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Recovery Strategy for the Northern Riffleshell, Snuffbox, Round Pigtoe, Mudpuppy Mussel and Rayed Bean in Canada (Final)


I. Background – Importance and Feasibility

16. Importance to People

In the past, the Round Pigtoe has been a commercially valuable species, being used in the pearl button industry (Oesch, 1995). The Round Pigtoe is one of 12 commercially valuable species in Kansas (Busby and Horak, 1993) and there has been a shift in market demand for larger mussels including several pigtoe species (Baker, 1993). Over harvesting seriously depleted some mussel stocks in the United States and the commercial harvest is now closed in many states. There was a brief mussel fishery in the Grand River in the early 1900s (Detweiler 1918) but there is no commercial harvest presently (COSEWIC 2004).

These five mussel species have otherwise no apparent economic significance. However, freshwater mussels are sensitive to environmental pollution and a diverse mussel community indicates a healthy ecosystem. Besides decreased biodiversity in Canada, the loss of the Mudpuppy Mussel, Northern Riffleshell, Round Pigtoe, Rayed Bean and Snuffbox may indicate further environmental degradation of southwestern Ontario watercourses which would adversely affect those people who depend on surface water for drinking, recreation or watering livestock.

17. Biological and Technical Feasibility of Recovery

Recovery of the Mudpuppy Mussel, Northern Riffleshell, Round Pigtoe, Rayed Bean and Snuffbox is believed to be both biologically and technically feasible as reproducing populations still exist as potential sources to support recovery, suitable habitat can be made available through recovery actions, threats can be mitigated and proposed recovery techniques are anticipated to be effective.

  • Mussels are slow growing and sessile animals that depend on their host fishes for the survival and dispersal of their young. The slow rate of population growth of freshwater mussels makes the natural recovery of decimated populations extremely difficult.
  • The habitat in the Ausable, Grand, Sydenham and Thames rivers could be improved significantly with proper stewardship of both agricultural and urban lands in the watershed.
  • Reductions in soil erosion and turbidity in all the watersheds can be achieved but would be challenging due to the number and intensity of the impacts.
  • Removing the impacts of dreissenid mussels to the St. Clair River delta population is not possible; however, it may be possible to establish managed refuge sites to reduce the impacts of zebra mussels on Northern Riffleshells and Round Pigtoes.