Detailed surveys in the Baltic Sea for the period 2007-2009 revealed that almost 3 million Long-tailed Ducks - Clangula hyemalis - have disappeared from the Baltic Sea since the previous survey in 1992-1993. This sharp decline in numbers resulted in the species being uplisted to Vulnerable.

The Steller’s Eider - Polysticta stelleri - was already listed as Vulnerable but decreased also by 66% in the Baltic Sea, while the fortunes of another sea duck, Velvet Scoter - Melanitta fusca are even worse, with the species now being listed as Endangered.

Overall, the numbers of sea duck species wintering in the Baltic Sea have declined by about 60%. As these sea ducks feed on bivalves (like mussels, clams and oysters, whose populations are also declining and changing in size and distribution), ecosystem changes and global warming are plausible causes.

Factors as predation, diseases and nutritional deficiencies are also present. But the direct threats identified are caused by human activities, eg degradation of the seafloor life caused by fishing as well as oil pollution, by catch in fisheries, hunting and pollution by hazardous chemicals. Not all of these factors are the ultimate reason for the decline but their cumulative effect and the fact that they can be contained by targeted management and legislation makes them important for consideration.