This study describes the age structure and sex‐specific growth patterns of Lahille's bottlenose dolphins (Tursiops truncatus gephyreus), a subspecies endemic to the Southwest Atlantic Ocean (SWAO). The ages of 120 animals collected in southern Brazil between 1976 and 2017 were determined. We found high frequencies of young animals, mostly males, with no sex bias among adults. A temporal change in the age structure of strandings was observed, and we conclude it is a consequence of increased bycatch rates of young dolphins after 2000. The oldest male and female were 27 and 44 years old, respectively, suggesting that females live longer than males in southern Brazil. Growth curve analysis using Gompertz and Laird‐Gompertz growth models estimated asymptotic lengths of 316.5 cm for females and 351.6 cm for males, (reached around 13 and 18 years old, respectively), supporting sexual size dimorphism for the subspecies. A second growth pulse was identified for males. Our work highlights the benefit of long‐term studies and contributes valuable information toward understanding the life history of Lahille's bottlenose dolphin. It will serve as baseline for future studies that seek to understand mortality patterns of bottlenose dolphins elsewhere and the effects of anthropogenic actions on the survival of these animals.

中文翻译：

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拉希勒宽吻海豚（Tursiops truncatus gephyreus）的搁浅和生长的年龄结构

这项研究描述了Lahille宽吻海豚（Tursiops truncatus gephyreus）的年龄结构和特定性别的生长方式），是西南大西洋（SWAO）特有的亚种。确定了1976年至2017年之间在巴西南部收集的120只动物的年龄。我们发现幼年动物的频率很高，大多数是雄性，而成年人之间没有性别偏见。观察到搁浅的年龄结构随时间变化，我们得出结论，这是2000年后幼海豚兼捕率提高的结果。年龄最大的男性和女性分别为27岁和44岁，这表明女性的寿命比男性长在巴西南部。使用Gompertz和Laird-Gompertz生长模型进行的生长曲线分析估计，雌性的渐进长度为316.5 cm，雄性的渐进长度为351.6 cm（分别达到13岁和18岁），这支持了亚种的性别大小二态性。确定了男性的第二个生长脉冲。我们的工作突出了长期研究的好处，并为了解Lahille宽吻海豚的生活史提供了宝贵的信息。它将作为未来研究的基线，这些研究试图了解其他地方的宽吻海豚的死亡率模式以及人为作用对这些动物生存的影响。