CCAMLR

Data on blubber thickness measured on 26,751 minke whales caught in the IWC Areas III and IV (0-130 E) by Japanese expeditions from 1971/72 to 1984/85 seasons were analysed. Statistically significant relation were detected between blubber thickness and body length in both mature males and pregnant females. Relation between thickness and foetus length for the latter was also detected. After adjustment for these factors, considerable yearly variations were shown in the thickness in December, in which 12 cases were detected significant out of 24 pairs of successive year comparison. Estimates were obtained for seven years for increment between December and February with a fair agreement between the sexes. Comparison based on the difference between the thickness in December in successive years was proved valid, by which index of krill availability were also esitmated. These two series of estimates of indices were summarized and evaluated. Possible process was discussed to detemine blubber thickness and it was suggested that this parameter is useful to monitor krill availability in the wider geographical range.

Aspects of the reproductive performance of Black-browed, Grey-headed and Wandering Albatrossess, Gentoo and Macaroni Penguins and Antarctic Fur Seals, recorded annually at Bird Island, South Georgia over the last decade (and similar data for Adelie and Chinstrap Penguins at Signy Island, South Orkney Islands) are summarised and reviewed. Breeding success of the Wandering Albatross, which breeds in winter and eats fish and squid, has remained constant, while population size has declined gradually but / significantly. The other species at South Georgia, which breed in summer and for which krill forms a significant proportion of their diet, have shown major fluctuations in some or all of: breeding population size, breeding success, foraging trip duration and offspring growth rate. 1977-78 and 1983-84 were summers of particularly poor reproductive performance by almost all species. Difficulties in provisioning offspring were mainly responsible; circumstantial evidence relating this to reduced availability of krill is discussed. The fluctuations in reproductive performance of the krill-eating, summer-breeding penguins at Signy Island are not synchronised with those at South Georgia. They correlate best (and especially for Chinstraps, which suffered badly in 1980-81 and 1982-83) with the date of ice break-out in late spring. Detailed comparisons between normal and abnormal years are made 'of a range of parameters of albatross, penguin and fur seal biology. The results are reviewed in terms of their suitability for detecting changes in the marine environment that may relate to prey availability and thus be influenced by commercial harvesting.