BIOLOGIYA MORYA, 2026, Vol. 52, No. 3, pp. 190-201 |
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Interannual and Seasonal Variations in Frequency of Occurrence of Killer Whales, Orcinus orca (Linnaeus, 1758), off the Northeastern Coast of Sakhalin Island, Sea of Okhotsk, in 2008-2021 Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russian Federation E-mail: The frequency of occurrence of the killer whale Orcinus orca (Linnaeus, 1758) off the northeastern coast of Sakhalin Island (Sea of Okhotsk) in 2008-2021 was studied. It was shown that the frequency of occurrence of this cetacean species in the study area exhibited significant seasonal and interannual variations. The maximum median seasonal frequency of killer whale occurrence off the northeastern Sakhalin coast occurred in August-September (0.039 ind./h), which was probably due to the maximum abundance of potential prey during this period. The highest frequency of occurrence of O. orca was recorded in 2012-2014 and 2021 (0.050 ind./h) and significantly differed from other years; the minimum value of this parameter was recorded in 2008 and 2016-2018 (0.016 ind./h). During the remaining six years of the study, the frequency of killer whale occurrence remained at 0.028 ind./h. Key words: killer whale, Orcinus orca, seasonal and interannual frequency of occurrence, northeastern Sakhalin, Sea of Okhotsk. |
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