Publication Abstract

Long term changes in the trophic levelof western Mediterranean fishery and aquaculture landings.

J.K. Pinnegar, N.V.C. Polunin and F. Badalamenti

We explored changes in western Mediterranean fishery and aquaculturelandings using trophic level (TL) estimates derived from nitrogen stable isotope analysiscombined with geographically detailed fishery data collated by the General FisheriesCouncil for the Mediterranean (GFCM). Our analyses confirmed earlier suggestions thatthere has been a significant decline in the mean trophic level of Mediterranean landings(by -0.15 TL over 26 years). However, this decline is suggested to be almost entirely aresult of increased landings of bivalve molluscs from mariculture and not due to changesin landings from capture fisheries. The mean trophic level of finfish landings has notchanged significantly since 1973, although both fish and total landings have becomesignificantly more diverse. Inspection of small pelagic fish landings revealed a markeddecrease in the contribution played by anchovy and replacement of this species by sardine.Since 1981, cage culture of high trophic level species such as sea bass (Dicentrarchuslabrax) and seabream (Sparus aurata) has become increasingly important, suchthat when clupeoid landings were excluded from the analyses, the mean trophic level offinfish landings was actually demonstrated to have increased over the past 26 years.

Reference:

J.K. Pinnegar, N.V.C. Polunin and F. Badalamenti (2003) Long term changes in the trophiclevel of western Mediterranean fishery and aquaculture landings.Canadian Journal ofFisheries and Aquatic Sciences 60(2): 222-265