Impact Spotlight

A to Z of Sea Lice Research

Highlights:

Sea lice infestations are often cited as the top animal health & welfare concern impacting the global Atlantic salmon aquaculture sector.
Sea lice research began at Huntsman Marine in 1988 and, today, is one of only a few topics that has the attention from all four primary fields of expertise offered by The Huntsman Marine Science Centre – Breeding & Genetics, Animal Health, Aquatic Toxicology, and Taxonomy & Biodiversity.
Huntsman Marine research teammates conduct numerous studies every year that address questions focused on sea lice in fish farming – collecting necessary datasets related to new anti-sea lice natural products, drugs, vaccines and pesticides, answering regulatory questions to ensure responsible use of approved treatments within aquaculture operations, and developing novel sea lice control strategies, such as use of cleanerfish species.

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Breeding & Genetics – We perfected closing the sea lice life cycle so we are able to produce tens of thousands of infectious copepodids each year to conduct controlled sea lice challenges with Atlantic salmon in the lab environment. We have used this infestation model to challenge individuals from more than 1,000 Atlantic salmon families, now into our fourth generation, to estimate heritability of Atlantic salmon sea lice resistance and inform broodstock selection within a commercial breeding program. Our challenges have recently also included comparing sea lice infestation rates of individuals from high resistance vs susceptible families when challenged together and separately to monitor selection program success. We are also now challenging rainbow trout families to assess relative susceptibility to sea lice when cultured in full salinity seawater.

Animal Health – Each year, Huntsman Marine completes numerous proprietary studies to collect extensive datasets that are submitted to regulatory authorities as new anti-sea lice natural products, drugs, vaccines and pesticides are developed for commercial use. A first step may involve screening compounds of interest for effectiveness at the lowest concentration required to cause mortality or immobility of sea lice through a series of in vitro benchtop Petri dish bioassays. These studies progress to in vivo tank-based trials with Atlantic salmon to demonstrate effectiveness (efficacy) to remove sea lice infestations, assess target animal safety of treated Atlantic salmon, and determine the compound withdrawal period – often conducted in different seawater temperature conditions and/or size of treated fish. Extensive sampling and processing capabilities are offered for blood, feces, fillet and other tissues to understand bioanalytical and pharmacological properties of the treatment compound while ensuring human safety following consumption of the edible portions of treated Atlantic salmon. We also provide expert assistance during the experimental design phase, backed by years of experience and intimate knowledge working directly with all sea lice life stages, to maximize study outcomes.

Toxicology – Approval for use in a commercial setting often also requires studies that characterize the potential for impacts from new anti-sea lice drugs and pesticides to other species that may inhabit the water column or seabed near Atlantic salmon sites during treatment. Of particular concern in Atlantic Canada is the American lobster as they are also crustaceans (like sea lice) and support a local high valued fishery. Huntsman Marine offers a suite of controlled challenges on all American lobster life stages to demonstrate non-target animal safety following treatment of Atlantic salmon farms. Recently published examples of our methods include: azamethiphos (Salmosan®Vet) on planktonic Stage I larvae (https://onlinelibrary.wiley.com/doi/abs/10.1111/are.16109), emamectin benzoate (SLICE®) on Stage IV+ settled juveniles (https://doi.org/10.1016/j.ecoenv.2018.06.075), and emamectin benzoate (SLICE®) on adult egg carrying berried females (https://doi.org/10.1016/j.scitotenv.2024.174840).

Taxonomy & Biodiversity – Regulators may approve use of a new anti-sea lice drug or pesticide treatment after completion of specific controlled laboratory studies as described above. However, initial uses may be restricted to a single or limited number of farms until extensive environmental monitoring is completed. Huntsman Marine undertakes freshwater and marine sampling using a variety of techniques to monitor for product residues and study their effects on water column and seabed biodiversity. Monitoring may occur over an extensive period – often months to years – after Atlantic salmon farm treatments. Our research vessel R/V Fundy Spray provides an excellent platform for marine studies in New Brunswick while we are able to undertake monitoring in other Atlantic provinces as well.

Cleanerfish Production – In recent years, aquaculture producers globally have explored use of cleanerfish species in net pens with Atlantic salmon as a non-drug biological method to control sea lice infestations. Huntsman Marine has produced hundreds of thousands of juvenile lumpfish to support local producer sea cage stocking mostly along the south coast of Newfoundland as the local sector explores this as part of their strategy into the future. Our total production capacity is millions of lumpfish fry each year to serve as cleanerfish should the industry decide to move more deliberately in this direction.