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Assessing the potential for development of thermal resistance of sea lice to warm water showers



Outbreaks of sea lice are a globally acknowledged challenge for salmon farming operations; they are a risk to wild salmon populations and a considerable amount of resources are being expended by industry and governments from many countries in order to manage these pests. Chemo-therapeutants and animal husbandry practices have been traditionally used to keep sea lice under control, but the parasite is becoming resistant to many of the chemicals that are being used. Therefore, there are strong incentives to look at other non-chemical approaches to dealing with sea lice. One of the more promising techniques being developed to remove sea lice from farmed salmon and to control the attached stages is the use of warm water showers. Previous ACRDP project results have demonstrated that the use of a warm water shower can effectively remove up to 95% of the mobile stages of sea lice from the fish in a 30-second treatment with very low mortality rates in the fish. However, a recent study has suggested the possibility that resistance of sea lice to the warm water or freshwater treatments may develop over time, in a manner similar to resistance to chemo-therapeutants. If this is the case, then the efficiency of the warm water shower may decrease over time, to a point where it becomes ineffective in the treatment of sea lice, and some other technology will have to take over.

The overall goal of this project is to test the concept that sea lice may develop resistance over multiple generations to the temperatures currently being used in the warm water shower to such an extent that the declining efficiency of the warm water shower eventually renders it useless. If this resistance occurs, understanding the rate of this potential change in resistance to warm water by the sea lice will enable better planning for the lifespan of this technology and the timescale for alternatives to be developed.

Program name

Aquaculture Collaborative Research and Development Program (ACRDP)


Three years: 2018-2021

Principal investigator

Shawn Robinson, research scientist, Fisheries and Oceans Canada, St. Andrews Biological Station, Maritimes Region

Team members

Joel Halse, engineer, Cooke Aquaculture Inc.


Keng Pee Ang, Vice-President of R&D, Cooke Aquaculture Inc.

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