T. J. Pitcher, R. Watson, (2000). “The Basis for Change 2: Estimating Total Fishery Extractions from Marine Ecosystems of the North Atlantic,” Fisheries Centre Research Reports No. 8 (Fisheries Centre, University of British Columbia, Vancouver, Canada

The reason for estimating total extractions of fish is to able to account for their impacts on marine ecosystems. Such an evaluation has not been attempted before, since ecosystem modelling techniques suitable for this purpose have only recently become available. Putting a figure on total extractions entails the difficult task of estimating, in addition to reported landings, discards, illegal, and unmandated catches, including disreported catches. These unreported extractions cast various types of shadows, many of which may be tracked and estimated quantitatively. Official figures often have an implicit assumption that such categories are zero, an unacceptable option for an ecosystem- based project. Some examples of adjustments for unrecorded catches are reported. We describe an innovative, well-funded NGO that tracks and publicizes illegal catch in the Southern Ocean and which may provide a model for other areas of the world such as the North Atlantic. We present an adjustment procedure based on a simple spreadsheet, divided into categories of unreported annual catch. Adjustment factors are based on reports from observers, confidential correspondents and on information published in a variety of sources. Over time the adjustment factors respond to changes in regulatory regime and hence the incentives and disincentives to mis-report. Once in place, this method provides preliminary estimates that may be refined without disruption. Preliminary estimates, set up as a ?straw man? for Atlantic Canada, suggest average figures since 1960 of around 30% for unreported extractions of cod and over 100% for herring. Although at first sight an adjustment procedure for illegal catch may appear controversial, we argue that such transparency is not only an essential part of a new fisheries regime that mimimizes deleterious impacts to marine ecosystems, but is also in conformity with the treatment of other kinds of fraud in contemporary society.

1198-6727, http://saup.fisheries.ubc.ca/report/method/pitcher04.pdf