From Physics to Fishers: A Multidisciplinary Approach to Evaluating Indicators of Fishery Benefits of Marine Reserves

Marine reserves are promising tools for fisheries management, and are especially suited for complex, multi-species fisheries. Recent work has focused on the design of reserves to achieve particular management objectives and on defining appropriate indicators for monitoring to determine whether these objectives are being met. In principle, there should be a strong correlation between biological, social and economic indicators that are all correlated with fish abundance and ecosystem health. In practice, different indicators are often inconsistent, and it is common for researchers and fishers to have conflicting opinions on how well reserves are meeting management goals. I suggest that these discrepancies are not necessarily due to conflicting opinions regarding management objectives, but rather that the inherent biases in different sampling schemes may cause different measures of the same parameter to be uncorrelated. For example, scientists tend to sample only snapshots in time and space in randomly chosen locations, while fishers sample over much greater temporal and spatial scales but in non-random locations. Furthermore, marine ecosystems are extremely complex, and failing to account for the full extent of this complexity may lead to erroneous measurement of biological trends. The purpose of this dissertation is to determine the causes of discrepancies between different types of indicators using a multidisciplinary approach. A detailed study of the Glover’s Reef Marine Reserve (GRMR) in Belize provides a basis for comparison. Chapters 2 to 4 of the dissertation focus on understanding how the GRMR has functioned to produce fisheries benefits, and elucidating some of the factors responsible for variation in species’ responses to reserve protection. Chapters 5 to 7 of the dissertation focus on comparisons of different indicators of changes in fish abundances, and explain the circumstances under which indicators may disagree. With a better understanding of the functioning of the GRMR based on both scientific and local knowledge, efforts can be made to develop more appropriate indicators, and these indicators can then be tested for use in other coral reef reserves worldwide