Chinook Salmon (Oncorhynchus tshawytscha): COSEWIC assessment and status report 2018 : Document information

Document information

COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows:

COSEWIC 2019. COSEWIC assessment and status report on the Chinook Salmon Oncorhynchus tshawytscha, Designatable Units in Southern British Columbia (Part One – Designatable Units with no or low levels of artificial releases in the last 12 years), in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xxxi + 283 pp. (Species at Risk Public Registry).

Production note: COSEWIC would like to acknowledge Brian Ma, Cedar Morton and Diana Abraham formerly of ESSA Technologies Ltd. for writing the status report on Chinook Salmon, Oncorhynchus tshawytscha, Designatable Units in Southern British Columbia Part One, prepared under contract with Environment and Climate Change Canada. This report was overseen and edited by Alan Sinclair and John Neilson, Co-chairs of the COSEWIC Marine Fishes Specialist Subcommittee. Many SSC members contributed reviews of this extensive document, and by doing so, materially improved its quality. In particular, Carrie Holt played a lead role in making DFO data available, as well as helping with the analyses, recommendations and review.

For additional copies contact:

COSEWIC Secretariat
c/o Canadian Wildlife Service
Environment and Climate Change Canada
Ottawa, ON
K1A 0H3

Tel.: 819-938-4125
Fax: 819-938-3984
E-mail: ec.cosepac-cosewic.ec@canada.ca
Web site: COSEWIC

Également disponible en français sous le titre Ếvaluation et Rapport de situation du COSEPAC sur le Saumon chinook (Oncorhynchus tshawytscha), unités désignables du sud de la Colombie Britannique (première partie – unités désignables ayant fait l'objet d’un nombre très faible ou nul de lâchers d'écloseries ces 12 dernières années), au Canada.

Cover illustration/photo: Chinook Salmon — Illustration provided by authors.

COSEWIC assessment summary

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 2: Lower Fraser, Ocean, Fall population

Scientific name: Oncorhynchus tshawytscha

Status: Threatened

Reason for designation: While the calculation of decline rates is complicated by hatchery releases from 1981 to 2004, this fall run of chinook spawning in the lower Fraser River has steadily declined in abundance. The abundance data over all available years was thought to best represent natural spawner abundance. Declines in marine and freshwater habitat quality, harvest and ecosystem modification in the lower Fraser estuary are threats facing this population.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Threatened in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 3: Lower Fraser, Stream, Spring population

Scientific name: Oncorhynchus tshawytscha

Status: Special Concern

Reason for designation: This spring run of chinook, which spawns in the lower Fraser River watershed, has declined over the last three generations. Declines in marine and freshwater habitat quality, and harvest, are continuing threats. Should the present low number of mature individuals decline further, this population may become Threatened.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Special Concern in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 4: Lower Fraser, Stream, Summer (Upper Pitt) population

Scientific name: Oncorhynchus tshawytscha

Status: Endangered

Reason for designation: This summer run of chinook spawning in the Pitt River in the lower Fraser River watershed has declined, and is now at its lowest recorded abundance. Declines in freshwater and marine habitat quality, and harvest, are continuing threats to this population.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Endangered in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 5: , Lower Fraser, Stream, Summer population

Scientific name: Oncorhynchus tshawytscha

Status: Threatened

Reason for designation: This summer run of chinook spawning in the Lillooet and Harrison Rivers in the Lower Fraser watershed has declined to low levels. Declines in freshwater and marine habitat quality, and harvest, are threats facing this population.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Threatened in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 7: Middle Fraser, Stream, Spring population

Scientific name: Oncorhynchus tshawytscha

Status: Endangered

Reason for designation: This population of spring run chinook spawning in the Nahatlatch and Anderson watersheds has declined to very low levels. Declines in freshwater and marine habitat quality, and harvest, are threats facing this population.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Endangered in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 8: Middle Fraser, Stream, Fall population

Scientific name: Oncorhynchus tshawytscha

Status: Endangered

Reason for designation: This population of fall run chinook spawning in the Seton and Anderson watersheds along the middle Fraser River has declined to very low levels, and decline is anticipated to continue. Declines in freshwater and marine habitat quality, and harvest, are threats facing this population.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Endangered in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 9: Middle Fraser, Stream, Spring (MFR+GStr) population

Scientific name: Oncorhynchus tshawytscha

Status: Threatened

Reason for designation: This spring run of chinook spawning in multiple middle Fraser River tributaries has declined in abundance. Declines in marine and freshwater habitat quality, and harvest, and pollution from mining activities are threats to this population.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Threatened in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 10: Middle Fraser, Stream, Summer population

Scientific name: Oncorhynchus tshawytscha

Status: Threatened

Reason for designation: This summer run of chinook spawning in multiple middle Fraser River tributaries has declined in abundance. Declines in marine and freshwater habitat quality are threats facing this population.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Threatened in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 11: Upper Fraser, Stream, Spring population

Scientific name: Oncorhynchus tshawytscha

Status: Endangered

Reason for designation: This spring run of chinook spawning in the Salmon and Raush Rivers in the upper Fraser watershed has declined in abundance. Declines in marine and freshwater habitat quality, and harvest, are threats facing this population. Anticipated changes to North Pacific weather systems that affect ground water availability, will impact spawning sites and overwinter survival.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Endangered in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 12: South Thompson, Ocean, Summer population

Scientific name: Oncorhynchus tshawytscha

Status: Not at risk

Reason for designation: This summer run of chinook to the South Thompson River has been steadily increasing in abundance, and the most recent population index is the second highest on record.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Not at risk in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 14: South Thompson, Stream, Summer 1.2 population

