Distribution and numbers of wintering sea ducks in Swedish offshore Waters.

The first survey of seaducks covering the offshore waters
of the entire Baltic was undertaken in 1992/1993, when,
however, the Swedish waters were covered with relatively
few ship surveys. The second all Baltic survey 2007–2011
included extensive aerial surveys of all Swedish offshore
waters. This paper presents the Swedish data from these
two surveys, supplemented with data from several other but
partial surveys back to the early 1970s. The most numerous
wintering seaduck in the Swedish waters was the Longtailed
Duck Clangula hyemalis with an estimated population
of 1.41 million in 1992/1993, decreasing with 69% to
0.44 million in 2007–2009. Hoburg bank south of Gotland
and the two Midsjö banks accounted for the vast majority
of these ducks. In 2009–2011 only small numbers of scoters
Melanitta fusca and M. nigra were found in Swedish Baltic
waters. The totals for the Eider Somateria molissima and
Red-breasted Merganser Mergus serrator were estimated at
20 000 and 8000, respectively. Larger numbers of Eiders (50
000) and scoters (20 000) were found on the west coast.