Eels at the Edge: Science, Status, and Conservation Concerns

<em>Abstract.</em>—Recent studies on leptocephali and glass eels of anguillid species in the western North Pacific and Indonesian Seas suggest that tropical eels have very different life history characteristics than temperate species, which may have important implications for their conservation and management. Some species in the Indonesian Seas region, such as the Indonesian mottled eel <em>Anguilla celebesensis </em>and the Indonesian longfinned eel <em>A. borneensis</em>, appear to have short spawning migrations and larval durations compared with temperate species. Species such as the Indonesian mottled eel <em>A. celebesensis </em>likely have multiple populations that spawn locally and recruit back to the same area. However, the giant mottled eel <em>A. marmorata </em>appears to have several separate populations in various regions of the Indian Ocean and western North and South Pacific oceans. The northern population of this species probably spawns in the North Equatorial Current region of the western North Pacific and has a long spawning migration more characteristic of temperate species. These findings suggest that the population structures of various tropical and temperate eel species may be quite different. Therefore some tropical anguillid species may require management at regional levels rather than as single panmictic species, as generally has been the case for temperate species.