Molecular diet analysis of Antarctic toothfish (Dissostichus mawsoni) collected from Subarea 88.1

The diet of Antarctic toothfish, Dissostichus mawsoni, collected from the 88.1 research subarea was analyzed by metabarcoding their stomach contents. As a result of metabarcoding analyzes of 436 stomach contents, which have been collected for three years (2018, 2019, and 2021), a total of 184 haplotypes and 38 species were obtained. As shown in previous studies, the main diet of D. mawsoni was fish species and relatively much lower proportions of cephalopods and crustaceans. Among them, both Macrourus caml and Cryodraco antarcticus were the two most abundant prey species, ranging from 25.41 % to 83.96 % with 64.43 % on average, supporting their importance as a diet of D. mawsoni in the 88.1 subarea. In the previous study, Chionobathyscus dewitti, Macrourus caml, and Macrourus whitsoni were the most dominant prey items in 88.3 and 58.4 subarea. Clustering analysis showed that prey compositions clearly reflected geographical distance, indicating that metabarcoding analysis of D. mawsoni stomach contents would be one of the efficient methods to monitor ecosystem sustainability in each research area. However, in addition to the geographical distance, the water depth where the fish were collected may also be one of the critical factors for the difference in the prey compositions. Long-term surveys should be conducted for statistical significance.