The data below comes from the websites of Mowi, Cermaq and Grieg. This is self – reporting. We know this reporting can be 50% lower than is actually occurring in the farms but it is informative[1].
The dotted line is the threshold put in place by the Province of BC in 2003 to protect wild salmon - 3 motile or adult stage lice per farm salmon. Companies were meant to keep their lice per salmon below this line. However, similar to everywhere in the world that this industry operates, sea lice on farm salmon in BC are becoming resistant to the drugs used to kill them and this means no company has reliably controlled their lice since 2015. When sea lice on salmon farms rise, young wild salmon die.
To help the farmers stay in compliance with the regulations senior DFO management gave the companies some relief. On March 1, 2020 Conditions of Licence issued by the federal government allowed each farm to exceed the longstanding threshold for 6 weeks every time the average number of adult-stage (motile) lice per farm salmon rises above 3. I fought this has hard as I could, but DFO management was determined to lower the bar so the farmers could not be prosecuted for damaging levels of sea lice. Last year 99% of young sockeye were heavily infected in the Discovery Islands, and we could not find these fish again further along on their migration route. Here is a report I put together on Download Sea Lice 2020
This year many of the most infected farms have new younger fish and so fortunately lice numbers are lower, but there are several hot spots.
Figure 1: The average number of sea lice per farm salmon has been lowered in the Discovery Islands since very high levels over the winter, but we see the green line is trending upwards again. As well, lice numbers are rising dangerously in the farms off Port Hardy including Bull Harbour. Both of these areas are on the Fraser River salmon migration route.
Figure 2: This is the average number of lice per farm, colour – coded by company. Mowi is currently reporting three farms above the threshold. These are the farms off Port Hardy.
Figure 3: This is the average number of juvenile (attached stages) which will molt into the motile stages that are counted within two weeks. This stage of lice is unregulated. These extremely high numbers are in Quatsino Sound at the Mowi farms Koskimo, Mahatta West and Monday Rocks farms. If Mowi doesn't get these lice numbers down right away they will heavily infect any wild salmon trying to migrate out of Quatsino Sound.
Here is a map of all the farms on the BC Coast
Sea lice infection at salmon farms in 2020 destroyed a very high proportion of the young salmon that were trying to get to sea. These fish will not return to spawn. photo Tavish Campbell
[1] Bias in self‐reported parasite data from the salmon farming industry - Godwin - 2021 - Ecological Applications - Wiley Online Library