Sockeye salmon

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Sockeye salmon
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Salmoniformes Family: Salmonidae Genus: Oncorhynchus Species: O. nerka
Binomial name
Oncorhynchus nerka (Walbaum, 1792)

Sockeye salmon (Oncorhynchus nerka), also called red salmon or blueback salmon, is an anadromous species of salmon found in the Pacific Ocean. The same species when it occurs in landlocked bodies of water is called the Kokanee.

[edit] Range

Its range is as far south as the Klamath River in California in the eastern Pacific and northern Hokkaido Island in Japan in the western Pacific, and as far north as Bathurst Inlet in the Canadian Arctic in the east and the Anadyr River in Siberia in the west. Landlocked populations occur in the Yukon Territory and British Columbia in Canada, and in Alaska, Washington, Oregon, Utah, Idaho, Montana, Colorado, and New Mexico in the United States.

[edit] Physical Description

Male and female sockeye salmon.

A Sockeye can be as long as 84 cm and weigh 6 to 8 pounds (2.5 to 3.5 kilos). It has an elongate, torpedo shaped body, with an adipose fin, and a bluntly pointed snout. The gill rakers located just behind the head are long and closely spaced. Its colouration changes as it migrates from saltwater to freshwater in preparation for spawning. In freshwater, its colour is bright red with a pale green head; females may have green and yellow marks or stains. Its colour in saltwater is bluish-green on top, silvery on the bottom, with uniform, shiny skin.

[edit] Reproduction

Prior to spawning the sockeye are blue tinged with silver in color during their ocean life. The males develop a hump on their back and their jaw and teeth become hooked when they move from salt to fresh water. Males and females both turn red with green heads, and a dark stripe on their sides prior to spawning.

Sockeye salmon spawn mostly in streams having lakes in their watershed. The young fish, known as fry, spend from zero to three years in the freshwater lake before migrating to the ocean, some stay in the lake and do not migrate to the sea. The fish that migrate spend from one to four years in the salt water, and thus are four to six years old when they return to spawn in autumn (September-December). Migration back to the home river, is thought to be done using the characteristic smell of the stream, and possibly the sun.

Some young fish spend as long as four years in fresh water lakes before migrating to the sea. In rivers without lakes, many of the young move to the ocean quite soon after hatching. These salmon mature after one to four years in the ocean. Some Sockeye Salmon live and reproduce in lakes and are called "kokanee." They are much smaller than the ones that go to the ocean and are rarely over 350mm (14 inches) long.

[edit] Ecology/Behaviour

Sockeyes, unlike the other species of Pacific Salmon, feed almost exclusively on plankton. They are able to do this as a result of their many gill rakers, which strain the plankton from the water. It is speculated that this diet is the reason for the striking hue of their flesh as well as their very low concentration of methyl mercury. They also tend to feed on small aqautic organisms such a shrimp.

[edit] Commerce

This species is netted for commercial canning, especially in Bristol Bay, Alaska, site of the largest harvest of sockeye salmon in the world, according to the Alaska Department of Fish and Game. The species has been preferred for canning due to the rich orange-red color of the flesh. More than half of the sockeye salmon caught today is sold frozen. Sockeye also tends to fetch a higher price than other salmon when sold fresh, as they are considered the most flavorful and flexible of the family.

[edit] References

• Oncorhynchus nerka (TSN 161979). Integrated Taxonomic Information System. Accessed on 30 January 2006.

[edit] External links

• FishBase entry for Oncorhynchus nerka
• Animal Diversity Web entry for rhynchus_nerka