Oncorhynchus tshawytscha
Written by Adam Schmoeger (Lincoln University)
Edited by Michael Hudson, Lincoln University, January 2006
Taxonomy
- Scientific name: Oncorhynchus tshawytscha (Walbaum, 1792)
- Popular Common names: Quinnat Salmon, Chinook Salmon, King Salmon, blackmouth, Tyee Salmon.
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Salmoniformes
- Family: Salmonidae
- New Zealand Status: naturalised
- Taxonomy sources: Bryant (1979).
Identification
Species Description
Oncorhynchus tshawytscha are generally silver in colour with black spots along the back. After entering freshwater and approaching spawning colour turns to brown or red. Colour change is more distinct in males than in females. Males also develop large hooked jaw near spawning. Most Quinnat Salmon (Oncorhynchus tshawytscha) in New Zealand weigh ten to fifteen kilograms and are up to a metre in length. Some individuals can be substantially larger than this and Quinnat Salmon in their native range are known to reach a metre and a half in length with the largest Salmon on record having been caught off the coast of Alaska and weighing in at 59 kilograms (McDowell, 2001).
Similar species
The most similar species to Quinnat Salmon are other Pacific Salmon (Oncorhynchus spp.) and Steelhead Trout (Oncorhynchus mykiss) which have a similar life cycle. Sockeye Salmon (Oncorhynchus nerka) are the only other species of Pacific Salmon found in New Zealand and are confined to the landlocked variety making them smaller and morphologically different than the Quinnat Salmon. Quinnat Salmon also share some physical characteristics (body form and black spots with silver background) with Rainbow Trout (Oncorhynchus mykiss); however differentiation of the two species is not difficult. Morphologically the most similar species is the Coho Salmon (Oncorhynchus kisutch), a species of Pacific Salmon native to the Northwestern United States and Western Canada. The Quinnat Salmon is differentiated from the Coho by the larger size and the black gums of the Quinnat Salmon (Quinn, 2005).
Geographic Distribution
Full natural and naturalised range
Quinnat Salmon are found as a native species on the Pacific Coast of the United States and Canada. Extending from California in the US, through Canada and throughout Alaska. They are also native to the western side of the Pacific occurring naturally in Japan and Russia. Quinnat Salmon spend most of their lives in the Pacific Ocean, Sea of Japan, Bering Sea, Sea of Okhotsk, and the Arctic Ocean. New Zealand is the only place in the world where Quinnat Salmon have been successfully naturalized and formed a self sustaining population outside of their native range (Quinn, 2005).
New Zealand and Canterbury naturalised ranges
Quinnat Salmon in New Zealand occur mainly in the Canterbury region when migrating into the region's large braided rivers to spawn. Other wild populations exist in the South (Clutha River) and several small populations in rivers on the West Coast. Landlocked populations are present in some mountain lakes from North Canterbury and south into the Otago region. However, the main populations of Quinnat Salmon in New Zealand occur in the Rangitata, Rakaia, Waitaki, Hurinui, and Waimakiriri Rivers. These major river runs are also the major self-sustaining runs of Quinnat Salmon. While other runs in some parts of New Zealand are self sustaining, many are supplemented by hatchery schemes (McDowell, 2001).
Natural History in Canterbury
Preferred Habitat
In the ocean Quinnat Salmon tend to cruise parallel to the coast line at a distance of 5 to 30 kilometers from shore. Quinnat Salmon in New Zealand prefer the large braided, cold water rivers of the Canterbury region. The fish migrate up these rivers where they spawn in small headwater streams with cold clear water, and gravel beds (McDowell, 2001).
Phelology/Breeding
Quinnat Salmon are one of several species of Pacific Salmon, all of which are native to the Northern Pacific Ocean and exhibit an anadromous and semelparous life cycle. Anadromous fish spend most of their life cycle maturing in the marine environment before they ascend freshwater rivers to spawn. When the eggs hatch the fry head downstream to begin the process over again. Semelparous fish are those who spawn once and then die after spawning (Quinn, 2005).
In their native range Quinnat Salmon fry spend six months to two years in the freshwater stream where they hatched before migrating to the ocean. In the ocean they feed on crustaceans and other smaller fish species. In the ocean Quinnat Salmon travel widely. Individuals from the Columbia River system (Washington State, and Oregon State, US) occasionally end up as far North as Alaska. More extreme are individual Steelhead Trout (a close relative of the Quinnat Salmon) from the same area being caught off the coast of Japan. Quinnat Salmon may spend as little as one year in the ocean gaining weight for the return journey, or as many as nine years. When the timing is right Quinnat Salmon migrate back up the rivers; typically to the same headwater stream and often the same pool they hatched from. Timing of different runs vary. In the United States runs are classified as Spring, Summer, or Fall. The time it takes to reach the spawning grounds also varies with different runs, usually between one and three months. Shortly after spawning the adult fish die and in the spring the eggs hatch (Quinn, 2005).
