Pacific Halibut

The Pacific halibut is found on the continental shelf of the North Pacific Ocean and Bering Sea. Fishing for the Pacific halibut is mostly concentrated in the Gulf of Alaska and the Bering Sea, off the west coast of Canada. Small halibut catches are reported in coastal Washington, Oregon, and California.

Halibut are demersal, living on or near the bottom of the water and prefer water temperatures ranging from 3 to 8 degrees Celsius (37.4 to 46.4 degrees Fahrenheit). Pacific halibut belong to the family Pleuronectidae. They are among the largest teleost fishes in the world. From November to March, mature halibut concentrate annually on spawning grounds along the edge of the continental shelf at depths from 183 to 457 m (600 to 1,499 ft).
Ketchikan Halibut Fishing

Halibut are strong swimmers and are able to migrate long distances. Halibut of all ages and sizes are involved in a predominantly clockwise (northwest to southeast) migration from their settlement areas (western part of the Gulf of Alaska and Bering Sea), reproductive fish also make regular seasonal migrations from more shallow feeding grounds in summer to deeper spawning grounds in winter.

Halibut are able to eat a large variety of fishes, including cod, turbot, and pollock, and some invertebrates, such as octopus, crab and shrimp. Sometimes, halibut leave the ocean bottom to feed on pelagic fish, such as salmon, sand lance and herring.

Spawning takes place during the winter months, with the peak of activity occurring from December through February. Most spawning takes place off the edge of the continental shelf in deep waters of 600 to 1,500 ft (183 to 457 m). Male halibut become sexually mature at seven to eight years of age, while females attain sexual maturity at eight to 12 years. Females lay 0.5 to 4.0 million eggs annually, depending on the size of the fish.
Fertilized eggs hatch after about 15 days. Free-floating larvae float for up to six months and can be transported several hundred miles counter-clockwise by North Pacific currents. During the free-floating stage, many changes take place in the young halibut, including the movement of the left eye to the right side of the fish. During this time, the young halibut rise to the surface and are carried to shallower water by prevailing currents. At six months, the halibut has its adult form and is about 1.4 in (3.6 cm) long. In the shallower water, young halibut then begin life as bottom dwellers. Most young halibut ultimately spend from five to seven years in rich, shallow nursery grounds such as the Bering Sea.

Young halibut are highly migratory and generally migrate in a clockwise direction east and south throughout the Gulf of Alaska. Halibut in older age classes tend to be less migratory, but continue to move predominately on a clockwise direction. Mature fish are also involved in winter spawning migrations towards deeper waters, migrating across several areas in some instances. Research has indicated small, localized spawning populations may occur in deep waters such as in Chatham Straight in northern Southeast Alaska. However, because of the free-floating nature of larvae and subsequent mixing of juvenile halibut from throughout the Gulf of Alaska, only one genetic stock of halibut is known in the northern Pacific.