Size Changes within a Southeastern United States Coastal Shark Assemblage: 1975–2018

Harvest may have myriad effects on target species, including a change in population size structure. To assess whether shifts occurred among managed coastal species of shark (superorder Selachimorpha), we examined the structure 12 caught during nearly five-decade-long fishery-independent survey conducted Onslow Bay, North Carolina, using standardized longline gear. We evaluated trends mean fork length (FL), median FL, and index maximum FL (L90%) for each separately across time linear regression models. also size-classes (200-mm bins) catch per unit effort over time. For 10 (excluding sample-size-constrained Tiger Shark Galeocerdo cuvier Bull Carcharhinus leucas), metrics indicated decreasing sizes time, although statistical confidence these patterns varied metrics. Strongest support declining was observed Blacknose acronotus (mean L90%), Dusky obscurus (L90%), Smooth Dogfish Mustelus canis Atlantic Sharpnose Rhizoprionodon terraenovae (L90%). Magnitude decreases L90% ranged from roughly 9% (Silky falciformis; 83-mm decrease) to 35% (Sandbar plumbeus; 541-mm decrease). Our findings indicate potential fishing pressure exert directional selection further research is needed regarding nature size-dependent catchability species-specific vital rates adequately evaluate dynamics. Furthermore, addition removal “great sharks,” small sharks, such as Shark, Dogfish, (i.e., “mesopredators”), suggest that harvest pervasive throughout this assemblage.