Data from: Murky waters: searching for structure in genetically depauperate blue threadfin populations of Western Australia

The blue threadfin (Eleutheronema tetradactylum) is an exploited fishery species in southeast Asia and Australia. Demographic studies have revealed fine-scale stock structure throughout the Australian coastline, with demographically isolated populations separated by only tens of km. Similarly, population genetic analysis revealed fine-scale structure across most of its Australian range with important implications for fisheries management. However, in northern Western Australia, genetic stock structure analysis showed a contradictory lack of structure. In the present study, one mtDNA marker and a suite of five microsatellite loci were used to further investigate the stock structure of Western Australian blue threadfin populations. By increasing sample sizes from previously investigated areas: Roebuck Bay (n = 93 adults) and Eighty-mile Beach (n = 92 adults and 163 recruits from two settlement cohorts), we were able to detect subtle genetic differentiation that was previously obscured by low levels of genetic polymorphism. Therefore, the same fine-scale stock structure that has been observed elsewhere in this species also appears to exist in Western Australia. This has clear ramifications for a revised management strategy that incorporates the fine scale structuring of northwest Western Australian stocks of the blue threadfin.

蓝四指马鲅（Eleutheronema tetradactylum）是东南亚与澳大利亚地区的商业化捕捞渔业物种。种群统计学研究揭示了澳大利亚沿岸海域内的精细尺度种群结构：仅相隔数十公里的种群便呈现出生殖隔离。与之类似，种群遗传分析在该物种澳大利亚分布的绝大多数区域中均检测到精细尺度种群结构，该结果对渔业管理工作具有重要指导价值。但在西澳大利亚北部海域，遗传种群结构分析却得到了与之相悖的无结构结果。本研究采用1个线粒体DNA（mtDNA）标记与5个微卫星位点组合，进一步探究西澳大利亚海域蓝四指马鲅的种群结构。通过扩大此前研究区域的样本量：罗巴克湾（Roebuck Bay，成体样本n=93）与八十英里滩（Eighty-mile Beach，成体样本n=92，以及来自2个定居批次的补充幼体样本n=163），我们成功检测到此前因遗传多态性水平较低而被掩盖的微弱遗传分化。由此可见，该物种在其他分布区域中观测到的精细尺度种群结构，同样存在于西澳大利亚海域。这一发现对修订纳入西澳大利亚西北部海域蓝四指马鲅精细种群结构的渔业管理策略具有明确的实践意义。