Movement behaviour of released wild and farm-raised dolphinfish Coryphaena hippurus tracked by pop-up satellite archival tags

Abstract

To gauge the effectiveness of supplementing native populations of dolphinfish Coryphaena hippurus, we compared farm-raised and wild fish in terms of their horizontal and vertical movement patterns, habitat preferences and thermal niche using pop-up satellite archival tags (PSATs) deployed in two disparate locations: the sub-tropical southeastern coast of Taiwan (wild, n = 4), and temperate Kagoshima Bay, Japan (farm-raised, n = 3). Tagged fish were tracked for periods of 7-40 days, reached depths > 100 m, and experienced temperatures of 15-30 degrees C in Taiwan, and 20-23 degrees C in Kagoshima Bay. Fish tagged in Taiwan made primarily northward movements during early summer but changed to a southward course in early winter. In Kagoshima Bay, tagged fish undertook southward excursions along the coast and movements were confined to the bay. Dolphinfish spent > 50% of their time near the surface and made more extensive vertical movements during the night than during the day; vertical movements were largely confined to the mixed layer. Depth distributions appeared to be limited by a Delta 6 degrees C change in temperature relative to sea surface temperature (i.e., > 90% of movements were within 6 degrees C of the warmest water available).