Study on the relationship between economic input growth in Marine protected areas and environmental governance in the North Pacific Coast of Costa Rica: Based on reef fish assemblages

Abstract

Reef fish communities under fishing pressure often experience reduced biomass, abundance, and altered size structure. The establishment of marine protected areas (MPAs) can help mitigate these declines. However, the success of MPAs, especially in developing countries with financial and socioeconomic challenges, largely hinges on effective enforcement. This study utilized underwater visual surveys (UVS) and baited remote underwater video stations (BRUVS) to evaluate population density, size distribution, and biomass of both economically valuable (e.g., target and ornamental species) and ecologically important (e.g., small/large predators and herbivores) fish groups within and outside a no-take MPA on the northern Pacific coast of Costa Rica.The results indicated that protective measures did not significantly affect the biomass of economically valuable fish species. However, there were notable differences in fish abundance and size distribution between no-take zones (where fishing is prohibited) and open-fishing zones. This suggests that, despite potential illegal fishing activities within the MPA, certain fish community components benefit from the protective measures.Specifically, herbivores and ornamental fish, which are often targeted by artisanal compressor fishing and the aquarium trade, exhibited higher biomass and abundance levels within the MPA. Additionally, significant shark species such as Galeocerdo cuvier, Carcharhinus leucas, and Carcharhinus limbatus were exclusively found within the MPA.The study also highlighted the crucial role of habitat quality, particularly high coral cover, in enhancing the biomass of ornamental fish.This research contributes to the growing body of evidence that MPAs, even with limited enforcement, consistently offer ecological benefits for reef fish communities