The age and growth of subtropical populations of the Brazilian and Caribbean sharpnose sharks (Rhizoprionodon lalandii and R. porosus respectively) were determined by combining direct and indirect ageing methods, maximising the use of available information. Using vertebrae ageing for R. lalandii, the theoretical maximum length L∞ and growth coefficient k were 661.9mm and 1.14 year–1 for males and 751.7mm and 0.59 year–1 for females. Vertebrae were not sampled for R. porosus. Values of L∞ and k from electronic length–frequency analyses (ELEFAN) were 762mm and 0.71 year–1 for male R. lalandii, 791mm and 0.67 year–1 for female R. lalandii, 1040mm and 0.41 year–1 for male R. porosus and 1165mm and 0.31 year–1 for female R. porosus. Growth during the first year of life in relation to birth size was 80.3% for R. lalandii and 55% for R. porosus. Both species exhibit rapid growth, primarily in the first year of life. The growth estimates for R. lalandii and R. porosus are even faster than those reported in previous studies from tropical populations.

中文翻译：

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大西洋西南部亚热带水域中两种尖吻鲨（Rhizoprionodon lalandii 和 R. porosus）的年龄和生长

通过结合直接和间接老化方法，最大限度地利用可用信息，确定了巴西和加勒比锐鼻鲨（分别为 Rhizoprionodon lalandii 和 R. porosus）的亚热带种群的年龄和生长情况。使用 R. lalandii 的椎骨老化，男性的理论最大长度 L∞ 和生长系数 k 分别为 661.9 毫米和 1.14 岁，女性为 751.7 毫米和 0.59 岁。R. porosus 没有对椎骨进行采样。来自电子长度-频率分析 (ELEFAN) 的 L∞ 和 k 值对于雄性 R. lalandii 为 762mm 和 0.71 year-1，对于雌性 R. lalandii 为 791mm 和 0.67 year-1，对于雄性 R. lalandii 为 1040mm 和 0.41 year-1。 porosus 和 1165 毫米和 0.31 年 - 1 女性 R. porosus。R. lalandii 和 R. porosus 在出生后第一年相对于出生体型的增长分别为 80.3% 和 55%。这两个物种都表现出快速增长，主要是在生命的第一年。R. lalandii 和 R. porosus 的增长估计甚至比之前热带种群研究中报告的还要快。