This publication summarises the findings of the scientific research projects carried out as part of EVA II, the second phase in the evaluation of shellfish fisheries policy in the Zeeland Delta and the Wadden Sea, and relates these findings to other studies on the ecological effects of shellfish fisheries in the Wadden Sea and elsewhere. Four policy questions were at the heart of the project: (1) what are the ecological impacts of shellfish fishery?, (2) did the policies implemented in 1993 achieve their objectives, (3) is current shellfish fishery in line with international obligations, (4) what possibilities for improvement do exist? These policy questions were translated into research questions. Numbers of large shellfish-eating birds declined. Some restoration of seagrass beds occurred, but restoration was not maximal. The area of littoral mussel beds in the Wadden Sea increased to more than 2000 ha, after having disappeared completely in 1990.