Research impact: Stopping the spread of sea lice

Sea lice pose a major threat to Canada’s aquaculture industry. They cause millions of dollars in annual losses to salmon producers and transmit parasites to wild salmon—a major environmental concern. Researchers discovered that sea lice are becoming resistant to the expensive drugs used to treat them, and it was unclear what complex genetic mechanism was causing it.

A Mitacs Accelerate intern from the Department of Pathology and Microbiology at the Atlantic Veterinary College took on the challenge of determining what genetic factors led to drug resistance, in partnership with Novartis Animal Health Canada. Learn more about what he discovered.

What is this research about?

Atlantic salmon, one of the most important species in aquaculture, contribute billions of dollars in yearly revenue. Sea lice (Lepeophtheirus salmonis), a parasite that infect these salmon, cause millions of dollars in losses each year for the salmon farming industry. Sea lice are also a major environmental concern due to the risk of transmission to the wild salmon population. Treatments for sea lice are very expensive and no sustainable treatment currently exists, largely due to drug resistance. The complex mechanisms enabling sea lice to become resistant are poorly understood.

This research aims to study the genes and pathways that may be involved in sea lice drug resistance.  Finding new treatments for sea lice would allow Canadian salmon farmers to reduce costs and increase their yield resistance, both will have large economic impacts.

What did the researcher do?

Sea lice are developing a drug resistance to the most effective therapy: SLICE™. To research how drug resistance may develop, the researchers studied genetic differences between genders, populations, and life stages of sea lice from the Bay of Fundy. They also studied the response of these different groups of sea lice to four primary drug compounds to better understand how sea lice may survive drug treatments.

What did the researcher find?

The researchers found gender, population, and life stage created the highest levels of genetic variability regardless of the drug treatment used. These findings highlight the large genetic diversity of sea lice. Drug treatments from the same class (pyrethroids) showed similar effects on gene expression.

SLICE™ had a distinct effect on gene expression compared to other drugs. The effect may be the result of its use as the primary treatment for sea lice in the Bay of Fundy. These findings provide useful information on the mechanisms used by sea lice to survive each drug treatment.

How can you use this research?

This research can be used to help identify genetic markers that can be further studied using more affordable quantitative methods. Identifying these genetic markers may provide potential targets for future drug development by the industry partner, Novartis Animal Health, Inc.

About the Researchers

This research was supported by the Mitacs Accelerate program.

Jordan Poley is a PhD candidate in pathology and microbiology at the Atlantic Veterinary College at the University of Prince Edward Island. Mark Fast is an Associate Professor and the Novartis Research Chair in Fish Health at the Atlantic Veterinary College at the University of Prince Edward Island. Spencer Russell is a Fellow and Research Manager in Aquatic Health at Novartis Animal Health Canada Inc.

In partnership with ResearchImpact, we are looking at outcomes from Mitacs Accelerate internships. ResearchImpact is a pan-Canadian network of 11 universities committed to maximizing the impact of academic research for the social, economic, environmental, and health benefits of Canadians. Both Mitacs and ResearchImpact are committed to illustrating that research has the potential to positively impact every aspect of life. 


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