||During April 2010 – February 2011, monthly surveys of seabirds and marine mammals were conducted aboard ships engaged in plankton surveys. After many years of little or no effort in far offshore areas of the DCS, this series of surveys provided the first recent ship-based data on seabirds, covering a large area (the entire Dutch Continental Shelf (DCS), including some Belgian and British waters) almost yearround. Due to changes in the design of the survey grid, the use of several ships, spells of bad weather conditions and seasonal differences in the number of daylight hours, the resulting coverage is not evenly spread in space and time. Still, both in terms of areas covered and detailed data gathered, this series of surveys complement the aerial surveys carried out under the same programme Shortlist Masterplan Wind. By surveying beyond the designated areas for round II offshore wind farms on the DCS, areas that might be targeted for round III, such as the shallow Dogger Bank area, got a first boost in T-zero survey effort. From April 2010 till February 2011 11 surveys, totalling to 48 at-sea days, 4610 5-minute counts were conducted over a distance of 9021 km. At a counting strip width of mostly 300 m (200 m over a very small percentage of the counts), this amounts to a total surveyed area of 2706 km2. The surveys have provided rough data on seabird distribution in far offshore areas. In total, 54,593 individuals of 90 bird species were recorded, from which 15,003 individuals of 36 species were recorded within the counting strip. Marine mammals were represented by 616 individuals of seven species, of which 389 individuals of six species were seen within the counting strip. Flying heights were noted for 5044 clusters of individuals, covering 75 species. Behaviour was noted for 1790 (clusters of) individuals. Apart from birds and marine mammals, 352 balloons were counted (of which 164 were within the counting strip) and proved omnipresent in periods of offshore winds. These surveys have identified several issues that should be taken into account in future planning of wind farms. Divers, which are the highest ranked species in terms of sensitivity to wind farms, can be encountered migrating anywhere in offshore waters and sightings of White-billed Divers at the Dogger Bank suggest the existence of a small wintering population of this near-threatened species. In relation to this, potential effects of wind farms on offshore species, such as Northern Fulmars, Atlantic Puffins, Little Auks and cetaceans, are unknown as current wind farms are located near shore where these species do not occur in large numbers.