Isotopic signatures of otoliths and the stock structure of canary rockfish along the Washington and Oregon coast

Canary rockfish are one of the commercially important rockfish species along the US Pacific coast. Yet little is known about their life history and stock structure. In this study 120 canary rockfish otoliths were collected from waters off the Washington and Oregon coast and subjected to stable O and C isotope (δ18O and δ13C) analyses. One powder sample was taken from the nucleus of each otolith, and the other from the 5th annual ring. Data from otolith nuclei can provide information on the natal sources and spawning stock separations, while data from age-1 to age-5 may indicate changes in fish habitat. Overall the δ18O values in otoliths of canary rockfish ranged from −0.2‰ to +1.7‰, whereas δ13C values of the same samples ranged from −5.4‰ to −1.4‰. The isotopic data and correlation of δ18O versus δ13C did not show clear separation between Washington and Oregon samples, similar to those for a previous study on yelloweye rockfish from the same region. These results suggest that canary rockfish may belong to a single spawning stock or population along the Washington and Oregon coast.