Current status: Answered by Mairi Gougeon on 14 May 2025
To ask the Scottish Government what assessment it has made of the potential impact of escaped farmed salmon on wild salmon populations in Scottish rivers and coastal waters.
The Scottish Government published its first national assessment of genetic introgression in wild salmon in 2021 using data collected under the National Electrofishing Programme for Scotland (NEPS) in 2018 and 2019, combined with targeted sampling in the vicinity of freshwater smolt rearing facilities: https://data.marine.gov.scot/dataset/national-assessment-influence-farmed-salmon-escapes-genetic-integrity-wild-scottish-atlantic
The research found evidence of introgression was concentrated in areas of marine aquaculture production on the west coast and areas with freshwater smolt rearing. Outside these areas, there was no strong evidence of introgression pressures. The results highlighted how important it is to reduce the risk of farmed fish escapes, to protect the integrity of wild salmon populations in areas of aquaculture production.
This was the first report of the National Introgression Programme for Scotland (NIPS) which is a nationwide project that is researching the link between fish farm escapes and introgression in wild salmon populations.
A larger number of sites were sampled in 2021 and 2023 as part of NEPS surveys (National Electrofishing Programme for Scotland). This should increase the spatial resolution of samples and confidence in the findings, while also allowing comparison across years. Analysis will be submitted shortly for peer review.
Following a large escape at one of its farms (Carradale) in 2020, Mowi funded a study to determine if introgression was occurring. No evidence of impact or introgression was found following the escape event. The report suggests that the effects of farm escapes can be complex depending on numbers of escapes, timing, status of wild stocks, and the maturation status of the escapees: https://www.gov.scot/publications/examination-levels-farm-wild-hybridisation-south-west-scotland-north-east-england-following-large-scale-farm-salmon-escape-event-2020/