呂宋鰻的生物地理分布機制之研究

Mechanism of the Biogeographic Distribution of Anguilla luzonensis

劉璧寧(Bi-Ning Liu)

指導教授 ： 韓玉山

國立臺灣大學/生命科學院/漁業科學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.02483

摘要

呂宋鰻 (Anguilla luzonensis) 又名黃氏鰻 (A. huangi)，於2009年被公布為Anguillag屬中的第十九種鰻魚。根據研究，呂宋鰻的產卵場和鱸鰻 (A. marmorata) 一樣位在北赤道洋流 (NEC) 上，故推測其幼苗的柳葉期與漂送途徑都和鱸鰻很相近。
前人研究已知，這兩種鰻魚在西北太平洋地區的分布，發現鱸鰻主要分布在菲律賓及台灣，最遠還可分布到日本九州南部，高捕獲量在台灣及菲律賓地區主要在前半年；而呂宋鰻主要分布似乎侷限在菲律賓呂宋島，在菲律賓地區，呂宋鰻的高捕獲量在七到九月；在台灣方面，呂宋鰻非常稀少，捕捉量八到十月較其他月份為高。
本研究欲了解: 1.洋流的選擇性漂送，以及2.呂宋鰻平均柳葉期之長短，是否為造成呂宋鰻的生物地理分布明顯位在菲律賓北部的主因。故利用鰻苗耳石日周輪，比較呂宋鰻及鱸鰻在菲律賓、台灣、及日本地區之柳葉期長短。研究結果顯示，距離產卵場越遠，鰻苗的平均柳葉期就越長。利用耳石日周輪天數推算呂宋鰻主力約在每年二到四月產卵，柳葉幼苗隨著北赤道洋流往西漂送，大約在五到七月時到達菲律賓東方海域，此時NEC分叉點偏南，因此柳葉鰻可能大多進到黑潮。由於呂宋鰻的平均柳葉期區間較鱸鰻者為短，再加上洋流系統的選擇性漂送，在這雙重原因之下，使得呂宋鰻在距離較遠的台灣及印度尼西亞地區的分布非常稀少，因而集中在菲律賓北部地區。
關鍵字: 呂宋鰻、產卵場、北赤道洋流、選擇性漂送、柳葉期、日周輪

關鍵字

呂宋鰻 ； 產卵場 ； 北赤道洋流 ； 選擇性漂送 ； 柳葉期 ； 日周輪

並列摘要

Anguilla luzonensis (syn. of A. huangi), a newly identified tropical Anguilla species, has been announced as the 19th species in 2009. According to previous study, A. luzonensis spawns in the North Equatorial Current (NEC) and has similar drifting routes and larval durations to A. marmorata. In theory, both species should have similar biogeographic distributions in Southeast Asia.
In the previous study, compared distribution of A. luzonensis and A. marmorata in the western Pacific regions, A. marmorata was dominant in Philippine, Taiwan and far to the south of Japan. High catches are in the first half of the year in Taiwan and Philippine regions, and A. luzonensis, however, was dominant mainly between July and September in Luzon Island but was rare in Taiwan areas, the high catches of A. luzonesis in Taiwan were mainly in August to October.
The hypothesis of this study (1) the selective transportation of larval A. luzonensis by ocean currents and (2) A. luzonensis have the shorter range of larval duration as their life history traits, are the main reasons why the biogeographic distribution of A. luzonensis are narrowly in the north of Philippine. The present study use the daily increment of glass eels’ otolith to compare the leptocephulus duration of A. marmorata and A. luzonensis in Philippine, Taiwan and Japan regions. The result shows when the farer to eels spawn site, the longer mean leptocephalus duration they have. Using the daily increment to back-calculate, A. luzonensis mainly spawns from February to April, the leptocephulus larval were western drifted by NEC , around May to July arrived to east of the Philippines. It would be preferably transported into the Kuroshio, when the NEC bifurcation latitude reaches its southernmost position. On the other hand, A. luzonensis may have a narrower range of larval duration than that of A. marmorata, and the selective transportation of larval A. luzonensis by oceanic currents, combined these two reasons, it cause the dominated biogeographic distribution of A. luzonensis concentrated in the Luzon Island of Philippines, instead of distributing in Taiwan and Indonesia where the regions were far from NEC bifurcation.
Key words: A. luzonesis, biogeographic distribution, spawn site, North equatorial
current (NEC), selective transportation, leptocephalus duration, daily increments

並列關鍵字

A. luzonensis ； biogeographic distribution ； spawn site ； North equatorial current (NEC) ； selective transportation ； leptocephalus duration ； daily increments

參考文獻

羅敏睿 (2013) Biogeographic distributions of Anguilla luzonensis in Taiwan and the Philippines. 臺灣大學漁業科學研究所碩士論文

熊觀梅 (2013) Effect of ENSO events on larval duration of the Japanese eel (Anguilla japonica). 臺灣大學漁業科學研究所碩士論文

Jellyman DJ, Graynoth E, Francis RICC, Chisnall BL and Beentjes MP (2000) A review ofthe evidence for a decline in the abundance of longfinned eels (Anguilla dieffenbachi) in New Zealand. Ministry of Fisheries Research Project EEL9802, Final Research Report, Auckland.

Kuroki M, Aoyama J, Miller MJ, Arai T, Sugeha HY, Minagawa G and Tsukamoto K (2005) Correspondence between otolith microstructural changes and early life history events in Anguilla marmorata leptocephali and glass eesl. Costal Marine Science 29: 154-161

Aoyama J, Wouthuyzen S, Miller MJ, Inagaki T and Tsukamoto K (2003) Short-distance spawning migration of tropical freshwater eels. The Biological Bulletin 204: 104-108