Scientific name: Oncorhynchus tshawytscha

Status: Endangered

Reason for designation: This summer run of chinook spawning in the South Thompson River has steeply declined in abundance to a very low level. Declines in marine and freshwater habitat quality, and harvest, are threats facing this population.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Endangered in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 16: North Thompson, Stream, Spring population

Scientific name: Oncorhynchus tshawytscha

Status: Endangered

Reason for designation: This spring run of chinook spawning in the North Thompson River has steeply declined in abundance to a low level. Declines in marine and freshwater habitat quality, and harvest, are threats facing this population. Anticipated changes in North Pacific weather systems that affect groundwater availability will impact spawning sites and overwinter survival.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Endangered in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 17: North Thompson, Stream, Summer population

Scientific name: Oncorhynchus tshawytscha

Status: Endangered

Reason for designation: This summer run of chinook spawning in the North Thompson River has steeply declined in abundance. Declines in marine and freshwater habitat quality, and harvest, are threats facing this population.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Endangered in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 19: East Vancouver Island, Stream, Spring population

Scientific name: Oncorhynchus tshawytscha

Status: Endangered

Reason for designation: This spring run of chinook to the Nanaimo River has been at a very low abundance for a long time. Declines in marine and freshwater habitat quality are threats facing this population.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Endangered in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 27: Southern Mainland, Ocean, Summer population

Scientific name: Oncorhynchus tshawytscha

Status: Data deficient

Reason for designation: This summer run of chinook to spawn in the remote glacial Homathko River watershed in the southern mainland has not been surveyed sufficiently to assess its population status.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Data Deficient in November 2018.

Assessment summary - November 2018

Common name: Chinook Salmon - Designatable Unit 28: Southern Mainland, Stream, Summer population

Scientific name: Oncorhynchus tshawytscha

Status: Data deficient

Reason for designation: This summer run of chinook to spawn in the remote glacial Klinaklini River watershed in the southern mainland of British Columbia has not been recently surveyed to assess its population status.

Occurrence: British Columbia, Pacific Ocean

Status history: Designated Data Deficient in November 2018.

Introduction

COSEWIC assessed the status of 16 of 28 Designatable Units of Southern British Columbia Chinook Salmon in November 2018. Those DUs were considered to have received only relatively small levels of artificial supplementation over the past three generations, or were previously considered by the Department of Fisheries and Oceans Canada to be Data Deficient. The results of the assessment are provided in this report. The list of the assessed Designatable Units is:

DU Number and Name

DU 2: Lower Fraser, Ocean, Fall population
DU 3: Lower Fraser, Stream, Spring population
DU 4: Lower Fraser, Stream, Summer (Upper Pitt) population
DU 5: Lower Fraser, Stream, Summer population
DU 7: Middle Fraser, Stream, Spring population
DU 8: Middle Fraser, Stream, Fall population
DU 9: Middle Fraser, Stream, Spring (MFR+GStr) population
DU 10: Middle Fraser, Stream, Summer population
DU 11: Upper Fraser, Stream, Spring population
DU 12: South Thompson, Ocean, Summer population
DU 14: South Thompson, Stream, Summer 1.2 population
DU 16: North Thompson, Stream, Spring population
DU 17: North Thompson, Stream, Summer population
DU 19: East Vancouver Island, Stream, Spring population
DU 27: Southern Mainland, Ocean, Summer population
DU 28: Southern Mainland, Stream, Summer population

The remainder (12) of the Southern British Columbia Chinook Salmon Designatable Units include those that have received more substantial levels of artificial supplementation over the past three generations. COSEWIC will meet in the near future to determine the status of those DUs. After that meeting, the final version (Part 1 and Part 2) of this report will be prepared.

COSEWIC executive summary

Chinook Salmon
Oncorhynchus tshawytscha

Designatable Units in Southern British Columbia
(Part One – Designatable Units with No or Low Levels of Artificial Releases in the Last 12 Years)

Wildlife species description and significance

Chinook Salmon is the largest-bodied of the Pacific salmon, and can be distinguished by small black spots on the lower lobes of their caudal fin, a pointed lower jaw, and black gums. In Canada, Chinook Salmon are an important food source for other fish and certain marine and terrestrial mammals, as well as a key target species for recreational and commercial fisheries, and highly significant to First Nations and Métis in British Columbia (BC) as a cultural symbol and connection to a way of life for subsistence.

Distribution

In Canada, Chinook Salmon occur in river systems that drain into the Pacific Ocean (incl. the Okanagan River system), the Bering Sea (Yukon River system), and the Arctic Ocean. For this status report, southern BC Chinook Salmon populations are subdivided into 28 Designatable Units (DUs) using methods based on COSEWIC guidelines and work by Fisheries and Oceans Canada to identify Conservation Units under the Wild Salmon Policy. The DUs that are defined and accepted for this assessment represent distinct groups of southern BC Chinook Salmon based on geographic distribution, life-history variation, and genetic data.

Habitat

Chinook Salmon spawning occurs from near tidal influence to 3,000 kilometres upstream near river headwaters. Successful incubation requires stable flows that are adequate to supply enough oxygen, but not so high as to cause gravel movement or streambed scour. Provided that adequate subgravel flow conditions are met, Chinook Salmon will spawn in a broad range of water depths, water velocities, and substrates. The suitable temperature range for egg survival is 0-15°C.

