Aquatic Species at Risk - Sockeye Salmon (Cultus population)

Species - Details

Cultus Lake sockeye salmon

Scientific name:
Oncorhynchus nerka
Taxonomy:
Fishes (freshwater)
Status:
Not listed under SARA. Designated endangered by COSEWIC.
Region: British Columbia Pacific Ocean

Related Information

Cultus Lake sockeye are one of the few salmon populations to spawn in a lake rather than in a stream or river. Like other sockeye, the Cultus Lake salmon die after spawning.

At a glance

The Cultus Lake sockeye salmon is an anadromous fish—that is, a fish that lives part of its life in freshwater before migrating to the sea. In the past 12 years, numbers of successfully spawning Cultus Lake sockeye have declined by 92 percent. The reasons for this population decline are thought to include fishing, poor marine survival, and, since 1995, the death of high numbers of fish before spawning. Habitat alterations may have also played a role in this decline.

About the Cultus Lake sockeye salmon

Unlike many other salmon, Cultus Lake sockeye don’t spawn until November or December. The fish spend their first two years of life in freshwater before migrating to the sea. The salmon spend a further two years in the ocean before returning to Cultus Lake to spawn. Sockeye salmon are plankton feeders, filtering tiny organisms from the water with their closely spaced gill rakers.

How to recognize a Cultus Lake sockeye salmon

Adult sockeye salmon living in saltwater usually have bluish backs and silver sides. When sockeye spawn, their bodies typically turn bright-red and their heads become green. However, it is not possible to identify a Cultus Lake sockeye salmon by appearance alone. Genetic testing must be used to differentiate Cultus Lake sockeye from other sockeye salmon.

Cultus Lake sockeye salmon

Fisheries and Oceans Canada

Cultus Lake sockeye salmon

Jeremy Sarrow, © California Academy of Sciences

Cultus Lake sockeye salmon

male and female sockeye salmon, U.S. Fish and Wildlife Service

Cultus Lake sockeye salmon

spawning sockeye swimming with a trout, U.S. Fish and Wildlife Service

Where the Cultus Lake sockeye salmon lives

Cultus Lake is located in southwest British Columbia, in the eastern Fraser Valley, south west of Chilliwack. The lake is 112 km upstream from the Strait of Georgia. The salmon live and spawn in the lake and migrate to the North Pacific Ocean through the Fraser River to the Strait of Georgia.

Why it’s at risk

The Cultus Lake sockeye salmon is at risk from being accidentally caught in the mixed-stock sockeye salmon fisheries, as well as from the various negative impacts to their lake habitat, including predation, colonization by Eurasian Watermilfoil, land development, water pollution and recreational use. In recent years, Cultus Lake sockeye has suffered significant pre-spawning mortality as have other stocks of Fraser River sockeye with similar run times. The salmon’s high rate of pre-spawning mortality is thought to be associated with infestations of Parvicapsula minibicornis, a parasite that attacks the salmon’s kidneys and gills.

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What’s being done

The Cultus Lake sockeye salmon is designated as endangered by COSEWIC. In January 2005, a final decision was made by the Government of Canada to not list Cultus Lake sockeye salmon under the Species at Risk Act (SARA), due to the significant socio-economic impacts on sockeye fishers and coastal communities.

Beginning in 1998, Fisheries and Oceans Canada put in place conservation measures to protect late run sockeye (including Cultus Lake sockeye). With the help of a number of partners, additional measures will further protect these populations. These measures include:

Captive Breeding Program

Cultus Lake sockeye are currently being reared at enhancement facilities in the lower Fraser area and on Vancouver Island. This project began in 2000 and is intended to operate through to 2007. The objective is to raise 500 mature individuals in captivity each year. The eggs spawned in captivity are released as fry in their first fall or as smolts in their second spring. The intent is to increase the recovery rate of the population.

Predator Removal

Adult northern pikeminnows are abundant in Cultus Lake and are predators of salmon fry. The removal of adult pikeminnows from Cultus Lake has been conducted on two separate occasions in the past. An evaluation of this previous work indicates that the removal of predators can increase survival of sockeye fry in the short term, and may have long term benefits with the careful monitoring of population structures.

The improvement of freshwater survival of smolts is critical to the recovery of the species, especially for the brood years when abundance is expected to be very low, such as 2004 and 2005. To date, this project has studied information on the effects of predator removal in Cultus Lake, identified appropriate removal methods (ie. techniques and time periods), estimated the size of the pikeminnow population and began removals during the spawning season. Ongoing analyses of results, including developing a model to assist in interpreting the potential effects of the removal program on salmon survival, will be conducted throughout the duration of the program.

Milfoil Removal

Habitat restoration work involves the removal of Eurasian Watermilfoil (a common yarrow plant that provides habitat for sockeye predators) in Cultus Lake. Milfoil removal has been conducted in the past, mainly as a control for "exotic weeds". Milfoil is an invasive species and ongoing watermilfoil assessment and removal will expose juvenile pikeminnows to predation by adult pikeminnows and to clear milfoil from prime salmon spawning habitat.

Smolt Assessment

Cultus Lake sockeye have been the subject of detailed scientific study for longer than any other salmon population in BC; ongoing stock assessment work on the status of Cultus Lake sockeye smolts and adults continues. These assessments are being carried out to determine the abundance, timing and biological characteristics of Cultus Lake smolts and adults as they migrate past the Sweltzer Creek enumeration fence. Migrants are counted and sampled at the enumeration fence for the entire migration period to provide population estimates, estimate survival rates, evaluate enhancement activities and determine whether any additional measures are needed to assist in the recovery of this endangered stock.

Assessment of Adult Marine Survival and Migration Route

A cooperative acoustic tagging project, lead by the Pacific Ocean Shelf Tracking Project (POST), is intended to provide a variety of information on the early marine migration and distribution of sockeye juveniles. DFO’s portion of the project involves purchasing a portion of the acoustic tags and providing the smolts for the surgical implantation of the tags.

Smolts are tagged using the POST technology and released into seawater. The tags are designed and programmed to remain active for the summer they are tagged and released, in order to indicate the juvenile (seaward) migration route. The tags then enter sleep mode to preserve the battery life until the season and year in which they are expected to return as adults.Each fish that survives natural hazards is expected to yield data on the timing and routes of both its seaward and return migration.

What can you do?

The Cultus Lake sockeye salmon will get the protection it needs only if all Canadians work together to reduce threats. Find out more about sockeye salmon and be aware of human-induced threats. Do your best to reduce these threats wherever possible to better protect the salmon’s critical habitat. Get involved with the Habitat Stewardship Program for Species at Risk (HSP) or another conservation organization.