Differential Production and Condition Indices of Premigrant Eels in Two Small Atlantic Coastal Catchments of France

• Main Authors: Acou, Anthony, Gabriel, Gaelle, Laffaille, Pascal, Feunteun, Eric
• Other Authors: ERT 52 Université de Rennes 1, Laboratoire de Biologie et de l'Environnement Marin, Université de la Rochelle, Fish Pass, American Fisheries Society, Casselman J.M. and Cairns D.K. (eds)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2003
• Subjects: [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Canada; Anguilla anguilla
• Online Access: https://hal.science/hal-04612765; https://hal.science/hal-04612765/document; https://hal.science/hal-04612765/file/Acou%20et%20al.%202009%20AFS.pdf

International audience This paper assesses potential production of premigrant European eels Anguilla anguilla based on analysis of sedentary eel populations in two small river systems in western France that are in close proximity. Abundance and biological characteristics were evaluated from electrofishing surveys conducted in three years in September and October, before the catadromous migration of silver eels. Mean density and biomass density of the eel population differed greatly between the systems (39 ± 6 ind.100 m-2 and 1352 ± 171 g.100 m-2 in the Frémur River and 3 ± 0.32 ind.100 m-2 and 385 ± 42 g.100 m-2 in the Oir River). Premigrants were dominated by males in the Frémur (85.8%) and by females in the Oir (79.0%). Estimated premigrant biomass density was 4.5-fold higher in the Frémur (254.5 g.100 m-2.year-1) than in the Oir (56.0 g.100 m-2.year-1). Mean Fulton’s K condition factor was significantly higher for both sexes in the Oir (0.20 ± 0.004 and 0.20 ± 0.003 for males and females, respectively) than in the Frémur (0.17 ± 0.002 and 0.17 ± 0.004, respectively). The large differences in densities and biological characteristics of eels from neighboring catchments suggest that huge variability of both quantity and quality of silver eel production can be expected at the scale of the European stock.