To reduce discarding of plaice Pleuronectes platessa in the North Sea flatfish fisheries, the major nursery areas were closed to large trawlers in 1995. The area closed was named the ‘Plaice Box’ (PB) and beam trawl effort fell by over 90% , while the exemption fleets of small flatfish beam trawlers, gill netters targeting sole (Solea solea) and shrimp (Crangon crangon) trawlers increased their effort. The objective of this paper was to evaluate the effectiveness of the PB as an example of a partially closed area established to reduce the discarding and improve the sustainability of the fisheries. Understanding how the PB has affected the ecology and fisheries is important because the PB is considered to be a failure by some stakeholders (especially the fishermen) , has jeopardized the credibility of fisheries science and eroded the support for marine protected areas as effective tools for fisheries management.