Sockeye salmon in Sakinaw (Oncorhynchus nerka) COSEWIC assessment and status report: chapter 15
Oncorhynchus nerka
Common name: Sockeye salmon (English)
Saumon rouge (French)
Population name: Sakinaw Lake sockeye salmon (Sakinaw sockeye)
Range of Occurrence in Canada: BC (Sakinaw Lake, Sechelt Peninsula, and coastal Pacific Ocean)
Extent and Area Information
Extent of occurrence (EO) (km2) (freshwater phase) | 6.9 km2 (Sakinaw Lake) |
specify trend (decline, stable, increasing, unknown) | Probably Stable |
are there extreme fluctuations in EO (> 1 order of magnitude)? | Unlikely |
area of occupancy (AO) (km2) (freshwater phase) | 6.9 km2, but all spawning occurs within an area <0.01 km2 |
specify trend (decline, stable, increasing, unknown) | Decline in suitable spawning area |
are there extreme fluctuations in AO (> 1 order magnitude)? | No |
number of extant locations | One (Sakinaw Lake) |
specify trend in # locations (decline, stable, increasing, unknown) | Stable (but number of spawning sites has declined) |
are there extreme fluctuations in # locations (>1 order of magnitude)? | No |
habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat | Probably declining |
Population Information
generation time (average age of parents in the population) (indicate years, months, days, etc.) |
Four years |
number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values) | Average is ~80 spawners over last full generation (range 14 to 122 between 1999 and 2002) |
total population trend: specify declining, stable, increasing or unknown trend in number of mature individuals | Declining since late 1980s |
if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period) | 99% in 3 generations (last 12 years; regression analysis). 93% (1990 vs 2001) or 87% (1991 vs 2002) in 3 generations (using endpoints) |
are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)? | Not in recent years, but annual fluctuations can be large |
is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise) populations between which there is little exchange, i.e., < 1 successful migrant / year)? | One population - Sakinaw is genetically and demographically isolated from all other sockeye populations |
list each population and the number of mature individuals in each | NA |
specify trend in number of populations (decline, stable, increasing, unknown) | NA |
are there extreme fluctuations in number of populations (>1 order of magnitude)? | NA |
Threats
- overfishing, mainly in mixed stock fisheries, is probably the primary threat and proximate cause of the collapse in population size
- loss of spawning habitat
- low summer water levels and high temperatures periodically hinder migration
- cumulative impacts from past logging operations
- residential development around lake and domestic water use
- depensatory predation from river otters, seals, lamprey and cutthroat trout
- loss of spawning habitat
- low summer water levels and high temperatures periodically hinder migration
- cumulative impacts from past logging operations
- residential development around lake and domestic water use
- depensatory predation from river otters, seals, lamprey and cutthroat trout
Rescue Effect (immigration from an outside source)
does species exist elsewhere (in Canada or outside)? | Yes (but this ESU reproduces only in Sakinaw Lake; other ESUs of sockeye salmon occur elsewhere in Canada and outside) |
status of the outside population(s)? | Variable |
is immigration known or possible? | No – Sakinaw is a distinct population. |
would immigrants be adapted to survive here? | No |
is there sufficient habitat for immigrants here? | NA |
Quantitative Analysis
Genetic analyses, population modeling.
Page details
- Date modified: