Diet composition and feeding strategy of Antarctic toothfish, Dissostichus mawsoni in Areas 48 and 88

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 area 48 (subarea 48.6) and 88 (subarea 88.1, 88.2, 88.3) as a part of Korean research plan for the exploratory longline fishery for Dissostichus spp. during 2025 season. Fish samples consisting of totally 527 (subarea 48.6: 280, subarea 88.1: 116, subarea 88.2: 50, subarea 88.3: 81) D. mawsoni were collected at various depths in each subarea (subarea 48.6: 768-2,150 m, subarea 88.1: 609-2,120 m, subarea 88.2: 727-870 m, subarea 88.3: 707-1,787 m)  by bottom longlines (trotline) using baited hooks with humboldt squid (Dosidicus gigas) and Pacific herring (Clupea pallasii) by Sunstar (subarea 48.6), Sein Master, Southern Park (subarea 88.1), King Star (subarea 88.2), and Green Star (subarea 88.3) fishing vessel in the area 48 and 88 from December 2024 to May 2025 (subarea 48.6: February-May 2025, subarea 88.1: December 2024, subarea 88.2: December 2024, subarea 88.3: February-March 2025). The diet composition and feeding strategy of D. mawsoni were studied using 280 specimens (from 63 to 182 cm in total length) in the subarea 48.6. D. mawsoni is a carnivore and piscivorous fish that mainly consumed fishes (mainly Channichthyidae and Macrouridae). The graphical method for feeding strategy revealed that D. mawsoni is an opportunistic and specialized predator on fishes (mainly Channichthyidae and Macrouridae) and showed narrow niche width. Calculated trophic level was 4.25 for D. mawsoni. The diet composition and feeding strategy of D. mawsoni were studied using 116 specimens (from 68 to 179 cm in total length) in the subarea 88.1. D. mawsoni is a carnivore and piscivorous fish that mainly consumed fishes (mainly Macrouridae). The graphical method for feeding strategy revealed that D. mawsoni is an opportunistic and specialized predator on fishes (mainly Macrouridae) and showed narrow niche width. Calculated trophic level was 4.25 for D. mawsoni. The diet composition and feeding strategy of D. mawsoni were studied using 50 specimens (from 25 to 160 cm in total length) in the subarea 88.2. D. mawsoni is a carnivore and piscivorous fish that mainly consumed fishes (mainly Nototheniidae). The graphical method for feeding strategy revealed that D. mawsoni is an opportunistic and specialized predator on fishes (mainly Nototheniidae) and showed narrow niche width. Calculated trophic level was 4.25 for D. mawsoni. The diet composition and feeding strategy of D. mawsoni were studied using 81 specimens (from 64 to 169 cm in total length) in the subarea 88.3. D. mawsoni is a carnivore and piscivorous fish that mainly consumed fishes (mainly Channichthyidae). The graphical method for feeding strategy revealed that D. mawsoni is an opportunistic and specialized predator on fishes (mainly Channichthyidae and Macrouridae) and showed narrow niche width. Calculated trophic level was 4.26 for D. mawsoni.