Descriptive analysis of the toothfish (Dissostichus spp.) tagging programme in Subareas 88.1 & 88.2 for the years 2000–01 to 2012–13

We provide an update of the descriptive analyses of the toothfish tagging programme in Subareas 88.1 and 88.2, including summaries of data for the 2013 season. Overall, a total of 37 047 Antarctic toothfish have been reported as released and 1903 recaptured, and 1155 Patagonian toothfish released and 95 recaptured since 2001. In recent years, most vessels have achieved or exceeded the required tagging rate of one toothfish per tonne of catch in the Ross Sea region.



Tag recapture data showed that most fish are recorded as being recaptured only a short distance from their point of release, typically less than 100 km. However, several long distance movements of tagged Antarctic toothfish between slope and north regions have been observed. Of those that have changed areas (i.e. between Shelf, Slope, North) in the Ross Sea region, 44 have moved from the Shelf to the Slope, 31 have moved from the Slope to the Shelf, 13 from the Slope to the North, and 5 from the North to the Slope (although 4 of those are suspected of being poor tag links based on growth rates and ancillary linking data). Three recaptured fish moved between the Ross Sea region and Subarea 88.2; One moving from the Ross Sea (SSRU 88.1K - shelf) to 88.2H (north), and two moving from Subarea 88.2 to the Ross Sea slope (SSRU 88.1H), one from 88.2H - north, and 1 from 88.2F - slope).



The total number of recaptures in 2012 was lower than in 2010 and 2011, but the total number of recaptures in 2013 was very similar 2010 and 2011 and about double that in 2009. The reason for the low number of recaptures in 2009 and 2012 is likely a consequence of inter-annual changes in the main location of fishing effort arising from ice conditions in those years.