Rearing occurs in freshwater, estuaries, and the ocean. In freshwater, the abundance of juveniles tends to be highest in shallow waters with low velocity and small substrate particle size. Water temperatures of 10-14°C provide suitable rearing conditions. Coastal estuaries offer an environmental transition zone for acclimating to the change from freshwater to saltwater. Shoreline vegetation provides an important refuge from predators as well as a productive environment for insects and plankton, both major dietary components for juvenile Chinook Salmon.

Chinook Salmon have been adversely affected in their freshwater habitat by numerous factors, including water withdrawals, construction of dams (for power generation or water diversion) that limit fish passage or entrain/harm migrating fish, and degradation of habitat through industrial, agricultural and urban usage. Salmon survival is also linked to conditions in the marine environment. Both natural and human-induced impacts on marine ecological processes, including climate change, contribute to changes in ocean conditions that affect Chinook Salmon growth and survival.

Biology

The generalized life history of Pacific salmon involves incubation, hatching, and emergence in freshwater, freshwater rearing, migration to the ocean and subsequent initiation of maturation, and return to freshwater for completion of maturation and spawning. Within this general life-history strategy, Chinook Salmon exhibit marked variation in age at seaward migration; length of freshwater, estuarine, and oceanic residence; ocean distribution and ocean migratory patterns; and age and season of spawning migration.

Two general behavioural and life-history forms of Chinook Salmon are generally assigned or discussed: stream-type and ocean-type. Stream-type Chinook Salmon were understood to spend up to one or more years as fry or parr in freshwater before migrating to sea, perform extensive offshore oceanic migrations, and return to their natal stream in the spring or summer several months prior to spawning. Ocean-type Chinook Salmon were understood to migrate to sea during their first year of life, normally within two to five months after emergence from the spawning gravel, spend most of their ocean life in coastal waters, and return to their natal stream in the fall, a few days or weeks before spawning.

In recent decades, it has become more accepted to consider a continuum of diverse life-history strategies ranging from ocean-type to stream-type. Variations within the ocean-type and stream-type behavioral forms have been identified based on the geographic origins of the fish and the resulting conditions to which they have adapted. Ocean-type Chinook Salmon can rear in freshwater for up to six months post-emergence, while stream-type Chinook Salmon may only remain in freshwater for a few weeks. This “plasticity” is critical for the persistence of Chinook Salmon as it spreads risk across many different strategies in the face of variable climatic conditions.

The duration Chinook Salmon remain at sea before homeward migration for spawning can range from 1 to 6 years, but more commonly ranges from 2 to 4 years. Peak migratory activity occurs in June for northern river systems and can range from April to September further south depending on migration strategy. This migration timing is not always correlated with spawning timing as the latter requires Chinook Salmon to access the spawning grounds, which can in turn depend on freshet timing and suitable stream temperatures.

Chinook Salmon diet varies by life stage. In freshwater, rearing Chinook Salmon feed on crustacea, aquatic insects, aphids, ants, mites, and spiders. In estuaries, food items include chironomid larvae and pupae, and crab larvae, copepods, and other small crustaceans. As smolts grow larger, small fish also become an important component of their diet. In the nearshore environment Chinook Salmon eat mainly forage fish, with invertebrates like pelagic amphipods, squids, shrimp, euphausids, and crab larvae comprising the remainder of their diet. Forage fish dominate the diet of adult Chinook Salmon, especially Herring, Sand Lance, and Northern Anchovy.

As with diet, predation on Chinook Salmon also varies by life stage. Spiny Dogfish, Northern Pikeminnow, Bull Trout, and River Lamprey are predators of juvenile Chinook Salmon during early freshwater and estuarine life stages. Avian predation is also key during these stages (for example, gulls, merganser). Southern resident killer whalesin the lower Strait of Georgia as well as northern resident killer whales have a preference for Chinook Salmon adults (≥2 years at sea). Hake, Mackerel, Sea Lions, Harbour Seals, White-sided Dolphins, and cormorants are also known predators of salmon in the marine environment. River otters, bears, and eaglescommonly prey on adult Chinook Salmon when they return to freshwater.

Population size and trends

Information about population sizes and trends is presented for each DU separately, including extent of occurrence and area of occupancy, habitat trends, sampling effort and methods (for abundance, enhancement, hatchery releases), fluctuations and trends, and threats and limiting factors.

Threats and limiting factors

Potential threats to Chinook Salmon include harvest, changes in freshwater and marine habitat, climate change, hatcheries, and pathogens/aquaculture.

Harvest impacts vary according to geographic region, depending on where fisheries intercept adult and rearing immature Chinook Salmon during their marine residence, as well as by fishery type (for example, troll, net, recreational fisheries). The annual total landed catch of Chinook Salmon in BC has declined considerably since the mid-1970s. Despite reduced harvests, over the past three generations many areas have experienced declines in spawning escapements due to the cumulative effects of harvest and other factors.

Most Chinook Salmon spend the majority of their lifetime in the marine environment where they are exposed to a wide array of limiting factors. A long-term warming trend in ocean temperatures combined with the effects of climatic cycles such as the Pacific Decadal Oscillation, has negative implications for prey availability. Climatic changes also threaten Chinook Salmon populations in freshwater through rising stream temperatures, as well as reduced glacier size and altered precipitation and snowpack patterns, all of which drive stream flow regimes. Many predator populations have also dramatically increased since the 1970s (esp. pinnipeds). While not as stressed by marine and freshwater pollutants as Chinook Salmon from other regions (for example, Lake Michigan), industrial discharge, storm water runoff, sewage and agricultural runoff are all critical challenges contributing to the species’ status as one of the most toxin laden fishes in BC.

