Bengtson, J.L. (1982–1984), Review of Antarctic marine fauna

To aid the development of a better understanding of the ecological relationships and processes in the marine system, a brief overview of the major faunal groups in Antarctic waters (excluding benthos) is provided. The aim is to assist in providing a background against which plans for future research and management programmes may be designed. 

Separate sections of the review deal with zooplankton, krill, cephalopods, fish, seabirds, seals, and whales. Each section provides information on species composition of particular groups of animals, their geographical distribution and abundance. Where information is sufficient there are descriptions of other biological parameters such as reproduction and growth, food habits and role in the ecosystem. 

Krill is considered separately from zooplankton because of its importance as a harvested resource and a prey item for many species in higher trophic levels. The Southern Ocean food web and its trophic relationships are also discussed.

USSR (1982–1984), Results of research into distribution and status of stocks of target species in the convention area - Atlantic, Indian and Pacific Ocean sectors of the Antarctic

The USSR has carried out coordinated fisheries research in the Antarctic since 1961. The results of more than 130 research cruises are summarised according to the three major sectors: the Atlantic Sector, the Indian Sector, and the Pacific Sector. For each particular sector the review contains:

• location, period of time and main objects of research cruises, 
• average annual hydraneteorological condition and its variability, 
• main target species and its biological and fishery description, 
• particulars of bioproductivity cycle.

The Atlantic sector has been studied more thoroughly. 

The biology and fishery description includes such items as geographical distribution, population structure, life span, modal length and weight, growth patterns, length and age at maturity, sex ratio, period of spawning, fecundity, food habits, natural mortality as well as optimum fishing parameters including optimum age, length and weight, fishing mortality and recommended minimum mesh size. The analyses of data collected have shown that the entire Antarctic area may be divided into two natural zones: zone of open Antarctic waters and zone of pack ice. These zones have distinct climatic and ice conditions, physical and chemical water characteristics, distribution of biogenic elements and processes of bioproductivity. The shelf areas have the higher level of fish productivity. The necessity to continue coordinated research is underlined and sane particular fields of investigation are listed.

Lubimova, T. (1982–1984), Soviet fishery investigations conducted in the Southern Ocean

Soviet oceanological and fishery investigations in the Southern Ocean have been carried out respectively since 1946 and 1961. More than 150 expeditions have been undertaken until now. The results of investigations are outlined in brief. Species composition, the distribution of bio-resources, bio-productivity and food chains of marine organisms in Antarctica have been found to be closely connected to the latitudinal vertical and circum­Antarctic patterns of the water structure to the south of the Antarctic convergence. 

Two different natural zones have been identified: the pack ice area and open water area. The ecosystem components, their status patterns of primary and overall productivity and existing food chains are discussed. Antarctic krill is the principal plankton form in the zone of the pack ice. The average annual level of krill production is 24-70 g/m² in this area. Some local small ecosystems along the area of the Antarctic current influence and within the shelf areas of sub-Antarctic islands have also been determined. The average estimations of fish productivity for the different parts of Antarctic waters are provided. The attention of the CCAMLR Scientific Committee has been drawn to particular scientific problems.

Poland (1982–1984), Summary of information on fish and krill distribution and abundance provided for the CCAMLR ad hoc data working group

Information on fish and krill distribution and abundance published recently in Poland is summarised. The locations of concentrations for Champsocephalus gunnari, Notothenia squamifrons, and (to some extent) N. rossii off Kerguelen are determined. The distribution of about 60 species on the South Georgia shelf and the Scotia area is investigated. For selected species, more detailed biological analyses are undertaken. The by- catch of juvenile fish in krill fishery is studied in particular during FIBEX. The existence of deep scattering layers in the Pacific sector is reported. 

Hydroacoustic surveys have indicated areas of largest and most permanent krill concentrations. These areas include the region of the Weddell-Scotia Confluence where the krill biomass exceeds 1000 tonnes/sq. mile. A concept for the formation of krill concentrations is proposed. The classification of different krill aggregations is made. It is proposed that the observed negative correlation between krill and phytoplankton concentrations is likely to be caused by different abiotic factors and does not necessarily reflect a relationship between krill and phytoplankton. The biological analyses of krill have led to a conclusion that the life span of krill is longer than two years. Large variability in the intensity and time of spawning is found while the location of spawning areas remains more or less unchanged. 

The overall surface density of krill biomass in Antarctica was estimated to be 100-400 million tons. 

A review of the Polish fishery and assessment of fish stock biomass off South Georgia is published separately as SC-CAMLR-III/BG/11.

Kock, K.H., G. Duhamel and J.C. Hureau (1982–1984), Review of the biology and present status of exploited Antarctic fish stocks

The biology and present status of exploited Antarctic fish stocks are reviewed on the basis of data available from 148 scientific publications. The development of Antarctic fisheries is depicted in brief. The fisheries are mainly located in the Indian and Atlantic Ocean sectors. To date, catches of 19 species have been recorded in FAO statistics. Apart from the Southern blue whiting and the Rajidae, all species belong to the sub-Channichthyidae ('Icefish'). A short description of the life cycle of 18 of these species is given. Available date on length and age at sexual maturity, natural mortality, age and growth, as well as those relevant to population dynamics and stock assessment, are summarized. 

