CCAMLR

In order to avoid several problems associated with assessing the D. eleginoides stock in Subarea 48.3, it has been proposed to use the FAO programme ANACO (Mesnil, 1989) which allows one to make coefficients of fishing mortality F more precise by using catch data on age groups without resorting to additional information on effort. VPBAS files for running the programme were created using our data as well as CCAMLR data. Some assumptions were made for this exercise. Assessments for the period 1984 to 1994 revealed that at a level of M = 14, the mean value of F is 0.148, while the toothfish spawning stock for 1989 to 1994 is between 17 and 29 thousand tonnes. The author believes that the ANACO cohort analysis programme has significant potential for further improving both stock assessments and calculations of F by adjusting the catch database and using variable parameters of natural mortality and mean fish weight.

Ichthyoplankton samples were obtained during the Italian Antarctic Oceanographic Cruise carried out in the western Ross Sea in November-December 1994. The present study focused on improvement of the knowledge of the larval fish community in relation to its distribution and relative abundance. A midwater trawl (Hamburg Plankton Net) was used to collect samples at 26 stations. Larval and juvenile specimens of twentyone species belonging to six families (Artedidraconidae, Bathydraconidae, Channichthyidae, Macrouridae, Nototheniidae and Paralepididae) were collected from surface to 380 m depth. Mean relative abundance of larval fish in the whole area was about 2.7 specimens / 1000 m3 of sea water filtered. The upper 100 m of the water column showed the greatest species diversity and abundance. Postlarvae and juveniles of Pleuragramma antarcticum were the most abundant, followed by larval and postlarval specimens of Chionodraco sp. It was noteworthy the high number of Trematomus lepidorhinus (570 larvae) found in a single station off Terra Nova Bay. Our data give evidence of a great species diversity of the larval fish community in the western Ross Sea and show a greater abundance of fish larvae in inshore than in offshore waters.

Exporatory fishing with bottom trawl conducted by the French trawler « Austral» off the Crozet archipelago (sub-area 58-6) does not allow to detect any other marine living resources than the only one Nototheniid fish Dissostichus eleginoides. The other species have no future for a commercial exploitation due to their sizes. Deep-sea fishing only (slope of the shelf :300 - 750 m) show some shoals of sub-adults and adults as observed in the division 58-5-1 (Kerguelen) located more easternly. Two geographical areas have been specially identified. Trends in yield are however not stable from one year to another and even along one fishing experiment despite a limited fishing effort. Two hypothesis are proposed to explain the trends: a quick col1apse or/and a high migratory pattern of this part of the stock. The running experiments do not allow to consider and work out a plan an high fishing effort (or in the future and even yearly fishing cruises in the sub-area.

This study was based on the data from the ichthyoplankton survey made in March-April 1989 by R/V "Vozrozhdenie" in the subtropical frontal zone over the South Atlantic ridge crest between 38°30’ - 45°S. and 15° - 20°W. Larvae were collected with BONGO and JUDAY nets in oblique arid vertical hauls at 500 - 0m. The method of delta-distribution of random values (Aitchison, Brown, 1957; Pennington, 1983) was used to count the larvae. The data obtained was taken to estimate the recruitment biomass (fish aged up to 1 year) in this species for the area of 87750 square miles studied. The abundance of larvae in this area was 4.3 x 10 ind., while the biomass of one year old fish obtained was 10750 tons. A whole chain of similar reproductive grounds is assumed to exist in the notal zone of the Atlantic and other sectors of the South Ocean to be able to sustain a large biomass of E. carlsbergi in waters of the south po1ar frontal zone.