What is Bottom Trawling?

Bottom trawling, which involves dragging weighted nets along the seafloor to capture groundfish and other marine life, has been used on the BC Coast for many years. Trawling allows fishers to catch large quantities of fish in relatively short amounts of time but has negative environmental impacts, including damaging delicate habitats, disrupting ecosystems by overfishing groundfish, reducing biodiversity, and unacceptably high bycatch. In British Columbia, the average annual bottom trawling catch is 38,500 tonnes, which includes groundfish and shrimp. This is unstainable and puts immense pressure on marine ecosystems.

Bottom trawling results in non-targeted species, called bycatch, being caught in the crossfire and discarded overboard, where the vast majority of them will die. Many groundfish, for instance, die due to the expansion of their swim bladders when they are removed from the water. Photo credit: Pacific Wild

The Damage Caused by Bottom Trawling in British Columbia

23% of the bottom trawling catch is bycatch, which is thrown back into the ocean. A significant amount of bycatch does not survive. Bycatch also includes protected species. Dragging the ocean floor causes severe damage to marine habitats; in British Columbia, bottom trawling has destroyed 50% of unique ancient glass sponge reefs, which also contributes to the release of more than one billion tonnes of carbon dioxide caused by bottom trawling globally.

Ocean floor destroyed after bottom trawling
According to a 2021 study, the practice of dragging is capable of releasing as much carbon dioxide as the entire aviation industry. Carbon is released from seabed sediment into the water, potentially increasing acidification. Photo credit: Howard Wood/2015 Goldman Environmental Prize

A report by Fauna & Flora International highlighted that at least 1.1 million square-kilometres of seabed globally is exposed to at least one pass of a trawl every year. Delicate habitats (such as the cold-water coral reefs we have in BC) are more vulnerable to negative impacts from dragging than other kinds of habitats like sandy plains. When damaged, reefs recover extremely slowly or not at all, with effects lasting well over 100 years.

Neighbouring Alaska recently experienced the impact that bottom trawl activities can have on crabs.

In 2022, the sudden cancellation of the snow crab harvest in Alaska’s coastal waters caused an estimated US$290 million in economic damages and triggered calls for the issuance of an emergency declaration.

While acknowledging other factors like climate change, Alaskan crabbers also pointed fingers at dragging companies for destroying underwater habitats, potentially directly impacting crab populations.

The situation is dire in Alaska, where estimates put trawler bycatch waste at 141,000,000 lbs per year. This bycatch includes significant populations of salmon, halibut, herring, and crab species, many of which are considered endangered, threatened, or of special concern. Photo credit: Ken Pardy on Facebook

The issue is not just that specific species will collapse. If even one species in our waters experiences drastic population declines, it could adversely affect the entire marine ecosystem. The result of this will be a marine desert, and local economies that rely on marine resources will suffer.

Bottom trawling in the United Kingdom: What British Columbia should not do

Bottom trawling in the United Kingdom has been an unmitigated disaster. A disturbing study has found that bottom trawling has taken place in 98% of the United Kingdom marine protected areas (MPA), with many protected areas showing complete surface area trawling. Dr. Jean-Luc Solandt, principal specialist in MPAs at the Marine Conservation Society in the UK, says the research demonstrates that MPAs in the UK are failing to safeguard marine habitats. Nick Underdown, head of campaigns at Open Seas, argues that the Scottish government’s claim that MPAs are protecting 30% of Scottish oceans is bluewashing.

“While bottom-trawling is still allowed, we will continue to release more carbon from the seafloor and prevent complex carbon-storing habitats from recovering.”

Dr Jean-Luc Solandt, principal specialist in marine protected areas at the Marine Conservation Society

Nick Underdown, head of campaigns at Open Seas, argues that the Scottish government’s claim that marine protected areas are protecting 30% of Scottish oceans is bluewashing. In the UK, many of the MPAs are “paper parks”, which researcher Michael Slezak defined as an established MPA on paper that, in reality, lacks sufficient management and enforcement for it to achieve its conservation goals effectively. According to Slezak’s research in 2014, only 24% of the world’s MPAs have sound management.

“Paper designations are worse than useless, because they give the illusion of protection when the health of Scotland’s seas is deteriorating.”

Nick Underdown, head of campaigns at Open Seas

How Can We Control or Reverse the Impacts of Dragging?

As of 2022, there are 129 active trawl licenses in BC. Vessels are usually on the water from early spring until late summer, spending roughly 30,000 to 40,000 hours on the water every year. Image credit: The Book Worm on Alamy Stock Photo

Fortunately, in British Columbia, the situation is not as dire. While bottom trawling has caused significant damage to BC’s marine ecosystems, there are currently closed zones on the BC coast established to protect ancient glass sponge reefs. However, enhanced protection from bottom trawling on the BC coast will only come with establishing the Great Bear Sea Marine Protected Area Network. The UK example indicates that the Great Bear Sea MPA Network needs to be committed to robust protection measures and enforcement, which comes from solid management. While government involvement is going to be important, it is equally critical to engage coastal communities. With their on-the-ground (or rather, on-the-water) expertise and vested interest in maintaining the longevity of coastal resources, they will play a significant role in ensuring that the goals of the MPA network are met. Ultimately, the success of the MPA network will be measured not just in terms of its protection of marine resources, but also in its ability to uplift coastal economies.



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