Posgrado en Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Mexico City, Mexico.
Centro Regional de Investigaciones Pesqueras Bahía Banderas, Nayarit, Mexico.
J Fish Biol. 2019 Oct;95(4):1072-1085. doi: 10.1111/jfb.14100. Epub 2019 Aug 5.
The age of 296 juvenile scalloped hammerhead sharks Sphyrna lewini caught by several fisheries in the Mexican Pacific Ocean from March 2007 to September 2017 were estimated from growth band counts in thin-sectioned vertebrae. Marginal-increment analysis (MIA) and centrum-edge analysis (CEA) were used to verify the periodicity of formation of the growth bands, whereas elemental profiles obtained from LA-ICP-MS transect scans in vertebrae of 15 juveniles were used as an alternative approach to verify the age of the species for the first time. Age estimates ranged from 0 to 10+ years (42-158.7 cm total length; L ). The index of average percentage error (I 3.6%), CV (5.2%), bias plots and Bowker's tests of symmetry showed precise and low-biased age estimation. Both MIA and CEA indicated that in the vertebrae of juveniles of S. lewini a single translucent growth band was formed during winter (November-March) and an opaque band during summer (July-September), a period of faster growth, apparently correlated with a higher sea surface temperature. Peaks in vertebral P and Mn content spatially corresponded with the annual banding pattern in most of the samples, displaying 1.19 and 0.88 peaks per opaque band, respectively, which closely matched the annual deposition rate observed in this study. Although the periodicity of growth band formation needs to be verified for all sizes and ages representing the population of the species in the region, this demonstration of the annual formation of the growth bands in the vertebrae of juveniles should lead to a re-estimation of the growth parameters and productivity of the population to ensure that it is harvested at sustainable levels.
2007 年 3 月至 2017 年 9 月期间，墨西哥太平洋的几家渔业共捕获了 296 尾年龄为 296 岁的幼年糙齿鲨（Sphyrna lewini），这些鱼的椎骨通过生长带计数进行了年龄估计。边缘增量分析（MIA）和中心边缘分析（CEA）用于验证生长带形成的周期性，而从 15 尾幼鱼的椎骨中获得的 LA-ICP-MS 横截扫描元素剖面则被首次用作验证该物种年龄的替代方法。年龄估计范围为 0 至 10 岁以上（总长 42-158.7 厘米；L）。平均百分比误差指数（I 3.6%）、变异系数（5.2%）、偏倚图和 Bowker 的对称性检验显示了精确的低偏差年龄估计。MIA 和 CEA 均表明，在糙齿鲨幼鱼的椎骨中，冬季（11 月至 3 月）形成一条透明的生长带，夏季（7 月至 9 月）形成一条不透明的生长带，这是一个生长较快的时期，显然与较高的海水温度有关。椎骨中 P 和 Mn 含量的峰值在大多数样本中与每年的条带模式空间对应，分别显示 1.19 和 0.88 个峰值/不透明带，这与本研究中观察到的年沉积率非常吻合。尽管需要对代表该地区该物种所有大小和年龄的样本进行生长带形成周期性的验证，但这种在幼鱼椎骨中每年形成生长带的证明，应该会重新估计种群的生长参数和生产力，以确保以可持续的水平进行捕捞。
