So why are they being farmed in the Pacific if they cannot intermingle?

The other week’s solar eclipse is being blamed for the escape of over three hundred thousand Atlantic salmon into the Pacific Ocean. Apparently, stronger-than-usual tides ripped open a net on a fish farm in Washington State on the weekend, near the border with British Columbia, and the fish swam out of their enclosure into the ocean. The resulting kerfuffle has raised some big questions.

What happens when Atlantic salmon invade the natural habitat of Pacific salmon? Nobody really knows. The farmed fish industry is downplaying the effects, saying the estimated 305,000 escapees are small fry in the grand scheme of things and that they’re unlikely to reproduce while not in their native habitat. (How a tightly packed enclosure on a foreign coast while being fed pellets qualifies as a native habitat, I do not know.)

Meanwhile, Washington’s Department of Fish and Wildlife is very upset, urging fishers to catch as many of the Atlantic salmon as they can. The fish are full-grown, weighing 4.5 kilograms and almost ready for harvest in the fall. Many West Coast fishers are concerned that they will prey on baby Pacific salmon. Atlantic salmon have been known to escape before and been found before along the B.C. coast, where they are considered an invasive species.

Bureau of Land Management -- A Pacific salmon spawning in British Columbia/CC BY 2.0

Some people have voiced concerns about sea lice and disease spreading to wild fish populations, but the company responsible for the Atlantic salmon, Cooke Aquaculture, says its fish don’t have these problems. This denial seems suspicious. Most other studies and books on this topic tend to conclude the same, as we wrote on TreeHugger: “Farmed fish are subjected to foul water conditions, crowding to the point of cannibalization, nutritional deficiencies, and abundant sea lice.”

As some critics have said, Pacific salmon face enough challenges as it is, without having an additional invader on the scene. The Globe and Mail quotes G.I. James, a member of the natural resources commission for the region: “It is potentially a disease issue and [an] impact on our fish … right now any impact to them is difficult to absorb.”

One can’t help but wonder why Atlantic salmon are being raised in the Pacific Ocean at all if an escape is so troublesome. Would it not make sense to raise fish species on whatever coast is closest to where they belong? Commenters on the Globe and Mail article seem curious about the same thing, agreeing that land-based fish farming would be a safer approach.

Fish farming in general is contentious. One organization called Farmed and Dangerous gives this scathing description of the practice:

"Salmon farmers often claim their industry is helping to 'feed the world.' In truth, the salmon farming industry is producing a luxury product for the western world that accelerates the depletion of wild fish stocks and strains the food chain in poorer nations. On average, it takes two to five kilograms of wild fish (used in the feed) to produce one kilogram of farmed salmon. In Chile, the ratio is often much higher with as much as 8 kilos of wild fish used to produce 1 kilo of farmed salmon (Terram Foundation Report). Most of the wild feed for BC farmed salmon is taken from the southern hemisphere, diverting local protein to raise a luxury product for northern consumers."

In the meantime, the public is trying to catch as many of the escapees as possible, but it must be a bit like looking for a needle in a haystack.