacean egg production ogives with emphasis on detecting seasonal trends. The relationship between the proportion of gravid females (by size) and season is a prerequisite to the estimation of egg production potentials of populations. The basic method consists of relating, for each sample, the proportion of berried females with their size through a three-parameter logistic function where the asymptote may be less than 1. We then provide guidance for detecting seasonal trends in the estimates of the parameters for the individual samples. This is accomplished by restricting the basic model such that some parameters are considered to be either fixed for all samples or as simple functions of time or environmental variables such as temperature. Parameter estimates are obtained via maximum likelihood methods, and comparisons between alternative models are presented graphically and using likelihood ratio tests. We illustrate the approach and its application with data for a tropical shrimp, Penaeus esculentus, from northern Australia. Nous presentons une approche pour I`analyse des enveloppes d`oeufs de crustaces qui insiste sur la detection des tendances saisonnieres. Le rapport entre la proportion de femelles gravides (par taille) et la saison est un prerequis pour I’evaluation du potentiel de production d’oeufs des populations. La methode de base est basee sur I’etablissement de rapports, pour chaque echantillon, entre la proportion des femelles porteuses d’oeufs avec leur taille grace a une fonction logistique a trois parametres dont I’asymptote peut etre inferieure a un. Nous don nons ensuite des conseils permettant de deceler les tendances saisonnieres dans les evaluations des parametres d’echantillons individuels. On y arrive en restreignant le modele de base de facon a ce que certains parametres soient consideres comme etant soit fixes pour tous les echantillons, ou soit de simples fonctions du temps de variables environnementales comme la temperature. Des evaluations de parametres sont obtenues par la methode de la vraisemblance maximum et des comparaisons entre plusieurs modeles possibles sont presentees graphiquement et utilisent des tests de rapports de ressemblance. Nous illustrons cette approche et son application avec des donnees obtenues pour une crevette tropicale, Penaeus esculentus, provenant du nord de l`Australie.

141. Spatial and Seasonal Variation in Demersal Trawl Fauna Associated with a Prawn Fishery on the Central Great Barrier Reef, Australia

R. Watson, M. L. C. Dredge, D. G. Mayer, (1990). Marine and Freshwater Research 41, 65-77.

bycatch, trawl, shrimp, Australia, coral reef, GBR


Regular monthly sampling at eight trawl sites in Great Barrier Reef waters identified variations in both species composition and the relative abundance of the more common species over a 2-year period. Faunal composition was affected more by the location of sample sites than by the time when samples were taken. Ordination analysis differentiated a ‘nearshore’ group of sites from a ‘midshelf’ and an ‘inter-reef’ group. The composition of ‘inter-reef’ fauna remained strikingly uniform below the 40 m depth contour regardless of proximity to coral reef formations. Classification of the samples also revealed weakly separated ‘wet’ and ‘dry’ season temporal groupings, with the former characterized by higher abundances of several ‘nearshore’ species.

142. Temporal and Spatial Zonation of the Demersal Trawl Fauna of the Central Great Barrier Reef

R. Watson, G. Goeden, (1989). Memoirs of the Queensland Museum 27, 611-620.

coral reef, GBR, MPA, Australia, bycatch


Management needs for zonation of the central Great Barrier Reef Marine Park by user activity prompted a study of the demersal trawl fauna from a range of sites. Cluster analysis revealed three distinct site assemblages: ‘coastal’ , ‘inshore’ , and ‘inter-reef’ , characterized by the conspicuous abundance of some species and the absence of other species. The location of these assemblages was related to water depth, sediment particle size composition and distance offshore but could not be explained by the distribution of fishing effort. Some sites, intermediate in location between these assemblages, were assigned to a ‘transitional’ assemblage in which sites changed affiliation temporally.

143. Velvet Prawns (Metapenaeopsis Spp) of Torres Strait, Queensland, Australia

R. A. Watson, J. Keating, (1989). Asian Fish. Sci 3, 45-56.

shrimp, prawn, Torres Strait, Australia, velvet prawn, biology, recruitment, reproduction,

The velvet shrimps, Metapenaeopsis rosea (Racek and Dall 1965) and M. palmensis (HasweIl1879), form a large part of penaeid shrimp catches from Torres Strait, Queensland, Australia, and are caught from 5 to 30 mm carapace length. Recruitment to the fishery occurs annually in January to March and abundance is greatest during May to October. Females are first found mature at 12 mm carapace length and spawning occurs year-round with peaks in April, July and October. Males begin to mature at 5 mm carapace length and all have joined petasmas by 9 mm carapace length. M. rosea males are heavier than their female counterparts at any given carapace length and no difference was found between male and female M. palmensis. Male and female M. rosea were heavier than those of M. palmensis at the same length. Until recently catches of these species were discarded but increasingly those of larger sizes are retained and marketed.

144. Growth, Mortality, Parasitism, and Potential Yields of Two Priacanthus Species in the South China Sea.

R. J. G. Lester, R. A. Watson, (1985). J. Fish Biol. 27, 307-318.

trawl, Hong Kong, China, growth, mortality, parasitology, yield, bigeye,

In the northern part of the South China Sea the ‘big-eye’ Priacanthus tayenus, spawned once a year in June, had von Bertalanffy growth parameters of k = 0.8 and Linf = 30 cm, and a mean total annual instantaneous mortality of Z = 2.0, calculated from adjusted catch curves and a mean length equation. The natural mortality rate M = 1.4, fishing mortality rate F = 0.6, and the exploitation rate (E) was 0.27. The maximum potential yield, calculated using Marten’s method, was 0.06 kg/recruit when F= 5.4. The fish were heavily parasitised by the protozoan Pleistophora priacanthicola. A second big-eye, P. macracanthus, spawned twice a year in May-June and September, had growth parameters of k=0.7 and Linf = 32, and population parameters of Z =2.0, F=0.7, and E=0.34. The maximum potential yield was 0.13 kg/recruit when F= 5.8. A marked reduction in fishing mortality occurred for both species between 1965 and 1966, coinciding with the onset of the Chinese Cultural Revolution. Our estimates of maximum potential yield correspond to fishing mortalities eight times estimated levels, though such heavy exploitation could risk recruitment failure.

