A new study published in Scientific Reports sheds light on the mounting problems faced by B.C. factory fish farm companies and the threat they pose to wild salmon populations. It reveals a disturbing trend: mortality events at Atlantic salmon farms are increasing dramatically, driven by harmful practices and worsening environmental conditions.

From 2011 to 2022, a whopping 561 mortality events were reported at B.C. salmon farms and the events have increased significantly over time.

What’s driving the deaths of factory-farmed salmon? Parasitic sea lice treatments gone wrong. Since 2020, methods used to control sea lice outbreaks have been the leading cause of fish mortality at factory farms. The industry uses various methods to try to control exploding parasite levels on their farms. One is to bathe their fish in a hydrogen peroxide bath in a well boat. As you can imagine, this is very stressful for the fish. After the process, the companies are allowed to discharge this toxic bath into our coastal waters.

These treatments clearly take a heavy toll on farmed salmon and demonstrate the unsustainable nature of these operations.

Watershed Watch’s Stan Proboszcz

Climate change and ocean warming are increasing the frequency and severity of harmful algal blooms and low oxygen levels, two other significant causes of fish farm mortality events. Farms on the west coast of Vancouver Island report more mortality events than other regions, likely due to their exposure to changing ocean conditions. We saw that first hand last year with die-offs at Grieg Seafood facilities in the Nootka region.

A juvenile salmon with sea lice. Photo by Tavish Campbell.

Why does this matter for wild salmon? Open net-pen salmon farms don’t just impact farm fish—they endanger wild salmon too. All these stressors (fish treatments, harmful algal blooms and low oxygen levels) can stress the farm fish and make them more susceptible to viruses and bacteria, which can in turn be amplified and spread to wild salmon.

It’s crystal clear factory fish farming is a disastrous sinking ship on our coast. Just a few weeks ago, a massive diesel spill occurred at Grieg Seafoods’ Lutes Creek fish farm in the beautiful Nootka Region of Vancouver Island. Now, this new science indicates that mortality events at salmon farms are skyrocketing. The big question is, will our governments get the message and speed-up the marine fish farm ban? Can you take a second to send the federal government a message about this?

We hope for more clarity on the fish farm ban in 2025, when the plan is supposed to be released by the federal government.

Study reference: Jyoti, S., Jia, B., Saksida, S. et al. Spatiotemporal patterns of mortality events in farmed Atlantic salmon in British Columbia, Canada, using publicly available data. Sci Rep 14, 32122 (2024). https://doi.org/10.1038/s41598-024-83876-5