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 fres hwater eels Anguilla spp. in the western Pacific, mitochondrial DNA sequenc es of 63 larvae were compared with those of adults. All larvae were definit ively identified as 1 of the following 6 species: A. marmorata, A. bicolor pacifica, A. reinhardtii, A. australis, A. megastoma or A. japonica. Specie s-specific patchiness in the distribution of these leptocephali in the west ern Pacific was apparent. A. marmorata showed 2 different areas of patchine ss in both the North and South Pacific (around 15 degrees N and 10 degrees S). Horizontal distributions of anguillid leptocephali are apparently close ly related to the freshwater habitat of adults by way of ocean currents. Ac cordingly, specific dispersal routes of leptocephali from likely spawning a reas to their freshwater habitats are suggested.