CCAMLR

Biological characteristic and distribution of the green Notothenia by depth are given based on the results of inventory trawling surveys carried out in 1984/1985 and 1986/1987 by the BMRT "Gizhiga" in the Antarctic Peninsula subarea. Also presented are the abundance and biomass indices and the estimate of this species biomass by location and for the subarea on the whole. According to the investigation data, the green Notothenia biomass in the Antarctic Peninsula subarea amounts to 54.6 thous. tons.

Mesh selectivity experiments for several finfish species were conducted during the Spanish antarctic cruise “ANTARTIDA 8611” using the covered codend technique.
This paper presents the results obtained for Notothenia gibberifrons and Champsocephalus gunnari.
Selection factors calculated following different methods with a codend mesh of 68 mm were 2.87 for Notothenia gibberifrons and 3.10 for Champsocephalus gunnari.

Hydroacoustic surveys of the distribution and abundance of krill, Euphausia superba Dana, were undertaken in the Prydz Bay region, Antarctica. Three surveys were carried out south of 60°S within an area of 1.28 x l06 km2 between 55°E and 95°E, during the austral summer months of 1980-81, 1983-84 and 1984-85. The surveys included a total of 25 transects and covered a distance of 22 500 km over the three seasons. The surveys formed part of the Australian contribution to the international BIOMASS program.
The results of the surveys and a discussion of the theory and methods employed including sources of error in the echointegration technique are presented. Quantitative data are presented on the abundance (biomass) of krill in the Prydz Bay region as a whole and the weight density of krill along each cruise track is presented in graphical form. These data demonstrate a patchy density distribution with surface densities reaching a maximum of over 100 g/m2 along the coastal margin.
Estimates of biomass for the entire study region of 1.28 x l06 km2 were 1.6, 3.5 and 3.7 million tonnes for the 1980-81 (FIBEX), 1983-84 (ADBEX II) and 1984-85 (SIBEX II) cruises respectively. It could not be concluded, however, that there had actually been changes in the abundance of krill in the region over the period between the surveys because of the wide confidence limits on the abundance estimates.
The precision with which changes in abundance can be detected can be improved by underway identification of target species, better calibration and improved survey design. More accurate estimates of biomass also require more accurate target strength measurements.

Current knowledge of the ecology, biology and life history of the Antarctic krill Euphausia superba Dana is reviewed. Emphasis is placed on recent developments, particularly on the results of various national and international research programmes loosely co-ordinated under the auspices of BIOMASS (Biological Investigations of Marine Antarctic Systems and Stocks). Attention is focused on topics which are either directly or indirectly applicable to the effective management of krill exploitation within the provisions set out by Article II of the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR).
The hydrography of the Southern Ocean is briefly reviewed and the horizontal distribution of krill on various scales ranging from the global to individual aggregations (e.g., swarms) is discussed. Factors likely to influence the distribution on all scales are discussed and the question of stock separation considered.
Recent attempts to assess the krill standing stock directly are examined, with particular emphasis being given to the First International BIOMASS Experiment (FIBEX) acoustic survey of 1981. General problems in assessing krill acoustically and by other direct methods are discussed, and some solutions proposed to the various associated problems.
A broad overview is given of recent progress in estimating krill production through studies of age and growth, energy budgets for individual animals, and predator consumption rates. Various models of interactions between krill and its major predators, including Man, are considered. It is concluded that neither the production estimates nor the models are adequate at present for setting optimum harvesting levels for krill.
Special attention is given to the phenomenon of aggregation in krill. Physical and biological characteristics of different types of aggregation, and the effect on them of environmental factors are discussed, as are various models of aggregation formation, maintenance and dispersal.
Finally, attempts are mads to consolidate current knowledge of aspects crucial to the ecosystem management approach espoused by CCAMLR. It is concluded that deficient information on Antarctic marine ecosystem components, and on interactions between them, precludes the implementation of a realistic multi-species management approach at present. The best prospect of obtaining the information needed for the future development of the required models appears to be through intensive studies in a number of relatively small, preferably biologically distinct, areas.