Spotlight on the Chinook Salmon: Okanagan Population

Okanagan Similkameen Conservation Alliance  chinook_salmon
The South Okanagan Similkameen valleys are home to two major river systems, the Similkameen River and the Okanagan River. These rivers are part of the Columbia River system that flows to the Pacific Ocean at Astoria, Oregon. The Chinook Salmon is one of the seven species of salmon that is native to North America and that uses this system.

Latin name: Oncorhynchus Tshawytscha (Okanagan population)
Federal Status: Threatened
Provincial Status: Blue Listed (vulnerable)

Characteristics


Also known as Ntitiyix (king salmon) by the aboriginal Okanagan peoples, this type of Chinook salmon is the only anadromous Chinook that return to Canada. An anadromous fish is one that migrates from salt water to spawn in fresh water. The Okanagan chinook uses the Okanagan River Basin as its freshwater spawning ground.

The Okanagan chinook is distinguished from other salmon species by its large size, small black spots on the tail fin, black gums at the base of the teeth in the lower jaw and the large number of digestive sacs.
Biology, Migration and Spawning. Adult anadromous Okanagan chinook migrate from the Pacific Ocean, up the Columbia River and into Osoyoos Lake and the Okanagan River. The accessible portion of the Okanagan River ends at the McIntyre Dam (see map), and spawning occurs between the dam and Osoyoos Lake. During migration, anadromous adults may hold in the Okanagan River at Osoyoos Lake until spawning temperatures are favourable. Temperatures need to be approximately 10 to 14 degrees celcius. The chinook enter the Okanagan River in June/July and likely hold until spawning in October. Peak spawning occurs generally in the third week of October. Fry rear in the Okanagan River and/or Osoyoos Lake for a period ranging from weeks to a year or more. Those migrating to the ocean probably exit Osoyoos Lake during April and May or in early July. The ocean phase of their life ranges from one to three years with adults returning primarily as four to five year olds. Some Okanagan Chinook appear not to migrate but instead come to maturity in Osoyoos Lake.

Population

The historic population of the Okanagan chinook was large in size and supported a significant food and trade fishery by the native Okanagan peoples. The current population of anadromous individuals is known to be approximately five to twenty-five adults. It is hard to estimate the population size of those that mature in freshwater. The Okanagan chinook has been historically persistent but with such low numbers its future is unlikely.

Threats

  • Loss of access to habitat upstream of McIntyre Dam.
  • Water quality issues in spawning and rearing habitats.
  • Invasive species of aquatic fish and plants in Osoyoos Lake.
  • Losses of migrating juveniles and adults to injury and predation at the mainstem dams and impoundments.

What is being done to help the Okanagan Chinook?

The Okanagan Nation Alliance Fisheries Department and the Osoyoos Indian Band are monitoring and collecting information on the Okanagan Chinook. Information such as escapement numbers (number of adults that have returned to spawn), biological information (age, sex, weight, length, DNA), interactions with other species in Osoyoos Lake and habitat surveys. All this information is being collected to better understand the Chinook and its requirements so that a recovery plan can be made for this species.

You can help by

  • Protecting rivers, streams and estuaries from pollution and introduction of invasive aquatic plant and animal species.
  • Maintaining riparian vegetation. See the Riparian Area Regulation.
  • Learning more about conservation efforts to protect this and other endangered and threatened species. Visit www.soscp.org.
  • Learn more about local plant and animal species from conservation groups, Ministry of Environment and local First Nations organizations.
  • Come to BC Rivers Day in September 27th.

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