Bigmouth shiner (Notropis dorsalis) COSEWIC assessment and status report: chapter 14

Technical Summary

Notropis dorsalis

Bigmouth shiner
Méné à grande bouche

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



COSEWIC: Rare (=Vulnerable, = Special Concern) 1985
Nature Conservancy Ranks
Global: G5

Canada

National: N3
Regional: MB – S3

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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