A report of diet of Antarctic toothfish (Dissostichus mawsoni) in the Ross Sea during the 2022/2023 austral summer

The Antarctic toothfish, Dissostichus mawsoni, is a large endemic fish species in the Southern Ocean, with a circumpolar distribution. This species is not only an important commercial fish, but also plays a key role in the Southern Ocean ecosystem, especially in the Ross Sea region. This work is a preliminary report on the feeding ecology of D. mawsoni based on the analysis on 70 stomachs sampled during 2022/2023 shelf survey in austral summer in the Ross Sea. Results showed that all individuals on the continental shelf had prey items inside stomachs, contrasting to over half empty stomachs found for individuals on the continental slope. Of the non-empty stomachs, fish was the predominant prey items in numbers, as well as in mass. On the continental shelf, Nototheniidae was the most important prey, with Trematomus spp. being the dominant species. On the continental slope, most of the non-empty stomachs were only found 1 prey taxa, with Macrourus caml being the most important prey in mass. These lines of evidence confirm spatial variability in the diet of D. mawsoni, possibly linking to the spatial availability of prey items in this region.