R. Watson, S. Guenette, P. Fanning, T. J. Pitcher, (2000). “The Basis for Change: Part I . Reconstructing Fisheries Catch and Effort Data,” Fisheries Centre Research Reports No. 8 (Fisheries Centre, University of British Columbia, Vancouver, Canada

Rational examination of marine policy requires an analysis of changes in the abundance of species and marine community structure with respect to past policy decisions. Abundance estimates themselves rely heavily on catch and effort statistics. There are official statistics of fish landings for many fisheries of the world. Fishing effort data is generally less available. Unfortunately, for a variety of reasons, landings data do not always reflect actual catches well. For example, discarded catches are left out of official statistics, which developed primarily to demonstrate the value of commercial landings. Illegal or unmandated (not subject to regulated reporting requirements) catches are seldom documented except in candid stock assessment discussions of major species. Through an exhaustive compilation of existing data sources and with the assistance of expert local consultants and/or partnerships, we can develop databases that present a more complete and accurate picture of the catches of marine species, including those of limited commercial significance. The importance of this process is demonstrated by our example from the Canadian North Atlantic fisheries. In this case a partnership arrangement has allowed the inclusion of the discards of fishes, crustaceans and marine mammals based on observer data. An outline of the database required to include and document ‘adjustments’ to official statistics is presented. This work will be extended to the entire North Atlantic region and beyond.

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