魚類耳石微化學的研究與應用(2/3)
Date Issued
2004-07-31
Date
2004-07-31
Author(s)
曾萬年
DOI
922313B002057
Abstract
Pacific tarpon Megalops cyprinoides are widely distributed in the tropical and subtropical
areas of Indo-Pacific Ocean. They spawn in the coastal waters, and then their larvae drift with
currents to estuarine nursery ground approximately 25 -30 days post-hatching. Young Pacific
tarpons were found in variety of environment, such as stream, estuary, inner bays, and mangrove.
The strontium (Sr) concentration is approximately 100 fold higher in sea water than in freshwater,
and Sr/Ca ratios in fish otolith were positively correlated to ambient salinity; thus the ratio was
widely used to study the fish migration between seawater and freshwater. To study the migratory
environmental history of Pacific tarpon, Sr/Ca ratios in otoliths of the fish, including
leptocephalus, young and adult, collected from Gongshytyan Creek and Tadu Creek estuary were
examined by Electron Probe Microanalyzer (EPMA). Sr/Ca ratios in otoliths of the fish at
leptocephalus stage were higher and similar among individuals. But the patterns of Sr/Ca ratios
beyond juvenile stage were very complicated, indicating that the fish after metamorphosis from
leptocephalus may migrate among different environment. If the fish stayed in the estuarine and
marine environment Sr/Ca ratios in otolith were greater than 4‰, but less than 4‰ if they moved
to freshwater. These demonstrated that the migratory environmental history of the tarpon can be
retrieved from the otolith Sr/Ca ratios and the habitat selection of the fish beyond juvenile stage is
facultative.
Subjects
Otolith
Pacific tarpon
Leptocephalus
Sr/Ca ratio
SDGs
Publisher
臺北市：國立臺灣大學漁業科學研究所
Type
journal article
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