Nooksack dace (Rhinichthys cataractae) COSEWIC assessment and status report: chapter 13
Rhinichthys cataractae ssp.
Nooksack dace
naseux de la Nooksack
Range of Occurrence in Canada: Fraser Valley, British Columbia
Extent and Area Information
Extent of occurrence (EO) km2 Calculated by GIS adaptation of maps from McPhail 1997 and Mongillo and Hallock 1997; changed to incorporate Brunette River watershed. |
630 km2 |
Specify trend in EO | Unknown |
Are there extreme fluctuations in EO? | No |
Area of occupancy (AO) km2 calculated from measurements of riffle area in 4 occupied watersheds (Pearson 2004; unpubl. data) based on overlaid grid of cell size one km2, total AO is the number of occupied squares that are intersected by the rivers |
< 0.03 km2 14 km2 |
Specify trend in AO Trend in last 10 years |
Decline |
Are there extreme fluctuations in AO? | No |
Number of known or inferred current locations | 4 |
Specify trend in # | Unknown |
Are there extreme fluctuations in number of locations? | No |
Specify trend in area, extent or quality of habitat | Decline |
Population Information
Generation time (average age of parents in the population) | 3 years |
Number of mature individuals (based on known populations) (These may be overestimates as some juveniles may have been included in the survey) Pepin Creek Unadjusted - 4400 Adjusted - 800 Bertrand Creek Unadjusted - 5700 Adjusted - 5700 Fishtrap Creek Unadjusted - 3900 Adjusted - 300 Brunette River Unadjusted - 38 300 Adjusted - Not Available |
Unknown |
Total population trend | Decline |
% decline over the last/next 10 years or 3 generations | Unknown |
Are there extreme fluctuations in number of mature individuals? | No |
Is the total population severely fragmented? | Yes |
Specify trend in number of populations | Unknown |
Are there extreme fluctuations in number of populations? | No |
List populations with number of mature individuals in each: Bertrand Creek: <5700 Pepin Creek: <800 Fishtrap Creek: <1000 Brunette River: Unknown |
Threats (actual or imminent, to populations or habitats)
Physical destruction of riffle habitat (e.g. dredging, channelization)
Lack of water in late summer due to ground and surface water extraction and impermeable urban areas.
Riffle loss to beaver ponding.
Sediment accumulation in riffles caused by bank erosion, gravel mining and/or urban storm drains.
Lack of water in late summer due to ground and surface water extraction and impermeable urban areas.
Riffle loss to beaver ponding.
Sediment accumulation in riffles caused by bank erosion, gravel mining and/or urban storm drains.
Rescue Effect (immigration from an outside source)
Status of outside population(s)? Washington State: S3 |
|
Is immigration known or possible? | Yes |
Would immigrants be adapted to survive in Canada? | Yes |
Is there sufficient habitat for immigrants in Canada? | No (assumed to be at capacity) |
Is rescue from outside populations likely? | No |
Quantitative Analysis
NA
Existing Status
Nature Conservancy Ranks (NatureServe 2006)
Global – G3
National
US – N3
Canada – N1
Regional
U.S: WA – S3
Canada: BC – S1
Province: BC – Red
American Fisheries Society: Threatened
COSEWIC: Endangered 1996, 2000, 2007
SARA: Endangered, Schedule 1
Global – G3
National
US – N3
Canada – N1
Regional
U.S: WA – S3
Canada: BC – S1
Province: BC – Red
American Fisheries Society: Threatened
COSEWIC: Endangered 1996, 2000, 2007
SARA: Endangered, Schedule 1
Status and Reasons for Designation
Status: Endangered |
Alpha–numeric code: B1ab(iii,v) + B2ab(iii,v) |
Reasons for designation: The species is considered a habitat specialist dependent on stream riffles with loose, small-grained substrates. This small fish is a representative of the Chehalis fauna, and considered to be a distinct subspecies of the longnose dace. It is known in Canada from only four locations in southwestern BC where its area of occupancy is severely limited, and subject to ongoing physical destruction of riffle habitat by urban, industrial, and agricultural practices (e.g. dredging, channelization). Streams where the species is found are also impacted by lack of water in late summer due to ground and surface water extraction. Other activities have led to sediment accumulation in riffles caused by bank erosion resulting from gravel mining and/or runoff from urban storm drains, leading to further degradation of water quality and habitat. |
Applicability of Criteria
Criterion A (Declining Total Population):
Not applicable – decline rates are unknown.
Not applicable – decline rates are unknown.
Criterion B (Small Distribution, and Decline or Fluctuation):
Meets Endangered B1ab(iii,v) + 2ab(iii,v). The EO is less than 1000 km2, and the AO < 1 km2. The species is known to exist at only 4 locations, populations are fragmented and there is continuing decline in the extent and quality of habitat and number of individuals.
Meets Endangered B1ab(iii,v) + 2ab(iii,v). The EO is less than 1000 km2, and the AO < 1 km2. The species is known to exist at only 4 locations, populations are fragmented and there is continuing decline in the extent and quality of habitat and number of individuals.
Criterion C (Small Total Population Size and Decline):
Not applicable, number of mature individuals is unknown.
Not applicable, number of mature individuals is unknown.
Criterion D (Very Small Population or Restricted Distribution):
Meets threatened D2, AO, < 20 km2, and known from only 4 locations.
Meets threatened D2, AO, < 20 km2, and known from only 4 locations.
Criterion E (Quantitative Analysis):
Not applicable.
Not applicable.
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