A number of Chinook Salmon populations are supplemented (“enhanced”) by hatchery fish, and there is substantial evidence that enhancement may pose risks to natural populations. However, the effects of enhancement vary among DUs and are poorly understood because of data limitations.

Protection, status, and ranks

Prior to the current assessments, the only Canadian Chinook Salmon that had been evaluated for protection status is Okanagan DU, which was assessed as Endangered by COSEWIC. The Okanagan DU is unique because it is the only Chinook Salmon population in BC that originates in the Columbia River drainage. As such, this DU was evaluated separately and is not included among the 28 DUs reviewed in this report.

Technical summaries

Scientific name: Oncorhynchus tshawytscha
English name: Chinook Salmon
French name: Saumon chinook
Range of occurrence in Canada (all DUs in this report): British Columbia, Pacific Ocean

Designatable Unit 2: Lower Fraser, Ocean, Fall population
Population du bas Fraser, type océanique, automne

Demographic information

Generation time:
3.8 years
Is there a continuing decline in the number of mature individuals?
Yes
Change in number of mature individuals based on last 3 generations observations:
-57 percent
p > 30 percent decline 85 percent
p > 50 percent decline 63 percent
Change in number of mature individuals based on all observations:
-17 percent
p > 30 percent decline 9 percent
p > 50 percent decline 0 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
175 km2
Number of mature individuals:
58,621

Threats

A threats calculator was completed. The main threats were harvest, ecosystem modifications and climate change. The overall threat was High (B). Exploitation rates have been at 20-30 percent for the last ten years and there is a possibility that this rate is higher than sustainable. Several low productivity years have occurred and it is unclear whether the exploitation rate is low enough to compensate. Ecosystem modifications are also relevant because a large portion of the Lower Fraser River and estuary are significantly altered, leading to a loss of critical tide marsh habitat.

Status and reasons for designation

Status: Threatened

Alpha-numeric codes: Meets Endangered, A2acd, but designated Threatened, A2acd, because the longer time series shows lesser decline.

Reasons for designation: While the calculation of decline rates is complicated by hatchery releases from 1981 to 2004, this fall run of chinook spawning in the lower Fraser River has steadily declined in abundance. The abundance data over all available years was thought to best represent natural spawner abundance. Declines in marine and freshwater habitat quality, harvest and ecosystem modification in the lower Fraser estuary, are threats facing this population.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Endangered A2acd. While the rate of decline over the last three generations caused by reduction in habitat quality and harvest exceed the threshold for Endangered A2acd, use of the rate of decline of mature individual over the entire time series is warranted because of the potential influence of stock enhancement.

Criterion B (Small Distribution Range and Decline or Fluctuation): Does not meet criterion. IAO meets criterion for Endangered and the quality of the freshwater and marine habitats is declining, but the population is not severely fragmented, “locations” does not apply and there are no extreme fluctuations.

Criterion C (Small and Declining Number of Mature Individuals): Criterion not met because the number of mature individuals exceeds the threshold.

Criterion D (Very Small or Restricted Population): Does not meet criterion for D1, as number of mature individuals exceeds the threshold. Threatened D2 does not apply as the number of locations is unknown and the IAO threshold of 20 km2 is exceeded.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 3: Lower Fraser, Stream, Spring population
Population du bas Fraser, type fluvial, printemps

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Yes
Change in number of mature individuals based on last 3 generations observations:
-16 percent
p > 30 percent decline 38 percent
p > 50 percent decline 20 percent
Change in number of mature individuals based on all observations:
21 percent
p > 30 percent decline 0 percent
p > 50 percent decline 0 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
105 km2
Number of mature individuals:
526 (index, not count)

Threats

A threats calculator was not completed. This stock migrates to the north, and most of the harvest occurs off Alaska.

Status and reasons for designation

Status: Special Concern

Alpha-numeric codes: Not applicable

Reasons for designation: This spring run of chinook, which spawns in the lower Fraser River watershed, has declined over the last three generations. Declines in marine and freshwater habitat quality, and harvest, are continuing threats. Should the present low number of mature individuals decline further, this population may become Threatened.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Criterion not met. While the two estimates of the rates of decline for indices of abundance are divergent, both estimates are below the thresholds.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met. While IAO meets criterion for Endangered and the quality of the freshwater and marine habitats is declining, the population is not severely fragmented, the number of locations is unknown and there are no extreme fluctuations.

Criterion C (Small and Declining Number of Mature Individuals): Does not meet, as there is no decline that meets thresholds.

Criterion D (Very Small or Restricted Population): Does not apply. Total number of individuals is unknown, but could be close to the threshold for Threatened. Threatened D2 does not apply as the number of locations is unknown and the IAO threshold of 20 km2 is exceeded.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 4: Lower Fraser, Stream, Summer (Upper Pitt) population
Population du bas Fraser, type fluvial, été (haute Pitt)

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Yes
Change in number of mature individuals based on last 3 generations observations:
-73 percent
p > 30 percent decline 98 percent
p > 50 percent decline 92 percent
Change in number of mature individuals based on all observations:
-73 percent
p > 30 percent decline 98 percent
p > 50 percent decline 92 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
191 km2
Number of mature individuals:
71 (index, not numbers)

Threats

A threats calculator was not completed.

