The biomass of Antarctic toothfish (D. mawsoni) in CCAMLR subarea 48.4 is estimated from tagging returns to average 1109 tonnes since 2010, with a five-year (2015-2019) average biomass of 1187 tonnes. Applying the CCAMLR agreed precautionary assumption of average biomass across the time series and harvest rate of γ = 0.038, implies a 2019/20 yield of 45 tonnes using the 5-year average biomass.

Historically, a precautionary approach has been applied in treating the 48.4 Antarctic toothfish as a separate stock. Based on the biological characteristics of the catches in Subarea 48.4, and the surrounding regions, the Antarctic toothfish around the southern South Sandwich Islands are now hypothesised as being part of a much larger stock that extends south into Subarea 48.2, 48.6 and possibly 48.5. The current method of assessment, based on tag returns, consequently, is considered to provide an estimate of the local biomass.