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COSEWIC Assessment and Update Status Report on the Copper Redhorse in Canada

Technical Summary

Moxostoma hubbsi

Copper redhorse
Chevalier cuivré

Range of occurrence in Canada: Quebec


Extent and Area Information

Extent of occurrence (EO)(km2)
Determined by circumscribing the area around the “current range” as shown in Figure 5.
2089 km2




specify trend (decline, stable, increasing, unknown)
Historic EO determined by circumscribing the area around the “historic range” as shown in Figure 5.
Historic EO: 6119 km2
The decline is estimated at roughly 66% since its discovery by Legendre in 1942.



are there extreme fluctuations in EO (> 1 order of magnitude)?
No


area of occupancy (AO) (km2)
Estimated by determining surface area of the river sections comprising the “current range” in Figure 5.
69 km2




specify trend (decline, stable, increasing, unknown)
Historic AO estimated by determining surface area of the river sections (and also of Lake Saint-Pierre) comprising the “historic range” in Figure 5.
555 km2
The decline is estimated at roughly 88% since its discovery by Legendre in 1942




are there extreme fluctuations in AO (> 1 order of magnitude)?
No


number of extant locations
3

specify trend in # of locations (decline, stable, increasing, unknown)
Decline


are there extreme fluctuations in # of locations (> 1 order of magnitude)?
No


habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat
Decline


Population Information

generation time (average age of parents in the population) (indicate years, months, days, etc.)
Current generation time approximately 25 years. Normal generation time probably 20 years.

number of mature individuals (capable of reproduction) in the Canadian population (or specify a range of plausible values)
A few hundred to a few thousand at most



total population trend: specify declining, stable, increasing or unknown trend in number of mature individuals
Decline
Aging population
Extremely low recruitment

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 the 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)?
Under study







list each population and the number of mature individuals in each
Under study


specify trend in number of populations (decline, stable, increasing, unknown)
Unknown


are there extreme fluctuations in number of populations (> 1 order of magnitude)?
Under study


Threats (actual or imminent threats to populations or habitats)

  • Intensification of agricultural activities which leads to eutrophication, siltation and contamination of watercourses
  • Deforestation
  • Urbanization
  • Fragmentation of the habitat by the presence of numerous dams
  • Pleasure craft traffic in the largest and most promising of the only two known spawning areas, in the Chambly rapids, during the spawning and egg incubation period
  • Uncertainty linked to the declining water levels of the St. Lawrence River
  • Introduction of the Tench, a ubiquitous and potentially competing species, in the Richelieu River
  • Changes in benthic communities that may occur with the presence of zebra mussels and habitat degradation (siltation and contamination)


Rescue Effect (immigration from an outside source)

does species exist elsewhere (in Canada or outside)?
No


status of the outside population(s)?
Not applicable

is mmigration known or possible?
No

would immigrants be adapted to survive here?
Not applicable


is there sufficient habitat for immigrants here?
Not applicable



Quantitative Analysis

Cannot be assessed


Status and Reasons for Designation

Status: Endangered
Alpha-numeric code: A2c; B1ab(v)+2ab(v)

Reasons for Designation: This species is endemic to Canada where it is now known from only three locations in southwestern Quebec that possibly represent a single population. The distribution and abundance of the species have been severely reduced due to a number of anthropogenic factors (e.g., urban development, agricultural practices, and the construction of dams) that have contributed to a decrease in water quality and habitat availability. The recent introduction of exotic species such as zebra mussel may further impact habitat quality.


Applicability of Criteria

Criterion A (Declining Total Population):
The present generation time of 25 years is based on an aging population, and was probably closer to 20 years in the recent past. Therefore, the species qualifies for Endangered under A2c since there has been an 88% reduction in the area of occupancy over the last 62 years.

Criterion B (Small Distribution, and Decline or Fluctuation):
The extent of occurrence (2089 km2) and area of occupancy (69km2) are well below the minimum threshold for Endangered. There are only three extant locations. The number of mature individuals is projected to decline because there is extremely low recruitment. Qualifies for Endangered, B1+2 a(v).

Criterion C (Small Total Population Size and Decline):
Number of mature individuals estimated at a few hundred to a few thousand at most and estimated continuing decline of 20% in the next two generations (i.e., 50 years) due to aging population and extremely low recruitment. May qualify as Endangered C1, but there is a lot of uncertainty regarding the reliability of those numbers. The species would qualify as Threatened, C1.

Criterion D (Very Small Population or Restricted Distribution):
Number of mature individuals greater than the minimum threshold. However, only two spawning locations known in a single river and therefore qualifies as Threatened, D2.

Criterion E (Quantitative Analysis):
Data are not available.