Controlling Sea Lice Infestations on Farmed Atlantic Salmon

Sea lice, Lepeophtheirus salmonis (Krøyer), are a well-documented parasite of farmed salmonids; infestations can be costly as a result of chemical treatments to salmonids as well as loss of fish due to mortality and morbidity.

Some medicinal treatments have been pursued by the salmon industry to control sea lice infestations on farms, but these methods are expensive, stressful to salmon, have detrimental environmental impacts, and can be hazardous to workers. A team from The University of Prince Edward Island, the Centre for Veterinary and Epidemiological Research, and the Atlantic Veterinary College developed an agent-based model to simulate the effects of cleaner fish on sea lice loads of farmed salmonids.

The goal of the study was to investigate the effects of different concentrations of wrasse (a marine fish with thick lips and strong teeth) on sea lice infestations of farmed salmon in a variety of treatment and infestation scenarios. They found that wrasse can effectively control sea lice, and the densities of wrasse needed for effective control depend upon the source of the infestation and the targeted level of control. Effective usage of wrasse can result in decreased use of chemical treatments and improved control of sea lice.

The model is available for you to run on and is the July 2016 Model of the Month! The full paper is also available in the papers section of