WG-FSA-97

Information on natural mortality rates of the mackerel icefish, Champsocephalus gunnari, from the period prior to large scale commercial harvesting is discussed. Methods based on population age structure and growth parameters are used. It is concluded that only in the three earliest years, 195 1, 1964 and 1966, do the data reflect an unexploited population. The best estimate of M from analyses Read More
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Long-lining operations for Dissostichus eleginoides off South Georgia were assessed for interactions with seabirds, and the effectiveness of measures employed to mitigate seabird mortality. In this study 61 lines were laid during April and May, all set at night using the Spanish double-line method with extra weights on the line and all deck-lights extinguished. Data were recorded during Read More
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Patagonian toothfish (Dissostichus eleginoides) was found in catches of 25 trawls in the offshore area of South Georgia, and in catches of 13 trawls in the Shag Rocks Shelf. It was caught at all strata depths, but the most abundant catches were at 260-320 m depth. On the whole, catches of Patagonian toothfish consisted of juveniles 21–37 cm in length, immature fishes 41–78 cm in length and Read More
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Available in YugNIRO data concerning distribution of Antarctic toothfish juveniles in the Indian Sector of the Antarctic are used in the paper. In the summer period of the southern hemisphere (January–March) juveniles of D. mawsoni with size from 4–9 to 30–75 cm were regularly registered in catches of bottom and pelagic midwater trawls in all the studied continental seas from 12 to 144°E.

According to the results of the long-term studies (1967–1991) in expeditions to the sub-Antarctic and Antarctic waters of the Indian Sector of the Southern Ocean, distribution areas of the Patagonian and Antarctic toothfish are clearly cut. It was concluded that the areas of these toothfish species were not overlapped in the area under review.

Data on incidental mortality of seabirds and marine mammals associated with longline fishing around the Falkland Islands between August 1996 and May 1997 are briefly summarised. For seabirds, the overall average rate of incidental mortality was 0.34 birds per 1000 hooks; excluding a single set when 87 birds were caught, the average was 0.05 birds per 1000 hooks. Black-browed albatrosses Read More
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The incidental mortality of birds in the fishery of Dissostichus eleginoides was analyzed for the Chilean fleet at Subarea 48.3 during 1996 to 1997. In 1996, 533 birds were killed and 478 in 1997. The most vulnerable species was Diomedea melanophrys representing 41,% of the total bird killed in both years, followed by Procellaria aequincotialis with 10% and 33% respectively. For 1995, 1996 and Read More
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Finfish stocks in the Antarctic Peninsula region (CCAMLR Statistical Subarea 48.1) have been exploited from 1978179 to 1988189 with most of the commercial harvesting taking place in the first two years of the fishery. Results of bottom trawl surveys conducted by Germany in the vicinity of Elephant Island in the 1980s showed that stocks of Champsocephalus gunnari, Notothenia rossii, Read More
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The population and conservation status of the world's albatrosses are reviewed within the framework of recent taxonomic changes. The latest estimates of size of breeding populations (pairs) at all known localities of each of the 24 proposed species are presented; population trends are assessed where sufficient data are available. Despite increased efforts in population monitoring, the status ( Read More
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Assessments of the abundance and potential yield of mackerel icefish (Champsocephalus gunnari) populations at Heard Island are developed from the results of four scientific surveys conducted in 1990, 1992, 1993 and 1997. The assessments include estimates of all the parameters required, based on the data collected during the surveys, including growth curves, natural mortality, ages and sizes of Read More
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This paper provides an assessment of the long-term annual yield for three species caught as by-catch in the commercial trawl fisheries in the Heard Island area (Statistical SubArea 58.5.2): Channichthys rhinoceratus, Lepidonotothen squamifrons and skates (Bathyraja spp.). These assessments were undertaken with the aim of examining the potential for the commercial trawl fisheries to Read More
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A new fishery was declared for Dissostichus spp in Division 58.4.3 for the 1996197 season. Results of a brief survey by an Australian vessel are presented, but catches were very low. A new proposal for an exploratory fishery in Division 58.4.3 is presented. This involves a random stratified trawl survey to be undertaken in parallel with commercial exploration, and the collection of a Read More
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Haul by haul data acquired by the UK from longline fishing for Dissostichus eleginoides around South Georgia were compared with data reported to CCAMLR and held in CCAMLR's longline database (database C2). Some instances of incomplete reporting were identified, where blocks of data appear to be missing from the CCAMLR database. One instance was identified of multiple hauls being submitted as Read More
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The management of Champsocephalus gunnari at South Georgia is complicated by the likelihood of substantial periodic variation in natural mortality rates. These may be associated with increased consumption of icefish by Antarctic fur seals in years of poor krill availability. Thus natural mortality of icefish may, in some years, increase by a large factor (assumed here to be 4) declining to Read More
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Long-lining operations from a single vessel fishing for Dissostichus eleginoides off South Georgia (Sub-area 48.3) were assessed over 48 days during April and May. All lines were set at night using the Spanish double-line method with extra weights on the line and all deck-lights extinguished to mitigate against bird mortality. Data were recorded during hauling using a randomised cluster Read More
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The technical information used in the stock assessment of the Patagonian toothfish (Dissostichus eleginoides) in diferent parts of the world, have been summarized in this document in order to facilitate the future research and management works of this species.

