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.

We applied discriminant analysis to morphometric data from Chinstrap Penguins (Pygoscelis antarctica) to obtain a function that can be used to predict sex. The function correctly classified 95% of 55 individuals. Bill depth was the most important discriminating variable, with males having deeper bills.

Discriminant analysis can use morphometric differences between known male and female birds to predict the sex of unknown individuals in field studies. Geographic variation in size and shape often limits the predictive value of a discriminant function to the population from which it was derived. Specific discriminant functions for populations of five species of fulmarine petrels (Northern Fulmar, Fulmarus glacialis; Southern Fulmar, F. glacialoides; Antarctic Petrel, Thalassoica antarctica; Cape Petrel, Daption capense; and Snow Petrel, Pagodroma nivea) assigned 81 to 98% of birds in the samples to the correct sex, but the validity of each discriminant applied to alternative populations remained questionable. Our approach to overcome this limitation is to combine data from the different species into a single discriminant. Adequate performance of this generalized discriminant in samples of different species shows its validity for use in other populations of any of these species. The generalized function calculates the discriminant scores for individual fulmarine petrels as: Y = HL + 2.38BD + 0.41TL – 0.21CL, where HL is head length, BD is bill depth, TL is tarsus length and CL is bill length (measurements in millimeters). The cut point to split sexes is different in each sample and may be calculated directly from discriminant scores, without reference to sexed birds, by using a maximum-likelihood method. Depending on species, the generalized method results in 84 to 97% correct classifications and can be applied to other populations of fulmarine petrels without requiring samples of birds of known sex.

Observations of nesting Adélie Penguins (Pygoscelis adeliae) were made at Ardley Island during spring 1990 when snow cover was unusually thick at some subcolony sites. Adélie Penguins at these sites had to delay egg laying until the snow melted. Maximum length of fasting periods comprising pre-breeding and incubation was 50 days. Long fasting seemed to have no detrimental effect on breeding. Furthermore, there was no relationship between penguin arrival mass and duration of fast. Even birds with small mass had sufficient reserves to undergo long fasting periods.
In spring 1990, when we started with a monitoring study for CEMP (CCAMLR 1990) at Ardley Island, there were still high quantities of snow at the subcolony sites. Adélie Penguins at Ardley Island inhabit both small rocky outcrops and flat, stony hillocks (storm bars). The latter had a distinctly thicker snow cover this time so that the pebbles necessary for nest building were unattainable. Consequently, we observed the behaviour of the penguins in this situation, recorded the laying dates and lengths of fasting periods