International eel symposium, 2003 - Quebec August 11, 2003
Poster Session

Spatiotemporal Variations in the Distribution of an eel (Anguilla anguilla, L.) Population in a Small Dammed Catchment (the Frémur)

Acou, A. Equipe Muséologie et Biodiversité, UMR 6553, Campus de Beaulieu, Université de Rennes1, 35042 Rennes cedex, France
Robinet, T. Laboratoire de Biologie et de l'Environnement Marin, Université de la Rochelle, Avenue Michel Crépeau, 17042 La Rochelle cedex, France
Guillouët, J. Fish Pass, Bureau Expert Gestion Piscicole, 8 allée de Guerlédan, ZA Parc rocade sud, 35135 Chantepie, France
Feunteun, E.* Laboratoire de Biologie et de l'Environnement Marin, Université de la Rochelle, Avenue Michel Crépeau, 17042 La Rochelle cedex, France (eric.feunteun@univ-lr.fr).

Presenter email address: anthony.acou AT univ-rennes1.fr

Abstract Text: A sub-population of European eel (Anguilla anguilla) was sampled along the length of a small coastal catchment during summer for seven consecutive years to determine spatiotemporal variations of population characteristics. Two hypothesis were explored: firstly, do habitat preferences vary among sizes and sex; secondly, are habitat preferences and spatial organisations patterns influenced by population parameters (density, size structure and sex ratio). Thus, years, spatial distribution, and habitat characteristics were simultaneously explored using a GLM approach. For each of the four selected length classes (< 150, [151-300], [301-450] and > 451 mm), variations of abundance were better explained by spatial (distance to the sea and to a dam) and temporal (yearly variations of downstream migration) factors than habitat one. Variation in eel size distribution between years was minimal for elvers and yellow eels even if high recruitment variability has been observed since 1996. This suggest that young recruits (i) delayed their upstream migration and/or, (ii) settled in deeper habitats and/or, (iii) had low survival during their migrating stages. Variability of the spatiotemporal distribution patterns was then discussed regarding the development of the river and the saturation of the habitats suggesting that the carrying capacity was reached in the whole river system.