| Sockeye salmon | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Subclass: | Neopterygii |
| Infraclass: | Teleostei |
| Order: | Salmoniformes |
| Family: | Salmonidae |
| Genus: | Oncorhynchus |
| Species: | O. nerka |
| Binomial name | |
| Oncorhynchus nerka (Walbaum, 1792) |
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Sockeye salmon (Oncorhynchus nerka), also called red salmon or blueback salmon in the USA, is an anadromous species of salmon found in the Northern Pacific Ocean and rivers discharging into it. There are also completely landlocked populations of the same species, which are known as kokanee or "silver trout."[2] Sockeye salmon is the third most common Pacific salmon species, after pink and chum salmon.[3] The name "sockeye" is an anglicization of suk-kegh (sθə́qəy̓), its name in Halkomelem, the language of the indigenous people along the lower reaches of the Fraser River (one of British Columbia's many native Coast Salish languages). Suk-kegh means red fish.[4] [5]
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Some sockeye live and reproduce in lakes and are called "kokanee", a word in the Okanagan language for this kind of fish.[6] They are much smaller than the ones that go to the ocean and are rarely over 350 millimetres (14 in) long. In Okanagan Lake and many others there are two kinds of kokanee populations - one spawns in streams and one spawns in the lake near the shore. As an aside, the Kokanee Glacier gets its name from Kokanee Creek, which enters Kootenay Lake near Nelson, British Columbia (see Kokanee).
The black kokanee, or "kunimasu" in Japanese, was deemed to be extinct after 1940, when a hydroelectric project made its native lake in northern Akita Prefecture more acidic. An attempt to save the species by transferring 100,000 eggs to Saiko Lake, 500 kilometers to the south, was thought to have failed. Tetsuji Nakabo, a professor at Kyoto University, announced in December 2010 that a team of researchers have discovered a population of the kunimasu in Saiko Lake.[7]
Sockeye salmon ranges as far south as the Columbia River in the eastern Pacific (though individuals have been spotted as far south as the 10 Mile River on the Mendocino Coast of California) and northern Hokkaidō 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.[8] Landlocked populations occur in the Yukon Territory and British Columbia in Canada, and in Alaska, Washington, Oregon, California, New York, Utah, Idaho, Montana, Nevada, Colorado, New Mexico, and Wyoming in the United States. Nantahala Lake is the only spot in North Carolina where kokanee salmon are found. The fish, which is native to the western United States, was stocked in Nantahala Lake in the mid-1960s by the N.C. Wildlife Resources Commission in an attempt to establish the species as a forage fish for other predator fishes in the lake. This stock has remained and become a favorite target for anglers.
Sockeye are blue tinged with silver in color while living in the ocean. .
Sockeye spawn mostly in streams having lakes in their watershed. The young fish, known as fry, spend up to three years in the freshwater lake before migrating to the ocean. Some stay in the lake and do not migrate. Migratory fish spend from one to four years in salt water, and thus are four to six years old when they return to spawn one summer (July–August). Navigation to the home river is thought to be done using the characteristic smell of the stream, and possibly the sun.
Some fish spend as long as four years in fresh water lakes before migrating. In rivers without lakes, many of the young move to the ocean soon after hatching. These salmon mature after one to four years in the ocean.
Sockeye salmon, unlike other species of Pacific Salmon, feed extensively on zooplankton during both freshwater and saltwater life stages.[9] Their many gill rakers strain the plankton from the water. This diet may be the reason for the striking hue of their flesh, as well as their very low concentration of methylmercury. They also tend to feed on small aquatic organisms such as shrimp. They also eat insects when they are at the juvenile stage.
Commercial fishermen net this species using seines and gillnets for fresh or frozen filet sales and canning, especially in Bristol Bay, Alaska, site of the largest harvest, according to the Alaska Department of Fish and Game. Canners prefer it due to its rich orange-red flesh. More than half of the catch is sold frozen.
Smoked Sockeye has a stronger flavor and firmer texture than Coho salmon.
US Sockeye salmon populations are currently listed under the U.S. Endangered Species Act[10] by the National Marine Fisheries Service as an endangered species in the Snake River (Idaho, Oregon and Washington area) and as a threatened species in Lake Ozette, Washington. Other sockeye populations in the upper Columbia River and in Puget Sound (Washington) are not listed under the Act.
The return abundance (population) of Fraser River sockeye in 2009 was estimated at a very low 1,370,000, [11] 13% of the pre-season forecast of 10,488,000. [12] That represented a decline from the recent (1993) historical cycle peak of 23,631,000 [13] and the return abundance was the lowest in over 50 years. The reasons for this (former) decline remain speculative. According to a “Think Tank” of scientists assembled to review the problem, there is no evidence that this decline was due to overfishing. [14] The evidence indicated this reduced productivity occurred after the juvenile fish began their migration to the ocean. Perhaps ironically, prior to the incredible abundance of the 2010 Fraser River run, Canada had begun a formal inquiry into the decline.[15]
The decline that had dismayed fishermen and biologists may have been connected to open-water fish farms located throughout the waters around the Campbell River, the Broughton Archipelago, and elsewhere, given that young salmon must swim through these areas journeying to the open ocean.[16] The fry may become infected with sea lice from the farms, killing many of them.[17]
Astonishingly, the number of Sockeye returning to British Columbia was around 30 million in 2010, the largest sockeye run in 97 years, in bizarre contrast to the unexpectedly low run in 2009.[18] The abundance of Sockeye stocks in 2010 are estimated to be over 260% higher than the predicted 11.4 million salmon.[19] The Sockeye populations of the last two years do not follow the general trend of gradual decline exhibited over the past century, and these unpredictable runs are speculated to be due to fluctuating water temperatures.[20]
Sockeye is an exception to 2010's forecast resurgence of Oregonian fish stocks. Spring Chinook, Summer Steelhead, and Coho are forecast to increase by up to 100% over 2008 populations. The sockeye population peaked at over 200,000 in 2008 and were forecast to decline to just over 100,000 in 2010. As an early indication of the unexpectedly high Sockeye run in 2010, on July 2, 2010, the United States Army Corps of Engineers reported that over 300,000 Sockeye had passed over Bonneville dam on the Columbia river. Lower temperatures in 2008 North Pacific waters brought in fatter plankton which, along with greater outflows of Columbia River water, feeding the resurgent populations.[21]
Proposed legislative efforts such as the Northern Rockies Ecosystem Protection Act are attempting to protect the headwaters of the sockeye salmon by preventing industrial development in roadless areas.
|title= specified when using {{Cite web}}" (in English). Fish Resources. USDA Forest Service. http://www.fs.fed.us/r6/fishing/regional/fishresources/salmon.html. Retrieved 9 September 2011.
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