First record of the at-sea swimming speed of a Pacific salmon during its oceanic migration

• Published in: Marine ecology. Progress series (Halstenbek) 2005-04, Vol.291, p.307-312
• Main Authors: Tanaka, Hideji, Naito, Yasuhiko, Davis, Nancy D., Urawa, Shigehiko, Ueda, Hiroshi, Fukuwaka, Masa-aki
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal migration behavior; Animal, plant and microbial ecology; Biological and medical sciences; Fisheries science; Fishery resources; Foraging; Fundamental and applied biological sciences. Psychology; Homing; Marine; Marine fishes; Oceans; Salmon; Sea water ecosystems; Speed; Swimming; Synecology
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps291307

The swimming behavior of the chum salmonOncorhynchus ketawas studied for 53 d of its 67 d oceanic migration from the central Bering Sea to the Japanese coast. We provide the first data on swimming speeds by a homing salmon, recorded at 5 s intervals by a fish-borne time-speed, depth, and temperature logger. Swimming speed rarely exceeded 1.0 m s–1, and horizontal swimming speed was 36.4 ± 15.2 km d–1. Cumulative horizontal swimming distance was approximately 2500 km, equivalent to 90% of the minimum distance between the release and recovery sites (2760 km). Swimming depth and speed peaked around dawn and dusk, and there was a smaller peak around midnight. The fish showed sequential up-and-down movement near the thermocline during daytime. Diurnal patterns of movement suggest that homing chum salmon spend a considerable time foraging, and the strategy is different between daytime and nighttime. Our findings indicate that over large distances of ocean, a homing salmon maintains a strong homeward orientation, but that passive transport by favorable water currents may help the migration.