Novel method for sterilising farmed salmon shows promising results

The Fish Site
by The Fish Site
8 February 2022, at 12:01am

Salmon that have been rendered sterile by an innovative technique have been shown to be just as healthy as their fertile counterparts.

A man holding a dead salmon in a laboratory
Senior scientist Øivind Andersen with non-sterile Atlantic salmon

© Jon-Are Berg-Jacobsen, Nofima

Over a period of several years, Nofima researchers and partners have developed a promising method for sterilising salmon – an outcome that means they can’t interbreed with wild salmon should they escape from farms, as well as potentially improve their meat quality, and reduce disease and mortality rates.

There are several ways to sterilise salmon, such as triploidisation and gene editing. However, triploid salmon have been rejected as an option in Norway due to welfare issues and the use of gene modified salmon in production is still not permitted.

Embryonic intervention

The technique developed by Nofima’s Øivind Andersen and Helge Tveiten - which they are calling "the Nofima method" - blocks a factor that is required for the development of reproductive cells at the embryotic stage, which means that the fish never become sexually mature. Except for having small gonads that produce neither roe nor milt, the sterile salmon have the same outward appearance and characteristics as fertile fish.

However, in order to further develop the Nofima method into industrial large-scale production of sterile salmon, satisfactory health and growth must also be documented.

Andersen and Tveiten have now examined important production traits in their sterile salmon throughout life by in-depth investigations of body growth, smoltification, stress tolerance, sea louse infestation and mortality at sea.

The sterile salmon show production characteristics that are at least as good as fertile farmed salmon, even when faced by a severe lice attack. The scientists also documented that the sterile salmon had no reproductive cells, from their embryonic stage to the time of slaughter.

Andersen and Tveiten have now started working on different strategies for large-scale production of sterile salmon in partnership with the fish farming industry.

The research is financed by the Norwegian Seafood Research Fund (FHF) and is in cooperation with Aqua Gen and AquaPharma.