CCAMLR

Areal cover is calculated for the Statistical Sub-areas (48.1, 48.2 and 48.3) from which the bulk of the commercial krill catch has been taken. Correspondingly, the areas of the following four regions are also calculated - (a) the CCAMLR Convention Area, (b) south of 55°S, (c) containing krill concentrations and (d) south of the mean summer position of the 0°C isotherm using specialised computer software based on a Lambert Geographical Projection. As a secondary step, the mean krill density estimate for the West Atlantic during FIBEX (First International BIOMASS Experiment) is expanded to give a global biomass for krill within each of the above four regions. Similarly, the maximum estimated krill density for the West Atlantic during FIBEX is used to obtain an upper limit for the biomass of krill in the three Statistical Sub-areas being considered. The implications of the results is that the impact being made by the current krill fishery on the krill resource in Sub-areas 48.1, 48.2 and 48.3 merits discussion.

Finfish have been harvested in the Atlantic sector of the Southern Ocean since the end of the 1960s mainly by the Soviet Union. Notothenia rossii marmorata ,vas the target species in the first peak years 1969-71 which yielded about 500,000 tonnes in 2 seasons around South Georgia. Since 1975/76 fishing has been mostly directed to the icefish Champsocephalus gunnari. and to a lesser extent Patagonotothen brevicauda guntheri. Catches of C. gunnari were highest at about 240,000, 220,000 and 100,000 tonnes in 1976/77-1977/78, 1982/83-1983/84 and 1986/87-1987/88.
N. rossii marmorata is the species most adversely affected by the fishery. The present stock size around South Georgia is less than 5 % of the level before the fishery started. Recruitment has fallen since the second half of the 1970s. At the present level of recruitment, simulation studies indicate that the stock size will recover slowly, only doubling over a period of 10 years.
Stock size of C. gunnari around South Georgia is largely dependent on the strength of the recruiting yearclass which also forms the bulk of catches in the fishery. Stocks of C. gunnari around the South Orkney Islands and in the Antarctic Peninsula region seem to be heavily depleted by fishing and are in need of conservation measures.
P. br. guntheri is the only species in the fishery which was unregulated until 1988/89. Stock assessment is largely influenced by uncertainties in the determination of the natural mortality. At high levels of M (0.8-0.9) stock size as well as recruitment indicate a downward trend.

An operational management procedure for krill in sub-Areas 48.1 + 48.2 + 4 48.3 requires a basis for the assessment of resource status, and an algorithm for specifying the levels of regulatory mechanisms (e.g. a catch control law) that depends on the results of the assessment. Developing and selecting a procedure requires a basis for the simulation testing of procedures, and an operational definition of CCAMLR Article II to provide criteria against which to assess procedure performance. Suggestions are made under each of these headings. Assessment of resource status is provided by the CPUE "Composite Index" proposed by the Workshop on the krill CPUE simulation study. Annual TAC'S are restricted to an initial ceiling (Cc) for a 5 year period, with a reference CPUE level (CPUEref) calculated as the average CPUE over that time. Thereafter TAC'S may increase by Cr% per annum. However, this increase may be suspended or reversed in any year depending on how many of the previous three year's CPUE values fall below a target level of 0.75 CPUEref. An operating model of kril1 dynamics in the region is developed for simulation testing purposes. A provisional operational interpretation of Article II is proposed: the primary objective is to prevent the expected lowest biomass of krill over a 20 year harvesting period failing below 60% its average unexploited level; subject to this constraint, accumulate catches should be as large as possible without substantial associated probability that TAC reductions may prove necessary during the 20 year period considered. Simulation tests, including one particular test of robustness to the assumptions of the operating model, are carried out to ILLUSTRATE the overall process proposed; for this illustrative exercise, the choice of catch control law parameters would probably lie between (Cc = 1 million tonnes; cr = 15%) and (Cc = 2 mi11ion tonnes: cr = 10%). Suggestions for proceeding with further investigations of possible operationa1 management procedures are made. It is proposed that possible alternative suggestions for such procedures should be made in a similar fashion to that set out in the paper. Suggestions by others for alternative forms and parameter values (or likely ranges) for the krill dynamics operating model used for testing procedures are encouraged.

Available information on key reproductive parameters of Champsocephalus gunnari has been reviewed and discussed in the light of existing conservation measures. Length at first spawning is c. 25 cm around South Georgia and Kerguelen Islands, but c. 35 cm around the South Orkney Islands and in the South Shetland Islands/Antarctic Peninsula region. Around South Georgia spawning takes place from March to May. Spawning around the South Orkney Islands and the South Shetland Islands probably occurs in June/July. Around South Georgia males start their spawning migration earlier than females. Fjords have been reported to be important spawning grounds. Fecundity is highest around South Georgia and Kerguelen but is decreasing towards higher latitudes.
Mesh size regulations presently in force offer very little protection to first spawners around South Georgia and juveniles and first spawners on the other South Atlantic fishing grounds. Spawning activities of Champsocephalus gunnari and those of other exploited species could be best protected by the establishment of permanent closed fishing season from 1 March to the end of each year's meeting of CCAMLR.