Spatial organisation of European eel (Anguilla anguilla L.) in a small catchment

• Published in: Ecology of Freshwater Fish
• Main Authors: Laffaille, Pascal, Feunteun, Eric, Baisez, Aurore, Robinet, Tony, Acou, Anthony, Legault, Antoine, Lek, Sovan
• Other Authors: Centre National de la Recherche Scientifique - CNRS (FRANCE), Université Toulouse III - Paul Sabatier - UPS (FRANCE), Fish-Pass (FRANCE), Université de Rennes 1 (FRANCE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2003
• Subjects: Ecologie; Environnement; Anguilla anguilla; Spatial organization; Artificial neural networks; Microhabitat; European eel
• Online Access: http://oatao.univ-toulouse.fr/6178/; http://oatao.univ-toulouse.fr/6178/1/Laffaille_6178.pdf; https://doi.org/10.1046/j.1600-0633.2003.00021.x

Modelling governing patterns of European eel (Anguilla anguilla L.) distribution of four eel size classes (< 150 mm, 150-300 mm, 300-450 mm, > 450 mm) in the Frémur basin (North-West France) was done using artificial neural network (ANN) techniques and ecological profiles. Our results demonstrate the high predictive power of the ANN models. Some macro and micro-scale factors, like distance from the sea, depth and flow velocity have the most significant influence in the models. Influence of distance from the sea appears to be very different from the spatial organisation usually described in river systems. In fact, the general tendencies of total eel densities according to distance from the sea showed that densities weakly increase upstream. Another outcome was the variations of habitat preference according to the eel size, even if this species is spread over practically every type of micro-habitat. Small eels were mainly found in shallow habitats with strong abundance of aquatic vegetation, whereas large eels tend to be found in intermediate to high depth with small to intermediate abundance of aquatic vegetation. Finally, we hypothesize that European eels change behaviour and microhabitat characteristic preference around a size of 300 mm.