Occurrence and biological characteristics of glass eels of the Japanese eel Anguilla Japonica at the Cagayan river of Luzon island, Philippines in 2009

Abstract

Background: The Japanese eel Anguilla japonica spawns in the North Equatorial Current in the Philippine Sea and their larvae are transported to their freshwater growth habitats in East Asia. Here we report the occurrence and biological characteristics of glass eels of A. japonica that were collected on northern Luzon Island of the Philippines, the southern limit of the distribution range of this species. Anguillid glass eels recruiting to the Cagayan River estuary in January and February 2009 were collected and identified using their morphological and genetic characteristics. Results: Among the 767 specimens, 52 glass eels collected in January were found to be A. japonica, while the remaining were tropical anguillid species. Age estimation revealed that the glass eels of A. japonica from northern Luzon Island were 147.2 ± 21.3 days old (mean ± sd) with a range between 111 and 185. The hatch dates of these A. japonica suggested that they were derived from at least four spawning events in the 2008 spawning season. Conclusions: Despite the increasing demand on the glass eels for aquaculture in the area where the five anguillid species simultaneously recruit, abundance of each species is yet unknown and investigations will be important for the protection of stock of the anguillids. © 2014 Yoshinaga et al.; licensee Springer.