Modern Research on the Natural Life History of the Japanese Eel Anguilla japonica

Abstract

Life history studies on freshwater eels (Anguilla spp.) date approximately from 1920s. Due to the wide application of new otolith microchemistry and DNA techniques, the knowledge on the life history and ecology of the eel has remarkably increased in the last 15 years. This paper briefly reviews recent findings of the natural life history of the Japanese eel Anguilla japonica, particularly speciation and evolutionary processes, discovery of the spawning ground, DNA microsatellite analysis of population structure, the relationship between sex ratio and population density, and otolith research and its application to migratory environmental history of the species. Recently, populations of Japanese, American and European eels have dramatically decreased, which may relate to overfishing, habitat degradation and global climate change, but the reason for decline is uncertain. Knowledge of life history traits of the eel is essential for effective management and conservation.