Migration Scales of Catadromous Eels: Diversity and Evolution of Larval Migration Based on Their Distribution, Morphology, and Early Life History

摘要

The long distance migrations of catadromous eels of the genus Anguilla consist of two different components, the larval migration toward their freshwater growth habitats and the adult migration back to the spawning area. These components have been poorly understood due to the critical lack of information about the spawning areas and migration routes. We examined the morphology and otolith microstructure of anguillid leptocephali to estimate the diversity of migration and its evolutionary origins. Leptocephali were examined from the Indo-Pacific region (12 species, N- 759), and glass eels (9 species, N= 653) were obtained from all over the world, including temperate and tropical eels. Tropical eels compose two-thirds of the genus Anguilla, but compared to temperate eels, information has been scarce in tropical eels, especially their leptocephalus larvae (Jespersen 1942).