Spatial Allocation of Global Fisheries Landings Using Rule-Based Procedures

R. Watson, (2004). 381-390. Paper published in proceedings of the Second International Symposium on GIS/Spatial Analysis in Fishery and Aquatic Sciences, University of Sussex, Brighton, U.K., 3-6 September, 2002

Examination of the effects of fishing on marine ecosystems requires historical catch data on appropriate spatial scales. Most commercial fishing data are currently only available in the form of landings data that do not delineate the marine area from which the catch was extracted. Even when statistics are available by defined spatial areas rather than by port landings, such as the statistical areas used by the Food and Agriculture Organization (FAO) of the United Nations, these reporting areas are often much larger in extent than the areas defined as ecosystems by most current ecological models and are difficult to use without modification. A rule-based spatial allocation procedure was employed using a Microsoft Visual Basic application called ?SimMap? that has the ability to create and decompose ArcView shapefiles. An ESRI plug-in (Map Objects Lite) was used to provide the ability to show shapefiles created dynamically as a result of the catch allocation process. By creating Access databases describing the distribution of some 1 500 commercial fisheries taxa, as well as the plethora of fishing access arrangements nations have with other nations, we were able to create procedures for spatially allocating broader fisheries catch statistics into a global system of 30-minute latitude by 30-minute longitude spatial cells. This paper presents the FAO catch data allocated to our global system of spatial cells for the year 2000. This sample output is indicative of the results achievable through the SimMap program which has previously been used to demonstrate the impacts of fishing on the marine ecosystems of the North and South Atlantic, including biomass and trophic levels, to calculate direct overlaps of fisheries with populations of marine mammals, and to illustrate the spatial distributions of catch values and energy consumption by fishing fleets. Using the SimMap program, anomalies in official fisheries landings reported by countries to the FAO have been detected and have led to revised global statistics and historical trajectories.