Bottom trawling is the practice of dragging enormous nets across the ocean floor to catch shrimp, cod, whiting, and other fish. A new preliminary study reveals the procedure emits as much planet-warming carbon as global aviation releases into the air.
Therefore, cutting down on this form of fishing by strategically conserving some marine areas would safeguard imperiled species and sequester monumental amounts of CO2. The scientists said that conservation efforts should protect strategic zones from other forms of fishing, mining, and drilling too. Like this, the overall fish catch will rise, providing more healthy protein to people.
Marine biologist Dr. Enric Sala, who led the study team of 26 climate scientists, biologists, and economists and who directs National Geographic’s Pristine Seas project, said:
It’s a triple win.
No-fishing zones would be regions that serve as nurseries, replenishing crustacean and fish populations which then discharge beyond the protected areas. The research found that 28% of the ocean would have to be protected to maximize fish catch. At the moment, only 7% of the ocean is protected, and under 3% is highly protected.
A separate study in California found this strategy to be effective. The researchers had the fishing grounds for California spiny lobster reduced by 35%, which resulted in a 225% overall increase in catch after six years.
Dr. Sala said:
The worst enemy of fishing and food security is overfishing.
Every year, bottom trawlers scrape about 1.9 million square miles of the seafloor. This releases carbon stores that, if left undisturbed, would have remained on the floor for tens of thousands of years. The carbon released gives rise to more acidic water, reducing the ocean’s capacity to absorb atmospheric CO2 and threatening marine life.
Dr. Sala recalled, describing the video call when his colleagues revealed the amount of emissions:
I could not believe it. Immediately I went to Google and checked the global emissions by sector and by country, and said, ‘Wow, this is larger than Germany’s.’
Russia, China, Italy, Denmark, and the United Kingdom are the world leaders in trawling emissions.
Aquatic ecologist Dr. Trisha Atwood, a researcher at Utah State University who was one of the study’s authors, likened trawling to deforestation for agriculture. She said:
It’s wiping out biodiversity; it’s wiping out things like deep-sea corals that take hundreds of years to grow. This study shows that it also has this other kind of unknown impact, which is that it creates a lot of CO2. I can tell you that the results are troubling.
The team recommends an international initiative to safeguard at least 30% of the planet’s lands and waters by 2030, a project that’s known as 30×30.
The peer-reviewed report offers an interactive roadmap for how countries can confront the interconnected crisis of wildlife collapse at sea and climate change. It follows a similar study focused on protecting land. Both are intended to inform a global agreement on biodiversity to be negotiated in Kunming, China, this autumn.
Furthermore, they stress that neither conservation measures nor transitioning away from fossil fuels alone will work – they need to happen in conjunction.
