COSEWIC Assessment and Update Status Report on the Copper Redhorse in Canada
- Assessment Summary
- Executive Summary
- COSEWIC History, Mandate, Membership and Definitions
- Lists of Figures and Tables
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Species
- Existing Protection or Other Status
- Technical Summary
- Acknowledgements and Information Sources
- Biographical Summary of Report Writer, Authorities Contacted, and Collections Examined
Range of occurrence in Canada: Quebec
Extent and Area Information
Determined by circumscribing the area around the “current range” as shown in Figure 5.
Historic EO determined by circumscribing the area around the “historic range” as shown in Figure 5.
The decline is estimated at roughly 66% since its discovery by Legendre in 1942.
Estimated by determining surface area of the river sections comprising the “current range” in Figure 5.
Historic AO estimated by determining surface area of the river sections (and also of Lake Saint-Pierre) comprising the “historic range” in Figure 5.
The decline is estimated at roughly 88% since its discovery by Legendre in 1942
Extremely low recruitment
Threats (actual or imminent threats to populations or habitats)
- Intensification of agricultural activities which leads to eutrophication, siltation and contamination of watercourses
- 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)
Cannot be assessed
Status and Reasons for Designation
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.
- Date Modified: