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.
Photo from Sierra Tierra via flickr.