Economic benefits and costs of spatial marine management

The exploitation of fish stocks has increased over time, as have negative impacts to the marine environment from anthropogenic activities like agriculture. A variety of management tools have been developed to address the subsequent deterioration in marine environmental health, including allocation of areas to marine protected areas (MPAs) or to co-management systems such as territorial user rights for fisheries (TURFs). This spatial management can benefit marine biodiversity as well as marine stakeholders such as fishers or tourism operators. However, we do not know (a) what the optimal spatial allocation of marine zones is from a socio-economic perspective, or (b) what influences decisions by fisher organisations about enforcement of marine users’ rights in co-management systems like TURFs.

Four research questions are addressed in this thesis through four papers. The first research question is: What are the challenges in estimating the economic benefits and costs of MPAs? This is addressed in Paper 1, where I review the literature to identify key challenges in estimating economic benefits and costs which are specific to MPAs. I find several key estimation challenges. These challenges included incomplete knowledge of marine ecology, and shortage of existing work which establishes causal links between ecological processes and market benefits. Even more challenging is the need for information about the non-market benefits of MPAs. Finally, although costs are often easier to estimate than benefits, there are more types of costs that are relevant to an economic analysis than are often recognised.

The second research question is: How does the spatially optimal allocation of marine zones change when monitoring and enforcement costs are taken into account, and do the benefits of enforcement outweigh the costs? In a case study in central Chile I find that, in certain scenarios, enforcement costs influenced the optimal spatial allocation of TURFS. Enforced zones are more attractive in areas closer to settlements, where monitoring costs are lower. In most areas in most scenarios, despite the costs of enforcement, enforcing marine user rights is shown to provide positive net benefits for fishers. As conservation targets are made more stringent, some areas would best be converted from TURFs to no-take MPAs.

However, we observe, in reality, that enforcement of marine zones does not always occur in the study area, suggesting foregone benefits for the environment and for fishers. This observation prompted my third research question: Given the demonstrated benefits of enforcement, why are artisanal fishers in Chile choosing not to fully enforce their marine user rights? For my third paper, I survey fishermen in the case study area to identify how the perceived costs and benefits of monitoring, a key enforcement activity, affect fishers’ decision not to monitor. Results show that the main reason fishers do not monitor is because they feel the government does not comply with their own enforcement responsibilities, namely apprehending and punishing poachers.

While investigating fishers’ preferences for monitoring, I identified potential problems in the interpretation of preferences when respondents are inconsistent in their choices. This inconsistency is known as scale heterogeneity. This discovery led to my final research question: How does choice inconsistency (scale heterogeneity) affect interpretation of preferences in discrete choice experiments? In the fourth paper, I present five experimental examples to demonstrate that the interpretation of preferences in discrete choice experiments is sensitive to the impact of scale heterogeneity. Given my findings, it is important to investigate the impact of scale heterogeneity when analysing and interpreting data from models which allow for scale heterogeneity. Future studies that employ scale heterogeneity models should explicitly state scale factors for all samples, choice contexts, and/or latent scale classes, and report rescaled preference parameters for the same. This will allow preferences for spatial marine management, or the non-market benefits associated with this management, to be more accurately assessed and reported.