Biogeographic distribution of Anguilla luzonensis in Taiwan and Philippines

• Main Authors: Ming-Jui Lo, 羅敏睿
• Other Authors: Yu-San Han
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/97505047391553450043

碩士 === 國立臺灣大學 === 漁業科學研究所 === 101 === Eels have been an important category in aquaculture in East Asian countries. But in recent years the stock size of eels has been in rapid decline. No matter it is eel fry or adult eels, their quantities are much less than the past. All the eel fry needed in eel farming come totally from the catches by fishermen. Under the circumstance of reduced stock size, things like species rehabilitation, emergence of newly farmed eel species or replacement by new species have become one of the targets of the researchers. A. luzonensis, also known as A. huangi, has been announced as the 19th species in 2009. Although this new species has been announced, the relevant research information on its biogeographic distributions, stock size, and biological features is quite meager. As such, this paper aims at exploring the biogeographic distributions and early life history of A. luzonensis. Samples used in this paper are from two parts. The first part is collections of A. luzonensis from 2008 to 2010. The second part is collections of A. marmorata from 1984 to 2008. The demarcation is the time (2008) when A. luzonensis was discovered. Collections made after 2008 are mostly in places in the Philippines, Taiwan, and Indonesia. Prior to 2008, they were mainly collected in Taiwan. After that, pattern identification is employed to establish the biological features and biogeographic distributions of A. luzonensis. The results indicate that high catches of A. luzonensis are mainly in the three months of July, August, and September in the Philippines. In the three months the amount of A. luzonensis caught is even more than that of A. marmorata. In Taiwan, A. luzonensis is extremely rare and from September to January more catches are seen. As to Indonesia, there is no finding yet. In terms of biological patterns and features, we can see that there is an overlap that leads to possible misidentifications from the comparison of fin difference ratio in A. marmorata and A. luzonensis. The associated change of pigmentation of A. luzonensis and its total length shows resemblance in the run chart compared to that of A. japonica in that there is a slow downward slope or even a standstill from VA to VIA3 stages. The comparisons of months with total lengths showed no obvious upward or downward trend. In this paper we have established the biogeographic distributions of A. luzonensis in the Philippines primarily.