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 ~94 m and experienced ambient temperatures from 17.8 to 23 °C. Movements appeared to be limited by a 3 °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.
Highlights
Dolphinfish landings in Taiwan are cyclic with peak fluctuations, but catches have declined in coastal areas in recent decades [22]
The objective of this study is to explore movement behaviors, thermal niche, and distribution of fish in this region, compared with those found in Southeastern Taiwan
pop-up satellite archival tags (PSATs) (models X-tag and high rate (HR) X-tag) made by Microwave Telemetry, Columbia, MD, USA were deployed on dolphinfish in the Northern East China Sea
Summary
Dolphinfish migrate in large numbers and traverse different fisheries management areas [6,7,8] but capture rates and abundance appear to be limited by 20 ◦C isotherms [3], sea surface temperature (SST), and seasonal changes in resources available for prey [4,9,10,11,12]. The abundant resources of the Kuroshio Current in the Northwest Pacific Ocean support important fisheries in Taiwan and Japan [17]. Dolphinfish landings in Taiwan are cyclic with peak fluctuations, but catches have declined in coastal areas in recent decades [22]. These cycles may be correlated with oceanographic conditions on recruitment patterns [22]
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