The indicator shows the abundance of seven marine bird species wintering at sea in the North Sea sections of Belgium, the Netherlands and Germany in the assessment period 2015 to 2020 compared against the baseline years (1991 to 2000). The status differed between the seven species assessed and is not related to the functional species group these species belong to.

By-catch of marine birds in fishing gear is an ongoing problem in the North-East Atlantic concerning a number of species. Though methods are developed, a considerable data paucity impairs a comprehensive assessment. In the few cases where an assessment was possible, the threshold value was either achieved or not achieved.

The human maritime activities shipping and offshore wind farming negatively affect marine birds wintering at sea in the south of the Greater North Sea (OSPAR Region II), whereas no negative effect of bottom-trawling fishery was found in the species examined. This pilot assessment helps to identify causes for decline in marine birds and to direct conservation measures appropriately.

Change in species composition within fish communities is assessed through change in the mean maximum length indicator. There is no consistent pattern across the assessed Regions, but long-term decreases to minimum values were found for the North Sea. Mixed patterns of increases and decreases were found within all other Regions.