Migration delays and mortality of adult Atlantic salmon (Salmo salar) en route to spawning grounds on the River Allier, France

During summer periods when water temperatures are high, Atlantic salmon Salmo salar are forced to halt their migration. This phenomenon was observed in our study in the River Allier in France. Between 200 and 1200 S. salar have come to spawn in the River Allier every year for the last 2 decades, but...

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Bibliographic Details
Published in:Endangered Species Research
Main Authors: Baisez, Aurore, Bach, Jean-Michel, Leon, Cédric, Parouty, Thimothé, Terrade, Renaud, Hoffmann, Marion, Laffaille, Pascal
Other Authors: Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Logrami (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Laboratoire Ecologie fonctionnelle et Environnement - EcoLab (Toulouse, France)
Format: Article in Journal/Newspaper
Language:English
Published: Inter-Research Science Center 2011
Subjects:
Climatologie
Management
Water temperature
Climate change
Long river
Atlantic salmon
Salmo salar
Online Access:https://oatao.univ-toulouse.fr/6228/
https://oatao.univ-toulouse.fr/6228/1/Terrade_6228.pdf
https://doi.org/10.3354/esr00384
Description
Summary:During summer periods when water temperatures are high, Atlantic salmon Salmo salar are forced to halt their migration. This phenomenon was observed in our study in the River Allier in France. Between 200 and 1200 S. salar have come to spawn in the River Allier every year for the last 2 decades, but the population has suffered a severe decline. In 2009, 30 individuals were radio tracked; of these, 11 died during the summer period, while the other 19 resumed their migration in the fall. This mortality level was higher amongst the S. salar that arrived towards the end of the migration period, i.e. those individuals that tended to spend the summer in the lower, warmer stretch of the river. In view of the continuing rise in freshwater temperatures, measures are urgently needed to reduce the impact of increased temperatures on fish in the River Allier. This could be achieved by (1) promoting summer delays further upstream by making it easier for fish to pass through dams and (2) by protecting the spawning adults, particularly in the locations of summer halt. This study is consistent with a growing body of literature that suggests that climate change could have devastating effects on the upstream migration phase of anadromous salmonids.

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