한국 남해 연안 해역에서 출현하는 멸치의 섭이 특성

Abstract

The Japanese anchovy Engraulis japonicus is widespread in the western North Pacific and it is an important species to link between plankton to higher trophic levels in pelagic ecosystem. To understand the spatio-temporal and ontogenetic variation in anchovy prey items in the southern coastal waters of Korea, I analysed the stomach contents of anchovy and the structure of the zooplankton community at three study sites (Jindo, Yeosu and Tongyeong) from July, 2011 to February, 2012. The food compositions of anchovy could be distinguished from the areas, season and the size of anchovy. Diet similarity analysis indicated that Jindo and Yeosu (80%) were clustered together, another group was Tongyeong. The main prey items in Yeosu and Jindo were cyprii stage of barnacle (>35%) and copepod Calanus sinicus (>22%) in July. However, predominant prey items in Tongyeong were small copepod Paracalanus parvus s.l. (41%) and Corycaeus affinis (22%). During the same period, the dominant zooplankton were cladocera Evadne tergestina (39%) in Yeosu, small copepod Paracalanus parvus s.l. (28%) in Jindo and cladocera Evadne tergestina (14%) in Tongyeong, respectively. The dominant prey items were barnacle larvae and copepod in Summer, phytoplankton and Pseudodiaptomus marinus in Autumn and Paracalanus parvus s.l. and cold water copepod Centropages abdominalis in Winter. Anchovy choose the prey item Calanus sinicus (3%) rather than cladocera Evadne tergestina (39%) which was dominant in the catching site in Summer. Pseudodiaptomus marinus (0.5%) and Centropages abdominalis (0.9%) were chosen rather than Paracalanus parvus s.l. (30%, 21%) for anchovy in Autumn and Winter, respectively. The dominant prey groups with three size group of anchovy were small copepods in 3~4cm group, cyprii and decapods larvae in 6~7cm group, and large zooplankton such as amphipods, euphausiids, large copepods and fish larvae in 10~12cm group, respectively. These results suggested that the food selectivity of anchovy might depends on the hydrologic condition and plankton community structures. Anchovy generally fed on larger prey items due to the ability of visual recognition. Also, ontogenetic differences in diet related with morphological change and spawning period. These selectivity can be explained by optimum foraging theory, which demonstrated that larger fish tend to select larger prey items in order to gain a more energy.