Satellite tracking of juvenile whale sharks, Rhincodon typus, in the Northwestern Pacific

Abstract

Four juvenile whale sharks, Rhincodon typus were tagged using smart position and temperature transmitting (SPOT2) satellite tags (Wildlife Computers Ltd.) during 2002 and 2004. Transmissions from three males (4.0–4.5 m total length) were successfully received via the Argos satellite system. Two sharks tagged in April had similar routes after being released. They spent the most time in open sea suggesting that it is an important period in the life history of juvenile whale shark in the Northwestern Pacific. In addition, they generally occupied areas where the water temperatures were between 23 and 32 °C. Another shark tagged in November moved above the sea ridges in the first month after being released then migrated along the eastern and northern coastal waters of Taiwan during winter. This shark stayed in the Kuroshio Current region where the water temperature was between 25 and 29 °C, then moved to the edge of the China Coastal Current region where the temperature was low (14–21 °C) and remained there. In the last 15 days of the tracking, the shark shifted to the coastal waters of Taiwan where the temperature was between 17 and 24 °C. Three individuals dive deep into waters where the temperature was 6 °C. The average swimming speed was between 28.3 and 34.6 km/day. They could accelerate to 11–13 km/h for a very short time period. Their movement patterns appeared to be related to boundary currents, which may bring abundant prey, and sharks stayed in waters with higher plankton densities for a longer time. These results provide important information on migratory routes of whale sharks in the Northwestern Pacific, and can be used as a reference for the conservation and management on the world's largest fish.