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Ichthyological Research

, Volume 49, Issue 4, pp 380–383 | Cite as

Identifying sea-run brown trout, Salmo trutta, using Sr :  Ca ratios of otolith

  • Takaomi Arai
  • Aya Kotake
  • Tomoya Aoyama
  • Hirofumi Hayano
  • Nobuyuki Miyazaki
Short Report

Abstract

 The migratory history of the brown trout, Salmo trutta, collected from Japanese rivers, was examined in terms of strontium (Sr) and calcium (Ca) uptake in the otolith, by means of wavelength dispersive X-ray spectrometry on an electron microprobe. Sea-run (anadromous) and freshwater-resident (nonanadromous) types of S. trutta were found to occur sympatrically. Otolith Sr concentration or Sr : Ca ratios of anadromous S. trutta fluctuated strongly along the life history transect in accordance with the migration (habitat) pattern from sea to freshwater. In contrast, the Sr concentration or the Sr : Ca ratios of nonanadromous fish remained at consistently low levels throughout the otolith. The higher ratios in anadromous S. trutta, in the otolith region from the core to 1500 μm, corresponded to the initial seagoing period, probably reflecting the ambient salinity or the seawater–freshwater gradient in Sr concentration. The findings clearly indicated that otolith Sr : Ca ratios reflected individual life histories, enabling the sea-run S. trutta to be distinguished from the freshwater-resident brown trout.

Key words Salmo trutta Otolith Sr : Ca ratios Migration Anadromy Life history 

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Copyright information

© The Ichthyological Society of Japan 2002

Authors and Affiliations

  • Takaomi Arai
    • 1
  • Aya Kotake
    • 2
  • Tomoya Aoyama
    • 3
  • Hirofumi Hayano
    • 3
  • Nobuyuki Miyazaki
    • 1
  1. 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. 2. Ocean Research Institute, The University of Tokyo, Nakano, Tokyo 164-8639, JapanJP
  3. 3. Hokkaido Fish Hatchery, Eniwa, Hokkaido 061-1433, JapanJP

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