Biomass abundance and distribution of fish in the Kerguelen Islands’ zone (Division 58.5.1)

A fish biomass survey cruise, named POKER 2006, was conducted during spring 2006/07 (September-October 2006) off the Kerguelen Islands (division 58-5-1), the northern part of the Kerguelen Plateau. The sweep-area method was used in the range 100 and 1000 m with random stratified stations of bottom trawling. Estimations of biomass and abundance are provided for eight commercial species. The total biomass reaches 245 000 tonnes and the Patagonian toothfish Dissostichus eleginoides produces half of the value (124 000 tonnes). The biomass is displayed between the shelf and the deep-sea. Such evaluation is still uncompleted because four of the species (D. eleginoides, Macrourus carinatus, Bathyraja eatonii and B. irrasa) extend deeper than 1000m, the limit of the POKER 2006 survey. Some shelf and slope’ species (Champsocephalus gunnari and Notothenia rossi) exhibit low levels of biomass when compared to the previous results (1987/88, SKALP survey). Other species (Channichthys rhinoceratus and Lepidonotothen squamifrons) seem to have increased, even doubled, their biomass during the period between the two surveys. Besides the commercial species, two species were abundant: Zanclorhynchus spinifer on the shelf and Alepocephalus cf. antipodianus in the deep-sea. The data on the latest are new. The geographical and bathymetrical distributions of the species allow to conclude to a very stable localisation of the fish concentrations. Cohorts of some species (D. eleginoides, C. gunnari) were visible in some geographical sectors. In addition, the survey allows to define the species distributions, both commercial that the others, important in the ecosystem. It is of a major interest for the management and conservation of fish populations in the area.