CCAMLR

In anticipation of the development of a new fishery for the oceanic squid Martialia hyadesi in the Scotia Sea a revision is presented of annual consumption of the species by higher predators and a brief review is provided of information about the life cycle and distribution obtained from research fishing and commercial catches. The species is consumed by seabirds, seals and whales and the most reliable data are from seabirds because comprehensive sampling can be carried out during the breeding season. A conservative estimate for total annual consumption by higher predators in the Scotia Sea is 245,000 tonnes compared with an upper estimate of 550,000 tonnes if less reliable data are included. M. hyadesi spawns in winter/spring, probably has a two year life cycle and, in common with other ommastrephids, is semelparous. It is proposed that the timing and catches of the fishery should be highly conservative and set with regard to the timing of breeding and consumption rates of the most sensitive of the dependent species. Most predators that have been studied consume M. hyadesi during the first year of its life cycle. Fishing on M. hyadesi after the chick-rearing season of the most sensitive predator (grey-headed albatross) would minimise competition locally and ensure that the fishery only exploited the stock after escapement from most higher predator species. It would also allow monitoring of predation on the stock prior to the fishing season as a form of pre-recruit assessment. Closing the fishery before recruitment of the next generation would ensure availability of prey for higher predators for the following chick rearing season. Preliminary data from a squid jigger undertaking research fishing around South Georgia in June 1996, under the auspices of CCAMLR, provide the basis for assessing realistic potential catch rates.

Observations on abundance of by-catch fishes were made during fishing operations for krill Euphausia superba Dana conducted by the Ukrainian trawler Grigory Kovtun in the vicinity of South Georgia (May to July, 1992), the Polish trawler Lepus on the fishing grounds of South Orkney Islands and South Georgia (March to May, 1993), and by the Japanese fishing vessels No.3 and No.5 Chiyo Maru in the South Georgia area (July to August, 1992) and Niitaka Maru to the north of the South Shetland Islands (January to February, 1994) to determine the proportion of juvenile fish forms in krill concentrations. In the South Orkney Islands area, eight hauls were subjected to analysis and there was no by-catch of juvenile notothenioids at all in the samples collected. In the area around South Georgia, six notothenioid species including one unidentified bathydraconid fish were found as by-catch juveniles during three surveys by different countries. Among the six species, Lepidonotothen larseni was the most abundant in the Polish and Japanese by-catch samples, and its estimated value of an arithmetic mean was 11541 ind./t krill and 34588 ind./t krill respectively. In the Ukrainian sample, most of by-catch juveniles were referred to Champsocephalus gunnari and L. larseni, and its arithmetic mean was 78523076 ind./t krill and 60352790 ind./t krill respectively. Thirteen species including four mesopelagic fish species were found in krill catches of 25 of 99 examined net hauls made in the South Shetland Islands area. Also among by-catch fish from this area, juvenile L. larseni was the most abundant and its arithmetic mean was 10247 ind./t krill. In all the three areas, a relatively low by-catch of the family Myctophidae was observed. Abundance of by-catch fish could have depended on the density of krill concentration. The large incidental catch of juvenile fish occurred in hauls with the relatively low krill CPUE, and fish by-catch was not found or rare in hauls for krill swarms of higher density.

One of the non-solved problems in krill exploitation has been the by-catch of fish larvae that use (or co-occurred) the krill swarms as their habitat. The detection of this problem started together with the massive antarctic krill exploitation during the 80's. There has been recognized several fish species whose larvae develop within the krill swarms, nevertheless, few have been the quantitative evaluations that give evidences that this technological interaction, is affecting the recovery of over-exploited populations or that commercial or noncommercial populations are diminishing.