Catch statistics show that exploitation has followed a similar pattern in the Atlantic and Indian Ocean sectors. Catches rose respectively from a little over 400,000 and 200,000 tonnes within one or two seasons, then declined rapidly after two seasons to less than 5% of the peak years. In general length-frequency distributions from commercial catches show a continuous decrease in the proportion of large individuals in the stock of the main target species. In some cases, these changes are substantial. Catch per unit effort (CPUE) data for the Atlantic Ocean sector are insufficient to reach any definite conclusion. In the Indian Ocean sector, the only information is from the Kerguelen area. The variations of the CPUE for the three main target species in this area are discussed. The calculations of fishing mortality have been made only for the main commercial species that are regularly caught and for which data on length and age are available for several years. Preliminary biomass estimates have been obtained by two independent methods: by production estimates and by the 'swept area' method. 

The authors conclude that, at the present stage, there are significant deficiencies in the information necessary for a scientific assessment of the stocks and for instituting fisheries management of the exploited Antarctic fish. The available data suggest that the stocks are not capable of sustaining the catches taken during the peak years. The results indicate that a fishing mortality slightly larger than the estimated natural mortality, would be the most appropriate level for the exploitation of most Antarctic fish stocks. By-catches of juvenile fish during krill fishing is considered to have a detrimental effect on fish recruitment. 

Ten recommendations are made dealing with the collection and handling of data to enable the best possible scientific advice to be given on fisheries management. 

The complete updated version of this document will be published in the BIOMASS Scientific Series.

Shimadzu, Y. (1982–1984), Comments on the report of the biomass workshop on the Antarctic fish biology (biomass report no. 12)

It was understood that a recommendation to review logbook format from commercial fishery has been achieved at woods Hole meeting this year and that basic biological information and preliminary assessment would be revised and presented at the Annual Meeting.

Beddington, J.R. and I. Everson (1982–1984), The assessment of exploited Antarctic fish stocks

Comments on the status of exploited fish stocks in Antarctica are provided in the context of assessing the methodology used by Kock et al (1984). Attention is drawn to the problems of interpreting the management guidelines of Article II of the Convention for the Conservation of Antarctic Marine Living Resources, that is to ensure that stocks should not fall below the level at which their net productivity is at maximum. The yield per recruit relationship may be viewed as a possible indicator of net productivity. However, attempts to manage on the basis of this relationship have an associated risk of recruitment decline. Some possible solutions to this problem are considered including the Kock et al (1984) approach to adopt Fo.1 as a target fishing mortality. The stochastic nature of recruitment makes the problem more complicated. In general all of these imply the need for a conservative management policy aimed at ensuring stable recruitment. 

The usage of catch per day fishing as unit of CPUE adopted by Kock et al (1984) is discussed. Catch per fishing hour is more likely to reflect the changes in stock abundance than catch per day. Separate analyses of CPUE by target species would be more desirable. 

Certain results of the Kock et al analyses seem clear regardless of whatever methodology might be used. The biomasses of the spawning stocks of several species, particularly Notothenia rossii, Dissostichus eleginoides and Pseudochaenichthys georgianus, have been reduced to levels where their stable recruitment must be in doubt. The status of the noto­theniids gives most cause for concern, as Kock et al report on a number of studies which indicate that there is a substantial by-catch of juvenile nototheniids taken in the krill fishery around South Georgia. 

Accordingly it is clearly necessary on the basis of available evidence to consider the immediate adoption of conservation measures for certain stocks in the convention area.

Slosarczyk, W., J. Sosinski, M. Mucha, K. Skora and A. Kornpowski (1982–1984), A review of Polish fishery and assessment of fish stock biomass off South Georgia

The review deals with the analysis of Polish catches off South Georgia in 1976-1982 and changes observed in the structure and biomass of the exploited fish stocks. Fisheries were carried out by 5-10 factory trawlers operating during the whole year with 2-3 month intervals, mostly in the Antarctic winter. In 1976-77, 1980/81 and 1981/82 the target species was Champsocephalus gunnari. In other years it was mixed fishery. The size of Polish catches depended more on the amount of fishing effort applied rather than on fish availability. The bulk of catches consisted of five species: Champsocephalus gunnari, Chaenocephalus aceratus, Pseudochaenichthys georgianus, Notothenia gibberifrons and N. rossii marrnorata. The statistical data on catch composition submitted by Poland to the FAO were corrected by proper separation of individual species in commercial catches. 

The analyses of catch length and age composition revealed a similar pattern for most of the species. At the beginning of the fishery, the larger and older specimens were dominant in the catches. This situation changed in the late seventies when younger fish began to predominate. The data indicates that the average length and age of C. gunnari and N. rossii marmorata has approached a point at which they reach sexual maturity, and in some cases (e.g. Dissostichus eleginoides) has already gone beyond this point. 

The material collected by observers on commercial vessels was used for fish biomass estimates by the "swept area" method. The estimates were obtained under the assumptions of an even fish distribution and 100% catchability of the trawl, and refer to the one-third section of the island shelf. These assumptions and other sources of errors are discussed. The biomass of fishable stocks in the first season of Polish catches was estimated at about 383,000 tons. Differences in the biomass of C. gunnari were the major factor influencing the magnitude of changes of the estimates in subsequent fishing seasons.

Kalinowski, J. (1982–1984), Distribution and stock of krill, Euphausia superba Dana, in December 1983 and January 1984 before and during the second international biomass experiment I (Sibex 1)

The preliminary results of hydroacoustic investigations conducted aboard the Polish vessel "Professor Siedlecki" (8.XII.1983 - 8.I.1984) are presented. In the first leg of the cruise (8-20.XII.1983) the area between Joinville Is., South Orkney Is., Elephant Is. was covered. The second leg covered the area of the Drake Passage and Bransfield Strait as a part of participation in SIBEX. It was found that total krill stock was much lower than during FIBEX (1981), especially in the Bransfield Strait. Large concentrations of krill were observed only to the north and south-west and south of Elephant Is. and to the north of King George Is.