Genetic variation and phylogeographic patterns of Harpadon nehereus in China offshore inferred from mitochondrial cytochrome b (Cyt b) sequences: with implications for its fishery management

Harpadon nehereus is an ecologically and commercially important fish species. To investigate the phylogeographic pattern and historical demography of H. nehereus, a 1073 base pair fragment of the mitochondrial cytochrome b (Cyt b) gene was analyzed in 305 individuals collected from 13 locations in China offshore. In total, 41 haplotypes and 42 polymorphic sites were detected. Mean haplotype diversity and nucleotide diversity were remarkably low with a range from 0.1630 ± 0.0990 to 0.4113 ± 0.1308 and 0.0002 ± 0.0002 to 0.0007 ± 0.0006, respectively. Insignificant genealogical branches corresponding to sampling locations were revealed both in maximum likelihood (ML) and minimum spanning (MS) trees. The AMOVA and pairwise F_st values indicated shallow genetic structure and the slight genetic variation mainly originated within individuals. Both mismatch distribution analysis and neutrality tests showed H. nehereus had undergone population expansion, which possibly occurred 0.07 million years ago. The bottleneck effect and recent population expansion, combined with larval drift in the ocean current, could be the critical factors in shaping the contemporary phylogeographic patterns and genetic structure of H. nehereus. Our result suggested that H. nehereus in China’s coastal waters may be regarded as an integrated fishery management unit from the perspective of marine resource protection and sustainable utilization. But further researches and comprehensive considerations were still necessary too.