#CBC: « New proof that fish farm escapees interbreed with wild salmon: DFO » #Toronto #Montreal #Calgary #Ottawa #Canada

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For so long as there have been fish farms on this province, there have been fish escaping from cages into the wild. Conservationists have suspected these escapees breed with native fish, altering their DNA.

Now they are saying they’ve proof.

One of the biggest escapes in Newfoundland occurred in 2013, when greater than 20,00zero salmon bought away from a farm in Hermitage Bay. That incident impressed DFO scientists to check the genetic materials of fish in salmon rivers on the island’s south coast.

« We looked at 19 rivers in the first year and hybrids were detected in 18 of those rivers, » stated lead researcher, biologist Brendan Wringe.

More than 1/four of river salmon are hybrids

« We weren’t surprised to find hybrids. We were surprised to find as many hybrids as we did and to find them as widely spread as we did. In total of the 17-hundred odd fish we sampled, about 27 per cent showed farmed origin. So they may have been hybrids or, more worryingly, feral fish. So that would be fish where both parents were of direct farm descent. »

Wringe stated salmon interbreeding worries scientists as a result of hybrid offspring is probably not as in a position to survive in addition to wild fish.

« Wild populations are adapted to local conditions: temperature, flow rate, pH [levels] are all important, whereas the farmed fish of course have been bred for fast growth in a closed environment, » he defined.

We would anticipate that hybridisation will seemingly result in common inhabitants decline.– Brendan Wringe

« So interbreeding is likely to reduce the productivity of the wild populations because the hybrids are not as well adapted. We would expect that hybridisation will likely lead to general population decline. However we don’t have enough information to say what the magnitude of those declines could be. »

Steve Sutton, coordinator of group outreach and engagement with the Atlantic Salmon Federation, believes there may be proof interbreeding is hitting wild shares arduous.

« Well, we know that salmon on the south coast of Newfoundland have been assessed as threatened by the Committee on the Status of [Endangered] Wildlife in Canada, » he stated.

Wild shares dropping

« The only monitored population we have in the area where they’ve done the research is on the Conne River, which at one time had runs of eight or ten thousand fish. That’s been much lower than that for a long time, but in the last couple of years we’ve seen another huge drop in that population, » stated Sutton.

« We’re down to less than a thousand the last two years and possibly less than 500 this year. So I think what we’re seeing the last two years are the impacts of this large interbreeding that occurred back in 2013. »

Escaped farm-bred Atlantic salmon. (Atlantic Salmon Federation)

Sutton is not simply nervous about large escapes just like the one in 2013. He’s involved concerning the ones of fewer than 100 farmed fish, which aren’t required to be reported.

« Well, there are some scientists who would suggest that those smaller escapes are probably actually worse than a single larger scale, » he stated.

« The reason is, if you have a single large escape and you have interbreeding then the genetic material that’s introduced to the population will eventually weed itself out. It will have impacts as it does that because those fish that carry that material will be less likely to survive. So you will get lower numbers of adults but eventually it will weed itself out. »

« The problem is, if you have these smaller escapes that are ongoing, you’re actually getting a constant input of foreign genetic material into those populations and so the population never really gets a chance to recover. »

Regulators must take motion

Conservationists like Sutton say they do not know whether or not salmon populations during which interbreeding has occurred can ever return to their pure state.

Sutton stated now that there is proof there are vital numbers of hybrid fish within the wild, it is time for the provincial authorities to tighten laws to forestall future escapes.

In the meantime, researchers like Brendan Wringe will maintain learning the issue.

« We are continuing to monitor the area as well as conducting ongoing studies and simulation studies to try and predict what potential impacts there might be, » he stated.

They hope a greater understanding of the results of interbreeding will sometime result in higher safety for wild salmon.

Note: « Previously Published on: 2018-09-23 07:30:00, as ‘New proof that fish farm escapees interbreed with wild salmon: DFO’ on CBC RADIO-CANADA. Here is a supply hyperlink for the Article’s Image(s) and Content ».

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