Effect of El Nino on migration and larval transport of the Japanese eel (Anguilla japonica)

To clarify the effect of an El Nino on the migration of Japanese eels (Anguilla japonica) in the western North Pacific, differences in migration patterns of eel larvae (leptocephali) in El Nino and non-El Nino years were compared qualitatively through a numerical particle-tracking model. Depending on interannual meridional displacements of the salinity front and bifurcation of the North Equatorial Current, transport of Japanese eel larvae to the Kuroshio was much less than to the Mindanao Current in an El Nino year, and recruitment to coastal habitats in Japan decreased in those years. In non-El Nino years, transport to the Kuroshio was twice as high, and recruitment to coastal habitats increased. If the spawning area of eels was independent of El Nino, transport differences between the two currents were not clear. in the western North Pacific, mesoscale eddies also played a significant role in dispersing eel larvae and prolonging their migration. Consequently, the changing oceanic conditions associated with climate change have resulted in decreased recruitment of Japanese eels, and the eddy effect on migration of the Japanese eel larvae needs to be added into the North Equatorial Current- Kuroshio system.