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Relative abundance, sex ratio and population structure of the Japanese eel Anguilla japonica in the Tanshui River system of northern Taiwan
Author(s) -
Tzeng W.N.,
Cheng P.W.,
Lin F.Y.
Publication year - 1995
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1995.tb05961.x
Subject(s) - japanese eel , japonica , biology , anguillidae , fishery , population , midstream , population structure , abundance (ecology) , sex ratio , population density , anguilla rostrata , ecology , fish <actinopterygii> , botany , demography , fossil fuel , sociology
From the Gong‐Shy‐Tyan (GST) Stream and the Tanshui River, Taiwan, eels ranged from 5.53 cm t.l . (elvers) to 72.5 cm t.l . Anguilla japonica accounted for 93‐99%, A. marmorata 1‐7% and A. bicolor pacifica less than 1% of all eels caught. Mean eel lengths increased from 10 cm t.l . at the downstream sites to 50 cm t.l . at the upstream sites. Females made up 92.8% of the sex‐determined eels. Population density, averaged approximately 0.14 eel m −2 (2.42 g m −2 ) and 0.25 eel m −2 (0.92 g m −2 ) in downstream sites of the GST and Tanshui River, respectively, and decreased substantially with upstream distance. Eels were rarely found in the heavily polluted and dam constructed areas in the midstream site of the Tanshui River.