Status and reasons for designation

Status: Endangered

Alpha-numeric codes: A2bcd

Reasons for designation: This summer run of chinook spawning in the Pitt River in the lower Fraser River watershed has declined, and is now at its lowest recorded abundance. Declines in freshwater and marine habitat quality, and harvest, are continuing threats to this population.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Endangered A2bcd because there has been a 73 percent decline in the index of mature fish in the past three generations as a result of declining habitat quality and harvest.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met. While IAO meets criterion for Endangered and the quality of the freshwater and marine habitats is declining, the population is not severely fragmented, the number of locations is unknown and there are no extreme fluctuations.

Criterion C (Small and Declining Number of Mature Individuals): Criterion not met; subpopulation structure is unknown and there are no extreme fluctuations.

Criterion D (Very Small or Restricted Population): Criterion not met.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 5: Lower Fraser, Stream, Summer population
Population du bas Fraser, type fluvial

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Yes
Change in number of mature individuals based on last 3 generations observations:
-36 percent
p > 30 percent decline 52 percent
p > 50 percent decline 43 percent
Change in number of mature individuals based on all observations:
-36 percent
p > 30 percent decline 52 percent
p > 50 percent decline 43 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
645 km2
Number of mature individuals:
52 (index, not count)

Threats

A threats calculator was not completed.

Status and reasons for designation

Status: Threatened

Alpha-numeric codes: A2bcd

Reasons for designation: This summer run of chinook spawning in the Lillooet and Harrison Rivers in the Lower Fraser watershed has declined to low levels. Declines in freshwater and marine habitat quality, and harvest, are threats facing this population.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Threatened A2bcd because there has been a 36 percent decline in the index of mature fish in the past three generations as a result of declining habitat quality and harvest.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met. While IAO meets criterion for Endangered and the quality of the freshwater and marine habitats is declining, the population is not severely fragmented, the number of locations is unknown and there are no extreme fluctuations.

Criterion C (Small and Declining Number of Mature Individuals): Criterion not met.

Criterion D (Very Small or Restricted Population): Criterion not met.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 7: Middle Fraser, Stream, Spring population
Population du moyen Fraser, type fluvial, printemps

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Not applicable
Change in number of mature individuals based on last 3 generations observations:
Not applicable
Change in number of mature individuals based on all observations:
Not applicable
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
103 km2
Number of mature individuals:
65 (index, not count)

Threats

A threats calculator was not completed.

Status and reasons for designation

Status: Endangered

Alpha-numeric codes: D1

Reasons for designation: This population of spring run chinook spawning in the Nahatlatch and Anderson watersheds has declined to very low levels. Declines in freshwater and marine habitat quality, and harvest, are threats facing this population.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Too few data to apply criterion.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met. While IAO meets criterion for Endangered and the quality of the freshwater and marine habitats is declining, the population is not severely fragmented, the number of locations is unknown and there are no extreme fluctuations.

Criterion C (Small and Declining Number of Mature Individuals): Criterion not met as subpopulation structure is not known and there are no extreme fluctuations.

Criterion D (Very Small or Restricted Population): Meets Endangered D1 as there are fewer than 250 mature individuals.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 8: Middle Fraser, Stream, Fall population
Population du moyen Fraser, type fluvial, automne

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Yes
Change in number of mature individuals based on last 3 generations observations:
-67 percent
p > 30 percent decline 90 percent
p > 50 percent decline 77 percent
Change in number of mature individuals based on all observations:
-67 percent
p > 30 percent decline 90 percent
p > 50 percent decline 77 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
63 km2
Number of mature individuals:
59 (index, not count)

Threats

A threats calculator was not completed.

Status and reasons for designation

Status: Endangered

Alpha-numeric codes: A2bcd; C2a(i,ii), D1.

Reasons for designation: This population of fall run chinook spawning in the Seton and Anderson watersheds along the middle Fraser River has declined to very low levels, and decline is anticipated to continue. Declines in freshwater and marine habitat quality, and harvest, are threats facing this population.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Endangered A2bcd because there has been a 67 percent decline in the index of mature individuals over three generations as a result of declining habitat quality and harvest.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met. While IAO meets criterion for Endangered and the quality of the freshwater and marine habitats is declining, the population is not severely fragmented, the number of locations is unknown and there are no extreme fluctuations.

Criterion C (Small and Declining Number of Mature Individuals): Meets Endangered C2a(i,ii) due to the continuing decline of all individuals in one population.

Criterion D (Very Small or Restricted Population): Meets Endangered D1 as there are fewer than 250 mature individuals.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 9: Middle Fraser, Stream, Spring (MFR+GStr) population
Population du moyen Fraser, type fluvial, printemps (MF+DetG)

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Yes
Change in number of mature individuals based on last 3 generations observations:
-28 percent
p > 30 percent decline 48 percent
p > 50 percent decline 22 percent
Change in number of mature individuals based on all observations:
-49 percent
p > 30 percent decline 87 percent
p > 50 percent decline 47 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
4490 km2
Number of mature individuals:
5931 (index, not count)

Threats

The most important threats specific to this DU are from ecosystem modifications. Irrigation diking and ditching in the Lower Fraser Basin contributes to a loss of backwater and off-channel habitat. These practices are increasingly expanding upstream along the Fraser River (a loss of rearing and overwintering habitat is also occurring due to conversion of agricultural land use to residential/commercial land use). Chinook salmon experts who participated in the IUCN Threats Calculator Workshop in February 2017 concluded that this DU should be assigned a threat impact of High - Medium (B/C). Wildfire activity in 2017 and 2018 have created significant habitat issues within this DU.

