Halibut in the older age classes tend to be much less migratory. Older fish often use both shallow and deep waters over the annual cycle, however they have much smaller home ranges than younger, more migratory fish. Research indicates that there may be small, localized spawning populations in deep waters such as in Chatham Straight in northern Southeast Alaska. However, because of the free-floating nature of eggs and larvae and subsequent mixing of juvenile halibut from throughout the Gulf of Alaska, there is only one known genetic stock of halibut in the northern Pacific. Halibut live quite a long time, but their growth rate varies depending on locations and habitat conditions.
Females grow faster and live longer than males.
The oldest recorded female was 42 years old and the oldest male was 27 years old. Halibut are the largest of all flatfish. The largest ever recorded for the northern Pacific was a 495-pound fish caught near Petersburg, Alaska. Sometimes halibut leave the ocean bottom to feed on pelagic fish such as sand lance and herring. Commercial halibut fishing probably began in 1888 when three sailing ships from New England fished off the coast of Washington state.