Relationships between Environmental Characteristics and the Density of Age-0 Eurasian PerchPerca fluviatilisin the Littoral Zone of a Lake: A Nonlinear Approach

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Abstract
We studied the spatial distribution of age-0 Eurasian perch Perca fluviatilis in the littoral area of a large lake (Lake Pareloup, France) using eight environmental variables as habitat descriptors. Nonparametric locally weighted scatterplot smother (Lowess) functions were used to visualize the relationships between spatial distribution and the habitat descriptors. The highest abundance was observed in the transition area between shallow water with dense vegetation cover and unvegetated open water. Habitat use depended on a combination of environmental variables, such as depth, distance from the bank, vegetation cover, and slope of the bank, with abundance exhibiting nonlinear responses to each variable. We hypothesized that these complex responses resulted from a trade-off between searching for food and avoiding predators. We then attempted to build a predictive model of age-0 perch abundance based on the environmental descriptors using an artificial neural network (ANN). The predictive quality ...