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Sockeye Salmon (Oncorhynchus Nerka)

Technical Summary

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 locationsOne (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 habitatProbably 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 individualsDeclining 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 eachNA
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


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.