CCAMLR

The study of diseases in wild penguins is important for the identification of endemic diseases and the detection of exotic diseases should these occur. It is also important in the understanding of the degree to which disease may be expected to influence the results of biological studies. Results may be confounded and interpretation made difficult by both the transient and long term presence of disease particularly if it is at the sub clinical level. We present here a compilation of diseases and parasites recorded for all species of penguins present both in the wild and in captivity. Normal values for blood biochemistry and haematology are given as an aid to the identification of illness in penguins.

Published in: Korean Journal of Polar Research, 4(2): 79-96 (1993)

This paper draws attention to the possible implications for the CCAMLR Ecosystem Monitoring Program (CEMP) of infectious and parasitic disease among penguin being monitored and to this end present a summary of all such diseases of penguin species found in the Antarctic and sub-Antarctic. Haematological and biochemical values for healthy penguins which may be of use in diagnosis are presented also. Just as environmental factors are being examined for their possible effect on the variables being monitored we suggest that health of monitored species also should be considered in CEMP.

Thirty eight regurgitated casts collected in a colony at Half-moon Island, South Shetland Islands, during January and February 1993, were analyzed to determine the importance of fish in the diet of the blue-eyed shag Phalacrocorax atriceps bransfieldensis. Fish species were identified by means of otoliths found in the casts. The size and weight of the fish were estimated from the otolith lengths, using equations derived from data on local populations. Fish remains were present in all casts, comprising 91% of prey items. From the 937 otoliths found, 562 fish were represented and 524 were assigned to 5 demersal benthic species: Nototheniops nudifrons, Harpagifer antarcticus, Trematomus newnesi, Notothenia coriiceps and Gobionotothen gibberifrons. N. nudifrons was the most frequent (68.4%) and important by number (37.9%), whereas N. coriiceps prevailed in mass (35.8%). With the exception of G. gibberifrons, the fish species (and their size and age ranges) were identical to those found in a similar study at Duthoit Point, Nelson Island. However, the relative importance of the fish species in the diet differed between shags from the two areas.

Forty stomach contents of the blue eyed shag Phalacrocorax bransfieldensis were sampled at Nelson Island, South Shetland Islands, in January 1994. The analysis of the diet showed that fish were by far the main component, followed by octopods, polychaetes and gammarids. Notothenia coriiceps, predominated in frequency (58%) and in weight (65%), whereas Nototheniops nudifrons was the most important by number (47%) . The comparison with data published on pellets analysis of shags from the same colony gave similar results. However, although the methodology used in the present study requires more time in the field, it reduces the errors arose from the examination of regurgitated casts, like erosion by digestion or loss of the otoliths through the gastrointestinal tract. The analysis of the stomach contents is complemented with information on shags’ foraging trips, obtained in the field by film records.

Local fish species were used to feed a captive blue-eyed shag Phalacrocorax atriceps bransfieldensis during 45 days of the austral summer at Jubany Station, King George Island, South Shetland Islands. The otoliths identified in pellets were affected by the digestive process and consequently the fish species were differentialy underrepresented in number and size (length/mass). Except Gobionotothen gibberifrons and Nototheniops nudifrons all the species were underestimated in number (N. rossii fully). G. gibberifrons was also the less affected is size, being Pagothenia bernachii, N. nudifrons, Trematomus newnesi and Notothenia coriiceps largely underestimated. Thus, preliminary correction factors were obtained to improve the accuracy of weight estimations of fish ingested, calculated y means of equations based on otolith-lengths. The shag produced a total of 16 pellets, with a frequency of 1 every 2.5 days. It ingested willingly a mean ration equivalent to 31% of its mass, which is a higher energy requirement than that experimentally observed in other not antarctic shag species. Algae and ploychaetes were found in the casts and came from the fish stomachs. Therefore, their importance in the diet of the blue-eyed shag could have been overestimated in previous studies.

Water temperature and krill abundance in Maxwell Bay, Antarctica, were examined using Pygoscelid penguins carrying appropriate sensors linked to position-determining devices. Fifty-three foraging trips from 49 penguins indicated that during December 1991 and January 1992 the temperature in the top 100 m of the water column was highest in the western section of the Bay which concurred with higher krill abundance as determined by a catch per unit effort index. This work demonstrates that abiotic and biotic features of the environment can be studied using animals to transport probes to the study site, provided information is given on the position of the animals when measurements are made.

Published in Journal of Animal Ecology (1994) 63, 000-000