Population genetic structure in the redefined vermilion rockfish (Sebastes miniatus) indicates limited larval dispersal and reveals natural management units

Abstract

Recent studies have revealed that the vermilion rockfish Sebastes miniatus is a cryptic species pair. The splitting of this species impacts stock size estimates and draws attention to the unintended consequences of current management policies. Differences in exploitation level between the species necessitated an evaluation of population structure and connectivity among regional management segments of the fishery. Analysis of gene flow and calculations of larval dispersal values were accomplished using 782 bp of DNA sequence data from the mitochondrial cytochrome b gene of 684 vermilion rockfish sampled from 16 sites between Kyuquot Sound, Canada, and San Quintin, Mexico. Significant genetic heterogeneity was found among sample sites (ΦST= 0.0742, p < 0.001 and FST= 0.0899, p < 0.001). Isolation by distance analysis produced a significant correlation, suggesting low average larval dispersal distance. Analysis of molecular variance showed significant partitioning of genetic variance across the biogeographic boundary at Point Conception (ΦCT= 0.0923, p < 0.001 and FCT= 0.0135, p < 0.001) with additional genetic barriers found at Cape Mendocino, Punta Colnett, Santa Monica Bay, and along the coast of Washington. These genetic barriers conform to oceanographic compartments previously proposed for the California Current Ecological Province and suggest natural management units for this species.