Harvest may have myriad effects on target species, including a change in population size structure. To assess whether size shifts have occurred among managed coastal species of shark (superorder Selachimorpha), we examined the population size structure of 12 species caught during a nearly five‐decade‐long fishery‐independent survey conducted in Onslow Bay, North Carolina, using standardized longline gear. We evaluated trends in mean fork length (FL), median FL, and index of maximum FL (L_90%) for each species separately across time using linear regression models. We also examined trends in size‐classes (200‐mm bins) and catch per unit effort for each species over time. For 10 of the 12 species (excluding sample‐size‐constrained Tiger Shark Galeocerdo cuvier and Bull Shark Carcharhinus leucas), size structure metrics indicated decreasing sizes over time, although statistical confidence for these patterns varied across species and metrics. Strongest statistical support for declining sizes was observed for Blacknose Shark Carcharhinus acronotus (mean FL, median FL, L_90%), Dusky Shark Carcharhinus obscurus (L_90%), Smooth Dogfish Mustelus canis (L_90%), and Atlantic Sharpnose Shark Rhizoprionodon terraenovae (L_90%). Magnitude of decreases in L_90% among these 10 species during the survey ranged from roughly 9% (Silky Shark Carcharhinus falciformis; 83‐mm decrease) to 35% (Sandbar Shark Carcharhinus plumbeus; 541‐mm decrease). Our findings indicate a potential for fishing pressure to exert directional selection on these coastal shark species, although further research is needed regarding the nature of size‐dependent catchability and species‐specific vital rates to adequately evaluate these dynamics. Furthermore, in addition to the removal of “great sharks,” decreasing sizes of small coastal sharks, such as Blacknose Shark, Smooth Dogfish, and Atlantic Sharpnose Shark (i.e., “mesopredators”), suggest that harvest may have pervasive effects on species throughout this assemblage.

中文翻译：

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美国东南沿海鲨鱼组合的大小变化：1975–2018

收获可能对目标物种产生多种影响，包括种群规模结构的变化。为了评估在管理的鲨鱼沿海物种（Selachimorpha）中是否发生了大小变化，我们使用标准化方法，对在北卡罗来纳州昂斯洛湾进行的近五年来与渔业无关的调查中捕获的12种物种的种群大小结构进行了研究。延绳钓装备。我们使用线性回归模型分别评估了每个物种的平均叉长（FL），中位FL和最大FL指数（L _90％）随时间变化的趋势。我们还研究了尺寸等级（200毫米箱）的趋势以及随时间推移每种物种的单位工作量捕获量。对于12种中的10种（不包括受样本量限制的虎鲨Galeocerdo cuvier和Bull Shark）leu鱼（Carcharhinus leucas），大小结构指标表明大小随着时间的推移而减小，尽管这些模式的统计置信度在物种和指标之间有所不同。观察到黑吻真鲨的规模下降最强的统计支持真鲨acronotus（平均FL，中位数FL，大号_90％ ），灰色真鲨真鲨鲀（大号_90％ ），平滑角鲨Mustelus犬（大号_90％ ），和大西洋Sharpnose鲨鱼Rhizoprionodon terraenovae（L _90％）。L的下降幅度_90％在调查期间的这10个物种中，大约从9％（Silky Shark Carcharhinus falciformis；减少83-mm）到35％（Sandbar Shark Carcharhinus plumbeus；减少541-mm）。我们的发现表明，捕捞压力有可能对这些沿海鲨鱼种类进行定向选择，尽管需要进一步研究大小依赖的可捕集性和特定于物种的生命率的性质，以充分评估这些动态。此外，除了去除“大鲨鱼”外，诸如黑鼻鲨，平滑狗鱼和大西洋尖鼻鲨（即“中指”）之类的小型沿海鲨鱼的规模不断缩小，这表明收获可能对整个物种产生普遍影响。这个集合。