Distribution and dispersal of anguillid leptocephali in the western Pacific Ocean revealed by molecular analysis

To determine the distribution and dispersal of leptocephalus larvae of freshwater eels Anguilla spp. in the western Pacific, mitochondrial DNA sequences of 63 larvae were compared with those of adults. All larvae were definitively identified as 1 of the following 6 species: A. marmorata, A. bicolor pacifica, A. reinhardtii, A. australis, A. megastoma or A. japonica. Species-specific patchiness in the distribution of these leptocephali in the western Pacific was apparent. A. marmorata showed 2 different areas of patchiness in both the North and South Pacific (around 15°N and 10°S). Horizontal distributions of anguillid leptocephali are apparently closely related to the freshwater habitat of adults by way of ocean currents. Accordingly, specific dispersal routes of leptocephali from likely spawning areas to their freshwater habitats are suggested.