Status and reasons for designation

Status: Threatened

Alpha-numeric codes: A2bcde

Reasons for designation: This spring run of chinook spawning in multiple middle Fraser River tributaries has declined in abundance. Declines in marine and freshwater habitat quality, and harvest, and pollution from mining activities are threats to this population.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Threatened A2bcde because there has been a 49 percent decline in the index of mature fish in the entire time series as a result of declining habitat quality, harvest, and pollution.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met.

Criterion C (Small and Declining Number of Mature Individuals): Criterion not met.

Criterion D (Very Small or Restricted Population): Criterion D1 not met because number of mature individuals exceeds thresholds. Threatened D2 does not apply as the number of locations is unknown and the IAO threshold of 20 km² is exceeded.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 10: Middle Fraser, Stream, Summer population
Population du moyen Fraser, type fluvial, été

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Yes
Change in number of mature individuals based on last 3 generations observations:
-38 percent
p > 30 percent decline 64 percent
p > 50 percent decline 26 percent
Change in number of mature individuals based on all observations:
-29 percent
p > 30 percent decline 48 percent
p > 50 percent decline 14 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
2616 km2
Number of mature individuals:
15598 (index, not count)

Threats

A threats calculator was not completed. However, expert knowledge indicates placer and hard rock mining, acid mine drainage, and contaminant leaching occurs at several “locations” in the Quesnel River and Cariboo River. Acid mine drainage has potential for long-term devastating impacts to the aquatic community and reduced productive capacity of these rivers. The 2014 Mount Polley mining disaster occurred in this DU and involved a breach of the copper/gold mine’s tailings pond, discharging toxic mud and water into Polley Lake. The Kenney dam, which is outside of the southern edge of the DU, may affect temperature and flow rates in the Nechako River, thereby changing the migration timing of Chinook salmon smolts).

Status and reasons for designation

Status: Threatened

Alpha-numeric codes: A2bc

Reasons for designation: This summer run of chinook spawning in multiple middle Fraser River tributaries has declined in abundance. Declines in marine and freshwater habitat quality are threats facing this population.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Threatened A2bc because there has been a decline of 38 percent in the index of mature fish in the past three generations as a result of declining habitat quality.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met.

Criterion C (Small and Declining Number of Mature Individuals): Criterion not met. The number of mature individuals is well above the threshold for threatened.

Criterion D (Very Small or Restricted Population): Criterion not met because the number of mature individuals exceeds threshold. Threatened does not apply as the number of locations is unknown and the IAO threshold of 20 km² is exceeded.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 11: Upper Fraser, Stream, Spring population
Population du haut Fraser, type fluvial, printemps

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Yes
Change in number of mature individuals based on last 3 generations observations:
-49 percent
p > 30 percent decline 79 percent
p > 50 percent decline 48 percent
Change in number of mature individuals based on all observations:
-43 percent
p > 30 percent decline 81 percent
p > 50 percent decline 28 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
4065 km2
Number of mature individuals:
13,786 (index, not count)

Threats

A threats calculator was completed. Chinook salmon experts who participated in the IUCN Threats Calculator Workshop in February 2017 concluded that this DU should be assigned a threat impact of High - Medium (B/C). There has been limited success at maintaining a harvest target of 30 percent for this DU, with the most recent brood year at 40 percent.

Status and reasons for designation

Status: Endangered

Alpha-numeric codes: A2bcd+3c+4c

Reasons for designation: This spring run of chinook spawning in the Salmon and Raush Rivers in the upper Fraser watershed has declined in abundance. Declines in marine and freshwater habitat quality, and harvest, are threats facing this population. Anticipated changes to North Pacific weather systems that affect ground water availability, will impact spawning sites and overwinter survival.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Threatened A2bcd, as there has been an estimated decline in the index of numbers of mature individuals of more than 30 percent in the last three generations and over the entire time series. Future decline of >30 percent is projected.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met.

Criterion C (Small and Declining Number of Mature Individuals): Criterion not met. The number of mature individuals is well above the threshold.

Criterion D (Very Small or Restricted Population): Does not meet criterion. The number of mature individuals is well above the threshold. Threatened D2 does not apply as the number of locations is unknown and the IAO threshold of 20 km² is exceeded.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 12: South Thompson, Ocean, Summer population
Population de la Thompson Sud, type océanique, été

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
No
Change in number of mature individuals based on last 3 generations observations:
+26 percent
p > 30 percent decline 7 percent
p > 50 percent decline 2 percent
Change in number of mature individuals based on all observations:
+64 percent
p > 30 percent decline 0 percent
p > 50 percent decline 0 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
1125 km2
Number of mature individuals:
116,888 (index, not count)

Threats

A threats calculator was not completed. However, there have been significant habitat alterations within this Designatable Unit, including dredging and removal of spawning gravel (Thompson River).

Status and reasons for designation

Status: Not at risk

Alpha-numeric codes: Not applicable

Reasons for designation: This summer run of chinook to the South Thompson River has been steadily increasing in abundance, and the most recent population index is the second highest on record.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Criterion not met. The number of mature individuals has increased in the last three generations.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met. While IAO meets criterion for Endangered and the quality of the freshwater and marine habitats is declining, the population is not severely fragmented, the number of locations is unknown, and there are no extreme fluctuations.

Criterion C (Small and Declining Number of Mature Individuals): Does not meet criterion, number of mature individuals exceeds thresholds.

