Science Advisory Report  2010/009

Recovery Potential Assessment for Spring Cisco (Coregonus sp.)

Summary

• In Canada, the only known spring cisco population has been observed at Lac des Écorces (46°31'48" N, 75°25'03" W) in the Laurentians (Quebec). Its survival and recovery depend on its sustained production within this habitat.
• Reproductive isolation of cisco spring, compared to lake herring (C. artedi), and the morphological differences observed support its genetic specificity.
• Despite the uncertainty related to the data, the trend over the last fifteen years, between 1994 and 2008, reflect a significant decline in the population.
• A recovery target representing 40% of the average abundance indices (number of catches per unit effort) before the decline during 1990s, or a target of around 5 individuals per hour per net, is proposed.
• The absence of key parameter estimates of population dynamics prevents making projections on the development of the spring cisco population.
• Lac des Écorces, as a unique habitat for spring cisco, is essential to the survival and recovery of the species. Knowledge about the habitat use by different life stages is still incomplete but nothing indicates that some parts of the lake are not used. Damage or loss of any and all parts should therefore be avoided.
• The introduction of competing and predatory species, especially rainbow smelt, caused changes in the fish community. Predation by rainbow smelt on spring cisco larvae in the deeper parts of Lac des Écorces, raises some concern. Controlling the rainbow smelt population could contribute to the recovery of spring cisco.
• Lac des Écorces has been subject to many disturbances due to urban and agricultural development over the last 50 years, which has significantly deteriorated the lake and could have caused loss of habitat. Although it is difficult to quantify the impact, salmonid sensitivity to the degradation of the biophysical environment is well known. Measures to mitigate threats to the habitat could contribute to the survival and recovery of the species.
• According to current available knowledge and information, the recovery of spring cisco remains uncertain, but possible.

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