IMIS

Over the observation period 50 sightings of at least 280 individuals were recorded. Vast majority of recorded sightings (90%) and individuals (at least 90%) were minke whales (Balaenoptera bonaerensis); humpback whales (Megaptera novaeangliae) were recorded in 5 cases. The largest minke whale groups were recorded in first ten-day period of April. Whales in such groups demonstrated feeding behavior, actively fed on the high density krill aggregations. Probably such aggregations were later fished by vessels on those fishing grounds. Group size varied from 2-3 up to few tens individuals (in the mean 6 ± 9.23 (standard deviation), median 3 individuals). In first ten-day period of April average number of individuals in groups was 12 whales ( ± 15.75 (standard deviation), median 8 individuals). Frequency of occurrence did not correlated with the time of day. Distance to the animals also varied from few meters to 5-7 kilometers. However, direct interactions of whales with the vessel were never recorded. By late April – early May, number of sightings sharply declined, they became sporadic. During that period fast migrations of small whale groups were recorded. Also minke whales demonstrated «nervous» behavior, coming to the surface frequently and moving fast and jerky. Humpback whales were recorded in groups of 2-3 individuals at late April near the South Orkney Islands and early May near the South Shetland Islands.