Exploring the ubiquity and form of size based feeding in marine fishes

SWEETING CJ; REID WDK; GALVAN DE

Edimburgo - Escocia

Congreso; 6th World Fisheries Congress; 2012

World Council of Fisheries Societies y The Fisheries Society of the British Isles;

Body size is a fundamental determinant of the ecology of fishes. Many metabolic processes scale with body size, which also acts as a proxy for many life history characteristics. Body size also dictates trophic interactions through factors like gape limitation or maximum swimming speed and a size hierarchy of trophic interactions among species is often assumed in food-web models. However the extent to which trophic position may vary within a species in relation to size is less well characterized and generally restricted to species of specific commercial or ecological significance, a consecuence of the logistical constraints of tradictional stomach content analyses. An alternative approach to trophic analyses has been the use of nitrogen stable isotope to elucidate trophic position. This study compiles over 400 analyse from the literature describing size based trends in nitrogen stable isotope feeding in marine fish. Analyses suggest that size based feeding in fish is common, and almost ubiquitous once considerations of statistical power are accounted for. Feeding predominantly follows linear or log-linear relationships with body size, although numerous patterns exist and with very few exceptions these reprrsented increases in trophic position with increasing body size. Analyses support arguments for ecosystem structuring based on individual body size rather than species identity. They also inform on the likely trophic impacts of ongoing and widespread declines in mean body size of species as a consequence of fishing.