Over the last 20 years there has been a large change in the fish community structure in Lille Rostavatn, northern Norway. The relative contribution of the cold-water adapted fish species, Arctic charr (<i>Salvelinus alpinus</i>) and burbot (<i>Lota lota</i>), has distinctly decreased whereas the more temperate-adapted fish species, grayling (<i>Thymallus thymallus</i>) and brown trout (<i>Salmo ...