Pesticide Dumping in Clayoquot Sound

While Grey whales mysteriously starve to death, salmon farms continue to dump hydrogen peroxide, shown to be acutely toxic to krill, in the waters off Vancouver Island’s west coast

by Dan Lewis

Clayoquot Sound | Photo: ©Sander Jain

Salmon lice are tiny crustaceans which occur naturally in the waters of the northeast Pacific — think of them like cockroaches of the sea.

Fish farms provide an ideal breeding ground for these parasites, with each facility presenting half a million farmed salmon trapped in a confined space. Because fish farms in BC use open-net pens, lice can swim in to infest the farmed fish, and then swarm back out to plague wild salmon as they pass the numerous pens dotted along their migration routes — twenty fish farms in Clayoquot Sound alone.

Sea lice continue to beset the salmon farming industry globally. No treatment has ever solved this problem, anywhere in the world. Clearly a new approach is needed, which is why we’re seeing a global shift to land-based salmon farming.

Three years ago, Cermaq Canada received a permit from the BC Ministry of Environment to use 2.3 million litres of a pesticide called Interox® Paramove® 50 (active ingredient: hydrogen peroxide). This permit allows them to suck the farmed fish out of their pens into a well boat, where they are soaked in a corrosive chemical bath to dislodge the sea lice. The fish are then poured back into the pens, and the pesticide is dumped right into the pristine waters of Ahousaht First Nation.

In 2018, Cermaq ended up using (and dumping) 65,874 kilograms of Paramove. Cermaq is now applying for another three-year permit, this time to use and dump just shy of one million litres.

New science coming out of Norway shows that peroxide treatments can be much more lethal to non-target species than was previously understood. A 2020 paper by the Institute of Marine Research showed that peroxide is toxic to krill at concentrations of 1/2,000 of the recommended dosage.

Paramove can persist in the environment for weeks, and tends to pool in shallow waters – the very place used for rearing by juvenile wild salmon and herring, as well as crab, shrimp, and other crustaceans in their larval life stages.

West coast Vancouver Island is home to a subpopulation of 200 Grey Whales – the summer residents. They like the abundance of tiny prey species such as mysids and amphipods. But grey whale prey are crustaceans – just like salmon lice – so they could become collateral damage in Cermaq’s chemical warfare. And Tofino whale watchers are very concerned, because since 2019, Grey Whales have been starving to death, which so far has resulted in at least 378 deaths.

Grey whales

Grey whales | Photo: ©Dan Lewis


A ticking viral bomb?

The Paramove treatments are stressful to farmed salmon, and weaken their immune systems. It can take up to two weeks for the fish to recover, during which period they are susceptible to disease outbreaks such as mouthrot and piscine orthoreovirus (PRV), and disease transfer from farmed to wild fish is dead easy.

Cermaq is spending millions of dollars on sea lice control, tumbling and pressure-washing their farmed fish in an attempt to dislodge the lice. They use Paramove 50 in wellboats to burn the lice off.

Because of their short life cycle, any lice which survive treatments (whether chemical or mechanical) are by definition resistant to the treatment used. Lice will adapt to anything we throw at them, and come back stronger.

The Clayoquot Sound UNESCO Biosphere Region is meant to demonstrate a working balance between conservation and sustainable development. Clearly, chemical treatments of sea lice are not sustainable. The world’s oceans are under incredible stress, and dumping pesticides in them will not help.

The federal government has promised to remove open-net pen salmon farms from the ocean by 2025. Indeed, in December 2020, eighteen fish farm licenses in the Discovery Islands were not renewed. All federal fish farm licenses in BC are set to expire in June 2022.

Wild salmon numbers in Clayoquot Sound are in precipitous decline – we are witnessing extinction play out before our eyes. Last year the Tofino hatchery was unable to collect Chinook eggs to rear – for the first time ever! If we lose wild salmon, we lose everything: ancestral forests, wildlife, and cultures. Why should we sacrifice food security, the wild salmon economy, and the iconic ecosystems of Clayoquot Sound to a sunset industry?

See: Escobar-Lux, R.H., Samuelsen, O.B. The Acute and Delayed Mortality of the Northern Krill (Meganyctiphanes norvegica) When Exposed to Hydrogen Peroxide. Bull Environ Contam Toxicol 105, 705–710 (2020).

Dan Lewis lives in Tofino and is a founding director of Clayoquot Action. Contact him at

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