Patterns of genetic connectivity can be used to define the geographic boundaries of fishes and underpin management decisions. This study used a genetic multi-marker approach to investigate the population structure of scalloped hammerheads (Sphyrna lewini) in the Indo–Pacific. Samples from 541 S. lewini were collected from 12 locations across the Indo–Pacific. Samples were analysed using two regions of the mitochondrial genome, nine microsatellite loci and two sets of Single Nucleotide Polymorphisms (SNP). Our study has four key findings; (1) genetic structure of S. lewini across the Indo–Pacific is affected by oceanic basins and can be separated into four distinct regions. (2) Within the central Indo–Pacific, connectivity is facilitated along continental shelves and strong signals of Isolation-By-Distance (IBD) were observed. (3) Mitochondrial haplotypes previously thought only to exist in the Atlantic Ocean are observed in Indo–Pacific populations, suggesting the haplotype should be reconsidered as more widespread than initially thought. (4) Results from microsatellites and SNPs largely agree, however a few differences are apparent with SNPs identifying more discrete population subdivision. Our findings suggest management at the spatial scales and boundaries identified in this study will necessitate international and national cooperation to conserve S. lewini populations.

遗传连通性模式可用于定义鱼类的地理边界并支持管理决策。本研究使用遗传多标记方法来调查印太地区扇贝双髻 ( Sphyrna lewini ) 的种群结构。从印度太平洋地区的 12 个地点收集了541 个S. lewini的样本 。使用线粒体基因组的两个区域、九个微卫星基因座和两组单核苷酸多态性 (SNP) 分析样品。我们的研究有四个主要发现；(1) S. lewini的遗传结构横跨印度太平洋的区域受到海洋盆地的影响，可以分为四个不同的区域。（2）在印太中部，大陆架沿线的连通性得到促进，并观察到强烈的距离隔离（IBD）信号。(3) 在印度-太平洋种群中观察到以前认为只存在于大西洋中的线粒体单倍型，这表明应该重新考虑单倍型比最初认为的更广泛。(4) 来自微卫星和 SNP 的结果基本一致，但在 SNP 识别出更离散的群体细分方面存在一些明显差异。我们的研究结果表明，在本研究中确定的空间尺度和边界的管理将需要国际和国家合作来保护S. lewini种群。