Aquaculture

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Norwegian researchers crack code for producing sterile farmed salmon

Breakthrough could ease concerns over escaped farmed salmon breeding with wild counterparts.

Norwegian research institute Nofima has 2,000 sterile salmon swimming in its tanks, thanks to a breakthrough that has taken 10 years.

The ability to produce sterile fish could be the solution to concerns over escaped farmed salmon breeding with their wild counterparts -- a major issue with farmed salmon opponents.

Nofima scientists found a method that only affects the fish’s ability to reproduce, and nothing else. The largest fish are now one year old, and weigh on average around 300 grams.

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“We must follow up on this fish over a longer period of time, but there are no indications that it will become sexually mature or develop the urge to migrate in order to spawn," said Senior Researcher Helge Tveiten.

"Naturally, intensive studies must be carried out on whether escaped sterile salmon actually migrate up rivers. This requires more research, but it would now appear that it is highly unlikely.

“The salmon we have researched do not develop gametes, and will never be sexually mature,” Tveiten added. “We see a tiny egg sac in the female fish, but no eggs are formed. The male fish develops what appears to be normal sexual organs, but they don’t have sperm cells.”

Research carried out on zebra fish identified a few genes that are decisive for the development of gametes, Tveiten noted, which paved the way for the research.

"In practice we don’t touch the genes, but affect a protein that is necessary to enable the fish to produce gametes," he said.

Tveiten’s work is part of the SalmoSterile research project, under the BIOTEK 2021 program financed by the Research Council of Norway (RCN). The project is a cooperation between the Norwegian Institute of Marine Research (NIMR) and several major industrial companies, including AquaGen.