GeneFlow

Genetic introgression is the gradual transfer of different versions of genes, known as alleles, from one population into the gene pool of another by interbreeding between the populations and by backcrossing of the resulting hybrids with the receiving population. Over multiple generations, this changes the genetic structure of the receiving population, introducing and spreading new alleles from the donor population for some genes throughout the receiving population.

There is increasing international concern that this long-term type of gene flow occurs from farmed salmon escapees into wild Atlantic salmon populations. The genomes of wild salmon encode adaptations to their local environment, so genetic introgression with new versions of genes might potentially result in the loss of these adaptations that help wild stocks to survive and thrive in their native rivers. Elevated levels of gene flow from farmed salmon escapees into wild populations have already been detected in rivers in Norway and Scotland, raising questions about whether genetic introgression is occurring in wild Irish salmon stocks in areas where there are salmon farms.

To investigate the genetic integrity of wild salmon populations in Ireland, IFI have formed a partnership with researchers at University College Cork (UCC) and Teagasc for the Marine Institute tender RFT ITT23-015: "provision of the services to determine the level of genetic introgression in Irish wild salmon from farmed escape salmon”. The project is funded by the Irish Government and the European Maritime Fisheries & Aquaculture Fund (EMFAF) as part of the EMFAF Marine Biodiversity Scheme 2021-2027.

Project Overview

The GeneFlow project will consist of four integrated tasks over a three-year period:

• Sampling Design: Development of a sampling plan to establish a comprehensive baseline capturing the genetic structure of up to 200 potential salmon populations in river systems around Ireland, including 144 rivers for which annual stocks are assessed by the Technical Expert Group on Salmon (TEGOS).
• Sample Collection: Electrofishing surveys to capture juvenile salmon in salmon rivers and collect genetic samples for analysis.
• Genetic Profiling: Building genetic profiles for the sampled salmon rivers and using diagnostic markers to detect the presence of alleles from farmed salmon in the wild populations.
• Interpretation & Reporting: Reporting of maps and tables indicating the level of genetic introgression from farmed salmon escapees.

The project also aims to establish an advisory group to develop and share developments in genetic profiling from the project among experts in salmon population genetics.