Genetic evaluation of an otter translocation program

The translocation of individuals from one population to another is a common technique in wildlife conservation. However, the outcome of translocation programs is not always properly evaluated and the relative contribution of released individuals to the resident population often remains unknown. We used mitochondrial DNA and autosomal genetic markers to evaluate the success of a translocation program of Eurasian otters (Lutra lutra) in Sweden. The program is regarded as successful because of subsequent population growths. Norwegian otters used for the restocking program could be genetically differentiated from Swedish otters. The releases took place at two sites. In an area south of the first site, where 47 otters were released, no genetic contribution of the introduced animals to the population could be observed and the genetic diversity was lower than before the releases. At the second site, the release of seven otters led to a change in genetic composition of the resident population. The results of this study suggest that the growth of the otter population after the restocking may not be as dependent on the releases as initially suspected. The genetic effects of the translocations appear to be restricted to areas in the immediate vicinity of the release sites.