REPORT ON A LONGLINE SURVEY CONDUCTED BY THE FV JANAS IN MAY 2008 ON BANZARE BANK, AND AN ASSESSMENT OF THE STATUS OF DISSOSTICHUS SPP. IN DIVISION 58.4.3B

In May 2008, a randomised longline survey, consisting of 15 standardised sets over 2 strata covering areas of commercial fishing activity was conducted from aboard the Australian flagged longliner FV Janas BANZARE Bank within CCAMLR Statistical Division 58.4.3b. Catch rates were very low, ranging between 0 and 225 kg.1000 hooks-1, consistent with toothfish being depleted to low densities across the majority of the surveyed area. Catches of toothfish consisted of both species of Dissostichus, with D. mawsoni found across the entire survey area while D. eleginoides was mainly found on the shallow areas on the western part of the Bank. Data on size distribution and size at maturity indicate that the D. mawsoni population is almost entirely large mature fish with a bias towards males, which are shown to mature at a smaller size than females. As the population does not contain juvenile lifestages, we hypothesise that the fish encountered originate from nearby populations in east Antarctica where juveniles of both sexes are caught. The D. eleginoides population consisted of approximately equal proportion of males and females, and few mature individuals were detected. Contrasts in the population characteristics of the two species of Dissostichus indicate that species specific management should be considered for this area. Data on major bycatch species Macrourus carinatus and Raja taaf, including size distribution, sex ratio and size at maturity, are also presented.