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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13954

Varying reef shark abundance trends inside a marine reserve: evidence of a Caribbean reef shark decline

Kathryn I. Flowers*, Elizabeth A. Babcock, Yannis P. Papastamatiou, Mark E. Bond, Norlan Lamb, Ashbert Miranda, Randolph Nuñez, Jasmine Valentin-Albanese, Gina M. Clementi, Megan C. Kelley, Demian D. Chapman

*Corresponding author:

ABSTRACT: Spatial comparisons of reef shark abundance inside and outside marine protected areas (MPAs) are common and generally report positive MPA effects, yet few studies have tracked abundance trends over long time periods. This is problematic because inside:outside comparisons at a single point in time cannot evaluate whether populations are declining. In Belize, the Caribbean reef shark Carcharhinus perezi is one of the most fished shark species and is more abundant inside MPAs. Although C. perezi relative abundance was stable inside the Glover’s Reef Marine Reserve (GRMR) from 2001 – 2013, using standard baited remote underwater video station surveys we document a decline in C. perezi relative abundance inside the no-take marine reserve from 2009 – 2019. We used a negative binomial generalized linear model and model averaging to test the effect of year, depth, and water temperature on C. perezi and nurse shark Ginglymostoma cirratum relative abundance. While model averaged results indicated a C. perezi decline, G. cirratum remained stable from 2009 – 2019. We hypothesize that the C. perezi decline is a result of fishing along the edge of GRMR, while G. cirratum stability is related to their behaviour and nationwide protection. Given the dynamic nature of fisheries regulations, economic pressures, and site-specific environmental conditions, our results emphasize the need for standardized long-term monitoring of reef sharks inside and around MPAs globally.