The Marine and Freshwater Institute is attempting to breed a new kind of farmed salmon, that is, one without any sex. RÚV reports that the idea behind this is to prevent farmed salmon from becoming sexually mature and thus being able to spawn with the naturally occurring local salmon population. If this experiment is successful, the result would also be applied to farmed Arctic char populations, 15 – 20% of which reaches sexual maturity before they are harvested.
“This is what’s called gene suppression; there are certain substances that we use on roe and once we do, certain genes that can determine what sex a fish is don’t get expressed. And thus are the fish sexless…,” says Ragnar Jóhannsson, the Institute’s Director of Aquaculture.
This is not considered genetic modification, since the fish’s genetic makeup isn’t touched. Rather, the expression of mRNA, which controls the production of proteins that are connected to sexual maturation. This is done by introducing substrates into cells. The project is being undertaken in collaboration with StofnFiskur, an organization involved in aquaculture breeding and genetics, and the University of Maryland, which holds the copyright on the process.
Ragnar believes the method is more promising than experiments with tri-chromosome triploid fish, as it involves less intervention. “What seems to have been the biggest problems with the tri-chromosome fish is that there have been more deformations and death and that seems to be because they can’t tolerate temperatures that are high or too low as well. And we have more than enough low temperatures here in Iceland.”
The project is still in the testing phase and no firm conclusions are expected for at least three years. “This naturally means that if we can produce fish that are sexless, there won’t be any danger if they get into rivers that they interfere with the naturally occurring fish,” says Ragnar.