The stock assesment of Dissostichus eleginoides from the subarea 48.3, between the split years 1992 to 1997, was estimated using the Sequential Population Analysis (SPA) model based in the catch at age data. The model was tunned by the standarized CPUE. For this last process GLlM was used and for the aplication of SPA the non-lineal function of Solver in Excel was used. The results show Read More
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The results of four fish surveys (EDUARDO L HOLMBERG 1994 to 1997) are analyzed to detect associations between the sizes of Champsocephalus gunnari (also age classes) , Gobionotothen gibberifrons, Notothenia rossii, Pseudochaeinichthys georgianus, Chaenocephalus aceratus and Dissostichus eleginoides and depth of catch, as well as among C. gunnari age classes. Except D. eleginoides median sizes Read More
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The survey comprised 51 bottom trawl hauls taken in subarea 48.3. Of these, one was discarded due to net damage. About 80% of the hauls were taken in the shelf of South Georgia Islands (41) and the remaining in the Shag Rocks area (9); 64% of the hauls were intended as replicates of the position of hauls in the previous cruises. Mean densities were obtained considering the spatial aggregation Read More
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The diet composition of mackerel icefish Champsocephalus gunnari caught in Subarea 48.3 in late summer of years 1994-97 was analysed using frequency of occurrence (F%) and coefficient "Q" (%) methods. Krill (Euphausia superba) followed by the amphipod hyperiid Themisto gaudichaudii was the main food item around South Georgia and Shag Rocks in the period investigated, except in 1994, when the Read More
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This work aims to the study of the distribution, size structure by depth, first maturity stage, weight/length, and length perimeter curve, of Patagonian toothfish (Dissostichus eleginoides) in the Argentine Sea, and atempts some explanation by a trophic analysis of such distribution.
The distribution of Patagonian toothfish extends between of 36°30'S and 55°S from 80 to 2500 m depth. Read More
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Longline fishing for Patagonian toothfish Dissostichus eleginoides commenced at the Prince Edward Islands in October 1996, but unsanctioned fishing commenced some months before this date. This paper summarizes the mortality of seabirds associated with this fishery during the year July 1996-June 1997. Data on seabird bycatches were obtained from fishery observers aboard 10 of 12 sanctioned Read More
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Satellite telemetry was used to identify the foraging zones of Shy Albatrosses Diomedca cauta breeding at two sites of Tasmania, Australia (Albatross Island in western Bass Strait and Pedra Branca to the south) to assess their level of interaction with longline fisheries. Adult birds from both colonies fed locally both in and outside the breeding season. Breeding birds from Albatross Island Read More
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The accidental/incidental capture of seabirds by longline gear may be causing a significant decline in the numbers of some species (most notably albatross Diomedea sp) in the Southern Oceans.
In response to the sea bird problem, the New Zealand Department of Conservation funded a programme in 1996 to develop a device to set baits underwater on commercial longliners.
Trials on two U Read More
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In response to the Department of Conservation's concerns for the accidental capture of seabirds by Surface Long Liners and subsequent contract 9513004, several concepts of bait placement devices were evaluated. Two methods being selected for further in depth evaluation.
The first concept being a towed paravane with an endless cable employed to transport and release the bait at the depth to Read More
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In 1994, an experimental longline fisheri for hake Merluccius spp. commenced in the shelf water of South Africa. Participants were required to record any birds caught, and these data were supplemented by ship-based observers on several vessels. Longlines are set at night, and the white-chinned petrel Procellaria aequinoctialis was the only seabird species caught while attempting to scavenge Read More
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The major recent advances in studies of albatross biology, ecology and conservation are reviewed. In addition to highlights arising during the first Albatross Conference, pioneering research on topics little covered therein (e.g., behaviour, moult, diet, physiology) are summarised. Important topics and opportunities for future research are suggested. The major historical and current threats to Read More
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The conservation status of albatrosses has been re-evaluated using the recent suggested taxonomic revisions of albatrosses and the new IUCN criteria for identification of threatened taxa. The evaluations of threat status and categories were prepared by independent albatross specialists before being critically reviewed and endorsed by Birdlife International.
This evaluation reveals Read More
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