Bigmouth shiner (Notropis dorsalis) COSEWIC assessment and status report: chapter 14
Technical Summary
Notropis dorsalis
Range of Occurrence in Canada: MB
Extent and Area Information
Extent of occurrence (EO)(km2)
[calculated from Figure 2]
< 10 000 km2
Specify trend in EO
Unknown
Are there extreme fluctuations in EO?
No
Area of occupancy (AO) (km2)
[calculated from Figure 3]
< 500 km2
Specify trend in AO
Unknown
Are there extreme fluctuations in AO?
No
Number of known or inferred current locations
8 (24 sites)
Specify trend in #
Probably no losses; 5 new sites since 1985
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat
Unknown
Population Information
Generation time (average age of parents in the population)
Unknown, but likely 1 year as in other shiners
Number of mature individuals
Unknown
Total population trend
Unknown
% decline over the last/next 10 years or 3 generations
Unknown
Are there extreme fluctuations in number of mature individuals?
Unknown
Is the total population severely fragmented?
Yes. Populations are fragmented to the degree that they are found in separate watersheds.
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:
Unknown
Threats (actual or imminent threats to populations or habitats)
There are no apparent or immediate threats identified in the Canadian population.
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
Not at Risk (see below)
Is immigration known or possible?
Yes
Would immigrants be adapted to survive in Canada?
Possibly
Is there sufficient habitat for immigrants in Canada?
Yes.
Is rescue from outside populations likely?
Negligible
Quantitative Analysis
N/A
Current Status
Canada
National: N3
U.S.
National: N5
Regional:CO – S4, IL – S5, IA – S5, KS – S2, MI – S?, MN – S?, MO – S?, NE – S4, NY – S3, ND – S?, OH – S2, PA – S2, SD – S5, TN – S1, WI – S4, WV – SX, WY – S5
Status and Reasons for Designation
Status: Not at Risk
Alpha-numeric code: N/A
Reasons for Designation: There are no demonstrable or potential threats and the species is not particularly sensitive to habitat disturbances. It has been found in five new locations since 1985. It may also be present in unsurveyed areas of suitable habitat in western Manitoba and possibly eastern Saskatchewan.
Applicability of Criteria
Criterion A (Declining Total Population):
N/A: Total population not in decline.
Criterion B (Small Distribution, and Decline or Fluctuation):
N/A: The EO is < 20 000 km2, and the AO < 500 km2, but there is no evidence of decline or fluctuation.
Criterion C (Small Total Population Size and Decline):
N/A: Population numbers unknown, but new sites have been discovered since last assessment and no evidence of decline.
Criterion D (Very Small Population or Restricted Distribution):
N/A: The number of mature individuals would be > 1000 and the AO is also > 20 km2, and the species occurs at more than 5 locations.
Criterion E (Quantitative Analysis):
N/A: No data available for a quantitative analysis.
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