Comparing activity restriction and habitat creation approaches in Marine Protected Areas (MPAs): a Bayesian belief network model approach.

Abstract

Marine Protected Areas (MPAs) often fail to meet their objectives due to inadequate protection, lack of user compliance and insufficient governance. Whilst typical MPA usage restrictions such as fishing bans are often effective for ecological success, such approaches can fail in meeting socioeconomic objectives due to negative impacts on the livelihoods of those dependent on MPA resources. These issues can further reduce MPA effectiveness through loss of community support. Additionally, suitable governance is often lacking, preventing even well-designed MPAs from operating successfully due to absence of enforcement, cooperation, education and funding. This study considers the concept of habitat creation as an alternative MPA management approach to fishing restrictions, as a potential tool for reducing ecological and socioeconomic trade-offs within MPAs. Through actively restoring existing habitats or introducing low trophic-level aquaculture as novel habitat, benefits to associated marine life can create increased fish stocks and tourism opportunities, with benefit to local economies. Using complex system modelling, this study compares habitat creation with restrictive fishing, in two ecologically and socioeconomically distinct MPAs: Nusa Penida, Indonesia, and Lyme Bay, UK, and considers the appropriate governance required for achieving such approaches. Whilst fishing restrictions at both sites resulted in predicted improvements to ecosystems but reduced employment, deeming them less effective, enhancing existing habitats in Nusa Penida, resulted in predicted reductions in trade-offs, through increased fish stocks, biodiversity, employment, and community support for MPA policies. Novel habitat creation, in the form of mussel farms in Lyme Bay, demonstrated similar positive effects. The need for some fishing restrictions in both scenarios was recognised, however, these were considered to be reduced in comparison to traditional MPA fishing restrictions. While habitat creation proved successful, its feasibility was considered dependent on MPA characteristics such as aquacultural capacity, fishing culture, tourism potential, and alternative employment options. Both habitat creation scenarios demonstrated the opportunity to diverge from limited state funding, through governance that enables private sector funding or carbon/nature credit systems, and active restoration projects demonstrated positive results with less need for legal governance in comparison to restrictive approaches. This study shows support for alternative approaches for marine nature protection, which in some cases may be easier to implement and gain support for than approaches such as fishing restrictions.