Results of the Japanese dedicated cetacean sighting survey in the western North Pacific in 2020 summer season
TAIKI KATSUMATA, TAKASHI YOSHIDA, TATSUYA ISODA, FUTOSHI YAMAGUCHI, MASAHIRO YAMAZAKI, MEGUMI TAKAHASHI, HARUNA MURATA AND KOJI MATSUOKA
A systematic large-scale vessel-based sighting survey was conducted in 2020 by Japan to examine the distribution and abundance of large whales in the western North Pacific. The research area was set between 30oN-48oN and 140oE-170oE. The survey was conducted between 31 July and 24 September. The research vessels Yushin-Maru, Yushin-Maru No.3 and Kaiyo-Maru No.7 were engaged in the surveys. A total of 6,698.6 n.miles was searched by the passing mode in the research area. Coverage of the searching efforts on the planned cruise track line was 89.5%. In total, seven large whale species including blue (4 schools/4 individuals), fin (58/76), sei (52/63), Bryde?s (298/391), common minke (2/2), humpback (2/2) and sperm (224/574) whales were sighted during the whole research. Photo-ID images were collected from blue (4 individuals), humpback (1), and killer (4) whales. Biopsy skin samples using a Larsen system were collected from blue (n=2), fin (n=12), sei (n=15) and humpback (n=2) whales. Satellite tags were attached on fin (n=6), sei (n=11) whales. The sighting data will contribute to the work on management and conservation of large whales.