Species diversity of freshwater glass eel (Anguilliformes, Anguillidae) of Yilan, Taiwan, with remark on two new records

Abstract

Yilan, Taiwan is the first place in East Asia where freshwater glass eels, the juvenile stage of Anguilla species, arrive by ocean currents. We collected glass eels by fyke net in Lanyang River estuary twice a month from July 2010 to November 2023. By morphological examination and sequencing of the mitochondrial cytochrome b gene, we identified seven species of Anguilla. Most of the glass eels captured in Yilan belonged to the species A. japonica, A. marmorata, and A. bicolor pacifica. Only a few were A. luzonensis, and two A. celebesensis were recorded. In addition, two species were recorded for the time time from Taiwan; A. interioris and A. borneensis were confirmed by cytochrome b sequencing. Thus, we increase the number of Anguilla species in Taiwan from five to seven.