Researchers look at wild fish reproduction

10 Mar 2014
According to the research, farmed salmon which escape into the wild could pose a threat to wild gene pools

According to the research, farmed salmon which escape into the wild could pose a threat to wild gene pools

Researchers at the UK’s University of East Anglia (UEA) believe farmed salmon should be sterilised to avoid breeding with wild fish.

According to the UEA research, while farmed salmon are genetically different to their wild counterparts, they are just as fertile. Since millions of farmed salmon escape into the wild, researchers say they could pose a threat to wild gene pools.

Professor Matt Gage, lead researcher, from UEA’s school of Biological Sciences, said: “Around 95% of all salmon in existence are farmed, and domestication has made them very different to wild populations, each of which is locally adapted to its own river system.”

“We know that recently-escaped farmed salmon are inferior to wild fish in reproduction, but we do not have detailed information on sperm and egg performance, which could have been affected by domestication. Our work shows that farm fish are as potent at the gamete level as wild fish, and if farm escapees can revive their spawning behaviour by a period in the wild, they clearly pose a significant threat of hybridisation with wild populations,” he added.

Some Norwegian rivers have recorded large numbers of farmed fish at present, as much as 50%, according to the research.

The UEA researchers say a viable solution is to “induce ‘triploidy’ by pressure-treating salmon eggs just after fertilisation”. According to the research, the resulting adult develops testes and ovaries but both are reduced and most triploids are sterile.

This research, Assessing risks of invasion through gamete performance: farm Atlantic salmon sperm and eggs show equivalence in function, fertility, compatibility and competitiveness to wild Atlantic salmon, was funded by the Natural Environment Research Council (NERC) and the Royal Society.