Studies on southern elephant seal (Mirounga leonina) were carried in Admiralty Bay (King George Island, South Shetland Islands) in summer 1978/1979. In the whole region of Bay the maximum number of 964 elephant seals was noticed on 5 Jan. 1979. The biggest nonbreeding colonies were observed in the mouth region of the Bay. In December the males made up 74% of the whole population, their number decreased to 17% in February. Most individuals belonged to the IV class of age (6—9 years old). Introductory observations of 24 h activity indicates four peaks of activity in the groups observed on the coast. The type of weather has influenced the activity of these groups and the frequency of descending to the sea.

Studies on performance capacity and selectivity of trawls used for industrial fisheries of krill (Euphausia superba) were carried out on the research vessel r/v „Profesor Siedlecki". It has been ascertained that performance capacity of the proposed trawl is about 0.86 and that chiefly small, 22—26 mm-long, krill specimens are passing through the trawl segments made of 12 mm-meshed fabric. This has an essential effect on the age-size structure of caught specimes of krill. It has been stated that the insets of less than 10 mm-mesh fabric in the bags and less than 12 mm-mesh fabric in the bellies of the trawl are practically inexpedient.

Twelve mineral elements and total ash were examined in regard to the possible use as the estimators of digestibility of natural food in Antarctic seals. Four of them: phosphorus, calcium, copper and zinc have proved to give most reliable results. The estimated total dry mass and organic matter digestibilities of fish food in Weddell seals (Leptonychotes weddelli (Lesson)) averaged 82 and 91%, while the corresponding values for krill eaten by crabeaters (Lobodon carcinophagus (Hombron and Jaequinot)) and leopard seals (Hydrourga leptonyx (Blainville)) reached approximately 87 and 91%, respectively.

Total toxicity of two types of mineral oil (from Zakum and Kuwait) was determined with respect to hydrobionts of the Antarctic ecosystem. Crustacean — Euphausia superba proved to be sensitive to hydrocarbon pollution of the sea environment (LC50 x 48 h-1 = 7.62 ppm). Fish — Notothenia rossi marmorata showed much lower sensitivity.