Difference in diet of Antarctic Toothfish (Dissostichus mawsoni) Between Area 88 and Subarea 58.4 of CCAMLR revealed by metabarcoding Analysis

The Antarctic toothfish (Dissostichus mawsoni) is an apex predator in the Southern Ocean ecosystem, and studying its diet can provide important insights into the food web structure of its habitat. This study aimed to investigate geographical differences in the dietary composition of D. mawsoni between CCAMLR Area 88 and Subarea 58.4, and their relationship with various environmental factors, particularly depth and geographical location. We summarize the metabarcoding analysis of a total of 2,192 toothfish stomach samples collected from various research blocks between 2017 and 2023. Consistent with previous studies, D. mawsoni predominantly preys on fish species, and fish prey composition showed clear geographical differences. Species from the genus Macrourus dominated both slope and shelf areas, although regional differences were observed, particularly in Subareas 88.1 and 88.3, where mollusks were more prevalent. Statistical analyses, including Principal Coordinates Analysis (PCoA) and Distance-based Redundancy Analysis (dbRDA), highlighted the importance of depth in shaping prey composition, with slope regions displaying more homogeneous prey communities. In contrast, shelf regions showed greater variability in prey composition, presumably due to more diverse environmental conditions. These findings underscore the ecological significance of geographical factors in influencing the feeding ecology of D. mawsoni, with implications for the sustainable management of this commercially important species. Future research should further explore the effects of climate change and fishing activities on the Antarctic food web and D. mawsoni populations.