Oceana divers found a dozen bodies of grey seal juveniles earlier this week, on the seabed of Bogskär islet, south of the Åland Islands (Finland). The divers, who documented the finding with videos and photos, are part of an Oceana team on board the research vessel Hanse Explorer, currently on a two-month expedition in the Baltic Sea.
The bodies of the animals, approximately 6 months old, were encountered about 20 meters from the coast of the islet, between seven and 11 meters depth. In at least one case, a juvenile seal's body was found together with a dead adult.
Bogskär is an isolated skerry, located 60 kilometers from the nearest coast in the middle of the Baltic Sea, between Finland and Sweden. This islet holds only a small automatic lighthouse with a helicopter landing pad. Bogskär is home to a small colony of grey seals, consisting of two dozen individuals. The rest of the colony appeared to be dynamic and in good health.
The cause of this mortality, with an undoubted impact given the small size of the colony and the age of the individuals concerned, has not yet been determined. The animals did not appear to have suffered from malnutrition or any apparent physical damage – there was no evidence of gunshots, traumatic injuries, or marks from fishing gear on their bodies. However, the hypothesis of entanglement and drowning of inexperienced young individuals in gillnets, which were subsequently removed without trace, cannot be ruled out. Baltic Sea experts consulted by Oceana say that poisoning by some type of toxic algae should be ruled out, given the season, but a viral epidemic could be one potential cause.
The Oceana team has contacted several Finnish seal experts in order to determine the cause of death and to try to prevent such incidents in the future.
Oceana is undertaking an expedition in the Baltic Sea, for the second consecutive year, with the aim of gathering information to reinforce its proposals to expand the network of marine protected areas in the sea by up to 30%, and to contribute to better fisheries management in the region, ending overfishing and illegal fishing.
"Baltic Sea marine environments are badly damaged. A situation such as the one documented by Oceana in Bogskär needs to be investigated, in order to identify the cause of these deaths”, said Hanna Paulomäki, marine scientist and Oceana Baltic Sea Project manager. “With better management of the entire ecosystem, coupled with continued reduction of the inputs of harmful substances and nutrients, it may be possible to prevent this kind of incident. Other important recovery measures for the Baltic Sea include the creation of an ecologically coherent network of marine protected areas and better management of fish stocks.”
Learn more: Oceana 2012 Baltic Sea Expedition