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Russell Wangersky: The not so wild, wild world of N.L. salmon

Atlantic Salmon
Atlantic Salmon

Sadly, the writing might on the wall for Newfoundland’s wild salmon.

And no, not just because of the terrible returns by breeding salmon to island rivers this year, a decline so great that the federal Department of Fisheries and Oceans closed the recreational salmon fishery to everything but hook and release fishing.

And it’s not just declines in 2017: 2016 had its cautions, too, with DFO science warning: “Seven of 14 (50 per cent) monitored rivers recorded declines in total returns of greater than 30 per cent in 2016 compared to their previous five-year mean. Declines of this magnitude over a wide geographic range are highly unusual for the NL Region warranting caution in managing stocks in 2017.”

No, the writing’s on the wall because a chunk of the island’s native wild salmon stock just isn’t as wild any more.

The provincial government might like to crow about the value of the aquaculture industry to the province’s economy. It might decide to appeal court decisions ordering the proper environmental assessment of massive new aquaculture projects like the one slated for Placentia Bay, a project led by Norwegian aquaculture giant Grieg. (That plan alone is set to launch 24 hectares of ocean cages.)

Absolutely no one might want to talk about sea lice infestations, treatment of farmed salmon with drugs, the problem of fish waste below ocean cages or the escapes of farmed salmon into the ocean.

But you can’t deny the DNA.

It, like murder, will out.

In 2014, DFO started a project to analyze the impacts of a major salmon escape from a southern Newfoundland salmon farm, saying, “Aquaculture escapees represent a continued threat to the genetic integrity of wild populations, and have been shown to interbreed with wild fish, which can impact local adaptation. In southern Newfoundland, wild Atlantic salmon populations remain at record lows and their status is considered “threatened” … Potential impacts associated with the developing aquaculture industry cannot be ruled out as a contributing factor on the survival of wild fish. In 2013, a large escape event (>20,000 individuals) occurred in southern Newfoundland where there were reports of mature escapees in local rivers.”

DFO launched a three-year genetic study of salmon rivers in the area, and the early results were concerning when they hit the press a year ago.

They are more concerning now. The results of that research are included in this year’s recently posted 2016 Assessment of Newfoundland and Labrador Salmon, and the word’s not good.

“For the first time the unambiguous, widespread detection of first- and second-generation wild- aquaculture hybrid salmon and pure aquaculture offspring (i.e. 35 per cent hybrids, 17/18 rivers within 75 km) has been reported,” the research says. “Results indicate that levels of hybridization were higher in smaller populations, hybridization had pre-dated the 2013 escape event, and some hybrids were reproductively viable.”

Let that sink in for a moment: the research says one in three fish are hybrids, it’s not just one escape that’s to blame, and the genetic genie is out of the bottle, because the hybrids are themselves reproducing.

“Genetic analysis of juvenile Atlantic Salmon from southern Newfoundland revealed that hybridization between wild and farmed salmon was extensive throughout Fortune Bay and Bay d’Espoir (17 of 18 locations), with one-third of all juvenile salmon sampled being of hybrid ancestry,” the report says. That’s a pretty hefty slug of aquaculture genetics finding its way into a natural population, and, as the stock status report points out, “The long-term consequences of continued farmed salmon escapes and subsequent interbreeding with wild Atlantic Salmon include a loss of genetic diversity.”

What’s it all mean? Well, narrowing the genetic diversity of species limited its ability to survive specific threats: disease can march much more quickly through a monoculture. Not only that, but if escapees from fish farms are getting close enough to wild populations to mate, they’re clearly close enough to spread any disease they might have developed in close-contact fish pens, or any parasite — like sea lice.

On the genetic side, one of the things that helps a population survive is its genetic variation; a fish with one kind of parentage might be better equipped — in fact, might be specifically ecologically adapted — for a particular Newfoundland river, for its flows and food stocks, for the fish’s own ability to convert particular food materials into muscle or fat.

Add a rubber-stamp monoculture aquaculture fish to the parental mix, and the next generation might not be anywhere near as successful.

Add that to the fact that scores of salmon smolt seem to be going to sea and not returning, and you have to ask how long we expect our own particular salmon to last.

 

Russell Wangersky’s column appears in 35 SaltWire newspapers and websites in Atlantic Canada. He can be reached at rwanger@thetelegram.com — Twitter: @wangersky.

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