Molecular Breeding and Biodiversity Research Group, Department of Genetics, Stellenbosch University, Stellenbosch, South Africa.
Department of Environment, Forestry and Fisheries, Rogge Bay, South Africa.
J Fish Biol. 2022 Jan;100(1):134-149. doi: 10.1111/jfb.14926. Epub 2021 Nov 8.
The common smooth-hound shark, Mustelus mustelus, is a widely distributed demersal shark under heavy exploitation from various fisheries throughout its distribution range. To assist in the development of appropriate management strategies, the authors evaluate stock structure, site fidelity and movement patterns along the species' distribution in southern Africa based on a combination of molecular and long-term tag-recapture data. Eight species-specific microsatellite markers (N = 73) and two mitochondrial genes, nicotinamide adenine dehydrogenase subunit 4 and control region (N = 45), did not reveal any significant genetic structure among neighbouring sites. Nonetheless, tagging data demonstrate a remarkable degree of site fidelity with 76% of sharks recaptured within 50 km of the original tagging location. On a larger geographic scale, dispersal is governed by oceanographic features as demonstrated by the lack of movements across the Benguela-Agulhas transition zone separating the South-East Atlantic Ocean (SEAO) and South-West Indian Ocean (SWIO) populations. Microsatellite data supported very shallow ocean-based structure (SEAO and SWIO) and historical southward gene flow following the Agulhas Current, corroborating the influence of this dynamic oceanographic system on gene flow. Moreover, no movements between Namibia and South Africa were observed, indicating that the Lüderitz upwelling formation off the Namibian coast acts as another barrier to dispersal and gene flow. Overall, these results show that dispersal and stock structure of M. mustelus are governed by a combination of behavioural traits and oceanographic features such as steep temperature gradients, currents and upwelling systems.
常见的光滑白眼鲛（Mustelus mustelus）是一种广泛分布的底栖鲨鱼，在其分布范围内，各种渔业对其进行了大量捕捞。为了协助制定适当的管理策略，作者根据分子和长期标记重捕数据，评估了南部非洲该物种分布范围内的种群结构、地点忠诚度和运动模式。8 个种特异性微卫星标记（N=73）和 2 个线粒体基因，烟酰胺腺嘌呤二核苷酸脱氢酶亚单位 4 和控制区（N=45），在相邻地点之间没有发现任何显著的遗传结构。尽管如此，标记数据显示出非常高的地点忠诚度，76%的鲨鱼在最初标记位置的 50 公里范围内被重新捕获。在更大的地理尺度上，扩散受海洋特征的控制，正如 Benguela-Agulhas 过渡区（分隔东南大西洋（SEAO）和西南印度洋（SWIO）种群）没有跨区运动所证明的那样。微卫星数据支持非常浅的基于海洋的结构（SEAO 和 SWIO）和沿着 Agulhas 洋流的历史向南基因流，证实了这种动态海洋系统对基因流的影响。此外，没有观察到纳米比亚和南非之间的运动，表明纳米比亚海岸外的 Lüderitz 上升流形成是另一个扩散和基因流的障碍。总的来说，这些结果表明，M. mustelus 的扩散和种群结构是由行为特征和海洋特征（如陡峭的温度梯度、洋流和上升流系统）的组合决定的。
