In Deep Trouble

Bottom trawling is known to be one of the most destructive and wasteful fishing techniques in the world. Dragging large weighted nets along the seafloor, bottom trawling wipes out vulnerable fish stocks, destroys habitats, and disrupts food chains.

What is trawling?

Trawling is an indiscriminate and non-selective  fishing technique in which large nets are towed behind fishing vessels, capturing everything in their path. Bottom trawling in particular involves dragging a large, weighted net along the seafloor, carving deep manmade highways through sensitive ecosystems and destroying already endangered coral and sponge reefs. In their wake, bottom trawl nets leave gaping ecological scars that may take decades to heal. Research suggests that trawling generates the most waste of any fishing method because the unwanted catch is dumped back into the ocean.

Many Canadians would be appalled to know that, globally, 437 million tonnes of fish ($560 billion in revenue) is wasted due to destructive fishing operations. Canada is a significant contributor to this global problem as  commercial mid-water and bottom trawl vessels bulldoze through our oceans.



As these large nets are dragged through the water column, or along the seafloor,  a wide variety of marine species are captured along with targeted fish. 

Non-target and undersized fish, sometimes endangered species,  that are pulled up in trawl netsare called bycatch and are routinely discarded overboard. This discarded dead, or dying bycatch is not just composed of fish, but invertebrates,  sharks and occasionally marine mammals.  On average, 23% of the reported fish and other marine species caught in trawl nets is thrown away as bycatch. 

The cumulative effects of trawling are summed up by Collie et al.’s  literature review that estimates that a single tow causes an average 55% reduction in abundance of animals in the trawled area. When specific species are considered, trawling is estimated to lead to upwards of 68% reduction in abundance of  invertebrate species.

The issue of bycatch is just  one example of how incongruent this fishery is with the sustainability of coastal communities and ocean prosperity. Coastal communities, in particularFirst Nations, have been fighting for the protection of herring, eulachon, rockfish, salmon and halibut for years. Many of these efforts have made great strides to protect these economically and culturally significant species inshore, while at the same time these same species are caught offshore by trawlers in the countless tonnes and thrown overboard, wasted as bycatch.s

55% of Canadians Believe trawling is Not allowed in Canadian waters, yet it is.

The Public’s Opinion & Views on Trawling

Trawling for Truth

Because trawling takes place in a largely out-of-sight out-of-mind way, Pacific Wild sought to understand how much the Canadian and British Columbia public knew about this industrial fishing practice. In June 2022, we commissioned an independent polling company, Research Co., to structure a series of questions that would gather preliminary data on public opinion regarding the bottom trawl fishery in B.C. This technical blog explores the results.

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Climate Change

The environmental impacts of the trawling industry stretches far beyond Canadian waters.  Bottom trawling is responsible for releasing more than one billion tonnes of carbon dioxide a year by disrupting carbon stored in the seafloor.  Preliminary research suggests that the global bottom trawling fleet releases an estimated 0.58 to 1.47 gigatons of CO2 each year purely through the disruption of ocean sediments — an equivalent or greater amount of annual CO2 emissions than the entire aviation industry.  Furthermore, trawling is also fuel intensive, consuming the greatest amount of fossil fuel per unit of fish landed of any fishing method. 

Despite the climate consequences of trawling, there is little to  no publicly available information on the effects of trawling on the climate in Canada, nor is it clear whether the government intends to research the industry’s total carbon footprint.  Turning a blind eye to  the climate consequences of trawling does not fulfill the letter or the spirit and intent of international agreements signed by Canada to be a climate leader. 

Ethics and observer program

On-board observers have been placed on board and tasked with monitoring the species, bycatch, collecting data for DFO and holding trawlers accountable for the behaviour on the high seas.  However, the observer program has been heavily scrutinized for its’ efficacy and ethics, with whistle blowers detailing accounts of sexual harassment, intimidation, harassment, and bribes, forcing observers to grossly under-report their findings or look the other way when infractions occur.  When COVID-19 swept the globe, the on-board observer program was put on hold, yet trawling never ceased operation. Human eyes were hastily replaced with electronic monitoring systems. Despite the alarming  red-flags in the on-board observer program, nothing can replace first hand observations from human eyes. Today in  2023, on-board observers are still largely absent from trawl vessels; meanwhile a DFO enforcement report details several hundred  violations aboard the 34 active trawling vessels in the 2022 fishing season until November 7, 2022. 

As trawling occurs offshore, far from the eye of fisheries managers the actual number and magnitude of violations is likely higher that what was observed and reported. In full knowledge of these violations, and with numerous additional active investigations underway,  the Canadian government is currently providing grants for further electronic monitoring equipment and the development of AI to monitor the fishery at sea  instead of phasing out this destructive fishing practice. 

MoviNG Forward

While we believe that an eventual ban of bottom trawling is necessary, we also understand that it is not that simple. Bottom trawling involves millions of dollars, generations of families, government subsidies and endless bureaucracy.

The paper ‘Dragnetting Coastal Communities‘ looks at the economic and political inequality in the B.C. trawling industry, and the problematic absence of transparency shielding the true ecological harm created by this fishing technique from public scrutiny and accountability. A significant increase in transparency is a fundamental component needed for policy changes.

Working towards evidence-based solutions and fisheries management that supports ecosystem-based management is the key to supporting communities and government through enacting these changes. Canada should look to other nations who have proactively taken steps to ban trawling, or at the very least, bottom trawling from their oceans.

The B.C. trawl fishery is operating along the very same waters, managed by the very same governmental structures that managed whales into oblivion, basking sharks to near extinction, and sea otters to extirpation. Yet somehow the end result is expected to be different. Right now factory trawlers are dragging the bottom of the continental shelf bulldozing the ocean floor, akin to bulldozing the rainforest for a few commercial species.

We urge the newly elected government to implement effective environmental protection strategies and fisheries management practices that are environmentally and socially beneficial. Stay tuned for more ways you can get involved and push for more sustainable fisheries.

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