SUMMARYMPAs are being established worldwide at an increasing rate, however empirical evidence for benefits to mobile species of small areas closed to fishing in temperate regions are little known. Using two North Sea prohibited trawling areas (PTAs) established > 80 years ago, social (fishers’ perceptions), management (fishing effort and compliance) and ecological (fish abundance and size) data were combined to assess the PTAs against their primary societal (conflict resolution) and secondary ecological (stock protection) objectives. Fishers perceived that the PTAs resolved conflicts between static and mobile gear sectors, despite evidence of non-compliance. However, few fishers perceived that they personally benefited from the PTAs. Fish abundance and size data from baited traps (BT) and video (BV) provided no evidence of PTA effects, but trawling effort was a significant predictor of BT fish abundance data and improved the model of BV fish abundance data. The absence of PTA effects on fish is attributable to non-compliance, the high mobility of the fish involved and their continued exploitation within the PTAs using static gear. This points to the need for greater understanding of the behaviour of fishers in relation to closures. The study also highlights the challenges of quantifying possible fishery benefits of small temperate closed areas and questions whether widely advocated fishery benefits may have enhanced initial support, but failure to deliver them may erode faith in such closures as a fisheries management tool.