Science Advisory Report  2013/042

Recovery potential assessment of Plains Minnow (Hybognathus placitus) in Canada

Summary

• The Canadian distribution of Plains Minnow is currently limited to Rock and Morgan creeks in Saskatchewan.
• Adults are habitat generalists and typically inhabit turbid, sandy, silty waters with a preference for backwaters and embayments. Little is known about young-of-the-year and juvenile habitat.
• Plains Minnow move upstream to spawn during periods of moderate to high flows which are required for successful reproduction. It has been estimated that more than 100 km of flowing river habitat is required for the development of larvae.
• Current population abundance in Canada is estimated at approximately 41,800 adults (80% confidence intervals 2,400–55,400) which is considered High but population trajectory is Unknown, resulting in an overall population status of Fair.
• Based on this abundance, if the population is stable then the risk of extirpation within 100 years is 2% (1–69%).
• To achieve a 99% probability of persistence, given a 15% per generation chance of catastrophic (50%) decline, requires approximately 60,600 adult Plains Minnow.
• Persistence (i.e., maintaining healthy, viable populations in all locations where they currently exist) rather than recovery reflects a more appropriate long-term goal for this species.
• Population growth of Plains Minnow is most sensitive to changes in the survival of immature individuals. It may also be sensitive to fecundity of first time spawners if post spawning mortality is high, or to survival in the second year if the population is stable or in decline.
• At least 12 ha of suitable habitat, including 115 km of barrier-free river, is needed to support the current estimate of abundance. Available habitat in Canada is estimated at 12 ha including 26.5 km of barrier-free river, therefore maintaining connectivity with Rock Creek in the U.S. is essential. The quality of this habitat is unknown.
• The greatest threats to Plains Minnow in Canada are habitat removal and fragmentation, alteration of natural flow regimes, exotic piscivores, and climate change.
• To avoid a decrease in population growth rate larger than 1%, transient harm (one-time removal of individuals) should not exceed a 12.5% reduction in adult abundance, or a 17% reduction in young-of-the-year abundance, or a 7.5% reduction in total abundance within a seven-year period.
• There are several sources of uncertainty regarding Plains Minnow biology, ecology, life history, habitat requirements, estimated population abundance, and Canadian distribution. A thorough understanding of the severity and impacts of threats facing Plains Minnow in Canada is also lacking.

This Science Advisory Report is from the December 12, 2012, Recovery Potential Assessment of Plains Minnow (Hybognathus placitus). Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

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