Abundance and size structure of a reef shark population within a marine reserve has remained stable for more than a decade

Abstract

Marine reserves, areas protected from ex ploitative anthropogenic processes, are being widely implemented to conserve biodiversity and initiate species recovery. Evidence supports the effectiveness of marine reserves in improving biological attributes such as biodiversity, density, biomass, and body-size for sedentary species or those with r-selected life histories. However, there is limited long-term time series- based information determining the effectiveness of these protected areas for elasmobranchs. Marine reserve effectiveness is commonly evaluated spatially by examining differences in species' biological parameters inside and outside of protective boundaries, which can often mask the occurrence of slow population declines. We used a temporal fishery-independent standardized longline survey at Glover's Reef Mar - ine Reserve, Belize, to monitor long-term population trends in the commercially important Caribbean reef shark Carcharhinus perezi for more than a decade. Linear models were performed to examine whether the factors habitat, year, or their interaction had a significant impact on C. perezi catch per unit effort (CPUE) and on catch demographic composition. Only the factor 'habitat' had a significant influence on CPUE, with the forereef catch significantly higher than in the lagoon. Our results support that the population of Caribbean reef shark at Glover's Reef Marine Reserve appears stable with no significant decline in CPUE or decrease in mean total length detected. This is evidence that marine reserves can be an effective conservation tool for reef-associated shark species.