Number of the Most Abundant Marine Mammals Species in the Vicinities of the Antarctic Peninsula, Scotia Sea, and Powell Basin

Summary

Russian research expeditions in 2020 and 2022 counted marine mammal populations across a 343,000 square kilometer area around the Antarctic Peninsula using visual observation surveys from the research vessel Akademik Mstislav Keldysh. The study estimated populations of approximately 1,200 humpback whales, 2,500 to 2,800 fin whales, and 2,000 to 3,000 Antarctic fur seals in the region. The distribution patterns of these species showed no evidence of competition for food resources either within the same species or between different species, suggesting that krill food supplies were adequate during both survey years.

Map showing marine mammal sightings during January 2020 surveys around the Antarctic Peninsula. The map displays locations where researchers observed different species during visual surveys from the research vessel Akademik Mstislav Keldysh.

Key Findings

In 2020, researchers counted approximately 1,200 humpback whales and 2,800 fin whales across the 343,000 square kilometer survey area.

In 2022, the survey found more than 1,200 humpback whales and approximately 2,500 fin whales in a similar area.

Antarctic fur seal populations remained stable at 2,000 to 3,000 individuals during both survey years.

There was no evidence of food competition either between different whale species or within the same species.

Fin whales showed scattered distribution patterns while humpback whales formed groups across the survey area.

The whale population estimates were consistent with previous Antarctic research studies.

Slightly lower fur seal numbers in 2022 may have been due to different sea ice conditions that year.

Researchers used direct visual observation surveys and mathematical spacing calculations to estimate populations.

Abstract

Observations were conducted from the R/V Akademik Mstislav Keldysh in the Drake Passage, the vicinities of the Antarctic Peninsula, the Scotia Sea, and the northern Weddell Sea during two cruises in January–early March 2020 (cruise 79) and during a single cruise in January–February 2022 (cruise 87). The data make it possible to assess the number of the most abundant sea mammals in the area near the South Shetland Islands, Scotia Sea, and Powell Basin. The 2022 observation area in the Antarctic was located about 150 km east of the 2020 area. The survey area, which was a bit larger than 343 000 km² in January–February 2020, hosted approximately 1200 humpback whales (Megaptera novaeangliae) and 2800 fin whales (Balaenoptera physalus). In 2022, this area hosted approximately 2500 fin whales and again more than 1200 humpback whales. The numbers of the Antarctic fur seals in each season here were assessed at approximately 2000–3000 animals. The type of distribution of these two whale species along the track of the vessel indicated the absence of intra- or interspecies food competition during the austral summers of 2020 and 2022. It was possible to evaluate the total numbers of Antarctic fur seal (Arctocephalus gazella); however, this assessment appeared less precise than the same ones for humpback and fin whales.

Published in

Oceanology

2023

Authors

Kharitonov, S.P., Tretyakov, A.V., Chukmasov, P.V., Chernetsky, A.D., Mischenko, A.L., Konyukhov, N.B., Dmitriev, A.E., Artemyeva, S.M., Pilipenko, G.Yu., Mamaev, M.S., Tretyakova, L.G., Rozhnov, V.V.

Institutions

Severtsov Institute of Ecology and EvolutionShirshov Institute of OceanologyZoological Museum, Moscow State UniversityMoscow State University

Methods

DataField

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