We conducted a satellite tagging survey of Japanese eels on Hachijojima Island!

On February 20-23, 2025, we conducted a spawning migration survey using satellite-based pop-up tags on farmed eels on Hachijojima. This is a new initiative in which farmed Japanese eels are transported to Hachijojima and released in coastal areas. Several dozen wild eels have been released along the coast of Japan so far. However, there is still room for improvement in the satellite tags, and only a limited number of them have been able to cross the Kuroshio Current, a strong ocean current, and travel south. It is known that wild eels also live on Hachijojima, about 300 km south of Tokyo Bay. Since the Kuroshio Current is often farther north than Hachijojima, it is thought that if the migration starts from Hachijojima, we will be more likely to observe the migration behavior to spawning grounds far off the coast of Guam. This time we released two eels at Hachijojima.

This research is conducted as a supplementary research project of the International Eel Resources Unit of the Fisheries Agency, led by the Institute of Freshwater Biology of Nagano University, in cooperation with the Atmosphere and Ocean Research Institute of the University of Tokyo, Kyushu University, Shinshu University, Miyazaki Prefecture, Kumamoto Prefecture, and the Fisheries Research Institute. We would like to thank the Hachijo Office of the Island Agriculture, Forestry and Fisheries Research Center for their cooperation in this survey.