Diet composition and feeding strategy of Antarctic toothfish, Dissostichus mawsoni in Subarea 88.1 for the exploratory longline fishery in 2021

The stocks of Antarctic toothfish, Dissostichus mawsoni were a relatively economically and ecologically important fishery resource in the waters of Antarctic. However, there is not enough data and information to assess the robust stocks and deliberate proper measurements for sustainable utilize, especially relate to diet and feeding strategy which may lead to think about ecosystem based stock assessments and fishery managements. Therefore, the Korean scientists analyze diet composition and feeding strategy of D. mawsoni in the research block 88 as a part of Korean research plan for the exploratory longline fishery for Dissostichus spp. during 2021 season. This study was carried out based on the results of stomach content identification of the D. mawsoni caught in the research block 88 in CCAMLR conversion area from December 2020 to January 2021. The diet composition and feeding strategy of D. mawsoni were studied using 548 specimens (54 to 183 cm in body length) in the research block 88, respectively. D. mawsoni is a carnivore and piscivorous fish that mainly consumed fishes. Macrourus caml, M. whitsoni, and M. spp. of Macrouridae was dominant taxa. Chionobathyscus dewitti of Channichthyidae were the second largest dietary component in the fish diet of D. mawsoni. Its diet also included small quantities of mollusks, crustaceans, stones, and cnidarians. In this study, fishes were the dominant prey item in all size classes (<100 cm, n=65; 100-120 cm, n=83; 120-140 cm, n=72; 140-160 cm, n=99; ≥160 cm, n=32). The graphical method for feeding strategy revealed that D. mawsoni is an opportunistic and specialized predator on fishes and showed narrow niche width.