Criterion D (Very Small or Restricted Population): Does not meet criterion. Criterion not met as the number of mature individuals exceeds thresholds. Threatened D2 does not apply as the number of locations is unknown and the IAO threshold of 20 km2 is exceeded.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 14: South Thompson, Stream, Summer 1.2 population
Population de la Thompson Sud, type fluvial, été 1.2

Demographic information

Generation time:
3 years
Is there a continuing decline in the number of mature individuals?
Yes
Change in number of mature individuals based on last 3 generations observations:
-47 percent
p > 30 percent decline 59 percent
p > 50 percent decline 48 percent
Change in number of mature individuals based on all observations:
-76 percent
p > 30 percent decline 98 percent
p > 50 percent decline 92 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
70 km2
Number of mature individuals:
138 (index, not count)

Threats

Chinook salmon experts who participated in the IUCN Threats Calculator Workshop in February 2017 recommended using the DU15 Threats Calculator as a proxy for this DU with the main difference being that juveniles in DU14 stay in freshwater for one year and utilize smaller rivers. These characteristics make the fish more vulnerable than DU15 Chinook salmon to water management issues and increased development. In the Bessette and Duteau Rivers, for example, Chinook salmon contend with dewatering events, agricultural runoff and rising stream temperatures. Considerable agriculture occurs in the DU with cattle ranching and farming adversely affecting the amount and quality of the riparian habitat. Dams occur in the headwaters of this system, diverting water out of the drainage and affecting mean annual discharge and seasonal low discharge. Based on these points and DU15 results, participants concluded that DU14 should be assigned a threat impact of High-Medium (B/C), implying a population decline rate of up to 70 percent over three generations.

Status and reasons for designation

Status: Endangered

Alpha-numeric codes: A2bcd

Reasons for designation: This summer run of chinook spawning in the South Thompson River has steeply declined in abundance to a very low level. Declines in marine and freshwater habitat quality, and harvest, are threats facing this population.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Endangered A2bcd as there has been a 76 percent decline in the index of number of individuals over the entire time series as a result of decline in habitat quality and harvest. It is appropriate to use the population trend over the entire time series because there has been no artificial enhancement.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met. While IAO meets criterion for Endangered and the quality of the freshwater and marine habitats is declining, the population is not severely fragmented, the number of locations is unknown, and there are no extreme fluctuations.

Criterion C (Small and Declining Number of Mature Individuals): Criterion not met.

Criterion D (Very Small or Restricted Population): Criterion not met.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 16: North Thompson, Stream, Spring population
Population de la Thompson Nord, type fluvial, printemps

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Yes
Change in number of mature individuals based on last 3 generations observations:
-91 percent
p > 30 percent decline 100 percent
p > 50 percent decline 100 percent
Change in number of mature individuals based on all observations:
-88 percent
p > 30 percent decline 100 percent
p > 50 percent decline 100 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
291 km2
Number of mature individuals:
181 (index, not count)

Threats

Chinook salmon experts who participated in the IUCN Threats Calculator Workshop in February 2017 recommended using the DU11 Threats Calculator as a proxy for this DU. Based on DU11 results DU16 should be assigned a threat impact of High - Medium (B/C).

Status and reasons for designation

Status: Endangered

Alpha-numeric codes: A2bcd+3c+4c

Reasons for designation: This spring run of chinook spawning in the North Thompson River has steeply declined in abundance to a low level. Declines in marine and freshwater habitat quality, and harvest, are threats facing this population. Anticipated changes in North Pacific weather systems that affect groundwater availability will impact spawning sites and overwinter survival.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Endangered A2bcd. Decline rates of 91 and 88 percent were observed for indices of abundance calculated for three generations from 2000 to 2015 and the entire time series, respectively. Future decline of >50 percent are projected.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met. While IAO meets criterion for Endangered and the quality of the freshwater and marine habitats is declining, the population is not severely fragmented, the number of locations is unknown, and there are no extreme fluctuations.

Criterion C (Small and Declining Number of Mature Individuals): Criterion not met.

Criterion D (Very Small or Restricted Population): Criterion not met.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 17: North Thompson, Stream, Summer population
Population de la Thompson Nord, type fluvial, été

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Yes
Change in number of mature individuals based on last 3 generations observations:
-62 percent
p > 30 percent decline 93 percent
p > 50 percent decline 75 percent
Change in number of mature individuals based on all observations:
-64 percent
p > 30 percent decline 98 percent
p > 50 percent decline 86 percent
Are there extreme fluctuations in the number of mature individuals?:
No
Index of Area of Occupancy*:
714 km2
Number of mature individuals:
3027 (index, not count)

Threats

A threats calculator was not completed.

Status and reasons for designation

Status: Endangered

Alpha-numeric codes: A2bcd

Reasons for designation: This summer run of chinook spawning in the North Thompson River has steeply declined in abundance. Declines in marine and freshwater habitat quality, and harvest, are threats facing this population.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Endangered A2bcd. Decline rates of 62 and 64 percent were observed for indices of abundance calculated for three generations using data from 2000 to 2015 and the entire time series, respectively, as a result of decline in habitat quality and harvest.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met. While IAO meets criterion for Endangered and the quality of the freshwater and marine habitats is declining, the population is not severely fragmented, the number of locations is unknown, and there are no extreme fluctuations.

Criterion C (Small and Declining Number of Mature Individuals): Criterion not met.

