This is the ASCOBANS species action plan for what is called Baltic harbour porpoise population primarily inhabiting the Baltic Proper. The population’s abundance has recently been estimated at only 497 individuals (95% CI 80 – 1091) and it has a wide overall distribution range. During the winter season, it stretches from the Åland and Archipelago Seas in the north, to the Southern Baltic Proper in the southwest, and perhaps even further west thereof. In the summer season, however, when calving and mating take place, the majority of the population aggregates at and around the Hoburg’s and Northern and Southern Mid-sea banks in the Baltic Proper. Thus, this area should be considered essential and probably the main breeding area for the Baltic harbour porpoise population. The population’s current status calls for immediate conservation actions. Bycatch in gillnet fisheries has been recognized as the primary threat for the survival of the Baltic harbour porpoise population, although high contaminant levels are also of serious concern. Continuous and impulsive underwater noise and possibly also reduced prey quality are further contributing factors.

The Jastarnia Plan serves as a framework for international collaboration towards achieving ASCOBANS’ interim goal of restoring the population to at least 80 per cent of carrying capacity, and, ultimately, a favourable conservation status for Baltic harbour porpoises.