In this study, genetic, otolith scale and egg retention analysis will be conducted on major hatchery (Conuma, Robertson and Nitinat) and wild or less-hatchery-influenced ‘natural’ populations (Kaouk, Megin, Tranquil and Burman) of WCVI Chinook salmon in the two southern Conservation Units on WCVI. Comparison of microsatellite genotypes and otolith thermal mark data from the same fish will be used to verify the genetic identification of fish from the major enhanced stocks in non-target systems and to determine if all such fish are direct hatchery strays (thermally-marked) or whether some are likely progeny (non-thermally-marked) of hatchery strays that spawned successfully in the wild.