A new scientific study claims farmed salmon can significantly amplify sea lice in coastal waters of British Columbia (BC), and that controlling lice outbreaks presents substantial challenges to industry, regulators, and salmon conservationists.
The study, ‘Dynamics of outbreak and control of salmon lice on two salmon farms in the Broughton Archipelago, British Columbia’, published in the online journal, Aquaculture Environment Interactions, modelled the exponential growth of lice on two Broughton-area farms located on the migration path of wild juvenile salmon, and confirmed that lice outbreaks on farmed salmon are primarily driven by louse reproduction and population growth in the farms.
According to the study’s lead author, Dr Martin Krkosek, currently a professor at the University of Otago, New Zealand, the study provides new information on the dynamics of lice outbreaks on farms “that help us better understand the challenges we face in controlling lice in areas where wild salmon may be at risk”.
The study also examined the use of the pesticide, emamectin benzoate, commonly known as ‘Slice’, to control lice.
Dr Craig Orr of Watershed Watch Salmon Society, one of the study’s authors, said: “While using pesticides to control lice may buy beleaguered wild salmon precious time, the continued use of chemical controls is not sustainable. Louse pesticides may have unintended consequences for non-target organisms in marine waters, and lice around the world quickly evolve resistance to their effects.”
The challenges of controlling lice outbreaks on farmed and wild salmon have led to calls from the Coastal Alliance for Aquaculture Reform and others for the industry to transition into land-based recirculating (closed containment) aquaculture technology.
To access the study: http://www.int-res.com/abstracts/aei/v1/n2/
