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Effect of temperature and current manipulation on smolting in Chinook salmon (Oncorhynchus tshawytscha): the relationship between migratory behaviour and physiological development

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Abstract:

We investigated the role of temperature and current on migration pattern and physiological change in Chinook salmon (Oncorhynchus tshawytscha) smolts. Chinook parr were implanted with passive integrated transponder tags and placed in circular tanks with directional current. Paired antennas in each tank allowed for the monitoring of movements with or against the current. Two temperature regimes, naturally increasing (warm) and constant (cool), were combined with high current (>0.5m·s–1) and low current (<0.1m·s–1) to create four experimental treatments. At 2-week intervals, fish were sampled for gill Na+,K+-ATPase activity and plasma cortisol concentration. Increasing temperature resulted in an earlier peak in movement than colder groups and showed a distinct peak in gill Na+,K+-ATPase activity. Current did not influence physiological parameters associated with smolting and was not found to initiate movement; movement was related to accumulated thermal units (ATU). The presence of a strong, directional current, however, resulted in a period of more defined movement, suggesting a possible influence of current once migration is underway. A combination of either photoperiod or ATU with gill Na+,K+-ATPase was most strongly linked to movement. ATU was also found to be more strongly correlated with the smolting process than daily mean temperature.

Nous étudions le rôle de la température et du courant sur le patron de migration et le changement physiologique chez les saumoneaux du saumon Chinook (Oncorhynchus tshawytscha). Des tacons munis par implantation d’une étiquette à transpondeur intégré passif ont été placés dans des aquariums circulaires avec un courant directionnel. Deux régimes thermiques, de réchauffement naturel (chaud) et de température constante (frais), combinés à un courant fort (>0,5m·s–1) et un courant faible (<0,1m·s–1), ont produit quatre conditions expérimentales. À des intervalles de deux semaines, nous avons fait des mesures de l’activité de la Na+,K+-ATPase de la branchie et de la concentration plasmatique de cortisol. Une augmentation de la température entraîne un pic plus précoce dans le mouvement que celui des groupes gardés à la fraîcheur et il y a un net pic dans l’activité de la Na+,K+-ATPase. Le courant n’affecte pas les variables physiologiques associées à la transformation en saumoneau et ne semble pas initier le mouvement, le mouvement étant associé aux unités thermiques accumulées (ATU). Cependant, la présence d’un courant fort et directionnel entraîne une période de mouvement mieux défini, ce qui laisse croire à une influence possible du courant, une fois la migration entreprise. Il y a un très fort lien entre, d’une part, une combinaison de la photopériode, ou alors des ATU, avec la Na+,K+-ATPase de la branchie et, d’autre part, le mouvement. Les ATU sont plus fortement reliées au processus de transformation en saumoneau que la température journalière moyenne.

Document Type: Research Article

Publication date: 2010-01-01

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  • Published continuously since 1901 (under various titles), this monthly journal is the primary publishing vehicle for the multidisciplinary field of aquatic sciences. It publishes perspectives (syntheses, critiques, and re-evaluations), discussions (comments and replies), articles, and rapid communications, relating to current research on cells, organisms, populations, ecosystems, or processes that affect aquatic systems. The journal seeks to amplify, modify, question, or redirect accumulated knowledge in the field of fisheries and aquatic science. Occasional supplements are dedicated to single topics or to proceedings of international symposia.
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