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Life history parameters of the crocodile shark, Pseudocarcharias kamoharai, in the tropical Atlantic Ocean
Journal of the Marine Biological Association of the United Kingdom ( IF 1.2 ) Pub Date : 2021-08-18 , DOI: 10.1017/s0025315421000588
Daniela Rosa 1 , Marco Gago 2 , Joana Fernandez-Carvalho 3 , Rui Coelho 3
Affiliation  

The crocodile shark (Pseudocarcharias kamoharai) is a small lamniform shark that is occasionally by-caught in pelagic longline fisheries targeting tunas and swordfish. Due to its biological features, this species is highly vulnerable to overexploitation. However, at present, the crocodile shark is not evaluated for its stock status by any of the Regional Fisheries Management Organizations. In this study, the biology of 391 specimens (220 females and 171 males), ranging from 44.2 cm to 101.5 cm fork length (FL), collected from the tropical region of the Atlantic Ocean, was examined. Ages were assigned from growth band counts in vertebral sections, with the modified von Bertalanffy growth model, using a fixed size at birth (L0) at 32 cm FL, producing the best fit: Linf = 105.6 cm FL and k = 0.14 y−1 for females; Linf = 94.6 cm FL and k = 0.18 y−1 for males. Maturity ogives were fitted to both length- and age-based data. The size (L50) and age (A50) at 50% maturity was estimated at 67.2 cm FL (5 years) and 81.6 cm FL (8 years) for males and females, respectively. Mean uterine fecundity was 3.7 pups per litter with a 1:1 embryonic sex ratio. Further work is needed regarding crocodile shark life-history characteristics, especially because there are no age validation studies of the band pair deposition periodicity. However, the parameters now presented can contribute to future evaluations of this species, which is especially important given its potentially vulnerable life history.

中文翻译:

热带大西洋鳄鱼鲨 Pseudocarcharias kamoharai 的生活史参数

鳄鱼鲨(假鲢鱼) 是一种小片状鲨鱼,偶尔会在以金枪鱼和旗鱼为目标的远洋延绳钓渔业中被副捕获。由于其生物学特征,该物种极易受到过度开发的影响。然而,目前,任何区域渔业管理组织都没有对鳄鱼鲨的种群状况进行评估。在这项研究中,检查了从大西洋热带地区采集的 391 个标本(220 名女性和 171 名男性)的生物学特性,这些标本的叉长(FL)从 44.2 厘米到 101.5 厘米不等。年龄是根据椎体切片的生长带计数分配的,使用改良的 von Bertalanffy 生长模型,使用出生时的固定尺寸(大号0) 在 32 cm FL,产生最佳拟合:大号信息= 105.6 厘米 FL 和ķ= 0.14 岁-1对于女性;大号信息= 94.6 厘米 FL 和ķ= 0.18 岁-1对于男性。Maturity ogives 适合基于长度和年龄的数据。规模 (大号50) 和年龄 (一种50) 在 50% 成熟时,男性和女性的身高分别估计为 67.2 cm FL(5 年)和 81.6 cm FL(8 年)。平均子宫繁殖力为每窝 3.7 只幼崽,胚胎性别比为 1:1。关于鳄鱼鲨的生活史特征需要进一步的工作,特别是因为没有对带对沉积周期性的年龄验证研究。然而,现在提出的参数有助于未来对该物种的评估,鉴于其潜在的脆弱生活史,这一点尤为重要。
更新日期:2021-08-18
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