1. Many marine ecosystems are in critical decline.

2. Iterative assessments of the costs, benefits, and problems associated with conservation initiatives such as marine protected areas (MPAs) can help to improve their effectiveness.

3. The increasingly popular framework of marine spatial planning (MSP) provides opportunities for improving marine management but also needs to avoid similar shortfalls to those identified for MPAs.

4. There is a critical need for realistic presentation of the scope and capacity of MPAs to counteract biodiversity loss, both in isolation and as part of marine spatial planning or other approaches to complementary management.

5. The purpose of this viewpoint is to generate increased momentum to integrate MPAs with other strategies and to recognize the important advances that have been made in MPA planning, implementation and management.