The first attempts to naturalize Quinnat Salmon were made in 1875 in Hawkes Bay but were unsuccessful. After more than twenty five years, and many attempts by regional acclimatization societies, the New Zealand Government decided to make one concerted effort to establish a population in the Waitaki River. In 1905 the effort proved successful and the first naturalized population of Quinnat Salmon in the world were firmly established away from their native waters. The homing instinct of Quinnat Salmon is not always precise and individuals of the species have a tendency to wander into and colonize rivers other than the river they came from. This wandering has allowed the species to conserve its genetic diversity across different runs in different river systems. This was true of Quinnat Salmon in New Zealand with fish appearing in the Rakaia 1909, and reaching as far north as the Wairau River in 1922. This spread, along with the help of government releases of hatchery raised fish, has helped create naturalized runs in the major braided rivers of the Canterbury region.
Since their establishment in Canterbury waters, Quinnat Salmon have adapted their particular life cycle to the region. To match the seasons of the Southern Hemisphere, New Zealand Quinnat Salmon begin their upstream migrations in November peaking early in the new year and reaching their spawning grounds by mid to late April. The time spent in the ocean by Quinnat Salmon in their native range is highly variable, ranging from one to nine years. In New Zealand waters adult Quinnat Salmon spend two to four years in the ocean with a very small percentage returning after only six months at sea. Also the time spent in freshwater by New Zealand Quinnat Salmon is shorter and less variable than their Northern counterparts. Most juveniles migrate out to the ocean almost immediately after hatching. Quinnat Salmon in New Zealand have also been successfully introduced as a landlocked species spending their adult life in freshwater lakes before migrating up feeder streams to spawn. Landlocked Quinnat Salmon are similar to ocean run fish with the main differences being a shorter life cycle and a smaller maximum size (Bryant, 1979).
How to find a Quinnat Salmon
The most popular method for finding Quinnat Salmon is with heavy fishing tackle between the months of November and February. While Quinnat Salmon are available at fish farms, the most popular way to become acquainted with these fish is recreational fishing. The best fishing is from early in the new year into February and March. Most fish are caught near the mouths of rivers early in the run and high in the headwaters as the season progresses. If you are not the fishing type there are numerous salmon farms in New Zealand where you could probably get a closer look at a Quinnat Salmon. Also some of the small headwaters where Quinnat Salmon spawn, as well as some sites of captive breeding or rearing, give an opportunity to see them in the water (McDowell, 2001).
Abundance and Conservation Status
While there are no Quinnat Salmon in the greater part of New Zealand (including no populations on the North Island) the Canterbury stocks, supplemented with hatchery released fish, are healthy. Outside of Canterbury Quinnat Salmon are uncommon and populations that do exist are often either landlocked or small ocean run stocks. Quinnat Salmon are threatened or endangered in much of their native habitat in the lower US and parts of Canada, most notably in the Columbia River Basin. While other places in the world have reported some ecological problems after supplemental runs of Quinnat Salmon have been established, these problems have been absent in New Zealand (McDowell, 2001).
- New Zealand: uncommon
- Canterbury: common
Significance for People
Modern Uses
Since the naturalization of Quinnat Salmon in New Zealand the numbers of fish present has risen enough to make them a potential and popular sport fish in salt and freshwater. With established runs of Quinnat Salmon in several rivers in the Canterbury region, they have become a highly sought game fish for New Zealand and international anglers. The popularity of Quinnat Salmon provides an economic boost for the region bringing in revenue from fishing licenses, bait and tackle, and bringing tourists into the area (McDowell, 2001).
In other parts of their native range Quinnat Salmon are harvested commercially. In New Zealand the commercial use of Quinnat Salmon is in aquaculture (fish farming). Farms raising captive salmon have become a major industry in New Zealand. The first salmon farms producing salmon for commercial sale were started in the late 1970's. Currently there are numerous saltwater farms in the Marlborough Sounds and around Stewart Island. All freshwater salmon farms in New Zealand are confined to the South Island, mainly in the Otago and South Canterbury Region. New Zealand is also, currently, the only place in the world were salmon farming has combined with hydropower. Several salmon farms are operating in the hydro canals in the Mackenzie Basin (NZ Salmon, 1998).
References
Bryant, M. G., (1979). The New Zealand Quinnat Salmon Fishery: Problems with Multiple Water use Conflicts and Management. Presented in Partial fulfilment for the requirement for the Degree of Master of Science in the University of Canterbury. University of Canterbury, Christchurch, NZ.
McDowell, R. M., Lagahetau, C., (Ed.) (2001). Freshwater Fishes of New Zealand. Auckland, NZ. Reed.
New Zealand Salmon Company Ltd, (1998). Annual Report. Dunedin, NZ. The Company.
Quinn, T. P., (2005). The Behavior and Ecology of Pacific Salmon and Trout. Bethesda, MD, USA. American Fisheries Society.
Search for Oncorhynchus tshawytscha in New Zealand science online
New Zealand Journal of Ecology articles containing Oncorhynchus tshawytscha.
Search NZ Royal Society journals for articles containing Oncorhynchus tshawytscha.
