Analysis of the Atlantic salmon migration dynamic (Salmo salar L.) on two rivers of the Mont-Saint-Michel Bay using hydroacoustic devices

• Main Author: Martignac, François
• Other Authors: Écologie et santé des écosystèmes (ESE), Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Agrocampus Ouest, Dominique Ombredane
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2016
• Subjects: Migration dynamic; Atlantic salmon; hydroacoustic; ecological continuity; high-Frequency recording data; technological innovation; acoustic camera; DIDSON; Dynamique migratoire; saumon atlantique; hydroacoustique; continuité écologique; acquisitions haute fréquence; innovation technologique; caméra acoustique; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Salmo salar
• Online Access: https://tel.archives-ouvertes.fr/tel-01610747; https://tel.archives-ouvertes.fr/tel-01610747/document; https://tel.archives-ouvertes.fr/tel-01610747/file/pdf2star-1507186154-Memoire_FMartignac.pdf

The Atlantic salmon (Salmo salar) is as emblematic as in a global decline, as most of the diadromous fish species. Dams have direct consequences on the river ecological continuity and indirect effects, such as the modification of the hydrological and hydrosedimentary dynamics which affects these populations. In Normandy (France), the Couesnon River’s estuary flood-gate dam has recently been replaced by a new dam proceeding to water releases at low tide stall. This functioning may decrease the salmon abundance or disturb their migration dynamic on this river. To study the dam influence, a split-beam echosounder has been settled upstream the dam and has recorded Philippe BOëTpermanently the salmon migrations during the summer period from 2010 to 2014. The hydroacoustic methods, non-intrusive and independent from the turbidity conditions, provide useful information, neither available nor quantifiable with other existing monitoring technics. To evaluate the disturbance of the estuarine damthe migration dynamic of the same species has also been monitored on a nearby river, the Sélune River, whose estuary is free-flowing. The hydroacoustic tool settled on this river, a DIDSON, belongs to the acoustic camera generation and benefits from recent technological improvements. The defined methodologies highlight the advantages and limits of both tools, revealing the information gain brought by the acoustic cameras. A dam functioning influence on the Atlantic salmon migration has been revealed, but no negative impact has been described on the salmon annual recruitment level. This study Le saumon atlantique (Salmo salar) est une espèce tant emblématique que menacée à l’échelle internationale, au même titre que la plupart des espèces de poissons diadromes. La présence de barrages, en entraînant une rupture de la continuité écologique des cours d’eau, participe à ce déclin. Le remplacement du barrage en porte à flot sur l’estuaire du Couesnon (Normandie, France) par un barrage procédant à des lâchers d’eau à l’étale de basse ...