In the waters of southeast Australia, two species of sawshark—the common (Pristiophorus cirratus) and southern (Pristiophorus nudipinnis) sawshark—are frequent by-catch in commercial fisheries. While harvesting of both species is currently considered sustainable, there has been no investigation of whether P. cirratus and P. nudipinnis display genetically distinct populations throughout their ranges. Such information is necessary for effective management of these species in commercial fisheries. This study examined population structure in both sawshark species through analysis of two mitochondrial genes: cytochrome b (Cyt-b) and NADH dehydrogenase subunit 5 (ND5). Results indicated contrasting levels of population structure, with P. cirratus consisting of two, possibly three, genetically distinct populations with two mitochondrial lineages and P. nudipinnis consisting of a single population. Tests for population expansion also highlighted differences between the two species. Population expansion was detected for the entire P. nudipinnis population, whereas this was only the case for one mitochondrial lineage in P. cirratus. The entire P. cirratus population displayed signals of demographic stability. It is hypothesised that the opening and closing of Bass Strait during glacial-interglacial cycles played a major role in shaping the population structure and expansion signatures observed in this study. Mitochondrial data also suggest that patterned and uniform brown P. cirratus are the same species. Fisheries managers should consider adopting two management units in southern Australia—one along the east coast (for the eastern P. cirratus population) and one along the south coast (for the southern P. cirratus population and the single P. nudipinnis population).

在澳大利亚东南部的水域中，商业渔业中经常捕获两种锯齿鲨（常见的锯齿鲈（Pristiophorus cirratus）和南部的锯齿鲨（Pristiophorus nudipinnis））。虽然这两个物种的收获是目前被认为可持续的，一直没有是否调查P. cirratus和P. nudipinnis整个范围显示基因不同的人群。此类信息对于在商业渔业中有效管理这些物种是必要的。这项研究通过分析两个线粒体基因：细胞色素b（Cyt-b）和NADH脱氢酶亚基5（ND5），研究了两种锯齿鲨物种的种群结构。结果表明人口结构的对比水平不同，P. cirratus由两个，可能是三个，遗传上不同的群体具有两个线粒体谱系和P. nudipinnis由单个群体。种群扩展测试也突出了这两个物种之间的差异。在整个P. nudipinnis种群中都检测到了种群扩展，而在C. cirratus中只有一种线粒体谱系。整个P. cirratus人口显示人口稳定的信号。假设在该研究中观察到的冰川海冰间期的巴斯海峡的开放和关闭在塑造种群结构和扩展特征方面起着重要作用。线粒体数据还表明，图案化的和均一的棕色P. cirratus是同一物种。渔业管理者应该考虑在沿东海岸澳大利亚南部一（东采用两个管理单位P. cirratus人口）和一个沿南海岸（用于南部P. cirratus人口和单P. nudipinnis人口）。