Freshwater stream migratory behavior of a silver eel (Anguilla japonica) observed using radio-telemetry system

Abstract

Downstream migratory behavior of a silver eel (Anguilla japonica) is reported using a radio-telemetry system in freshwater reaches (1.6–3.5 km from the river mouth) of the Amikake River, Kagoshima Prefecture, Japan. The silver eel individual, released on 20 October 2020, moved from the freshwater reaches to just downstream of the upper tidal limit on the night of 22 October 2020, during a period of rainfall and rising water level. After remaining near the tidal limits for 1–2 weeks, the silver eel left the study area. Rainfall and rising water level occurred once, just before and after the last eel location record, respectively.