We conducted a satellite tagging survey of downstream eels in Lake Hamana and Hachijojima!

On November 23, 2023, we conducted a satellite pop-up tagging study of spawning migration using natural downstream eels (eels that mature and leave for spawning migration to the sea, also known as silver eels due to their body color) from Lake Hamana in Lake Hamana and Hachijojima. In particular, the Hachijojima release is a new initiative in which natural Japanese eels from Lake Hamana are transported to Hachijojima and released in coastal areas. So far, dozens of downstream eels have been released off the coast of Japan, but there is still room for improvement in satellite tagging, and only a limited number of eels have been able to overcome the strong Kuroshio Current and migrate south. It is known that wild eels also live on Hachijojima, about 300 km south of Tokyo Bay, but since the Kuroshio Current is often farther north than Hachijojima, it is thought that if they start their migration from Hachijojima, there is a better chance of observing their migration to spawning grounds far off the coast of Guam. This time, four eels were released in Lake Hamana and five on 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, Little Leonardo, 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.