Bottom Trawling Fishing Gear Releases Huge Amounts of Carbon From Sea Floor

Graphic: Annabel Driussi for Our Daily Planet

By Ashira Morris, ODP Staff Writer

The ocean floor stores a massive amount of carbon, and when fishing boats drag heavy nets across it, that releases as much carbon as the entire aviation industry, according to a new study by 26 marine biologists. Right now, a measly 7% of the ocean is protected, and even within parts of the ocean that are marine protected areas, bottom trawling is still happening.

“The ocean covers 70% of the earth—yet, until now, its importance for solving the challenges of our time has been overlooked,” said Dr. Boris Worm, a study co-author and Killam Research Professor at Dalhousie University in Halifax, Nova Scotia. 

Why this Matters: Bottom trawling is harmful beyond its carbon impact. It’s like clear-cutting a forest underwater, knocking down the slow-growing natural structures like fragile deepwater corals that support life. Trawling is often used to catch shrimp, Atlantic cod, and other fish, but it inevitably ensnares lots of other marine life. The massive nets are extremely indiscriminate in what they catch and scoop up sea turtles, marine mammals, and baby fish too young to bring to market. We need to protect 30% of the ocean in the next decade and ensure that much more of the ocean is truly protected and in particular, not disturbed by bottom trawling. 

Protected Areas Mean More Fish: In order to protect our fishing communities, countries need to set aside protected areas for the fish to spawn and grow. There’s strong evidence that creating areas where fishing isn’t allowed means more fish where it is, called the “spillover effect.” Last year, a study found that the catch of California spiny lobster increased by 225% after the fishing boundaries for the crustacean were reduced by about a third for six years. 

The report, titled “Protecting the global ocean for biodiversity, food and climate,” puts an emphasis on the solution: it provides a framework for countries to prioritize marine areas for protection. Right now, a measly 7% of the ocean is protected, and even within parts of the ocean that are marine protected areas on paper, bottom trawling is still happening

In order to keep the planet habitable, we need to protect 30% of the ocean in the next decade. Establishing parts of the ocean that are truly protected — not disturbed by bottom trawling and other destructive human activity like mining and oil drilling — has the triple benefit of:

  • safeguarding biodiversity
  • mitigating climate change and
  • boosting fish populations beyond the protected area’s boundaries. 

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