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River Redhorse (Moxostoma Carinatum)

Technical Summary

Moxostoma carinatum

river redhorse

chevalier de rivière

Range of Occurrence in Canada: southcentral Ontario and southern Quebec

Extent and Area Information

Extent of occurrence (EO) (km2)150 000 km2
specify trend (decline, stable, increasing, unknown)Possibly stable in Ontario and decrease in Quebec
Are there extreme fluctuations in EO (> 1 order of magnitude)?No
Area of occupancy (AO) (km2)
For rivers with multiple extant sites (except Ottawa River), calculated as length of river between uppermost and lowermost sites multiplied by an average width of 0.10 km. For the Ottawa River, the average width was 1 km (pers. comm. Tim Haxton) Not determined for species from waterbodies with single site.
Grand – 5
Trent – 5
Ottawa – 150
Mississippi – 3.5
Madawaska – 5
Richelieu– 10
Total – 178.5
specify trend (decline, stable, increasing, unknown)Possibly stable in Ontario and decrease in Quebec
are there extreme fluctuations in AO (> 1 order magnitude)?unknown
number of extant locations
Locations interpreted as discrete open circles on Fig. 3.
specify trend in # locations (decline, stable, increasing, unknown)In some watersheds, the species has likely disappeared (Ausable, Châteauguay, Yamaska) or suffered a large decline (St. Lawrence River)
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 habitatStable in Ontario
Declined in Quebec

Population Information

generation time (average age of parents in the population) (indicate years, months, days, etc.)>5-10 years
number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values)Unknown
total population trend: specify declining, stable, increasing or unknown trend in number of mature individualsUnknown
if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period)Unknown
are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?Unknown
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)?Yes
list each population and the number of mature individuals in eachUnknown
specify trend in number of populations (decline, stable, increasing, unknown)Decline
are there extreme fluctuations in number of populations (>1 order of magnitude)?No


- habitat degradation, pollution, siltation, habitat fragmentation by dams

Rescue Effect (immigration from an outside source)

does species exist elsewhere (in Canada or outside)?United States
status of the outside population(s)?Michigan(S1), New York (S2?), Pennsylvania (S3)
is immigration known or possible?Immigration from Michigan and New York populations to Ontario rivers improbable and from Pennsylvania possible
would immigrants be adapted to survive here?Yes
is there sufficient habitat for immigrants here?Unknown

Quantitative Analysis

Not applicable

Current Status

COSEWIC: Special Concern (1987)
Special Concern (2006)

Status and Reason for Designation

Special Concern
Alpha-numeric code:
Not Applicable
Reason for designation:
This freshwater fish species occurs in Ontario and Quebec, and although it has been collected at new locations in both provinces, sometimes in large numbers, this is thought to reflect the use of more effective sampling techniques such as boat electrofishing. It has likely disappeared historically from the Ausable, Châteauguay and Yamaska rivers, since the use of boat electrofishing has failed to collect it recently. Threats to the species include habitat degradation (pollution, siltation), stream regulation that affects water flow (dams) and habitat fragmentation (dams). The Canadian range is highly fragmented and rescue effect is improbable because of the precarious conservation status in adjoining U.S. states.

Applicability of Criteria

Criterion A (Declining Total Population):
Criterion thresholds not met.
Criterion B (Small Distribution, and Decline or Fluctuation):
Met criterion B2 (AO of 178.5 < 500 sq. km) and a) for severely fragmented but no continuing decline or extreme fluctuations.
Criterion C (Small Total Population Size and Decline):
Criterion thresholds not met because population sizes not known.
Criterion D (Very Small Population or Restricted Distribution):
Criterion thresholds not met because number of mature individuals not known or AO (178.5 > 20 sq. km) and no. of locations (about 25 > 5) exceed minimum thresholds.
Criterion E (Quantitative Analysis):
Not available.