Movements and Habitat Use of Dolphinfish (Coryphaena hippurus) in the East China Sea

Abstract

To refine the regional and global stock and ecological assessments of dolphinfish in fisheries, it is necessary to have information on the species habitat use, fisheries interaction, migration corridors, and on changes in spatial-temporal patterns over their ontogeny. In order to inform management, pop-up satellite archival tags (PSATs) were deployed on dolphinfish (Coryphaena hippurus) in the Northern East China Sea to get data on the movement patterns and habitat utilization of this species in this location. During October-November 2018, four dolphinfish (94-102 cm fork length) were captured by set-nets and PSAT tagged. Tagged dolphinfish retained PSATs for 5-31 days-at-liberty (total 69 days) and linear dispersion from deployment to pop-up locations ranged from 63 to 204 km. According to most probable tracks, tagged fish made primarily northward movements. Tagged fish reached depths of similar to 94 m and experienced ambient temperatures from 17.8 to 23 degrees C. Movements appeared to be limited by a 3 degrees C change relative to sea surface temperature (SST) and were confined to the mixed-layer. Diel diving patterns indicated dolphinfish spent >80% of daytime activity and 40% of nighttime activity near the surface, where variability in diving patterns was more pronounced. The vertical diving patterns showed pronounced changes during dawn and dusk, where dolphinfish mirrored the movements of diel migrating prey organisms. Our preliminary results provide vertical distribution patterns of dolphinfish in a location that supports important fisheries. This information will be useful for management to develop stock assessments which support the sustainable use of this species.