Science Advisory Report 2008/030

Recovery Potential for the Speckled Dace (Rhinichthys osculus)

Summary

• Speckled dace is common in the western United States but its geographic range protrudes into Canada only in the Kettle-Granby River drainage in the west Kootenay area of southern B.C. The Canadian population of speckled dace was designated Special Concern by COSEWIC in 1980, and upgraded to Endangered in 2002 because of its isolation in a single drainage.
• The life history of the speckled dace in Canada is not well known. The species appears to prefer riffle or other faster water areas with a rocky bottom. Spawning has never been observed in nature, and survival of the various life stages is not known. There are large knowledge gaps concerning habit use, and there has been no consistent census within its Canadian range.
• Human-induced threats are only quantifiable if we make assumptions about reproductive potential, habitat preference and distribution. Threats include water withdrawal for irrigation, a proposed 25-megawatt run-of-river hydroelectric generation project at Cascade Falls on the Kettle River, and watershed alteration by logging.
• The viability of the speckled dace population is not expected to be reduced by the planned hydroelectric development, and there are several tools that could be used to manage instream flow so as to protect dace habitat in the Kettle River.
• Quantitative estimates of its abundance by river reach, as well as studies of its habitat use by life stage and season, are required. This information will be necessary to evaluate future population status and the importance of specific habitat for survival and recovery. Given the data limitations, it is not possible to quantify the importance of specific habitat types. Based on the qualitative information available, the maintenance of adequate flow regimes in riffle habitat likely is an important strategy for ensuring population persistence. At present, there are insufficient data to quantify potential mortality related to reduced riffle flow. A target abundance for a healthy population of speckled dace cannot be established without better data on the current abundance and capacity of the system.
• In the absence of information that indicates the population has declined, the recovery goal to maintain the persistence and present range of the population in Canada is realistic from a biological perspective.

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