Interactions between natural and farmed fish populations: information from genetic markers

Studies on genetic changes in farmed fish populations are reviewed, and the potential interactions between wild and farm escapee, and between wild and stocked, fish populations are discussed. Examples of the application of genetic markers in studies concerning survival and reproduction of stocked fish, and genetic and ecological interactions between stocks, are given for brook trout, Salvelinus fontinalis , brown trout, Salmo trutta , rainbow trout, Salmo gairdneri , cod, Gadus morhua , Guadalupe bass, Micropterus treculi , walleye, Stizostedion vitreum vitreum and chum salmon, Oncorhynchus keta . The various studies produced different results. Evidence for successful reproduction and genetic interactions between released and wild stocks have been found in a few cases. Stocked genetic material sometimes had a lower reproductive success than wild material. In one case the transplanted genetic material failed to acclimatize, and was apparently lost from the genepool in two generations. Investigations on the genetic and ecological interactions between wild and farmed populations are of great importance to the preservation of wild populations and their genetic resources.