Researchers have discovered that a specific gene plays an important role in determining mature salmon size and the decision to return to spawn, which may help maintain sustainable salmon populations in future.
The longer a salmon is at sea before maturing, the larger it becomes, and the more offspring it can have. Large female salmon lay more eggs and large male salmon are better at winning fights with other males within the rivers. In other words, size matters.
“We have found a single gene that explains a huge 39% variation in age at maturity in salmon, and thus also in size,” said Sigbjørn Lien, professor from the Norwegian University of Life Sciences (NMBU).
Previously, maturity was assumed to be a property that is controlled by a large number of genes rather than just one.
But this new gene has two main variants. Salmon that inherit one variant of the gene instead of the other may have a difference in age of puberty of almost a year.
Also salmon that have one of each variant will become larger if the salmon is female, but smaller if it is male.
In other words, it is the gender of the fish that determines which gene variant is dominant if the fish has both variants. It is therefore likely that salmon with both gene variants have the most offspring on average.
To conduct the research, the scientists isolated the DNA from scales from 1500 salmon from 57 salmon populations in Norway and Finland.
It is hoped that this new research, published in Nature, may also be used to help nature re-establish large salmon in rivers where they have become extinct.
