Movement and growth of tagged toothfish around South Georgia and Shag Rocks (Subarea 48.3)

In 2000 the UK started a toothfish (Dissostichus eleginoides) tagging programme. The aims were to investigate the spatial and temporal movement of fish and to validate growth estimates. Since then approximately 2,260 toothfish have been tagged and released during groundfish surveys and CCAMLR observer trips. Of these, about 900 have also been injected with either Strontium Chloride or Oxytetracycline which places a marker on the otolith indicating the date of injection and release. To date, 50 fish have been recaptured, mostly from around Shag Rocks where there is greatest fishing activity. Most of the fish recaptured to date were tagged and released during the experimental pot fishing in 2000 and 2001, and have been at liberty from one to two years. Four fish were tagged and recaptured from the same longline vessel in 2002 after up to two months at liberty. The fish tagged during the groundfish surveys may not yet be large enough to be available to the longline fishery and there have been no recaptures of these fish tagged at South Georgia or elsewhere in the South Atlantic. Similarly, tags originating from elsewhere (e.g. the Patagonian shelf) have not been recaptured at South Georgia. 13 tags have been recovered at 42°S after about one year at liberty from some opportunistic tagging carried out on a toothfish pot vessel in international waters at that latitude in 2001.