Distribution and biology of grey notothen (Lepidonotothen squamifrons) around South Georgia and Shag Rocks (Southern Ocean) CCAMLR Subarea 48.3.

Lepidonotothen squamifrons (Family Nototheniidae) is a demersal Southern Ocean endemic fish. Historically a commercially targeted species and common as bycatch, changes to CCAMLR fisheries regulations in 1989 have meant it is now only caught in sub-area 48.3 during research surveys. Data collected during groundfish surveys at South Georgia and Shag Rocks from 1986 to 2012 were analysed to investigate distribution, size, maturity, and diet. Distribution was patchy with aggregations in specific ‘hotspots’ to the east of Shag Rocks and the west of South Georgia. Reliable biomass estimates were not possible due to this skewed distribution creating large confidence intervals, but length-frequency analysis showed recognisable cohort progression and a trend of increasing size over time indicating a potential recovery of the stock. Mean length at first maturity for males and females (37-38cm ) was very similar to that described for the Indian Ocean basin population. Stomach content analysis (2005 - 2012) showed a varied diet dominated by salps/tunicates, but with ontogenetic and depth variations in prey composition. Enhanced knowledge of L. squamifrons in this region will be valuable in future research on habitat and foodweb modelling and spatial marine management.