Sea Lice Management


of monthly averages below trigger threshold

BC salmon farmers minimize on-farm sea lice numbers through sophisticated monitoring & mitigation programs

For 52 of previous 58 months, sealice count has been below trigger threshold. Government of Canada - Open Canada Portal (2020)

Advances in Managing Sea Lice

Sea lice occur naturally in BC waters on many species of fish. Farmed salmon smolts, from the freshwater hatcheries, entering the ocean do not have lice. Lice can be transferred to farmed salmon from the environment and from other fish. The industry management of sea lice continuously improves through research and extensive testing of alternative measures and as a result now has innovative options to manage this pest.

BC salmon farmers recognize wild Pacific salmon as iconic species and are deeply dedicated to their conservation and committed to recovery efforts in their production regions. While they are aware that stock declines can be largely attributed to the detrimental impact of a variety of factors, including climate change, historical logging practices, urban development, industrial pollution and over-fishing,1 they recognize that excessive sea lice loads can impact the health of wild juvenile salmon. Since some stocks of juvenile salmon pass by salmon farms during their spring out-migration from coastal waters to the open ocean, salmon farmers take extra precautions during this period to ensure that sea lice numbers on farms are minimized.

Sea lice levels on BC salmon farms have been regulated since 2003: first by the BC Ministry of Agriculture—and since 2011, by Fisheries and Oceans Canada (DFO), under its Pacific Aquaculture Regulations.2 Aside from two challenging outbreaks in two areas of the coast in 2019, DFO has stated salmon farmers have been successful in managing sea lice. On June 28, 2019, former DFO Minister Wilkinson stated:

“During most years, more than 90 per cent of BC farm sites have been below the regulatory sea lice threshold during the wild salmon out-migration period…”3

All BC salmon farms must hold an Aquaculture License issued by DFO.4 Each Aquaculture Licence specifies conditions regarding specific operational and reporting requirements that farmers must adhere to in order to operate legally and be in compliance with the Fisheries Act and regulations.5 The conditions of license contain provisions to ensure that salmon farms are operated in an environmentally sustainable manner that minimizes the risk to wild fish stocks and the marine resource. Failure to comply can result in investigation and enforcement actions under the Fisheries Act.6

Salmon farm conditions of license specify area-based and site-specific sea lice monitoring requirements for each farm. In general, the sea lice-related conditions of license divide each year into 3 sea lice monitoring ‘windows’ defined by the out-migration pattern of the juvenile salmon:7

  • Non-migration Window: July 1 – January 31
  • Pre-migration Window: February 1 – February 29
  • Out-migration Window: March 1 – June 30.

During the non-migration period, each farm must conduct a sea lice count on the farmed salmon at least once per month – and submit the results to DFO by the 15th of the following month. If the count exceeds the threshold of 3 motile sea lice per fish, the farm must notify DFO within 7 days – and conduct sea lice counts every 2 weeks thereafter as long the the count continues to exceed 3 lice per fish.8

During the pre-migration window, 2 sea lice counts must be conducted – with results submitted to DFO within 48 hours of each counting event. If either of these counts reveal over 3 motile sea lice per fish, DFO must be notified – and presented with a plan describing the measures that will be taken to ensure that sea lice levels are below the threshold level by the start of the out-migration window. In addition, sea lice counts must be conducted every 2 weeks thereafter as long as sea lice levels continue to exceed 3 lice per fish.9

During the out-migration window, sea lice counts must be conducted within the first week of the window – and once every 2 weeks thereafter. The results of each counting event must be submitted to DFO by the 15th of the following month. If the sea lice count exceeds the threshold of 3 lice per fish, DFO must be notified within 48 hours – and a plan must be presented describing the sea lice management measures that will be undertaken to reduce sea lice levels below the threshold level within 42 days.10

Want to learn more? Take a deeper dive on how BC salmon farmers are managing sea lice.


1 Report of BC Minister of Agriculture Advisory Committee on Finfish Aquaculture. (2018). p.16.

2 Fisheries and Oceans Canada. Pacific Aquaculture Regulations.

3 Fisheries and Oceans Canada. 2019. Government of Canada announces enhancements to sea lice enforcement in British Columbia.

4 Fisheries and Oceans Canada. Aquaculture licensing in BC.

5 Fisheries and Oceans Canada. Marine Finfish Aquaculture License conditions.

6 Ibid.

7 Fisheries and Oceans Canada. Marine Finfish Aquaculture License conditions. Section 6.1. p. 10.

8 Ibid. Section 6.5. Page 11

9 Ibid. Section 6.5. Page 11

10 Ibid. Section 6.5. Page 12