Effects of Introductions of Salmonids into Barren Lakes

Abstract

There are still many lakes in the Palearctic that are barren of fish because of deglaciation history. Early transplantations of fish into such lakes have been documented, and there is a continuous activity of that kind going on for example in Scandinavia and at the North American west coast. Introductions of fish into barren lakes produce noticeable responses in the invertebrate fauna. For example, in a large mountain lake in northern Sweden the fairy shrimp Polyartemia forcipata disappeared after the introduction of Arctic char, and after a period of spectacular growth the fish now tend to get stunted. Changes in the invertebrate fauna after the introduction of new species of fish have been recorded also in many lakes with more complicated species compositions, and also in very large lakes such as Lake Michigan. In the Scandinavian mountain lakes there seems to be a correlation between the composition of fish species and the crustacean plankton. Further studies of introductions into barren lakes should provide a better understanding of predator–prey relations on the whole and, in the long run, of management of fish populations.