1995年の瀬戸内海燧灘東部におけるカタクチイワシとマイワシの食性の比較

抄録

To examine the potential food competition between Japanese anchovy Engraulis japonicus (range in total length: 30–102mm) and Japanese sardine Sardinops melanostictus (23–116 mm), stomach contents and nitrogen stable isotope ratios were compared between the two species simultaneously caught by drag-net in eastern Hiuchi-nada, central Seto Inland Sea, Japan, from July to September 1995. The stomach content items of Japanese anchovy were very similar to those of Japanese sardine, and the dominant prey items in percentage of weight of the both species were Corycaeus affinis, Microsetella norvegica, Paracalanus parvus, cypris larva of Balanomorpha, Penilia avirostris and alima larva of Stomatopoda. Compositions of zooplankton prey items of the two species in the same day showed a greater similarity than for the same species in different sampling days. Moreover, the values of the stable isotope ratio were not different between the two species. The results suggest the feeding habits of Japanese anchovy and Japanese sardine were similar, and hence there is an interspecific food competition in the case of limited food availability.