DISCOVERY OF THE SPAWNING AREA FOR JAPANESE EEL

AT the beginning of this century, the Danish oceanographer Johannes Schmidt outlined the spawning area of Atlantic eels Anguilla spp. in the Sargasso Sea 1,2. But the spawning location of the Japanese eel A. japonica in the Pacific Ocean has eluded researchers for over 60 years. I report here the discovery of their spawning location. By measuring oceanographic conditions and collecting the transparent leaf-like eel larvae, termed leptocephali (see Fig. 1), we determined the Japanese eel spawning area to be in the North Equatorial Current west of the Mariana Islands, at a salinity front near 15-degrees-N, 140-degrees-E. This discovery shows that the key similarity between the spawning sites of Atlantic and Pacific eels is the placement of leptocephali into the major ocean currents that will return them to their juvenile rearing habitats.