DNA barcode, population genetic structure and a novel perspective on the global fishery management units of the dolphinfish Coryphaena hippurus (Perciformes: Coryphaenidae)

Coryphaena hippurus (dolphinfish) is an important epipelagic top predator and global fishery resource. Global fishing indices indicate a tenfold increase in catch, and intense fishing may reduce genetic diversity and increase vulnerability to extinction. Here, we assess population genetic patterns in dolphinfish using cytochrome c oxidase subunit I, a molecular marker not previously applied to this approach. We observed genetic diversity indices similar to those previously described for the mitochondrial NADH dehydrogenase subunit 1 gene in C. hippurus, with both markers showing moderate to high genetic diversity. However, these findings should be interpreted with caution, because cytochrome c oxidase subunit 1 has limitations that prevent direct inferences about the effects of fishing pressure on genetic variation. Our analyses revealed low genetic distinction among populations from the Pacific, Indian and Atlantic Oceans, except for the Mediterranean basin, which retained a mean ΦST difference of 59% from the other basins. This pattern is consistent with findings for NADH dehydrogenase subunit 1 and nuclear single-nucleotide polymorphisms, which indicated subgroups within the Mediterranean basin potentially associated with environmental variation. Despite this differentiation, no evidence supported a molecular operational taxonomic unit endemic to the Mediterranean basin. Future management plans must consider Mediterranean populations separately.