The 2025 South Georgia Groundfish Survey took place over the South Georgia and Shag Rocks shelf on the FV Sil between the 25th January and 7th of February 2025. Seventy-eight 30-minute trawls were completed in depth zones 1 (100-200 m) and 2 (200-350 m) as part of the standard trawl survey. This included 18 at Shag Rocks, 13 in the NE, 10 in the SE, 14 in the SW and 23 in the NW of South Georgia. An additional 20 deeper trawls (350-720 m) were undertaken in the NW of South Georgia and at Shag Rocks.
Biomass of mackerel icefish, Champsocephalus gunnari, was estimated at 64,964 tonnes with a lower 1-sided 95% CI of 26,958 tonnes. Catches of mackerel icefish were highest in the NE and at Shag Rocks, with low catches in the NW region (which is usually the area of highest catches). Dietary analysis, based on 881 stomachs, showed krill to be the dominant prey (76 % by mass) at the time of the survey.
Catches of juvenile toothfish (Dissostichus eleginoides) in depth zones 1 and 2 were 1154 kg, with a further 1696 kg caught in the deeper trawls. Few toothfish were caught in Depth Zone 1. Two distinct cohorts (~40-44 cm; 48-55 cm) were caught in Depth Zone 2, with evidence of a third cohort (56-60 cm TL). Depth Zone 3 included larger fish, with a clear cohort of fish of 60-70 cm TL.
Catches and biomass estimates of South Georgia icefish, Pseudochaenichthys georgianus, and Scotia Sea icefish, Chaenocephalus aceratus, were higher than any previous survey, with catches of P. georgianus more than double the previous high. Twenty-one tonnes of grey rockcod, Lepidonotothen squamifrons, were caught in a single trawl at Shag Rocks and the total catch was higher than any previous survey. Excluding the 21 tonnes catch, the total catch was still higher than all but the 1987 survey (when 117 trawls were undertaken in depth strata up to 350m). A neuston (surface) net was trialled on the survey and proved straightforward to deploy and effective at catching fish larvae.