Censuses of wintering seabirds in off-shore areas along the Baltic coast of Sweden : Progress report for 2007

1. Formerly, only limited data were available on the distribution of seabirds in Swedish offshore waters. Some data were obtained in connection with the International Waterfowl Counts in Sweden during the 1970s. Moreover, some offshore banks and parts of the Swedish offshore waters were covered from boats at the first all Baltic survey of seabirds in 1992/932. This report summarises the results of the Swedish part of the second all-Baltic survey of wintering seabirds planned for the winter of 2007.3. Due to problematic weather conditions only part of the area (the waters from the Falsterbo peninsula and southern part of Öresund north to the archipelagos north of Oskarshamn, including the offshore waters around the island of Öland) could be surveyed and the census will continue in the winter of 2008.4. The survey was done from the air, flying transects from the shoreline/outer archipelago out to deep water (> 30 m depth) at fixed distances between the transects, counting all seabirds within specific survey belts.5. The totals for all species counted along the transects are presented in a Table, whereas the results for the seaduck species (Long-tailed Duck, Velvet Scoter, Common Scoter, Eider and Red-breasted Merganser) are presented more fully with some distribution maps and comparisons with earlier surveys.6. The total population of seabirds in the area was estimated to be 148000 individuals, with Long-tailed Duck and Common Scoter being the dominant species with estimated totals of 80000 and 40000, respectively.7. The results from two important wintering areas (North and East of Öland and the south coast of Scania) indicate marked decreases for the Long-tailed Duck.8. The Common Scoter, on the other hand, has increased markedly in the area, but this increase is probably due to a change in distribution for the species. The other three seaduck species discussed more in detail seem to occur in the same numbers as previously recorded.9. The studies undertaken so far very clearly indicate the need for more thorough studies to elucidate the situation for the Long-tailed Duck and to establish whether the marked decreases indicated are due to a more global population decrease or just the result of temporary changes in the distribution. An increased knowledge of the situation for the Long-tailed Duck (the most common species in the Baltic in the winter) is of very high concern given different exploitation plans for the Baltic offshore areas such as localization of wind farms, the Russian - German pipeline etc