Using molecular markers and PCB analysis to infer the origin of the otter ( Lutra lutra ) found on the Knardijk , The Netherlands , in 1998 Hugh

It is presumed that the oUer (Lutra hara) became extinct in the Netherlands in 1988. Since then much effort has been made to restore the freshwater habitat aiming for a return of this top-predator. In 1998 from the central part of the Netherlands an otter was repOlted as a tratlic casualty. It was not known if this individual was a rudiment of the original Dutch population or if it had escaped from the European otter breeding programme. To infer its origin. samples were taken for PCB and DNA analysis. Microsatellite DNA analysis was used to study 81 ottcr samples from thrce populations in Europe and from the breeding programme, including this individual. Cluster analysis indicates that it is unlikely that thi::.. otter originated from the Dutch population and it was with high probability assigned to the breeding programme. The levels of PCBs found in the otter were in the same range as found in the last Dutch otters. but were also similar to levels found in a two ycars old otter that was born and died in captivity. This indicates that PCB levels are not always good indicators for discrimination between captive and wild otters. Key,t'Ords: otter, Lllfra llIlra. DNA PCBs.