DISTRIBUTION AND ABUNDANCE OF SKATES ON THE KERGUELEN PLATEAU (CCAMLR DIVISIONS 58.5.1 AND 58.5.2)

Three species of skates are commonly taken as incidental by-catch in the Patagonian toothfish longline and trawl fisheries, and the mackerel icefish trawl fishery on the Kerguelen Plateau, Bathyraja eatonii, B. irrasa and B. murrayi. The three skates are widely distributed across the Kerguelen Plateau, showing different spatial distributions, linked mainly with depth. In the Australian EEZ, B. eatonii and B. irrasa are most abundant to the north and northwest of Heard Island out to the edge of the EEZ, and down to depths of 1100m and 1500m respectively. B. irrasa occurs much deeper, down to 2300m in the HIMI region. The smallest species, B. murrayi, occurs only in the shallower waters down to 700m, and are most abundant close to Heard Island to the north and northeast. The catch rates of skates from the trawl fisheries at HIMI are low and do not show any evidence of depletion in the main fishing grounds at this stage. The marine reserves and the conservation measures employed by CCAMLR in the HIMI fishery appear to provide effective protection for the skates at least in the trawl fisheries. This study provides the first review of skate by-catch across both the HIMI and Kerguelen fisheries. We recommend ongoing monitoring of species specific bycatch levels, and further research to determine the life history parameters of these species, particularly for B. irrasa which is taken both in the trawl and the longline fisheries.