Science Advisory Report  2011/053

Recovery Potential Assessment for Rocky Mountain ridged mussel (Gonidea angulata) in British Columbia

Summary

• The Rocky Mountain ridged mussel (RMRM) was originally designated as a species of special concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and under the Canadian Species at Risk Act (SARA) in 2003. In 2010, it was re-assessed by COSEWIC, and based on recent population trends, identified past impacts, ongoing and future potential threats, it was designated Endangered.
• The completion of a Recovery Potential Assessment (RPA) is required to inform the SARA listing decision, and provides the scientific background, identification of threats and probability of recovery of a species.
• Data from recent surveys show that RMRM is sporadically distributed and limited to the Okanagan Basin. In addition, limited information on the population and size structure, with little evidence of recruitment, indicates the species is in decline and at risk of extirpation.
• There is very little known about the specific life history parameters for RMRM, or its ecosystem role, specific micro-habitat requirements and preferences, confirmed glochidia fish host species and limiting factors to recruitment.
• Identified habitat pressures and threats include: channelization of the Okanagan River; dams and weirs; development of shoreline and littoral zone; pollutants; other introduced species, and the potential threat of dreissenid mussels.
• Ongoing or planned mitigation measures include: improvement of water quality; managing Okanagan Lake levels, and possibly the Okanagan River Restoration Initiative.
• Protocols and guidelines are needed to assess the impacts of continuing habitat pressures for consistent protection of the functional habitat characteristics of mussel habitat as well as potential glochidia host fish habitat.
• Allowable harm activities provide the required biological information required to increase productivity and survival should be restricted to areas of greatest abundance at a level that is comparable to natural mortality (which needs to be determined).
• Expected population trajectories associated with specific scenarios are outlined including extirpation, stabilizing existing populations, and expanding populations to previously occupied habitats in the Okanagan Basin.
• Recommendations are made for research activities to provide specific biological information needed for a sound management plan to reverse the decline and ensure the persistence of stable self-sustaining RMRM populations.

This Science Advisory Report is from the Fisheries and Oceans Canada, Canadian Science Advisory Secretariat, regional advisory meeting of 25 February, 2011 on Recovery Potential Assessment (RPA) of Rocky Mountain Ridge Mussel.Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.

Complete document (PDF, 109 KB)

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