Abstract
Understanding shark abundance and distribution is critical for effective conservation and management. We assessed the impact of habitat type and proximity to Marine Protected Areas (MPAs) on shark abundance in the Upper Florida Keys. Catch Per Unit Effort (CPUE) was used to estimate shark relative abundance across different habitats, including mangroves, coral reefs, and seagrass beds, exploring how these factors relate to distance from Sanctuary Preservation Areas (SPAs). CPUE was significantly influenced by both sampling date (p < 0.05) and distance from SPAs (p < 0.01), with higher catch rates observed closer to SPAs. Additionally, a comparison of two fishing gear types — longlines and drumlines — revealed no significant variance in CPUE (p = 0.151), between the two gear types. A regional comparison showed no significant differences in shark abundance across the study areas (p = 0.4335). While no significant differences were observed across habitat types (p = 0.9288), there were marked variations in species composition, with Ginglymostoma cirratum (nurse shark) being dominant. The Shannon Diversity Index indicated low species diversity (0.615), with uneven distribution of individuals among species. Size measurements revealed significant variations in total length across species, habitats, and sexes (p < 1e-04), with larger individuals found in offshore reef habitats. These findings emphasize the value of protecting both inshore and offshore habitats and demonstrate the role of MPAs in supporting shark populations, particularly larger species. The study provides insights into the ecological and management considerations necessary for shark conservation in the Florida Keys. Although this study was preliminary in nature, the results offer valuable insights into the ecological dynamics of shark populations in the Florida Keys and provide key considerations for future conservation and management efforts.