Feeding ecology of Engraulis japonicus based on stomach contents and stable isotope].

Jing Wang, Ri-Jin Jiang, Cui-Lin Hu, Zhe Li, Yi Xiao, Yong-Jiu Xu, Zhou-Ting He, Han-Xiang Xu

Ying yong sheng tai xue bao = The journal of applied ecology 2021 Jun

filter terms:

Engraulis japonicus, an important fishery resource, is a key species in ecosystem trophodynamics studies. In this study, we examined stomach content of E. japonicusby stable isotope analyses, with samples collected from the East China Sea in 2008-2009 and 2020. The aim of this study was to demonstrate their diet composition, diel and ontogenetic changes in feeding habits and trophic level. Results of the stomach content analysis showed that E. japonicus mainly fed on planktonic crustaceans and small fish. The main prey species were Euphausia pacifica [index of relative importance (IRI)=87.6%; frequency(F)=57.6%], Paracalanus parvus (IRI=3.2%, F=15.3%), and Themisto gracilipes (IRI=2.1%, F=13.1%). Results of the stable isotope analysis showed that Copepoda were the main food source of E. japonicus, followed by Euphausiacea, and the contribution rate of Amphipoda was the least, which was less than 1%. There was significant diel change in diet composition. Feeding intensity was higher in the daytime than at night, with the highest in the dusk and the lowest at midnight. Ontogenetic change in feeding habit occurred when fork length reached 90 mm, over which the fish fed both zooplankton and small fishes. The δ13C of E. japonicus was between -21.66‰ and -18.14‰, with an average of (-19.92±0.86)‰. The δ15N of E. japonicus ranged from 4.07‰ to 10.78‰, with an average of (8.14±2.48)‰. Both δ13C and δ15N values were positively correlated with fork length. Trophic level of the fish was 3.4 with stomach content analysis and 2.7 with stable isotope analysis. The results would provide important reference for understanding nutritional status of pelagic small fish, and offer some basic data to establish ecopath model.

Citation

Jing Wang, Ri-Jin Jiang, Cui-Lin Hu, Zhe Li, Yi Xiao, Yong-Jiu Xu, Zhou-Ting He, Han-Xiang Xu. Feeding ecology of Engraulis japonicus based on stomach contents and stable isotope]. Ying yong sheng tai xue bao = The journal of applied ecology. 2021 Jun;32(6):2035-2044