Science Advisory Report  2012/068

Recovery Potential Assessment of Silver Shiner (Notropis photogenis) in Canada

Summary

• Silver Shiner is currently known to occur in four distinct watersheds of the Great Lakes basin: Bronte Creek, Sixteen Mile Creek, Grand River and Thames River. Records also suggest that Silver Shiner may also occur in the Saugeen River; however, it is plausible that these collections may have originally been misidentified.
• Adult Silver Shiner are generally found in run, riffle, and pool areas of streams with moderate to fast flow and little to no aquatic vegetation. Very little information exists related to Silver Shiner juvenile habitat preferences. Spawning is thought to occur in the spring when water temperatures are between 18.1 and 23.5°C.
• If Silver Shiner has a maximum age of 3 (short-lived): to achieve ~99% probability of persistence, given a 10% chance of catastrophic decline (50% reduction in abundance), requires ~780,000 adult Silver Shiner and at least 0.871 km² of suitable habitat,
• If Silver Shiner has a maximum age of 10+ (long-lived): to achieve ~99% probability of persistence, given a 15% chance of catastrophic decline (50% reduction in abundance), requires ~700 adult Silver Shiner and at least 0.07 km² of suitable habitat.
• At current abundances, and assuming all habitat is in fact suitable, there is very little risk of extirpation for any of the four populations, if Silver Shiner is long-lived. If the species is short-lived, Bronte Creek is at greatest risk of extirpation (up to 100%), followed by Sixteen Mile Creek (up to 33%), Thames River (up to 20%) and Grand River (up to 12%). Risk to Sixteen Mile Creek can be reduced if suspected habitat is occupied at the same densities as known habitat (up to 11%). Risk for each population is < 2% if the populations grow to carrying capacity.
• The greatest threats to the survival and persistence of Silver Shiner in Canada are related to the presence of contaminants and toxic substances, increases in nutrient loading, increase in turbidity and sediment loading, and issues related to water flow management. Lesser threats that may be affecting the survival of Silver Shiner include exotic species, barriers to movement and incidental harvest, although the current knowledge on the level of impact that these threats may have on Silver Shiner is very limited.
• Population growth of Silver Shiner is most sensitive to changes in the survival of immature individuals or the fertility of first time spawners. This is especially true if Silver Shiner is short-lived.
• There remain numerous sources of uncertainty related to Silver Shiner including their preferred habitat, the distribution and extent of suitable habitat, life history characteristics, specifically conflicting aging interpretations, and the factors limiting their existence.

This Science Advisory Report is from the September 24-25, 2012 Recovery Potential Assessment of Silver Shiner (Notropis photogenis). Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.

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