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

Abstract

To clarify the effect of an El Niño on the migration of Japanese eels (Anguilla japonica) in the western North Pacific, differences in migration patterns of eel larvae (leptocephali) in El Niño and non-El Niño 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 Niño year, and recruitment to coastal habitats in Japan decreased in those years. In non-El Niño 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 Niño, 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. © 2007 International Council for the Exploration of the Sea. Published by Oxford Journals. All rights reserved.