Migratory history and habitat use by New Zealand freshwater eels <Emphasis Type="Italic">Anguilla dieffenbachii</Emphasis> and <Emphasis Type="Italic">A. australis</Emphasis>, as revealed by otolith microchemistry |
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Authors: | Takaomi Arai Aya Kotake P Mark Lokman Katsumi Tsukamoto |
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Institution: | (1) Otsuchi Marine Research Center, Ocean Research Institute, The University of Tokyo, 2-106-1 Akahama, Otsuchi, Iwate 028-1102, Japan (e-mail: arai@wakame.ori.u-tokyo.ac.jp), JP;(2) Ocean Research Institute, The University of Tokyo, Nakano, Tokyo 164-8639, Japan (e-mail: AK, kesshu@ori.u-tokyo.ac.jp; KT, ktpc@ori.u-tokyo.ac.jp), JP;(3) Department of Marine Science, University of Otago, P.O. Box 56, Dunedin, New Zealand (e-mail: mark.lokman@stonebow.otago.ac.nz), NZ |
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Abstract: | The migratory history of Anguilla dieffenbachii and A. australis, collected from a coastal lake of New Zealand, was examined using analysis of strontium (Sr) and calcium (Ca) concentrations.
Line analysis of Sr : Ca ratios along the life history transect of each otolith showed a peak (Ca. 16–20 × 10−3) between the core and elver mark, which corresponded to the period of their leptocephalus and early glass eel stages in the
ocean. The mean Sr : Ca ratios from the elver mark to the otolith edge indicated that eels had different migratory histories,
which included freshwater residency in some eels (average Sr : Ca ratios, 1.7 × 10−3–2.4 × 10−3) but not in others (average Sr : Ca ratios, 3.1 × 10−3–6.5 × 10−3). These findings suggest that New Zealand freshwater eels have a flexible migration strategy and an ability to adapt to various
habitats and salinities.
Received: November 25, 2002 / Revised: January 17, 2003 / Accepted: January 17, 2003 |
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Keywords: | Anguilla dieffenbachii Anguilla australis Migration Otolith Sr : Ca ratios Marine resident |
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