When the pups three weeks old they are released to the southern Baltic. Twenty-three of them have been released and one male has been kept for breeding. In February 2001, one male and one female pup were born in the breeding ground. They were both released close to Falsterbo in the southern Baltic when three weeks old. Wild-living grey seal males can reach an age of more than twenty years.
Females can reach more than thirty years and give birth to pups at high age.
Anna Roos Forsmarks Kraftgrupp AB and IL Recycling are the main sponsors of the breeding ground. Also Scandinavian Airlines, SAS, supports the project with air transports when releasing pups. The project leader is Anna Roos of the Swedish Museum of Natural History. During the summer of 1997, a young grey seal was placed in a quarantine ground at Forsmark. He has now been moved to Hel marine Station in Poland to support a new project for breeding grey seals in captivity.