长江口近海小黄鱼食性及营养级分析

根据2003年3~12月东海区渔业资源监测调查的渔获样品,对小黄鱼胃含物进行分析。结果表明:小黄鱼食物组成以甲壳类为主(IRI=8583.10),重量所占比例为43.37%,尾数所占比例为79.66%,出现率为69.77%,其次为鱼类(IRI=1554.87),重量所占比例为55.26%,尾数所占比例为13.91%,出现率为22.48%;优势种类为糠虾、磷虾、七星底灯鱼、脊腹褐虾和鹰爪虾等。摄食强度存在季节变化,空胃率春季最高,达78.50%,其余依次为冬季(58.70%)、秋季(42.50%)和夏季(33.33%)。食物组成也存在季节变化,根据出现率,各个季节均主要摄食甲壳类;根据重量百分比,春季以甲壳类为主食,其余季节均以鱼类为主食。根据小黄鱼摄食饵料的类群组成变化,长江口近海小黄鱼的营养级为2.72级,属于第三营养级中的低级肉食性动物。

Study on feeding habit and trophic level of redlip croaker in Changjiang esturary

Stomach contents of redlip croaker(Larimichthys polyactis) were collected in Changjiang esturary from Mar.to Dec.in 2003.The diet composition of redlip croaker were analysed.The result showed that crustaceans was the dominant in the whole composition,with IRI 8 583.10,component weight in 43.37% of the studied redlip croakers,accounts for 79.66% of component individuals and 69.77% for frequency of occurrence.Secondly,fish component weight in 55.26% of the studied redlip croakers,accounts for 13.91% of component individuals and 22.48% of occurring with IRI 1 554.87.The dominant species were Mysidacea sp.,Euphausia sp.,Benthosema pterotum,Crangon affinis and Trachypenaeus curvirostris.The feeding intensity was showed difference among seasons,the highest percentage of empty stomach was in spring(78.50%),and others successively were in winter(58.70%),autumn(42.50%) and summer(33.33%);The major diet composition was also showed difference among seasons,the main food item was crustaceans with the highest occurring of the total food in all seasons,but with the highest weight percentage of the total food only in spring,fish was the highest weight percentage in others seasons.The average trophic level of redlip croaker was 2.72,which is in the third nutrition layer(lower carnivores).