Criterion D (Very Small or Restricted Population): Does not meet criterion. The number of mature individuals is well above the threshold. Threatened D2 does not apply as the number of location is unknown and the IAO threshold of 20 km2 is exceeded.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 19: East Vancouver Island, Stream, Spring population
Population de l'est de l'île de Vancouver, type fluvial, printemps

Demographic information

Generation time:
3.5 years
Is there a continuing decline in the number of mature individuals?
Unknown
Change in number of mature individuals based on last 3 generations observations:
Unknown
Change in number of mature individuals based on all observations:
Unknown
Are there extreme fluctuations in the number of mature individuals?:
Unknown
Index of Area of Occupancy*:
41 km2
Number of mature individuals:
< 250 (index, not count)

Threats

A threats calculator was not completed. The habitat in this Designatable Unit is more heavily modified than the average across all DUs in this report.

Status and reasons for designation

Status: Endangered

Alpha-numeric codes: D1

Reasons for designation: This spring run of chinook to the Nanaimo River has been at a very low abundance for a long time. Declines in marine and freshwater habitat quality are threats facing this population.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Too few data to apply criterion.

Criterion B (Small Distribution Range and Decline or Fluctuation): Criterion not met. While IAO meets criterion for Endangered and the quality of the freshwater and marine habitats is declining, the population is not severely fragmented, the number of locations is unknown, and there are no extreme fluctuations.

Criterion C (Small and Declining Number of Mature Individuals): Unknown.

Criterion D (Very Small or Restricted Population): Meets Endangered D1 as there are fewer than 250 mature individuals.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 27: Southern Mainland, Ocean, Summer population
Population du sud de la partie continentale (C.-.B.), type océanique, été

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Unknown
Change in number of mature individuals based on last 3 generations observations:
Unknown
Change in number of mature individuals based on all observations:
Unknown
Are there extreme fluctuations in the number of mature individuals?:
Unknown
Index of Area of Occupancy*:
154 km2
Number of mature individuals:
Unknown

Threats

Chinook salmon experts who participated in the IUCN Threats Calculator Workshop in February 2017 concluded that this DU should be assigned a threat impact of Low (D). Some risk exists from ecosystem modifications due to independent power producers (minimal) and from avalanches/landslides due to the steep terrain in this system. However, this DU is data limited. Threat Calculator results for this population are based on those from DU28. Many issues need to be further investigated. There are a number of 'Unknown' Threat Calculator scores that, if populated, could change the overall threat rating.

Status and reasons for designation

Status: Data Deficient

Alpha-numeric codes: Not applicable

Reasons for designation: This summer run of chinook to spawn in the remote glacial Homathko River watershed in the southern mainland has not been surveyed sufficiently to assess its population status.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Too few data to apply criterion.

Criterion B (Small Distribution Range and Decline or Fluctuation): Too few data to apply criterion.

Criterion C (Small and Declining Number of Mature Individuals): Too few data to apply criterion.

Criterion D (Very Small or Restricted Population): Too few data to apply criterion.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Designatable Unit 28: Southern Mainland, Stream, Summer population
Population du sud de la partie continentale (C.-.B.), type fluvial, été

Demographic information

Generation time:
4.5 years
Is there a continuing decline in the number of mature individuals?
Unknown
Change in number of mature individuals based on last 3 generations observations:
Unknown
Change in number of mature individuals based on all observations:
Unknown
Are there extreme fluctuations in the number of mature individuals?:
Unknown
Index of Area of Occupancy*:
447 km2
Number of mature individuals:
Unknown

Threats

A threats calculator was completed. Chinook salmon experts who participated in the IUCN Threats Calculator Workshop in February 2017 concluded that this DU should be assigned a threat impact of Low (D). Some risk exists from ecosystem modifications due to independent power producers (minimal) and from avalanches/landslides due to the steep terrain in this system. However, this DU is data deficient. Many issues need to be further investigated. There are a number of 'Unknown' Threat Calculator scores that, if populated, could change the overall threat rating.

Status and reasons for designation

Status: Data Deficient

Alpha-numeric codes: Not applicable

Reasons for designation: This summer run of chinook to spawn in the remote glacial Klinaklini River watershed in the southern mainland of British Columbia has not been recently surveyed to assess its population status.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Too few data to apply criterion.

Criterion B (Small Distribution Range and Decline or Fluctuation): Too few data to apply criterion.

Criterion C (Small and Declining Number of Mature Individuals): Too few data to apply criterion.

Criterion D (Very Small or Restricted Population): Too few data to apply criterion.

Criterion E (Quantitative Analysis): Not done.

*Following methods used for the COSEWIC Fraser Sockeye Salmon Status Report, the area of occupancy of each DU is calculated as two times the spawning length, and is reported in square kilometres. This method is equivalent to overlaying a 2×2 km2 grid over the stream, and adding up the total area.

Preface

COSEWIC history

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions (2018)

Wildlife species
A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.
Extinct (X)
A wildlife species that no longer exists.
Extirpated (XT)
A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.
Endangered (E)
A wildlife species facing imminent extirpation or extinction.
Threatened (T)
A wildlife species likely to become endangered if limiting factors are not reversed.
Special concern (SC)
(Note: Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.)
A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.
Not at risk (NAR)
(Note: Formerly described as “Not In Any Category”, or “No Designation Required.”)
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.
Data deficient (DD)
(Note: Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” [insufficient scientific information on which to base a designation] prior to 1994. Definition of the [DD] category revised in 2006.)
A category that applies when the available information is insufficient (a) to resolve a species' eligibility for assessment or (b) to permit an assessment of the species' risk of extinction.

The Canadian Wildlife Service, Environment and Climate Change Canada, provides full administrative and financial support to the COSEWIC Secretariat.

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