Summer diet composition and feeding ecology of large yellow croaker (Larimichthys crocea) in Guanjing Yang

Abstract

The population of large yellow croaker(Larimichthys crocea) has declined since the 1970s.Despite the decline,little is known about the feeding behavior and diet of this species.Our objective was to document the dietary composition of large yellow croaker.We collected 579 specimens from the sea near Guanjing Yang,Fujian province during June 2010.We documented the stomach contents of each individual and calculated the occurrence frequency(F%),individual number percentage(N%),weight percent(W%),and an index of relative importance(IRI).In addition,we compared diet composition of the zooplankton and nektonic assemblages in the ambient water.We identified 32 species in the diet.The most abundant were decapoda,fish,euphausiacea,mysidacea,amphipoda,crabs,copepoda,and stomatopoda.Decapoda(%IRI=49.14%) and fish(%IRI=20.47%) were the most important prey groups in the diet.Euphausiacea(%IRI=18.31%) and Mysidacea(%IRI=2.34%) constituted the second most important prey groups.Leptochela gracilis(IRI=976.10,%IRI=35.38%) and Pseudeuphausia sinica(IRI=505.27,%IRI=18.31%) were the most important prey species.Our data suggest that the large yellow croaker is carnivorous and feeds primarily on decapods,fish,and macro zooplankton.The trophic level of the wild large yellow croaker is lower than nektonic-animal feeders but higher than planktonic-animal feeders.The dominant species of the zooplankton assemblage was copepoda,primarily Acartia pacifica(Y=0.14),Labidocera bipinnata(Y=0.09),and Calanus sinicus(Y=0.06).The percent mean abundance of Euphausiacea and Mysidacea was 0.83%.Fish,crabs,and decapods were the most abundant nektonic organisms.We hypothesize that the large yellow croaker exhibits selectivity for food,preferring small decapods,fish larvae,euphausiacea,and mysidacea to other groups.