Atlantic salmon (Salmo salar) clarification note for COSEWIC assessment and status report 2010

This note is to clarify the treatment of farm-raised (either land-based or sea cage-raised) Atlantic salmon in COSEWIC assessments for all designatable units assessed by the Committee on the Status of Wildlife Species in Canada (COSEWIC) in 2010. Farm-raised Atlantic salmon refer to those fish that are raised in aquacultural facilities for commercial purposes or that escape from such facilities and return to rivers to spawn. This clarification is in response to a query from Fisheries and Oceans Canada, received in September of 2015, on how COSEWIC would treat farmed salmon in future re-assessments of Atlantic salmon.

COSEWIC has developed a series of guidelines^{Content Footnote2} to evaluate whether or not populations of animals or plants, which have been directly or indirectly manipulated by humans, should be included in COSEWIC assessments. For instance, the prohibitions specified by SARA apply to individuals in the population identified and assessed by COSEWIC. Clear definition of whether wild and manipulated components are part of the assessed population (the “wildlife species” in SARA terminology) is essential to determining which individuals or components would be subject to SARA prohibitions. This determination must be made based on whether manipulated populations are genetically or geographically distinct from populations in the wild.

At least two of these guidelines justify the exclusion of aquaculture-produced Atlantic salmon from COSEWIC assessments.

Guideline #2: COSEWIC will generally not consider as part of the wildlife species being assessed any manipulated populations established for purposes other than species conservation (for example, those established for commercial purposes) provided the population is geographically or genetically distinct from the wildlife species under assessment, and there is no intention that the population contribute to the wild population. Under such a scenario, COSEWIC will clearly indicate why the population is excluded.

Aquaculture Atlantic Salmon are raised for commercial purposes, not for conservation of the wildlife species, and are genetically distinct from wild salmon and are thus excluded from assessments under this guideline.

Guideline #6: If introgression is known or suspected, COSEWIC will consider whether it is likely to negatively affect the conservation of the wildlife species. A net negative impact is one predicted to result in a reduction in the average fitness of individuals of the wildlife species being assessed (reflected, for example, by a reduced probability of survival, reduced population growth rate, and/or reduced ability to adapt to environmental change). Under these circumstances, F1 hybrids, if identifiable, and their progeny would not be included as part of the wildlife species being assessed. Where introgression in a population is considered extensive, it may be prudent to exclude the entire population from the wildlife species being assessed. Instead, these populations may be identified as a threat to the wildlife species.

There is a considerable body of evidence indicating that Atlantic Salmon that escape from fish farms survive, return to streams to spawn, and hybridize with wild Atlantic Salmon, and that such interactions with farmed salmon results in the reduced performance and fitness of the recipient wild population^{Content Footnote3-5}. Consequently, escaped farm-raised Atlantic Salmon, provided that they can be identified, are excluded from assessment.