For recent years Dissostichus eleginoids is the main target species of trawling and long-line fisheries in the vicinity of the Kerguelen Islands. Results of research made by the author on board the fishing vessel "Poltava" in the summer season 1991-1992 were the base for the present paper. Regular direct distribution of size groups D. eleginoides in depth range within the fishing area on the northern slope of shelf was revealed. Difference in feeding spectrum of these groups was noted that in this case characterized quality composition of food supply in different depths. Seasonal (summer) migration of size groups was directed from less depths to greater ones. In April in depths of 550-600 m the group of D. eleginoides was supposed to he which in December-February occurred in depths of 350-400 m. Feeding on fish and squids primarily D. eleginoides under definite conditions might turn to more assessable (Hyperiida), secondary (jelly-like fish) or incidental (bottom crustaceans, octopoda, vessels' wastes) food. Seasonal change in quality composition of D. eleginoides in depths of 500-600 m was revealed, i.e . cold-water jelly fishes (Salpae, Ct,enophora, Scyphomedusae) being the basic food component in December-February were replaced with natal-subtropic species of the squid (Chiroteuthis veranyi) in March-April.

The cephalopods of the Antarctic are supposed to have a very high biomass level However, they have not been fished nor any fishable aggregations of them detected to date in the CCAMLR Convention Area. The squid Moroteuthis ingens has been constantly present in bottom trawl catches on Ob Bank during aimed fishery for Lepidonotothen squamifrons. At maximum, the proportion of squid in the total catches exceeded half of the catch, reaching 1310 kg per hour of trawling. All the squid were in prespawning state. The squid aggregation was apparently composed of mating individuals. At has been concluded that target searching and fishing for Moroteuthis ingens with a midwater trawl over the seamaunts in the sub-Antarctic may be expected to bring forth good commercial yields.
The crabs (craboids) of the Antarctic are now an object of intense interest for the scientific and fishery organizations of the member countries of the CCAMLR, especially in view of the development of experimental fishing by a U.S. vessel on the shelf of South Georgia. The biology and the environmental aspects of the life of craboids in the Antarctic are but insufficiently known. The Anomura faune on Ob Bank is represented by a single species, Paralomis aculeata. The craboids have been constantly found in bottom trawl catches during target fishery for Lepidonotothen squamifrons, the frequency of their occurrence being 25 to 30%. Considering, that a routine bottom trawl was used with the footrope so designed that there was little probability of the benthic animals (craboids included) being captured, a conclusion has been made of the possibile sufficiently high abundance of Paralomis aculeata population on Ob Bank.

Four species of shark have been known to date to occur in the sub-Antarctic waters: Lamna nasus, Somniosus microcephalus, Etmopterus lucifer, E. granulosus. A specimen of Squalus acanthias was captured in February 1995 on the shelf of the Kerguelen Islands from the depth of about 195 m and duly described . Squalus acanthias is believed to be one of the most widespread shark species in the World Ocean. The fact of capturing this species in the Kerguelen waters enlarges by far its range and adds to the list of ichthyofauna of the Antarctic, more particularly to the scanty fauna of cartilaginous fishes. The occurence of Sq. acanthias in the waters of the Kerguelen Islands is thought to suggest natural enlargement of the range of this ecologically plastic species.

AS many as 18 species of benthopelagic fishes belonging to 12 families were caught in trawls during the integrated surveys in December 1977 and in January 1978 on Elan Bank consisting of two sublatitudinal sea-bottom elevations with prevailing depths from 960 to 1350 m. Among these fishes there were found both species inhabiting exclusively in sub-Antarctic and Antarctic waters (endemies) and those having a wider geographical range. The 900-1000 m depth range was characterized by the greatest diversity of fish species, their numbers, however, being the smallest in those particular depths. Sub-Antarctic and Antarctic fish species were the dominant group. The proportion of deep-dwelling fishes increased with depth and they were quite abundant. Most abundant on Elan Bank were Macrourus whitsoni, Antimora rostrata and Alepocephalus sp. cf. antipodiana. The paper contains an annotated list of species and a brief analysis of their vertical distribution by area and depth with the information about their biological state.

Interactions between longliners, fishing for Patagonian toothfish Dissostichus eleginoides in the west of Kerguelen islands during 1995 - 96 cruise, and marine mammals occured with Kerguelen Fur Seals Arctocephalus gazella. They catch 0.75 % of toothfish on long-lines where interaction occured, but 2.2 % were lost alongside the vessel.