Steelhead Trout (Chilcotin River Designatable Unit)

Oncorhynchus mykiss

SARA Status
No Status
NS
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

SARA Status

  • No Status NS
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX
COSEWIC Status
Not at Risk
NR
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

COSEWIC Status

  • Not at Risk NR
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX

Description

Steelhead Trout (sometimes referred to as “Steelhead Salmon”) is the anadromous form (i.e. fish which migrate from marine to freshwater environments to spawn) of Rainbow Trout (Onchorhynchus mykiss), which is a salmonid found in freshwater tributaries to the Pacific Ocean. Steelhead Trout have a similar appearance to Rainbow Trout, especially during earlier life cycle stages. Individuals of this species can vary in colouration depending on how much time they have spent in freshwater as opposed to the marine environment. With a shorter length of time spent in freshwater, a Steelhead will appear similar to Pacific Salmon, having dark blue backs with spots and silver sides. The longer time spent in freshwater, the more a Steelhead looks like a Rainbow Trout: bright silver with orange and pink tints amongst its scales.

As adults, Steelhead range from 50 to 85 centimetres in length and have a more streamlined, torpedo-shaped body than resident Rainbow Trout. Steelhead Trout are also distinguished from resident Rainbow Trout by their older age of maturity and larger size.

Steelhead can spawn repeatedly during their lifespan. At maturity, the male’s jaw will grow long and develop a knob at its tip (also known as a “kype”) , similar to Pacific Salmon. As they prepare to spawn, Steelhead acquire a pink or red lateral line that extends over the gill covers, and their overall colouration darkens to grey or brown.

Eggs are deposited into redds in clean gravel located in fast-flowing riffle habitat. Newly hatched alevin rely on this gravel habitat and remain in it until they emerge as fry. Fry spend time in their natal tributary stream and potentially in the Chilcotin River mainstem, primarily in glide and pool habitat, before entering the marine environment as smolts. Suitable Steelhead Trout freshwater habitat depends on prey availability as well as water quality conditions such as dissolved oxygen, temperature, and pH; eggs and alevin have higher requirements for these attributes than other life stages. Marine habitat for Steelhead is also subject to these conditions as well as salinity.

Chilcotin Steelhead stocks have declined dramatically over the last three generations and are now at their lowest on record. The number of spawners was high and variable with little trend prior to 2000. The 58 mature fish observed in the most recent survey (2017) represent only five percent of the average number of spawners prior to 2000.

Habitat

The global range of Steelhead Trout is in the coastal waters and tributary streams of the Pacific basin, from the Kamchatka Peninsula in Russia, east along the Aleutian Islands, throughout southwest Alaska, the Pacific coast of British Columbia and southeast Alaska, and south along the west coast of the United States to northern Mexico. In Canada, Steelhead Trout are found in larger British Columbia watersheds, from south coastal areas to northwestern B.C.

Based on genetic data, Steelhead Trout in the Chilcotin region and Thompson River are considered discrete from other Canadian Steelhead Trout. Furthermore, DNA studies have concluded that Chilcotin and Thompson Steelhead are genetically distinct from each other. As such, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has determined that Thompson Steelhead and Chilcotin Steelhead should be assessed as two distinct designatable units (DUs).

Threats

Chilcotin Steelhead Trout face a number of threats, including declining habitat quality in both freshwater and marine environments, and bycatch mortality from salmon fisheries.

Further Information

In April 2016, British Columbia’s Ministry of Forests, Lands, and Natural Resource Operations produced a Provincial Framework for Steelhead Management in British Columbia [PDF], intended to provide provincial direction for steelhead management and to guide the implementation of regional management actions in British Columbia. Strategic actions in this plan relate to: the regulation of fisheries, habitat restoration and protection, the engagement of stakeholders, First Nations, and DFO, stock assessment, licensing improvements, partnership with DFO through the existing Integrated Fisheries Management Plan, the development of a risk assessment framework, and hatchery assessment.

On December 7, 2017, the Chair of the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) informed the Minister of Environment and Climate Change Canada that COSEWIC would be engaging in an emergency assessment (EA) of the Interior Steelhead Trout (Thompson population and Chilcotin population) of the south central interior of British Columbia, per sections 28.1 and 28.2 of the Species at Risk Act. The emergency assessment is premised on an application supporting biological information indicating that there is an imminent threat to the survival of the species, and what appears to be a dramatic decline in the numbers of mature fish returning to spawn.

Results of the emergency assessment of Steelhead Trout (Thompson River and Chilcotin River Designatable Units) were made public on February 13, 2018, and are available on the Species at Risk Public Registry.

To find out if this species is protected by provincial or territorial laws, consult the provinces' and territories' website.

Steelhead Trout (Chilcotin River Designatable Unit)

Steelhead Trout (Chilcotin River Designatable Unit). Photo Credit: DFO

Steelhead Trout (Chilcotin River Designatable Unit)
Photo Credit: DFO

Scientific name: Oncorhynchus mykiss
SARA Status: Under consideration
COSEWIC Status: Endangered
Regions: British Columbia and Pacific Ocean

Region map

Region map, British Columbia

Regions: British Columbia and Pacific Ocean

Did You Know?

The extended lifespan of Steelhead Trout may allow individuals to reach an age of over 13 years.

Related information

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