Study of the downstream migration behavior of Atlantic salmon (Salmo salar) smolts near Poutes dam (Allier, France) using 2D acoustic telemetry

• Main Author: Lemaire, Marine
• Other Authors: AGROCAMPUS OUEST, EDF R&D, Laboratoire national d’hydraulique & environnement, 6 quai Wattier, 78401 Chatou, Stéphane Tétard
• Format: Master Thesis
• Language: French
• Published: HAL CCSD 2015
• Subjects: Smolt; Atlantic salmon; Downtream migration; Poutes dam; 2D acoustic telemetry; Saumon atlantique; Dévalaison; Barrage de Poutès; Télémétrie acoustique 2D; [SDV]Life Sciences [q-bio]; [SDV.SA]Life Sciences [q-bio]/Agricultural sciences; Salmo salar
• Online Access: https://dumas.ccsd.cnrs.fr/dumas-01256599; https://dumas.ccsd.cnrs.fr/dumas-01256599/document; https://dumas.ccsd.cnrs.fr/dumas-01256599/file/2015_Lemaire_Marine_halieutique.pdf

On the Loire-Allier system, the Atlantic salmon smolts (Salmo salar) have to travel through more than 900 km from their growth habitat to enter the ocean. All along their downstream migration, they encounter disruptions of connectivity such as dams and weirs. Poutes dam is on the Allier River at 860 km upstream the estuary. Even if it is equipped with upstream and downstream migration devices, delays in downstream migration remain. In 2013 and 2014, a study about the downstream migration using rotative screw trap upstream Poutes headpond showed that peaks of smolts occur in March whereas the smolts have not been recorded in the bypass until mid-April. Downstream migration is studied here, from upstream Poutes headpond until smolts arrival in the bypass stretch. To be more specific their behavior in the headpond and near the dam is studied. A hundred wild smolts have been followed using acoustic telemetry (with JSAT technology) which allows a 2D positioning. Data show that the dam induces to a delay (transit in the headpond lasts 9.3 days) which can be explained by an hesitation to use the bypass and by a desorientation in the headpond (several attempts to pass through dam and back and forth until the end of the headpond). Data also highlight a seasonal effect in smolts behavior. Around mid-April a change in juvenile behavior is observed: they seem to first move downstream passively and then become active. Sur le système Loire-Allier, les smolts de saumon atlantique (Salmo salar) doivent parcourir plus de 900 km pour rejoindre l’océan depuis leurs habitats de croissance. Tout au long de leur dévalaison, ils rencontrent des ruptures de connectivité telles que des barrages ou des seuils. Situé à 860 km de l’estuaire, le barrage de Poutès, bien qu’équipé de dispositifs permettant la dévalaison et la montaison, induit un retard dans la migration des smolts. En 2013 et 2014, une étude de la dévalaison par tambour rotatif en amont de la retenue de Poutès a montré que des pics migratoires se produisent en mars alors ...