The native range of this genus encompasses the entire pacific coast in the Northern hemisphere. They have also been relocated to Europe for culture purposes.

HABITS:

These large anadromous piscines are well renowned for their remarkable migrations and spawning runs. They spend their non-adult life stages in fresh water where they feed upon a variety of aquatic insects and fish. During the latter part of their juvenile stage they go through a series of physiological changes during a smoltification process that enables them to endure the osmoregulatory stresses encountered in the marine environment. While in the ocean they have access to an abundant supply of food and exhibit high growth rates until they reach sexual maturity. These salmonids are predacious pelagic feeders usually found in cold, flowing, oxygen rich water.

SPAWNING:

As mentioned previously, the pacific salmon are anadromous fish and excluding the rainbow trout, which has recently been placed into this genus, are semelparous. That is they spawn once and die. Fish in this genera mature after 1-5 years at sea at which time they embark on their final nostalgic journey to their natal rivers to spawn and die. When these fish reach the headwaters of these rivers and streams the male builds a redd (nest), the pair spawns, and then together cover the eggs with the pea-stone sized substrate. In culture systems eggs are often surgically removed from ripe females rather than stripped and mixed with milt stripped from a running male. Often a "wet fertilization" method is used which requires water to be mixed with the milt and eggs to trigger the closing of the micropile. Eggs are incubated in hatching trays with a continuous flow of fresh water.

GROWTH:

The genus Oncorhynchus includes many species of pacific salmon all of which have different growth rates; therefor, only culture worthy species will be discussed. The pink salmon grows rapidly and may attain a weight of 2-3kg 2 years post-hatch. The coho salmon may reach 15kg after 5 years of growth, but is generally marketed as a pan-sized fish (350g) after 6 to 8 months. The sockeye salmon or red salmon occasionally reached a maximum length of 100cm; however, its freshwater cousin, the kokanee, is often much smaller. Chum salmon may be the largest representative of this group reaching 20kg after 4-5 years of growth.

USES:

Pacific salmon are a valued food fish. These species are thus raised for the whole fish, fillet, and canned market. The multitude of human-built hydroelectric dams have led to the decline in natural stocks of these majestic beauties on the West Coast of the United Stated. Hatcheries are actively producing these fish to augment the natural populations in this area. They are also prized as a game fish and are stocked for recreational purposes.

CULTURE:

Pacific salmon are raised using four basic methods. They are propagated using pond culture, sea ranching, net-pen culture, and raceways. Some research is underway developing saltwater pond rearing techniques.

REFERENCES:

Avault, J.W. 1996. Fundamentals of Aquaculture. AVA Publising Company Inc., Baton Rouge, Lousiana.

Bardach, J.E, J. H. Ryther, and W.O. McLarney. 1972. Aquaculture The farming and husbandry of freshwater and marine organisms. John Wiley and Sons, New York.

Iverson E.S. and K. K. Hale. 1992. Aquaculture sourcebook a guide to north american species. Van Norstrand Reinhold, New York.

Laird, L. and T. Needham. 1990. Sea water culture of salmonids. Pages 288-648 in Aquaculture volume 2, editor Gilbert Barnabe. Ellis Horwood Limited. West Sussex, England.