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    Results from the random stratified trawl surveys to estimate distribution and abundance of Dissostichus eleginoides and Champsocephalus gunnari in the Heard Island region (Division 58.5.2) for 2010 and 2011

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    G.B. Nowara, S.G. Candy and T. Lamb (Australia)

    Random stratified trawl surveys were completed in September 2010 and in March to May 2011 on the RV Southern Champion, adding to the time series of annual surveys in Division 58.5.2 that commenced in 1997. An earlier survey in April 2010 was not completed, but valid hauls from this, as well as the September 2010 survey were used in the stock assessment as they provided valuable additional information on abundance. Catches of D. eleginoides were at half or lower than in surveys from both years than the average catch for the previous four years (2006-2009).  Catches of C. gunnari were very low, with the 2011 catch, at less than 0.5 t, 15% of the earlier four year average, and the 2010 catch being 60% of the 2011 catch. In 2011 the abundance of L. squamifrons was higher, and C. rhinoceratus lower than the average. Macrourid catches have been stable over recent years, with a fall in 2011. Skate catches were just below and just above average for 2010 and 2011 respectively. A notable increase in the catch of invertebrates was reported in the 2010 survey, consisting mostly of poriferan sponges, anemones and sea stars. The 2010 catch was 2.5 times higher than the 2006-2009 average. Invertebrate bycatch returned in 2011 to a level more common in previous years, dominated by asteroids, anemones, ascidians and poriferans. This data will be incorporated into models being developed at the AAD to predict the location of vulnerable benthos. An analysis of numbers and biomass of young toothfish estimated from the survey area from 2001 to 2011 found no significant trends in abundance.