Farmed Fish and Sea Lice Endanger Wild Salmon Stocks

Contradicting previous research into the interplay between farmed and wild salmon, a new report finds that lice borne by farmed fish infect and kill wild salmon species. The report (which is currently in press), conducted by Martin Krkosek of the University of Otago in New Zealand, states unequivocally that “survival is negatively correlated with the abundance of lice on salmon farms, for both pink and coho salmon.”

The farmed fish live in dirty and overcrowded conditions in which lice can thrive. When these fish mingle with wild stocks (in the case of this study, coho and pink salmon), where normally lice would be unable to thrive, the lice can attach themselves to and harm the wild fish. Especially when the fish are young and vulnerable, this can be deadly.

Until this research was conducted, the aquaculture industry had been touting a flawed study using incorrect timetables that showed no correlation between the presence of lice and any harm to the wild fish. Turns out that wasn’t quite right, and that aquaculture does in fact hurt wild fish.

This poses a problem for fish lovers and environmentalists alike. On the one hand, farmed fish increase the availability of lean proteins to people which could otherwise be unable to afford them. At the same time, though, wild fish stocks are already dangerously overfished — almost to the brink of extinction in the cases of some species. Indeed, one high profile study said that all wild fish stocks will have collapsed by 2048. Add to this the federal policies that further drive down wild salmon stocks, and these small lice have suddenly become a big problem. Ironically, aquaculture — which was supposed to reduce overfishing — is now leading to reduced fish stocks.

One potential solution to this conundrum is indoor aquaculture. It has few of the harms associated with traditional aquaculture — no need for pesticides or antibiotics and very little waste — with all of the benefits. Even better, since the farmed fish are sequestered from wild stocks, sea lice would not even be a threat to wild salmon. As this technology gets off the ground, all of us fish lovers can only hope that wild salmon can make it from season to season.

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Photo from Sierra Tierra via flickr.


Jim Ven
Jim Venabout a year ago

thanks for sharing.

Cristian Prisacariu
Past Member 6 years ago

Wild salmon is very sensible fish. Fish farmers should take more care.

Abbe A.
Azaima A6 years ago


Ryder W.
Past Member 6 years ago

eating and farming animals is never a good thing. they just need to be left alone.

Monica D.
Monica D6 years ago

It sounds like indoor farmed fish might help solve some problems, but I wonder whether they might (like factory farmed animals) give rise to other issues. Fundamentally I think, like other commenters, that humanity should restrain its numbers and demands on the planet so that nature and wildlife can survive in reasonable numbers.

Grace Adams
Grace Adams6 years ago

It sounds as if indoor urban aquaculture could solve the sea-lice problem and some other problems as well. Keeping their water clean at least partly by growing edible greens and herbs on plastic mats on top of the indoor fish tanks sounds like it would be much kinder to the fish than growing them outdoors in such dirty water that large quantities of antibiotics are needed to even grow the fish big enough to eat.

K s Goh
KS Goh6 years ago

Thanks for the article.

june t.
reft h6 years ago

humans don't seem to learn from their mistakes until it's too late, unfortunately.

Susan T.
Susan T6 years ago

Its a big red flag that farmed fish have an abundance of lice. This is not a healthy food.

"In July 2003, the Environmental Working Group EWG released a report stating that farm raised salmon purchased in the United States contain the highest level of PCBs in the food supply system. In the report, EWG reported that farm raised salmon have 16 times PCBs found in wild salmon, 4 times the levels in beef, and 3.4 times the levels in other seafood. EWG recommends that consumers choose wild salmon instead of farm raised salmon, and they should eat an 8 oz serving of farm raised salmon no more than once a month."

EWG concluded this was because of the food fed to the farmed salmon.

BTW - studies have shown that wild salmon can survive with less food better than farmed so it's quite conceivable that wild salmon could become extinct from diseases/weakening of their genetic stock (from farmed), & farmed die off from a food shortage. Wild salmon are innately hardier than farmed, but due to the conditions of farmed salmon some of the diseases incubated there can be fatal to wild salmon.

IMO, you should ONLY buy wild caught salmon. Have it once a month for a treat. Otherwise there are other fish you can eat which are in less trouble like halibut.

Ernest R.
Ernest R6 years ago

It’s encouraging that people are beginning to realize that the present, and growing, overpopulation is too much for our planet to sustain. Reduced birthrates in formerly high birthrate countries like Italy, Spain, Portugal and France are good news except for the threat of being overrun by exploding populations in Africa, the Muslim world and India. Of course there are people who welcome these additions to the overpopulation even in their own countries. I am not one of them.