Canada has adopted the United Nations Aichi biodiversity target to protect 10% of coastal and marine areas through marine protected areas or “other effective area-based conservation measures” (OECMs) by 2020. However, the contribution and efficacy of OECMs to biodiversity conservation is not well studied. This paper examines whether areas closed to fishing on the Scotian Shelf in Atlantic Canada have the potential to serve as OECMs for groundfish conservation and recovery. Based on long-term survey data, results show that three area closures did not enhance population growth rates of the majority of 24 common groundfish species, and additional measures are needed to protect and rebuild severely depleted groundfish. Our study provides impetus toward articulating the criteria of OECMs, improving their design, monitoring, and testing, and placing them within the broader context of sustainable ecosystem-based management.