CCAMLR

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.

This research examines the energy budget of breeding female Antarctic fur seals, both when food was plentiful and when it was scarce. The energy expenditure and change in body mass of lactating female Antarctic fur seals, Arctocephalus gazella, foraging at sea was measured in two years using doubly labeled water at South Georgia Island. There was no difference between years in mass gain, water influx, mass-specific field metabolic rate (FMR), or absolute FMR. Mean at-sea FMR over both years was 9.52 ± 0.55 W/kg (n = 22), a value that is 6.7 times the predicted basal rate but only 1.9 times the FMR measured onshore. Comparable results have been reported for similar-sized northern fur seals.
Krill, the nearly exclusive prey of breeding females, were very scarce in 1984 at South Georgia. Fur seal foraging trips were twice as long in 1984 as in 1985 and total mass-specific energy expended by females during these trips was significantly greater. In addition, females were significantly lighter at parturition in 1984, and both pup mortality and the proportion of pups that died from starvation were double the 1985 values. Female condition at parturition and average foraging-trip duration (i.e., offspring-provisioning rate) appear to reflect prey availability. The similarity between years in mass increase suggests that females do not return to feed their pups until they replenish their own reserves. Antarctic fur seal females may have a limited ability to increase the relative time spent foraging because even in normal years only 5% of their time at sea is spent resting. This contrasts with northern fur seals, Callorhinus ursinus, which typically spend 17% of their time at sea inactive. Apparently these northern seals can increase their foraging effort by increasing the proportion of time spent foraging. This would account for the observed between-year difference in at-sea FMR of C. ursinus while foraging-trip duration remained fairly constant.

STATLANT data reported to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) are used to discern visible trends in catch and effort for the Antarctic krill (Euphausia superba) fishery between 1972/73 and 1987/88. With time the annual krill catch rose gradually to a peak of some 500 000t in 1981/82 before droping to a low level in 1983/84 and stabilising at about 400 000t thereafter. Indications are that in terms of both catch and effort the Soviet and Japanese fisheries in Statistical Sub-areas 48.1, 48.2 and 48.3 dominate exploitation of krill in the CCAMLR Convention Area. Monthly fishing patterns (November to April) are similar in all areas, except in Sub-area 48.3 when fishing is predominantly confined to the winter months (April to August). Trends in the fishery with respect to independent estimates of krill abundance and minke whale (Baleonoptera acutorostrata) catches are discussed.

The paper contains a description of the statistical method used for assessment of the fishing intensity based on actual fishing effort and estimating the initial krill biomass prior to beginning of the fishery. Application of the statistical method for assessment of the initial krill biomass may be realistic provided that the conditions exist, which permit to determine the catchability of the midwater trawl. Two methods were used for this purpose: modelil1ing the probabilistic-statistical theory of fishing traw1s and hydroacoustic method. The latter method is based on comparison of the catch and the krill biomass estimate produced by the echo integrating apparatus used in the layer fished with the trawl. As applied to the estimate of trawl catchability in the krill fishery, this method is reliable enough as multiple echo location of one and the same shoal is actually out of the question because of poor swimming ability of the krill. The paper suggests the comparison of estimates of krill catchability obtained by the hydroacoustic method and from the models of probabilistic-statistical theory of fishing trawls in order to illustrate the closeness of the two methods. The estimates of the krill biomass resulting from the catch statistics and from the hydroacoustic survey carried out with the use of the echo integrating apparatus are also compared.
Theoretical bases of the calculation methods used are stated in a concised form with references to corresponding literary sources. Basic principles of the statistical method of assessment of the fishing intensity and of the probabilistic-statistical theory of the fishing trawls were developed by Dr. Yu.V.Kadilnikov, Head of the AtlantNIRO Laboratory, with the exception of the methods of standardizing the fishing effort which were worked out by Ivanova V.F. She also made all calculations of the fishing intensity. Characteristics of the krill distribution, computations of trawl catchability, trawl catchability by the hydroacoustic method and krill biomass from the results of the hydroacoustic surveys were estimated by Kasatkina S.M. Trawl parameters were calculated by the senior scientist Myskov A.S.

The results of investigations are presented on selective properties of experimental trawls with a square- and diamond-shaped mesh, on the traumatic rate of krill passed through a mesh and remained in the trawl,on the survival rate. When trawls with a square-shaped mesh were used the highest screening rate was observed in the cod end instead of the belly,the selective properties of the retaining part of the trawl are improved and at the same time the selectivity range of retained fish gets lower, from 14 mm to 9.3 mm.