CCAMLR

The diet of the Antarctic Blue-eyed Shag Phalacrocorax atriceps bransfieldensis was analyzed based on the identification of the prey items in 50 regurgitated casts collected at Duthoit Point, Nelson Island, in February 1991. Benthic organisms, chiefly fish, were found to be the main components. Fish remains occurred in 100% of the casts and represented 68% by number and 90% by weight of the total prey items. From a total of 2112 otoliths found, 1176 fish specimens were identified belonging to 4 demersal-benthic species: Harpagifer antarcticus, Notothenia neglecta, Nototheniops nudifrons and Trematomus newnesi. For these populations in the study area, equations to estimate total length and weight from otolith length are provided. H. antarcticus and N. neglecta were the most frequent (92%) and important by weight (66%) respectively. The cephalopods beaks found in the samples indicate benthic octopods as the second group in importance behind fish. Other invertebrates such as polychaetes, gastropods, bivalves and crustaceans were occasional. The presence of algae and stones in the casts are also discussed and it is suggested that they were ingested accidentally. Our results are in general agreement with those published for other Antarctic localities which indicate that P. atriceps is a benthic coastal feeder, with fish as its main food item.

The use of Shag’s pellets as an appropriate technique to monitor the abundance of littoral fish populations is presented for consideration of the CCAMLR Ecosystem Monitoring Program Working Group. The effectiveness of the method is based on the very good agreement found between the fish species identified by the examinations of otoliths present in regurgitated cast and those regularly sampled with trammel-nets in the same area. Supporting literature for this proposal is also provided.

According to the suggestion made by the Working Group at the CEMP-CCAMLR Meeting held in Viña del Mar (Chile) in August 1992, the information about four complete censuses on the Antarctic fur seal, Arctocephalus gazella, carried out on Cape Shirreff and San Telmo Island, has been compiled with the purpose to clarify its population size, between the Antarctic seasons 1965-66 and 1991-92.
The results show that the population size of this species, in the study area increased during 26 years, form 50 animals counted in January 1966 to 10768 individuals registered in January 1992. It is recommended that future censuses carry out in the Cape Shirreff also include the breeding colonies of San Telmo Island, because these animals are part of the same population. San Telmo Island is a part of the SSSI No 32, designed by the Parties at the XV Antarctic Treaty Consultative Meeting.

A preliminary survey on 2 species of penguins, chinstrap and gentoo was made in the penguin rookery on Barton peninsula near King Sejong Station during 1992/93 breeding season based on the CCAMLR standard method. A total of 96 nests for chinstraps and 121 nests for gentoos were monitored to document breeding chronology and give a measure of breeding success. The nests to be monitored were selected from several locations scattered in the colony. The nests were visited by 2-3 day interval and the change in the nest content were followed. Chicks were hatched out at 50% of the monitored nests on 18. December and 25, December respectively for gentoos and chinstraps. The number of chicks per nest which were raised successfully to the creche stage was used as a measure of breeding success. Of the whole nests which had been checked from the beginning of the observation. 1.45 chinstrap chicks and 1.32 gentoo chicks were raised to the creche stage. Of the nests which were active until the conclusion of the breeding success measurement. 1.67 chinstrap chicks and 1.54 gentoo chicks reached the creche stage. The growth of chicks were measured from the beginning of January to the beginning of February. Chinstraps grew from 0.61 to 3.43 kg and gentoos from 0.56 to 4.59 kg during the measurement period. After the chicks entered late creche stage, they were banded to determine the survival and return rates in the following years. Some suggestion for the further research in this rookery are also mentioned.

The effects of flipper bands, implanted tags/gastric lavage and external instrument attachment on the performance of Adelie penguins were investigated over three seasons at Bechervaise Island, Mac. Robertson Land, Antarctica. The return rates of birds carrying bands and/or implanted electronic transponders were compared to investigate the contribution of bands to bird mortality and to determine rates of band and tag loss. There was a reduction in return rates of birds banded for more than one season, but no evidence of band or tag loss over a single winter. The attachment of satellite tracking devices during the incubation period or for several consecutive trips during chick rearing resulted in increased foraging trip durations and reduced breeding success. Attachment for a single foraging trip post-hatching caused no significant increase in foraging trip durations nor any detectable effect on water turnover rates. No reduction in fledging rates of chicks from nests of stomach lavaged birds was detected over two breeding seasons. The implications of these findings for the CCAMLR Ecosystem Monitoring Program are discussed.

Diving behaviour of Chinstrap penguins (Pygoscelis antarctica) was recorded continuously by time-depth recorders from two adults breeding chicks. Their diving behaviour could be split into bouts by using log frequency method. Organization of dive bouts does not differ within each individuals among days on which dives are recorded but differed between individuals, suggesting that ecological and physiological restrictions differed between the two individuals.