Spatial distribution and population structure of juvenile Antarctic toothfish (Dissostichus mawsoni) in the South Shetland Islands (Subarea 48.1)

In the present study we provide new insights on the spatial distribution and population structure of juvenile D. mawsoni caught during bottom trawl survey on the shelves around the South Shetland Islands (CCAMLR Subarea 48.1). Fish samples were collected during five summer cruises conducted from 2001 to 2007. Juveniles were relatively evenly distributed on the shelves around Elephant Island and northern lower South Shetland Islands. Although they were caught in all depth strata, they were most abundant between 100 and 300 m depth. The sampled population was composed of 150 specimens measuring between 22 and 78 cm TL, equally distributed between sexes, most of them with gonads at immature stage of maturity. Both males and females showed a positive allometric body growth, suggesting a good condition factor. Based on counts of annual growth increments from sagittal otolith sections, age estimates ranged between 2 and 7 years in males and between 2 and 8 years in females, respectively. Annual growth rate was estimated from the age-length keys, spanning from 10 to 5 cm TL. Present data have been discussed in comparison with the biological traits of adults reported elsewhere.