Suivi de la migration d'avalaison des anguilles par une conduite de débit réservé - Archive ouverte HAL
Article Dans Une Revue Bulletin Français de la Pêche et de la Pisciculture Année : 2003

Survey of downstream migration of silver eels through discharge pipe on a reservoir dam

Suivi de la migration d'avalaison des anguilles par une conduite de débit réservé

Résumé

The survey of the catadromous migration of eels through a major dam was operated on a pipe insuring a minimal legal discharge of the dam of Bois Joli on the Frémur River (Northern Brittany, France : height, 13.7m ; Volume, 3 Millions of m3). Part of the silver eels used this pipe to emigrate, at the beginning of the downstream run when it represented the only possible downstream passage, but also later when the dam spill enabled a second emigration pathway. Because of the low discharge and of the design of the pipe, it is assumed that eels look for a possible seawards passage. Downstream passage through the pipe was estimated to represent 12% of the downstream run and thus contributes significantly to the transit of silver eels. The contribution of the migration pathways to the migration runs are thought to depend upon the water discharge. Despite its modification to facilitate emigration, the discharge pipe induced the mortality of 11% of migrating silver eels. Mortality was mainly due to abrasion. In many cases, passage through discharge facilities probably induces high or even total mortality depending upon management options, characteristics of the dam and design of the discharge facility. This induced mortality is likely to reduce significantly the production of breeders by river systems. Marked eels that passed the dam before the emigration peak stopped for a few weeks to one year. This observation confirms that reservoirs decreases migrations speed and efficiency. The dams and other works should be managed in order to facilitate passage and reduce mortality of emigrating silver eels.

Dates et versions

hal-04611118 , version 1 (13-06-2024)

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Identifiants

Citer

A. Legault, Anthony Acou, J. Guillouët, E. Feunteun. Suivi de la migration d'avalaison des anguilles par une conduite de débit réservé. Bulletin Français de la Pêche et de la Pisciculture, 2003, 368, pp.43-54. ⟨10.1051/kmae:2003035⟩. ⟨hal-04611118⟩
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