This report provides a summary of sea lice mitigation events reported at salmon farms in British Columbia to Fisheries and Oceans Canada (DFO).
A sea lice mitigation event occurs when actions are taken to reduce sea lice abundance at a salmon farm. Mitigation measures often occur over several days and may include in-feed treatments, mechanical removal, medicinal or non-medicinal bath treatments, harvest, or a combination of treatments. The goal is to reduce the number of sea lice on farmed salmon to below the management threshold set in the Conditions of Licence.
The current sea lice management threshold at which action is required is 2.4 motile sea lice (L. salmonis) per fish. In 2025, the threshold was 2.8 and before 2025, it was 3 motile sea lice per fish. If the sea lice abundance at a farm is found to be above the threshold during the juvenile wild salmon out-migration window from March to June, salmon farmers must take action to reduce the abundance below the threshold within 28 days. Prior to July 2024, licence holders had 42 days.
Licence holders must monitor the effectiveness of certain mitigation types to help prevent the development of resistance to treatments. Any reduced efficacy must be reported.
Sea lice mitigation events at B.C. salmon farms graph
Industry sea lice counts at BC marine finfish aquaculture sites
Average number of lice per fish on BC salmon farms