International Day of the Baltic Harbour Porpoise: Celebrating a Unique Baltic Species

This Sunday, 17 May 2026, marks the International Day of the Baltic Harbour Porpoise (IDBHP), observed each year on the third Sunday of May. Introduced in 2002 by ASCOBANS, the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas, the day exists for one reason: to remind us that the Baltic Sea's only native cetacean is running out of time.

The Baltic Proper harbour porpoise (Phocoena phocoena) is one of the most endangered marine mammal populations in the world. Listed as Critically Endangered by both IUCN[1] and HELCOM[2], the population has declined drastically since the mid-twentieth century. The most recent population-wide estimate, produced through the SAMBAH[3] acoustic monitoring project, placed the number of individuals at approximately 500, a figure that is already over a decade old. 

The SAMBAH II survey, completed in August 2025, is the most important data-gathering effort since the original SAMBAH project. It provides the foundation for updated abundance estimates, distribution maps, and habitat assessments—information urgently needed for conservation planning. In early 2026, the CUMBIAH project (Union for the Conservation Management of Harbour Porpoise Populations in the Baltic Sea and their Habitats) began analyzing these data, which will directly inform future management measures. 

The threats driving this decline are well documented: bycatch in fishing gear remains the most significant pressure, compounded by environmental contaminants, prey depletion, and underwater noise. Strandings and monitoring data add to the concern, pointing to a population under severe pressure and with very limited capacity to withstand further losses.

Conservation frameworks are in place. Under ASCOBANS, countries have committed to the Recovery Plan for Baltic Harbour Porpoises, known as the Jastarnia Plan, and its Steering Group has met annually since 2005 to evaluate progress and to set priorities. At the EU level, the Common Fisheries Policy, the Habitats Directive, and relevant fisheries measures provide further obligations for Member States, while HELCOM’s Baltic Sea Action Plan reinforces regional commitments.

Yet, despite these commitments, implementation has not kept pace with the urgency of the population decline of the Baltic Proper harbour porpoise.

IDBHP is a chance to celebrate the Baltic harbour porpoise and raise its profile. ASCOBANS encourages institutions, organisations, and individuals around the Baltic Sea to mark the day by sharing information and engaging local communities and advocating for measures that reduce threats to this unique population. 

Those organizing IDBHP events are invited to share them with ASCOBANS through the Secretariat’s social media channels https://www.facebook.com/ascobans/ and https://bsky.app/profile/ascobans.bsky.social , or by email at [email protected].

Read more: https://www.ascobans.org/campaign/international-day-baltic-harbour-porpoise 

Infographic: https://www.ascobans.org/publication/infographic-baltic-harbour-porpoise