Biomass, abundance and distribution of fish in the Kerguelen Islands EEZ (CCAMLR Statistical Division 58.5.1)

摘要

‘POKER 2006’, a bottom trawl fish biomass survey, was conducted from September to October 2006 in the northern part of the Kerguelen Plateau (CCAMLR Statistical Division 58.5.1). The swept-area method was used in the depth range from 100 to 1 000 m with 207 random stratified stations. Estimates of biomass and abundance were produced for eight commercial species. The total biomass was 245 000 tonnes and Patagonian toothfish (Dissostichus eleginoides) accounted for half of the value (124 000 tonnes). The fish biomass was distributed between the shelf and the deep sea. However, this evaluation remains incomplete as four of the species (D. eleginoides, bigeye grenadier (Macrourus carinatus), Eaton’s skate (Bathyraja eatonii) and Kerguelen sandpaper skate (B. irrasa)) extend deeper than 1 000 m, the limit of the POKER 2006 survey. Some shelf and slope species (mackerel icefish (Champsocephalus gunnari) and marbled rockcod (Notothenia rossii)) exhibit low levels of biomass when compared to the results of previous surveys (SKALP surveys, 1987 and 1988). Other species (unicorn icefish (Channichthys rhinoceratus) and grey rockcod (Lepidonotothen squamifrons)) seem to have increased, even doubled, their biomass during the period between the two surveys. In addition to the commercial species, Zanclorhynchus spinifer was abundant on the shelf and Alepocephalus cf. antipodianus was abundant in the deep sea; the data on the latter are new. Data on the geographic and bathymetric distribution of the species provide evidence of geographically very stable species-specific concentrations. Distinct cohorts of some species (D. eleginoides and C. gunnari) were detected in some sectors. The survey has defined the distribution of species, commercial or not, that are important in the ecosystem and are of major interest for the management and conservation of fish populations in the area.