Results of the Japanese dedicated cetacean sighting survey in the western North Pacific in 2019 and 2020
Taiki Katsumata, Isamu Yoshimura, Masaomi Tsunekawa, Shinya Kawabe, Koji Matsuoka
International Whaling Commission
A systematic large-scale vessel-based sighting survey was conducted in 2019 by Japan to examine the distribution and abundance of large whales in the western North Pacific. In this year, as a first attempt, the survey was also conducted in autumn and winter season, which information was very poor so far. The research area was set between 25??N-45??N and 128??E-150??E (a part of sub-areas 2, 6E and 7 for common minke whale???s RMP Implementation). The survey was conducted between 10th May, 2019, and 18th March, 2020, divided into four seasons (Early summer, Late summer, Autumn and Winter season). The research vessels Yushin-Maru, Yushin-Maru No.2, Yushin-Maru No.3 and Kaiyo-Maru No.7 were engaged in the surveys. A total of 9,415.9 n.miles was searched by the passing mode in the research area. Coverage of the searching efforts of the planned cruise track line was 94% for early summer, 86% for late summer, 75% for autumn and 70% for winter survey. In total, seven large whale species including blue (7 schools/8 individuals), fin (51/81), sei (34/66), Bryde???s (161/204), common minke (43/49), humpback (86/130) and sperm (182/481) whales were sighted during whole research. Photo-ID images were collected from blue (8 individuals), humpback (26 individuals), killer (7 individuals) whales. Biopsy skin samples using a Larsen system were collected from blue (n=5), fin (n=7), sei (n=5), common minke (n=1), humpback (n=3) and killer (n=1) whales. Satellite tags were attached on blue (n=1), fin (n=6), sei (n=14) and Bryde???s (n=1) whales. The sighting data will contribute to the work on management and conservation of large whales.