Fishing by Dragging Nets Over the Ocean Floor Releases as Much Carbon as Air Travel: Report
Bottom trawling, a method of fishing that involves dragging heavy nets across the ocean floor, releases as much carbon dioxide into the environment as the whole aviation industry, concludes a new report published in Nature journal Wednesday.
The seabed is the planet’s largest carbon sink and disrupting it can increase ocean acidification and endanger oceanic biodiversity, noted the groundbreaking study. The report, authored by 26 marine biologists, climate experts, and economists, calls for protections to be placed on strategic sea areas to yield the most climate, seafood, and biodiversity benefits. Currently, only 7% of the world’s oceans have some kind of protected status; the report calls for extending protection to 30% of the Earth’s seas. That percentage coincides with the 2030 target set by a 50-country cooperative earlier this year.
“Ocean life has been declining worldwide because of overfishing, habitat destruction, and climate change,” Enric Sala, Ph.D., explorer-in-residence at the National Geographic Society and lead author of the report, told The Guardian. “In this study, we’ve pioneered a new way to identify the places that – if strongly protected – will boost food production and safeguard marine life, all while reducing carbon emissions.”
China, Croatia, Denmark, France, Italy, the Netherlands, Norway, Russia, Spain, and the U.K., are among the biggest sources of carbon emissions from trawling.
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While India does not feature on the list, trawling is an established component of its fishing industry, accounting for roughly 50% of the country’s marine fishery production. However, efforts have been made to reign it in, in recent years, not so much from an emissions perspective but to manage overfishing. Trawlers use fine mesh nets to scrape up all life off the seafloor, often including juvenile fish and eggs. Annual trawling bans have become a norm for some states where the fishing industry is centered; Goa, Karnataka, Kerala, Odisha, and Tamil Nadu, for instance, all impose annual moratoria on trawling that range from 47 to 90 days during the monsoon, to allow coastal fish stocks time to replenish.
In 2019, the Centre started the slow process of regulating trawling at a wider scale.
“It was agreed that there is a need to reduce the number of trawlers for two main reasons. One that there is excess catch and two to reduce the damage on the ocean bed and to the ecology that bottom trawlers cause,” director of the Bay of Bengal Programme Inter-Governmental Organisation, Yugraj Yadava, told Mongabay at the time.
However, around the same time, China increased its trawling in the southern Indian Ocean, raising environmental concerns for India.
The new report makes trawling — and ocean protection — a global concern that calls for coordinated effort beyond any country’s individual regulation. And it may not take much — protecting just 4% of the ocean at strategic locations would cut trawling’s carbon emissions by 90%, the report concludes.
As report co-author Juan S. Mayorga, Ph.D., a marine data scientist with the Environmental Market Solutions Lab at the University of California, Santa Barbara, and with Pristine Seas at the National Geographic Society, told The Guardian: “The solution depends on what society – or a given country – cares about, and our study provides a new way to integrate these preferences and find effective conservation strategies.”