A 15-year Study of the Spatial Distribution of Rutilus rutilus and Perca fluviatilis in Late Summer in Two Shallow Lakes With Contrasting Trophic State

Roach (Rutilus rutilus) and perch (Perca fluviatilis) are dominant species in northern-temperate lakes of Europe, their relative importance depending on trophic state habitat complexity. We studied the distribution roach over a 15-year period two Danish lakes, Lake Væng, undergoing major changes water clarity macrophyte coverage, permanent turbid Søbygård. used multi-mesh sized gill nets 5-6 different sections following same program all years. Both were evenly distributed among habitats, Væng during Søbygård whole study period. During clear-water however, was uneven density negatively correlated with coverage density, but strength relationship differed between small (≤ 8 cm for <10 perch) larger fish. Our results suggest that key determining these shallow lakes.