It really shouldn't be a surprise that salmon farming is a major threat to wild salmon. Agriculture in all of its forms is a direct threat to nature. I can hear some of you now, "How can he say that!?!" I don't want to go down that road too far, but here are a couple of examples of agriculture's direct assault on our wild world beyond the clearing of fields and the fouling of our waters with e coli. I want you to go here for an article by someone else about ocean dead zones such as the one at the mouth of the Mississippi River. OK, now you know about agricultural runoff and other runoff from human development that creates dead zones in our oceans. Now I want you to go here for another agricultural direct assault on our wild world (to the washed, it is important to bring the unwashed up to speed). Let's talk about the bighorn sheep die offs, go here, here, and here. Let's look at the grazing issue and it's damage to our watersheds and wildlife, go here and here. And we would be remiss if we didn't look at the agency created at the behest of agricultural interests, the USDA's Wildlife Services, here. OK, washed, I believe the unwashed are up to speed. Now, onto why salmon farming is a serious threat to wild salmon survival.
I once caught the strain of influenza that killed so many people at the end of World War I, La Grippe or Spanish Flu. No, I'm not that old. I caught the strain in 1986, or at least that is what I was told, it was one hell of an illness. My little sister was in a hospital with it, I was told another child died down the hall from her from it. I honestly cannot verify any of this because quite frankly I was in horrible shape at home. It was the only time during my 40+ years of life on earth that I wouldn't have minded taking an exit from this world. I believe I lost 24 pounds in a week and much more. I only remember laying there in the fetal position for what seemed like days and I remember my friends at school when I returned having decided that I must have died. Well, high school had its interruptions for me, horrible flu in 1986 and just weeks before my senior pictures, I caught chicken pox, yay me. The chicken pox had its advantages, though, when I came back to my high school baseball team with all those scars it scared everybody. So, coach decided I could pinch hit that day. Apparently, the opposing catcher hadn't had chicken pox and wouldn't give his pitcher a target in the strike zone when I was up there because he was crouched behind the right-handed batter's box. He said to me, "are those chicken pox? Are you contagious?" And I'm all like yeah and maybe, who knows dude. I got four straight balls way outside and took my base and a pinch runner came in for me because apparently I looked like death warmed over. Otherwise, it was a pretty normal time in my life. Why is it I feel like I was a bit character in one of those John Cusack movies? I know you live for my sidebars.
Anyway, back to the narrative (some blog posts take on a life of their own and I am powerless to stop them). Agriculture's assault on the wild as it pertains to wild salmon. In the Atlantic Ocean you had to worry about escapement, those farm Atlantic salmon could escape and intermix with the seriously endangered wild Atlantic salmon and you make a very bad situation worse. That has happened, those horses left that barn and still are. Escapement is the primary concern with any approval of those superfish, the salmon that have been genetically modified with the conger eel genes. So continue to be on the watch for that coming down the pike and do what you can to stop it.
However, escapement really wasn't a problem with salmon farming in the Pacific mostly due to the fact that Atlantic salmon cannot make hybrids with our Pacific salmon. They can make hybrids with brown trout, but brown trout are supposed to be in Europe and not here. So it makes sense there hasn't been a Pacific salmon x Atlantic salmon hybrid in a lab or in the wild (that we know of). You may want to research this further, try page 14 of this.
The real problem with salmon farming in the Pacific using Atlantic salmon comes from disease and pollution. The salmon farms are breeding grounds for sea lice and a few very frightening viruses that kill wild Pacific salmon about as efficiently as smallpox killed off Native Americans (I encourage people to read 1491 and 1493 by Charles C. Mann, fascinating stuff, especially when you see how European immune systems were more robust and equipped to fight disease than Native American immune systems that had evolved under completely different conditions). It was far more thorough than my very quick pitch there, but anyway the problem with salmon aquaculture is akin to European diseases wiping out Native Americans and also European diseases killing off bighorn sheep (which you should be familiar with by now because I gave you some great research above).
I make an effort to only buy wild salmon. Naturally, as a consumer, whether or not you can trust the labels (especially on seafood) is precarious at best. I do encourage you to make the effort to only buy wild salmon. There are a number of reasons for this but mostly I am talking about a few viruses that began in aquaculture in Europe and have made their way to British Columbia, the U.S. and Chile according to just about everyone except the Canadian government and the Canadian aquaculture industry. Feel free to watch this documentary on the subject. There's a link to watch the documentary on the page there.
The viruses are infectious salmon anaemia you may see it referred to as ISA. The second virus weakens the heart of farmed and wild salmon, it is known as Piscine reovirus (PRV) and you can read about it here. Researchers now believe PRV is the cause of heart and skeletal muscle inflammation (HSMI).
The problem with farmed salmon is that they are likely to get disease living in confined and crowded spaces, they are likely to live longer while they have these diseases and since the salmon farms are located right smack in the middle of many of the great wild salmon runs they will infect wild fish causing untold numbers to fail to make it back to spawn.
Researcher Jennifer Ford of Dalhousie University, in Halifax, Nova Scotia might have had a solution she shared in 2010 in National Geographic. "The clearest solution would be to move [salmon farms] to land or to some place where there aren't wild salmon populations that they can impact." National Geographic October 28, 2010.