Influence of some topographical variables on the spatial distribution of lake fish during summer stratification
Brosse, Sébastien; Dauba, Francis; Oberdorff, Thierry; Lek, Sovan
published: Jun 28, 1999
ArtNo. ESP141014503009, Price: 29.00 €
We describe the influence of topographical characteristics on the spatial distribution of the fish community in a mesotrophic reservoir during thermal stratification. Our approach was based on 60 hydroacoustic transects covering the whole Lake Pareloup (France). Each transect was divided into sections 100 m long, constituting a total pattern of 732 sampling units. For each of them, the relationships between topographical characteristics (i.e. depth of the lake, distance from the bank, slope and depth at which the fish were located) and abundance of fishes were studied. Each environmental variable was divided into classes covering its range of variation. The Kruskal-Wallis non-parametric test revealed significant heterogeneities of the data for each of the four variables. A pairwise comparison showed distinct patterns of fish density along the four topographical variables. Principal Component Analysis (PCA) was performed and revealed a fish spatial distribution along a gradient of topographical variables. We established the relationships between fish densities and the four environmental variables, which revealed a clear fish summer habitat preference: the fish (predominantly roach) were mainly located in the surface stratum, in shallow gently sloping littoral areas. The fish distribution may be due to a trade-off between feeding, predation avoidance and endogenous fish requirements.