Impacts & Issues: Sea Lice

The proliferation of sea lice on salmon farms creates a lethal problem for wild salmon. These parasites latch onto the fish and in the right conditions multiply far beyond normal levels.

Research presented by Dr. Micheal Kent (Pacific Biological Station) and Dr. T.T. Poppe (University of Oslo) shows that adult Atlantic salmon, the main species farmed in BC, are more susceptible to sea lice than Pacific species.

While these parasites occur naturally in BC coastal waters on adult salmon, sea lice thrive in the factory-farm conditions of salmon farms, with up to a million fish on one site. Repeated infestations are transforming the farms into year-round sea lice reservoirs.

The presence of sea lice on farms leads to the infection of fragile juvenile wild salmon as they emerge from their natal streams and migrate past the fish farms.

Peer reviewed, published research indicates infestations as low as 1 to 3 lice can be fatal to juvenile pink and chum salmon (Morton/Routledge, Alaska Fisheries Research Bulletin, Winter 2005).

A recent study estimates the total salmon mortality caused by sea lice originating on farms to be up to 95% of wild juvenile pink and chum salmon (Krkosek, Lewis, Morton, Frazer, Volpe, PNAS, 2006).

“If you meet anyone who still imagines that sea-cage farming does not harm wild fish, please direct them to read the paper recently published in the Proceedings of the National Academy of Sciences. One does not have to be a scientist to read it. The senior authors paid extra to have the paper accessible by the public. Criticism of the paper and the responses of the senior author can also be found online.“ Dr. Neil Frazer

For more info:

• The Myths & Realities of the Salmon Farming Industry in BC (Sept. 2009)
• Fraser River Sockeye may be impacted by sea lice from fish farms
• Sea Lice: A Science Primer - Watershed Watch Salmon Society and Coastal Alliance for Aquaculture Reform (Nov. 2008)
• Photos from Sea lice Sampling - Ruby Berry (2007)
• Bear Witness - Alexandra Morton (Sept. 2007)
• Neil Frazer’s submission to the Special Committee on Sustainable Aquaculture (Oct. 2006)
• Early Numbers Show Another Pink Salmon Collapse in the Making (Sept. 2005)
• Sea Lice Action Plan Will Not Protect Wild Salmon (Jan. 2005)
• Sea Lice and Farmed Salmon: Fatal Combination - WaveLength Magazine (Dec/Jan. 2004)
• Farmed Fish Parasites Devastate Wild Salmon (June 2001)