145. The Life Cycle and Morphology of Tetracerasta Blepta, Gen. Nov. Sp. Nov. And Stegodexamene Callista, Sp. Nov. (Trematoda: Lepocreadiidae) from the Long Finned Eel, Anguilla Reinhardtii Steindachner.

R. A. Watson, (1984). Aust. J. Zool. 32, 177-204.

parasitology, Australia, trematode, lifecycle,

Two new lepocreadiid digeneans, Tetracerasta blepta, gen. sp. nov., and Stegodexamene callista, sp. nov., are described from the intestine of the long-finned freshwater eel, Anguilla reinhardtii, in the Brisbane River, Queensland, and from the Australian bass, Macquaria novemaculeata, in the Richmond River in New South Wales. Their life cycles have been elucidated and completed in the laboratory, by means of uninfected hosts. Both lepocreadiid species use the prosobranch gastropod, Posticobia brazieri, as their first intermediate host. Cercariae of T. blepta penetrate and encyst in the pharyngeal muscle, external muscle, and viscera of fishes in the genera Gobiomorphus and Hypseleotris, and in several species of tree frog tadpoles. The cercariae of S. callista are often eaten or accidentally inhaled by several small fishes, including Retropinna, Craterocephalus, Pseudomugil and Ambassis, and encyst in the pharyngeal muscle and viscera. All developmental stages are described and illustrated.

146. Metazoan Parasites of Pike, Esox Lucius Linnaeus, from Southern Indian Lake, Manitoba, Canada.

R. A. Watson, T. A. Dick, (1980). J. Fish Biol. 17, 225-261.

pike, freshwater, impacts, parasitology, Canada,

Metazoan parasites of pike Esox lucius from Southern Indian Lake, Manitoba were studied to reveal species composition, differences with host age, sex, and location and season of capture. Pike hosted 18 species of metazoan parasites, two of which, Tetraonchu, monenteron and Proteocephalus pingui.5, made up over 84% of metazoan parasite numbers. Some parasite species exhibited defInite patterns of abundance with host age and season which resulted from c, hanges in host diet and behaviour. No differences in parasite abundance existed between the host sexes. Ranking of parasite abundances was significantly different between two sampling sites only 2 km apart as a result of intermediate host distribution. Impoundment could greatly change pike parasite levels. An initial decrease in parasite numbers could be followed by a rapid increase.

147. The Metazoan Parasites of Whitefish Coregonus Clupeaformis and Cisco C. Artedii from Southern Indian Lake, Manitoba.

R. A. Watson, T. A. Dick, (1979). J. Fish Biol. 15, 579-587.

parasitology, freshwater, impacts, Canada,

Metazoan parasites of whitefish Coregonus clupeaformis and cisco C. artedii from Southern Indian Lake, Manitoba were studied to reveal: species composition, differences with host age, sex, and location and season of capture. Whitefish hosted 19 species, 18 of which were also in cisco with generally lower intensity levels. Parasites exhibited definite patterns of abundance with host age and season, the primary causes being dietary and behavioural. No differences in parasite abundance existed between host sexes. Ranking of cisco parasites was significantly different between two sampling sites while whitefish parasites did not differ. Whitefish and cisco from sites 40 miles (64 km) apart had significantly different abundances of Tetracoty/e intermedia but not Triaenophorus crassus. An increase in the abundance of copepod-vectored cestodes with a concomitant decrease in abundance of amphipodvectored parasites is predicted after flooding and diversion.

148. The Whitefish Pike Parasite Triaenophorus Crassus

T. A. Dick, R. A. Watson, (1977). Manitoba Nat. 17, 26-31.

parasitology, freshwater, tapeworm, Canada,

“Parasites”! This word conjures up two unpleasant images in the thoughts of man; the first, individuals who benefit at the expense of other members of society without themselves making a contribution. The second image is that of death caused by parasites such as malaria, of malnutrition caused by hookworms, and of damage to the productivity of crops and livestock. It is not surprising then that any host animal which has parasites is immediately condemned unfit to eat. But this is not always the case and certainly not so for the tapeworm Triaenophorus crassus in whitefish. The presence of T. crassus larvae (an immature stage) coiled in a cyst in the flesh of whitefish or ciscoes is objectionabte to the consumer housewife, who quickly reaches for unparasitized marine fishes. Wormy fish are condemned and the commercial fishermen receive little reward for their efforts to harvest these products of our great western lakes.

149. Commercial Prawn Catches in the Torres Strait

P. Channells, R. Watson, P. J. Blyth, (1988). Australian Fisheries, 23-26.

shrimp,prawn,Australia,Torres Strait,Fisheries,Fisheries management,

Commercial prawning is a major industry in Torres Strait attracting the attention of more than I 00 vessels in a combined total annual catch of about I 000 tonnes. However, the present fishery is based on a highly mobile fleet and any change in this feature of the industry could have a dramatic effect. For this reason the Torres Strait prawn fishery needs to be looked at in conjunction with the northern prawn fishery and east coast fisheries as management practices in any one of the three areas is likely to have some effect in the other fisheries. This article presents an overall view of the Torres Strait fishery based on large-scale data collected on the fishery over the past nine years. The data shows the fishery as a whole is not being overfished but, the absence of detailed fishing information on specific areas and changes in the species composition of the catch suggest that, much more investigation remains to be carried out.

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