Is our attempt to estimate biomass of Antarctic fish from a
multi-species survey appropriate for all targeted species? Notothenia rossii in the Atlantic Ocean sector – revisited

Notothenia rossii was the first target species of the fishery in the Southern Ocean. The species has been heavily fished at the beginning of the 1970’s. The closure of the fishery for this species was one of the first conservation measures CCAMLR adopted in 1985. Fish biomass within a CCAMLR Subarea or part of a subarea is commonly estimated targeting a number of species including N. rossii at the same time. These surveys are conducted under the assumptions that the target fish species are more or less evenly distributed over the area at the time of the survey. This assumption is violated in the case of N. rossii which shows an abundance which is extremely skewed in that a large proportion of the population tends to aggregate in small areas while most of the area of distribution is only thinly populated. In order to provide more accurate estimates of the species it is suggested that an acoustic survey combined with a number of identification hauls might be the most promising approach to estimate biomass of N. rossii more adequately.