The diet of Antarctic toothfish (Dissostichus mawsoni) captured by bottom longlines on the Ross Sea continental shelf was examined during four consecutive summer research surveys (2012–2015) within the Ross Sea polynya. The surveys included three areas: south-west continental shelf (Core area), McMurdo Sound and Terra Nova Bay. Toothfish diet comprised mainly small notothens, especially Trematomus spp. (which accounted for 20–52% of total prey weight by area) and icefish (30–57% of total prey weight by area). Notothen prey were mainly Trematomus loennbergii, with Trematomus scotti regularly observed. The most important icefish prey were Chionodraco spp., of which Chionodraco hamatus was most frequently identified, and Neopagetopsis ionah. Dragonfish (Bathydraconidae) were rarely observed, except in 2012 when Gymnodraco acuticeps accounted for ~11% of prey weight. Antarctic silverfish (Pleuragramma antarcticum) were regularly observed but contributed little by weight (0.4–3.6% total prey weight by area). Invertebrates were a relatively small component of toothfish diet, with the prawn Notocrangon antarcticus and the amphipod Eusiris spp. found in ~3–24% and 0–9% of stomachs, respectively, but they were small and weighed little. Icefish (particularly Dacodraco hunteri) were more important than notothens in toothfish diet in Terra Nova Bay. The results indicate that D. mawsoni are predominantly benthic feeders, with no evidence of substantial feeding away from the seafloor in the days before they were caught. In contrast with previous McMurdo Sound diet studies, Antarctic silverfish were of relatively minor importance as a prey item for Antarctic toothfish in other areas of the Ross Sea shelf, which is consistent with a coastal and fast-ice distribution of silverfish and/or a seasonal change in the distribution of silverfish.

The diet of Dissostichus mawsoni captured by bottom longline in the Ross Sea region was examined during 2003, 2005 and 2010. The diet of sub-adult toothfish was similar to adult toothfish, comprising mainly benthic fishes and cephalopods. Sub-adult toothfish ate a greater variety of smaller prey than adults, including smaller fish and prawns. Grenadiers (Macrourus spp.) were the most important fish and overall prey species. On the continental slope, icefish (Channichthyidae) and eel cods (Muraenolepididae) were also important fish prey, while Psychroteuthis glacialis was the most important cephalopod prey. On oceanic features, toothfish fed mainly on Macrourus spp. but also fed on Antimora rostrata, cephalopods and the occasional mesopelagic to epipelagic fish. Diet varied significantly with toothfish size and location on northern parts of the Mawson and Iselin banks of the Ross Sea continental slope. There was no significant temporal change in diet composition.