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Results of the Japanese dedicated cetacean sighting survey in the North Pacific in the 2022 summer season
Taiki Katusumata, Yujin Kim, Shinya Kawabe, Masahiro Yamazaki, Aoi Irie, Kanae Kawajiri, Tatsuya Isoda, Koji Maki, Yasuaki Sasaki and Koji Matsuoka
This paper describes the results of a sighting survey conducted in the North Pacific (between 35°–44°N and 140°–154°E) from 2 August to 30 September 2022. The total searching distance in the research area was 4,485.8 nautical miles. Photo-ID images, biopsy skin samples and satellite tagging were not obtained in this survey because there were no opportunities to conduct these experiments.
A systematic large-scale vessel-based sighting survey was conducted in summer 2022 by Japan to examine the distribution and abundance of large whales in the North Pacific. The research area was set between 35°–44°N and 140°–154°E. The survey was conducted between 2 August and 30 September. The research vessels Yushin-Maru and Kaiyo-Maru No.7 were engaged in the surveys. A total of 4,485.8 n.miles was searched by the passing mode in the research area. Coverage of the searching effort on the planned cruise track line was 87.1%. In total, five large whale species were sighted: fin (4/4), Bryde's (231/252), common minke (2/2), humpback (2/3), and sperm (156/300) whales. Photo-ID images, biopsy skin samples and satellite tagging were not obtained in this survey, because there were no opportunities to conduct these experiments. The highlight of this survey was that the SST in the northern part of the research area was higher than in the previous surveys, and Bryde's whales were distributed farther north in the 2022 survey. The sighting data will contribute to the work on the assessment, management and conservation of large whales in the North Pacific.