Imprecise and weakly assessed: Evaluating voluntary measures for management of marine protected areas

Voluntary measures may be an alternative or addition to legislation for marine protected areas (MPAs), yet the effectiveness of these measures is rarely analyzed. The application and effectiveness of voluntary measures was reviewed for MPA management in developed nations where complex jurisdictions and legislative processes make voluntary measures appealing to management. Four types of voluntary measures were identified: sacrifice of access, sector- or activity-specific restrictions, voluntary stewardship, and education or outreach, with sector- or activity-specific measures being the most common. Very few papers (only 20 of 144) provided thorough assessments of outcomes or effectiveness of voluntary measures; of these, less than a quarter pointed to successful outcomes in connection with voluntary measures for MPAs or marine conservation more broadly, while half indicated mixed or uncertain results. The main factor to which failure of voluntary measures was attributed was the lack of leverage to discourage non-compliance. Key factors for the success of voluntary measures included community support, cohesive user organizations, and good governance (i.e., leadership, financing, a perception of fairness). To improve efficacy of voluntary measures for MPAs, empirical research is needed to establish effective circumstances where, when, and how voluntary measures can be applied to address management objectives.