Fish Farms And Drug-Resistant Sea Lice

When we think of pest and disease management on industrial farms, we often think of pesticides used on crops or antibiotics used in animal feeds that allow farmers to push their operations to intensive levels. We don’t tend to think about fish! But, a report by the Living Oceans Society outlines how fish farms are no different.

Fish farming, like other industrial farming, is not completely separate from the ecosystem surrounding it. Many fish farms breed fish in enclosures set in “wild” waters, and fish (and lice) can both enter and escape such enclosures. This has far-reaching effects on wild fish populations around the farms.

In the Spring of 2018, scientists noticed that levels of parasitic sea lice on farmed and wild salmon in the Clayoquot Sound area of British Columbia had reached epidemic proportions—affecting 96% of the sampled wild juvenile salmon. What’s worse, the infestations were often at a level that would cause death. According to the report, a drug called SLICE controls sea lice in farmed salmon. But the growing spread of sea lice in wild populations suggests not only that sea lice have developed a resistance to the drug, but also that resistance may have spread beyond fish farm enclosures. Topping all of this off, the report suggests that “regulators and industry knew resistance was developing as early as 2014,” but repeatedly denied it.

The report underlines that dealing with sea lice is a serious business. For example, just one to three lice can kill a juvenile salmon, and lice counts found that the wild juveniles in areas surrounding fish farms had an average of 8.04 lice per fish, with some lice counts reaching up to 50 per fish. The report also emphasizes how regulators knew the farmed lice would gain a resistance to this drug, and that this resistance would spread to wild populations. They knew this, because this has also occurred previously in other regions.

For their part, the Living Oceans Society suggests that the best course of immediate action is for the industry to shift production to land-based, closed-containment farms. Of course, this will raise red flags for animal advocates, as this alone does nothing to address the issue of sea lice drug resistance and could indeed create bigger disasters when breaches happen. For most animal advocates, the findings from this report will instead provide further evidence as to why we should eliminate fish farms entirely.