2006–2013 fish distribution and biomass in the Kerguelen EEZ (CCAMLR DIVISION 58-5-1) for the bathymetric range 100–1 000 m

Three fish biomass surveys have been recently undertaken in the northern part of the Kerguelen Plateau (POKER 1, 2006; POKER 2, 2010; POKER 3, 2013) with the chartered trawler FV “Austral” repeating the same random and stratified sampling stations in the bathymetric range 100 – 1000 m. Data on the bathymetric and geographical fish distribution are available for 19 bottom-dwelling species (13 neritic and 6 deep-sea for their upper bathymetric range).  The high number of stations (up to 200 each time) allows to be confident with the estimation of fish biomass ranging from 247 000 to 268 000 tons for a ground area of about 183 000 km². Patagonian toothfish (Dissostichus eleginoides), with up to 40% of the total biomass on the shelf and surrounding deep-sea, is the dominant species in terms of biomass but other species (Notothenia rossii, Channichthys rhinoceratus, Zanclorhynchus spinifer, Lepidonotothen squamifrons, Champsocephalus gunnari, Bathyraja eatonii) including never exploited fish form the bulk of the biomass. Local densities are often specific to some species. Previously overexploited species by the trawl fishery show clear and recent strong recovery. It is the case for mackerel icefish Champsocephalus gunnari and marbled notothen Notothenia rossii. Evolution of biomass of other unexploited species (i.e. Channichthys rhinoceratus), unrelated to fishery impact seems still unclear. Such study is the first ones taking into account all the fish components of a surveyed area in the Southern Ocean.