Publication Abstract

Using size-based indicators to evaluate the ecosystem effects of fishing

Y.J.Shin, M.J. Rochet, S. Jennings, J. Field and H.Gislason

Fish size is central to key ecological and biological processes and may reflect (1) within-population changes or (2) genetic changes in body size and life history, (3) predator-prey relationships or (4) changes in competitive interactions. Moreover, fishing is considered to be size selective. Targeting large fish that are more valuable is known to modify the size structure and the functioning of fish assemblages, with consequences for productivity and resilience of fish stocks. Therefore, size-based indicators (SBIs) of fish assemblages may provide a relevant integration of the effects of fisheries on community ecology. The usefulness and relevance of SBIs to ecosystem-based management of fisheries is assessed through a review of empirical and modelling studies. First, theoretical and empirical bases are presented. Then, the measurability (sampling constraints, availability of size data, statistical biases), the sensitivity (quantification of fishing effects), the responsiveness (time of response), and the specificity (discrimination of fishing and environmental effects) of SBIs are systematically evaluated and documented. Finally, some pragmatic propositions are made to improve the use and interpretation of SBIs in the perspective of an Ecosystem Approach to Fisheries.

Reference:

Y.J. Shin, M.J. Rochet, S.Jennings, J. Field and H. Gislason (2005). Using size-based indicators to evaluate the ecosystem effects of fishing. ICES Journal of Marine Science, 62(3): 384-396.