CCAMLR

The environmental and/or life history factors affecting genetic exchange in marine species with potential for high dispersal are of great interest, not only from an evolutionary standpoint but also with regard to effective management. Previous genetic studies have demonstrated substantial differentiation among populations of the Patagonian toothfish around the Southern Ocean, indicating breakdown of gene flow across large distances between inhabited shelf areas. The present study examined genetic structuring through analysis of microsatellite loci and restriction fragment length poymorphism (RFLP) of the mitochondrial ND2 gene and control region of the toothfish population in the SW Atlantic, allowing examination of the relative effects of the Antarctic Polar Front (APF), deep-water troughs and distance between sites. Mitochondrial DNA (mtDNA) data indicated a sharp genetic division between the Patagonian Shelf/North Scotia Ridge and the Shag Rocks/South Georgia samples, whereas microsatellite data showed much less distinct structuring and an intermediate position of the North Scotia Ridge samples. We suggest these data indicate that the APF, as a barrier to larval dispersal, is the major inhibitor of genetic exchange between toothfish populations, with deep-water troughs and distance between sites contributing to genetic differentiation by inhibiting migration of relatively sedentary adults. We also suggest that differences between mtDNA and nuclear DNA population patterns may reflect either genome population size effects or (putative) male-biased dispersal.

An exploratory fishery for Antarctic toothfish (D. mawsoni) has been in operation for seven seasons in Subarea 88.1 and for three seasons in Subarea 88.2. A large amount of data on toothfish and the associated bycatch from the fishing operations has been collected. This report is somewhat different to earlier reviews of the exploratory fishery. In the first instance, it reports catches by the new SSRUs used to manage Subarea 88.1; secondly, the report includes catch data from all countries fishing in the area, whereas previous reports included data from only New Zealand vessels; and thirdly, the reported catch is confined to C2 data.
The catch of D. mawsoni was 2414 t, and contributed 87% of the total catch in 2004. D. mawsoni was the dominant species caught in all 12 SSRUs fished. In 2004, about 12 t of Patagonian toothfish (D. eleginoides) was taken, almost entirely from SSRU 881B. The main bycatch species was Macrourus whitsoni, which contributed about 11% of the 2004 catch. Bycatch of skates (mainly Amblyraja georgiana) was only 19 t (less than 1% of the total catch1). Other bycatch species (including morid cods, icefish and moray cods) each contributed less than 1% of the catch overall.
Because of changes in the ice conditions and fleet composition, no two seasons have been the same. In 2001, 2003, and 2004, ice conditions restricted fishing and resulted in new areas being explored. The change in fishing patterns between seasons is reflected in the mean length and age composition of the catch. In the past few seasons, there has been a trend towards fishing in deeper water and this is reflected in an increase in the length and age of the toothfish catch and in the bycatch, particularly the increase in catch of morid cods and icefish.
An approach to allocating the rattail catch to the SSRUs in Subarea 88.1 was examined. The indicative catch limits appear to be little better than the catch limits set for the 2004 season. Further examination of the problem is warranted.

Experimental fishing for Patagonian toothfish took place during the period from 28 June to 27 July, 2003. This experience was carried out by a Spanish longliner, following commercial procedures, in a restricted area south of Madagascar and north of the Prince Edward and Marion Islands and the Crozet Islands, and outside EEZ and CCAMLR waters. A total of 57 sets were taken at between 360 and 1950 metres depth. The Patagonian toothfish appeared in all those sets carried out with values comprised between 53 and 1158 kg. Northward distribution of Patagonian toothfish is closely related to the extension of the sub-Antarctic Front to the north. The prospected area would seem to be located at the edge of the main ground, in which a residual recruitment effect persists. The total CPUE was 42.21 kg/1000 hooks. Depth is the most important factor in Patagonian toothfish distribution within the study area.

Based on the last year's record of the operation and the advice by WG-IMAF/WG-FSA, the extension of the fishing season for the exploratory longline fishery for Dissostichus spp. in Statistical Subarea 48.6 north of 60°S is proposed.

Mitigation measures for incidental fur seal entanglements employed by Japanese krill trawl vessels are illustrated.

The rationale for the proposed main review of the Scientific Observer Manual and a report on intersessional work undertaken in 2004 are presented.

Status report on the implementation of IPOA-Seabirds is presented.

The progresses in the developing of the Chilean NPOA-S are described. At the moment, an Executive and a Technical Group have been constituted. First steps taken had been the selection of mitigation measures to be applied; the design of experiments to test specific combinations of mitigation measures, and the discussion of the Objectives and Goals of the NPOA-S. The final draft of the NPOA-S will be ready on December 2004.

Implementation of NPOAs requires in first place an assessment of all longline fisheries with presumption of occurring seabird incidental mortality. Chile took this responsibility in 2001 and started the NPOA-S process by estimating the seabird bycatch at the Patagonian toothfish fishery in southern Chile, a fishery and zone with high probabilities of having significant levels of incidental mortality. Final results of this study are presented now. Seabird bycatch rate during 2002 had a markedly temporal pattern, with very high values from September to December (0.37 to 1.28 birds/1,000 hooks). Main species caught was the black-browed albatross (96% of total birds). Considering the monthly fishing effort and bycatch rate, during 2002 a total estimated of 2,162 birds were incidentally killed. This result determined the initiation of the NPOA to reduce seabird incidental mortality in all longline fisheries in Chile, which is being developed during 2004 with the close collaboration of all industrial fishery companies. Despite this bycatch levels, black-browed albatross population at Gonzalo island, Diego Ramirez, seems to be increasing.