Pacific halibut chronology of bomb radiocarbon in otoliths from 1944 to 1981 and a validation of ageing methods

Abstract

Pacific halibut Hippoglossus stenolepis of known age were used to create a reference chronology of radiocarbon levels for the years 1944–1981. Levels of radiocarbon in Pacific halibut otoliths pre‐1958 were among the lowest reported to date, but radiocarbon levels increased dramatically post‐1960. Subsequently, this reference chronology was used to validate ages determined using the standard break and burn and surface ageing technique. These older fish were collected at a later date but were born during this period of rapidly increasing radiocarbon levels. Otolith cores were compared to the reference chronology based upon the presumed birth year determined from annulus counts and year of capture. The ages derived from both break and burn and surface ageing methods were determined to be accurate.