Not so sexy salmon

MAY 1, 2019

by Bangor University

New research reveals that farmed salmon have smaller 'jaw hooks' or 'kype'- a secondary sexual trait, likened to the antlers of a stag, making them less attractive to females than their wild salmon cousins.

This new finding published in the peer–reviewed science journal Royal Society Open Science, implies that farm-bred salmonare less sexually attractive than their wild brethren, and that despite only being bred in captivity since the 1970's, within some 12 generations, that they are already diverging from wild salmon.

The findings form part of a wider research project into the differences between wild, farmed and hybrid salmon.

William Perry, a Ph.D. student at Bangor University's School of Natural Sciences and the paper's lead author explains:

"Farmed Atlantic salmon do sometimes escape from the nets and can interbreed with wild salmon, creating hybrids.

"Initially, the fact that any escaped salmon are less 'attractive' because of their smaller 'kype' may seem like good news, as they're less likely to breed. That's not the whole story however. Because farmed fish do not have to compete for mates, there is no element of sexual selection happening, making the farmed and hybrid fish poorly adapted to breeding in the wild. So, when you do see high levels of farmed escapees, and inevitable interbreeding within a wild salmon population, this could reduce the long term health of that population.

Continued

Sterilise farmed salmon to save wild species, critics say

Millions of farmed fish escape globally each year, destroying wild salmons' genetic traits

LEWIS SMITH

Sunday 09 March 2014

Farmed salmon escaping into rivers and the sea are posing such a threat to declining wild populations that sterilisation should be compulsory, researchers have concluded.

Millions of farmed salmon are able to escape globally each year and there is increasing evidence they are destroying genetic traits evolved by the wild populations.

More than 95 per cent of the world’s Atlantic salmon, Salmo salar, are farmed, and a new study assessing their breeding capacity has found that the farmed stocks are just as fertile as the wild populations. They are also more aggressive, helping them out-compete their wild rivals.

Scientists now fear that wild populations will be damaged irreversibly, losing traits that have evolved to keep them adapted to their environment, unless sterilisation is introduced as mandatory.

Publication of the study comes just days after it was confirmed that more than 150,000 fish escaped the Ness of Copister farm in Shetland when the net cages containing them were damaged in the January storms.

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