Interchanges and movements of humpback whales in Japanese waters: Okinawa, Ogasawara, Amami, and Hokkaido, using an automated matching system

Humpback whales in the western North Pacific exhibit distinct interchange patterns among Japanese regions, suggesting the existence of multiple subgroups within the population. Using an automated matching system with 80.9% accuracy, researchers analyzed 3,532 fluke photo IDs from Hokkaido, Ogasawara, Amami, and Okinawa. The study found higher interchange indices among Japanese areas compared to previous studies linking Ogasawara/Okinawa to Hawaii or Mexico, indicating shared use of these regions by the same population. High within-region return indices suggest site fidelity, while Hokkaido may serve as a migration corridor between northern feeding and southern breeding grounds. These findings imply at least two geographic groups: one utilizing Ogasawara and the Mariana Archipelago, and another using Amami, Okinawa, and the Philippines, migrating along the Ryukyu and Philippine Trench.

Kobayashi, N., Kondo, S., Tsujii, K., Oki, K., Hida, M., Okabe, H., Yoshikawa, T., Ogawa, R., Lee, C., Higashi, N., Okamoto, R., Ozawa, S., Uchida, S., & Mitani, Y. (2022). Interchanges and movements of humpback whales in Japanese waters: Okinawa, Ogasawara, Amami, and Hokkaido, using an automated matching system. Plos One, 17(11), e0277761. https://doi.org/10.1371/journal.pone.0277761