Wild Salmon in Trouble Video: The Link Between Farmed Salmon, Sea Lice and Wild Salmon

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Background on the movie

BC's wild salmon are cultural icons that undertake epic migrations, fuel coastal ecosystems, and contribute immensely to BC's economy. Unfortunately, wild salmon also face many threats; one of the most immediate is from salmon farms and sea lice. Watershed Watch Salmon Society is a leader in publicizing the threat open net salmon farming poses to wild salmon. We recognized that although the sea lice issue has received considerable media attention, it is a complicated topic and good visual resources are needed to help people understand the connection between salmon farms, sea lice and wild salmon. We created this animation to answer some of the questions we hear regularly and provide an overview of the salmon life cycle so the public can make informed decisions regarding the seafood they purchase.

The film was animated by Markus Radtke, original music and narration performed by Earle Peache, and technical direction and post production for the web by David Montie. If you would like to help spread the word about sea lice and wild salmon in trouble, please forward this link via or see our distribution instructions page to find out how you can help circulate the film. For other inquires about the film contact us. Wild Salmon in Trouble was produced in conjunction with the Coastal Alliance for Aquaculture Reform and with additional support from the Patrick Hodgson Family Foundation.

What is a sea louse?

Sea lice are external parasites that feed on the mucous, blood and skin of salmon. While a few lice on a large salmon may not cause serious damage, large numbers of lice on that same fish, or just a couple on a juvenile salmon, can be harmful or fatal. Sea lice can cause serious fin damage, skin erosion, bleeding, and deep open wounds. The sea louse, which resembles a tiny horseshoe crab, is well adapted to life as a marine ectoparasite. Their flattened head is covered by a shield, and their legs are specialized to allow them to grasp and feed on fish. Female sea lice have what looks like two tails trailing behind that are actually strings of eggs.

What is the connection between sea lice and salmon farming?

Although sea lice occur naturally in the Northern Hemisphere, louse infestations have only recently put wild salmon populations at risk because of salmon farming. Stocking thousands of fish in small areas makes fish farms ideal breeding grounds for lice, and drastically increases the number of lice in surrounding waters. Understandably, lice find it easy to parasitize farmed fish because of their high densities. The vast majority of salmon farmed around the world are Atlantic salmon which are inherently more susceptible to sea lice than most other salmon species. Wild Atlantic salmon populations are very low and aren't sold in most stores or restaurants. If you're buying Atlantic salmon, then it is probably farm-raised.

Fish farms are typically located in sheltered bays and inlets near rivers usually on or near the migratory routes juvenile salmon use to reach the open ocean. Salmon farms create an unnatural reservoir of sea lice that is especially detrimental to juvenile salmon heading for the ocean simply because of their small size. One or two sea lice may be enough to kill a juvenile salmon. Much higher numbers have been observed recently on juvenile pink salmon near BC’s salmon farms.

Are sea lice a problem elsewhere?

The problems associated with sea lice from salmon farms are not limited to British Columbia. Major infestations of sea lice, both on wild and farmed salmon, have been reported everywhere salmon farms have been established. Salmon farmers monitor and treat farmed salmon for sea lice with chemical pesticides that lower lice levels; however, even very low numbers of lice per farmed salmon can add up to billions of sea lice eggs being released into surrounding waters. There are also concerns and evidence that sea lice may become resistant to the current treatment of choice—a chemical called Slice that is added to the fish feed.

The Weight of Evidence

An abundance of peer-reviewed and published science shows that:

For more information see our aquaculture page.

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