A long-term study by Norway’s Institute of Marine Research has found that a salmon population with a high proportion of farmed salmon ancestry remained productive despite significant genetic introgression.
Researchers examined salmon in the Guddalselva river in western Norway between 2000 and 2021. The population contained an average of 37% genetic contribution from farmed salmon.
Using genomic data and genetic identification of more than 4,000 adult salmon and smolts, the researchers assessed whether fish carrying farmed salmon genes produced fewer offspring than fish with predominantly wild ancestry.
The study found that salmon with higher levels of farmed ancestry produced somewhat fewer offspring, but the difference was not statistically significant.
According to researcher Alison Harvey, the findings suggest that a high degree of farmed salmon ancestry did not prevent the development of a productive salmon population in Guddalselva. However, she cautioned that the results relate to a single, relatively newly established population and should not be interpreted as evidence that escaped farmed salmon have no negative impacts on wild stocks.
