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A Comparative Study of Smoltification in Sea Trout( Salmo trutta L.) and Atlantic Salmon ( Salmo salar L.): Seawater Tolerance and Thyroid Hormone Titres

A Comparative Study of Smoltification in Sea Trout( Salmo trutta L.) and Atlantic Salmon ( Salmo... Plasma thyroxine (T 4 ) concentrations and seawater tolerance were measured in one–year–old (S1) and two–year–old (S2) Atlantic salmon ( Salmo salar L.) smolts and S2 sea trout ( Salmo trutta L.) smolts reared under natural temperature and photoperiod regimes in western Ireland (09°34‘W 53°55‘N). The S2 salmon and sea trout showed significant surges in T 4 titres during April–May, which coincided approximately with the period of maximum seawater tolerance. However, no T 4 surges were observed in S1 salmon during the sampling period (February–June). Nevertheless, S1 salmon exhibited a clear increase in seawater tolerance, indicating that they can complete smoltification without an observed elevation in T 4 titres. The seawater tolerance of S2 sea trout progressively increased during the smolt period. The results demonstrate clear differences in seawater tolerance and the development of smoltification between sea trout and salmon. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Biology and Environment: Proceedings of the Royal Irish Academy Royal Irish Academy

A Comparative Study of Smoltification in Sea Trout( Salmo trutta L.) and Atlantic Salmon ( Salmo salar L.): Seawater Tolerance and Thyroid Hormone Titres

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Publisher
Royal Irish Academy
Copyright
Copyright © 2006 RIA
ISSN
0791-7945
eISSN
2009-003X
DOI
10.3318/BIOE.2006.106.1.35
Publisher site
See Article on Publisher Site

Abstract

Plasma thyroxine (T 4 ) concentrations and seawater tolerance were measured in one–year–old (S1) and two–year–old (S2) Atlantic salmon ( Salmo salar L.) smolts and S2 sea trout ( Salmo trutta L.) smolts reared under natural temperature and photoperiod regimes in western Ireland (09°34‘W 53°55‘N). The S2 salmon and sea trout showed significant surges in T 4 titres during April–May, which coincided approximately with the period of maximum seawater tolerance. However, no T 4 surges were observed in S1 salmon during the sampling period (February–June). Nevertheless, S1 salmon exhibited a clear increase in seawater tolerance, indicating that they can complete smoltification without an observed elevation in T 4 titres. The seawater tolerance of S2 sea trout progressively increased during the smolt period. The results demonstrate clear differences in seawater tolerance and the development of smoltification between sea trout and salmon.

Journal

Biology and Environment: Proceedings of the Royal Irish AcademyRoyal Irish Academy

Published: Jan 1, 2006

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