Chiselmouth (Acrocheilus alutaceus) COSEWIC assessment and status report: chapter 14
Technical Summary
Acrocheilus alutaceus
British Columbia
Extent and Area Information
Trend
Likely stable, although several small lake populations deliberately extirpated
Fluctuations in extent of occurrence
No
Area of Occupancy
<500 km2 several hundred linear km of stream length; half a dozen lakes
Trend
Likely stable
Fluctuations in area of accupancy
Unknown, but unlikely
Number of extant locations
Present in at least 8 major drainages
Trend in # locations
Stable
Fluctuations in # locations
No
No. locations from which populations have been extirpated
Several (deliberate, but exact number unknown)
Habitat trend
Unknown
Population Information
Number of mature individuals in the Canadian population
10 000 – 30 000 (estimate)
Population trend
Unknown
Fluctuations in number of mature individuals
Unknown
Are populations fragmented?
Populations are relatively isolated from one another, but the exchange rate of individuals between pops. Is unknown
Populations and the number of mature individuals in each
(L = 2000-5000 M = 1000-2000
S = < 1000)
1) Blackwater/Nazko/Euchi niko L
2) Salmon/Muskeg S
3) Similkameen M
4) Okanagan L
5) Kettle L
6) Upper Chilcotin S
7) Nicola L
8) Shuswap M
Trend in number of populations
Likely stable
Fluctuations in number of populations
Probably not
Threats
- Cumulative impacts of agriculture, forestry, and livestock grazing may be impacting chiselmouth in some rivers (e.g. Okanagan, Nicola), and these impacts will likely get worse in the near future.
- Populations in some lakes may be subject to extermination as competitors of game fish species.
Rescue Effect: Low for most pops.
Does species exist elsewhere in Canada?
No
In the U.S. ?
Yes – ID , NV , OR and WA
Status of the outside populations?
ID -S5, NV -S?, OR -S4, WA -S4
Is immigration known or possible?
Dams and natural barriers prevent most natural migration
Would immigrants be adapted to survive here?
For Columbia R. pops , likely; possibly not for Fraser basin pops .
Is there sufficient habitat for immigrants here?
yes
Quantitative Analysis
None
Existing Status
CDC Ranks
Global– N5
National U.S. N5
Canada– N3
Regional U.S. ID - S5, NV – S?, OR – S4, WA – S4
Canada BC – S3, Provincial Listing Blue (Special Concern)
COSEWIC– DD 1997
Status Designated May 2003
Not At Risk
Reasons for Status Designation
The Canadian distribution of this species is restricted to a few disjunct populations in south-central British columbia where they are found in low densities, but appear to be stable and are not subject to any known factors that could put them at risk.
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