Genetic identification of blue rockfish (Sebastes mystinus) and deacon rockfish (S. diaconus) to enable life history analyses for stock assessment

To better inform stock assessment and management decisions, we used multiple approaches for estimating and comparing species-specific characteristics of the spatiotemporal composition of catch and life history traits of blue rockfish (Sebastes mystinus) and deacon rockfish (S. diaconus). We confirmed the species-level distinction of blue rockfish and deacon rockfish by using the results of genetic identification of individual fish from fin tissue samples and otoliths. Those results reveal the systematic relationships of these species with other rockfish species and enabled an evaluation of differences in distribution and life history (growth) between the 2 species in different management areas. Our evaluation of population structure found no significant differentiation within deacon rockfish and slight differentiation in blue rockfish that may not be biologically significant. Along the U.S. Pacific coast, deacon rockfish accounted for the majority of individuals sampled north of Monterey Bay, California, whereas blue rockfish were the more frequently observed species in waters of Monterey Bay and southern California. Modest but significant differences in growth parameters between the 2 species were observed by species, sex, and state (California or Oregon). The multidisciplinary nature of this study and the techniques and protocols we established provide a model for future research on and assessment of species complexes.