Science Advisory Report  2010/025

Recovery Potential Assessment of Pugnose Shiner (Notropis anogenus) in Canada

Summary

• The current and historical distribution of the Pugnose Shiner is limited to four distinct areas of the Great Lakes basin: Lake Erie drainage; southern Lake Huron drainage; eastern Lake Ontario drainage; and, Lake Huron drainage (Figure 1). Three populations are thought to be extirpated.
• Pugnose Shiner is typically found in clear, heavily-vegetated lakes and embayments, and slow-moving streams. Although Pugnose Shiner has also been recorded from river systems, it should be noted that its presence in these systems is restricted to areas with characteristics similar to coastal wetlands and lake systems.
• Based on an objective of long-term,  self-sustaining population, recovery targets of at least 1 929 adult fish requiring up to 5 ha of habitat were required. In the absence of mitigative efforts or additional harm, a Pugnose Shiner population could reach this recovery target in 17 to 39 years. However, by affecting at least a 14% increase in survival rates, recovery strategies such as habitat rehabilitation or enhancement can reduce the recovery time of a heavily impacted population by half.
• The greatest threats to the survival and persistence of Pugnose Shiner are related to the degradation and loss of preferred habitat. These threats encompass the physical loss of habitat, including the removal and control of aquatic vegetation and habitat modifications, and habitat degradation through sediment and nutrient loading.
• The introduction of exotic species (fishes and aquatic macrophytes) may be negatively affecting Pugnose Shiner populations. The degree to which incidental harvest through the baitfish industry and trophic dynamic shifts are affecting Pugnose Shiner is currently unknown, but these threats may have a negative effect on the persistence and recovery of Pugnose Shiner populations.
• The dynamics of Pugnose Shiner populations are particularly sensitive to perturbations that affect survival in the first two years of life, and the fecundity of first-time spawners. Harm to these characteristics of Pugnose Shiner life history should be minimized to avoid jeopardizing the survival and future recovery of Canadian populations.
• There remain numerous sources of uncertainty related to Pugnose Shiner biology, ecology, life history, YOY and juvenile habitat requirements, population abundance estimates, population structure, and species distribution. A thorough understanding of the threats affecting the decline of Pugnose Shiner populations is also lacking. Numerous threats have been identified for Pugnose Shiner populations in Canada, although the severity of these threats is currently unknown.

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