No more than 500 harbour porpoises are left in the Baltic Sea. The survival of this species – one of the smallest marine mammals - is in no small part linked to a global treaty supported by UN Environment.

The international Agreement on the Conservation of Small Cetaceans in the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS) celebrates its 25th anniversary this year. The agreement was negotiated under the Convention on Migratory Species, whose secretariat is hosted by UN Environment.

Dolphins and all toothed whales other than the sperm whale are covered by the agreement. The mammals cross international borders and depend therefore on transboundary protection measures.

Numerous dangers threaten individual animals and even entire populations of marine mammals. Bycatch and accidental capture in fishing nets - in which animals are entangled and suffocate - are the foremost dangers. Thousands end up in fishing nets every year. In the long term, the aim is to reduce the mortality rate to zero.

Marine litter causes fatal injuries, while heavy metals and chemical compounds such as polychlorinated biphenyls enter the food chain and accumulate in the animals' bodies. Overfishing makes it a challenge for them to find enough food every day. Dwindling habitats and climate change also make life difficult for the animals - with unpredictable consequences. Noise pollution, also caused by shipping traffic and the construction of offshore installations, deprives marine mammals from their natural habitats and can lead to behavioral changes, physical damage and even death.

Scientific data are a precondition for targeted conservation measures. Over the past 25 years, ASCOBANS has supported many research projects, including a conservation plan for the Baltic harbour porpoise.

Ten European countries have joined ASCOBANS since the agreement was opened for signature at the UN Headquarters in New York on 17 March 1992.  ASCOBANS is now developing strategies to tackle increasing threats to marine mammals off the coasts of Europe. Additional Member States may contribute to this in future.

For more details please contact veronika.lenarz@cms.int