The Effectiveness of Periodically-Harvested Closures in Meeting Ecological and Socioeconomic Objectives
Available at: https://digitalcommons.calpoly.edu/theses/1652
Date of Award
MS in Biological Sciences
Periodically-harvested fisheries closures (PHCs) are a widespread form of community-based marine spatial management used throughout the Indo-Pacific that also is currently being intensively advocated by conservation organizations for supporting productive fisheries and healthy marine ecosystems. However, local implementation of PHCs has historically been designed to support occasional and efficient exploitation of fish stocks, and not necessarily sustainable fisheries yields and stock conservation. The efficacy of PHCs for achieving their historical cultural objectives of periodicity and efficiency of harvest, simultaneously with achieving contemporary fisheries objectives of fisheries productivity and conservation is undetermined. As a result, the utility of PHCs for supporting contemporary ecosystem-based fisheries management is uncertain given environmental, social and climate change. We developed a biological-economic fisheries model of PHCs to test the value of this form of marine resource management for achieving cultural, fisheries and conservation objectives under sustainable and overfishing scenarios. Our results reveal PHCs to be more effective at achieving the multiple objectives than either non-spatial or fully-protected area management when fisher impact on fish behavior is considered. These results describe the performance of PHCs in general when fish behavior is considered, but does not provide detailed guidance for a particular PHC. Thus, we modified and calibrated our biological-economic fisheries model with empirical data from Nakodu Village on Koro Island in Fiji. The calibrated model allowed us to estimate the effectiveness of Nakodu Village’s current PHC management and predict consequences of future management actions. Results suggest that 5-year PHC closures are optimal for simultaneously achieving fisheries productivity and conservation goals in Nakodu Village. These findings challenge the dogma that PHCs are simply a cultural legacy and warrant further investigation of the utility of PHCs for supporting ecosystem-based management beyond the Indo-Pacific.