Tag Archives: trawlers

Ocean trawling doesn’t just destroy ecosystems. It also releases massive emissions

Ocean trawling, a fishing method that involves dragging heavy nets across the seafloor to catch seafood, generates as much carbon as the entire aviation industry, a new study finds. The practice has been repeatedly condemned by environmental groups for destroying ecosystems and depleting fish populations but continues to be widespread

Image credit: Flickr / Will-travel

Marine sediments are the largest pool of organic carbon on the planet and a crucial reservoir for long-term storage. If left undisturbed, organic carbon can remain there for millennia. They’re also essential for marine wildlife. However, disturbance of these carbon stores can reactivate sedimentary carbon to CO2 — which can then increase ocean acidification and add to the build-up of atmospheric CO2.

“The ocean floor is the world’s largest carbon storehouse. If we’re to succeed in stopping global warming, we must leave the carbon-rich seabed undisturbed,” Trisha Atwood of Utah State University, a co-author of the paper, told AFP. “Yet every day, we are trawling the seafloor, depleting its biodiversity and mobilizing millennia-old carbon and thus exacerbating climate change.”

Atwood and a group of US researchers found that ocean trawling is responsible for between 0.6 and 1.5 gigatons of carbon emissions a year, compared with the aviation industry’s emissions of close to one gigaton. Most of this pollution happens in less than 4% of the ocean, specifically in the sovereign fishing waters of countries, known as Exclusive Economic Zones (EEZ).

This is the good news in a sense, because it means that the practice could be stopped much easier than if it were in international waters — which are often a sort of no man’s land where enforcing rules is difficult.

Trawling carried out by boats in Chinese EZZ generates the largest volume of emissions or about 770 million metric tons of CO2, the study found, followed by Russia, Italy, UK, Denmark, France, the Netherlands, Norway, Croatia, and Spain. Since most trawling occurs within countries’ waters, governments could halt the practice, the researchers argued

To figure out the numbers, the researchers reviewed mining records and other data to compile a map of the carbon stored in seabeds globally. Then they overlaid the map with data from the NGO Global Fishing Watch, showing where trawlers were active. Finally, they modeled the emissions released when carbon-rich sediment is disturbed by the vessels.

But the massive number of emissions from trawling isn’t the only impressive finding. The researchers found that an area isn’t depleted of carbon after being trawled once. Emissions are still released for up to 400 years at a rate of 40% of the initial year’s emissions as new layers of sediments are disrupted. For Atwood, this was “the extremely shocking part” of the study.

The researchers suggested countries start documenting these ocean emissions along with land-based emissions in their greenhouse gas inventories. This would help hold the trawling industry accountable, just as the electricity and the transportation industries are targeted for emissions reductions. This should be accompanied by a global agreement to protect further areas of the ocean, they argued.

Campaigners have proposed to preserve 30% of the ocean by 2030, a target the researchers support and encourage. To stop 90% of the seabed emissions from trawling, only 3.6% of the ocean would need to be protected, according to the study. Now 2.7% of the ocean is fully or highly protected, meaning that no fishing, mining, or habitat destruction is allowed there.

The study was published in the journal Nature.

Deep-water fishery makes a comeback in a rare conservation success story

Successful environmental stories are something rare to find, especially during the current climate crisis. But there is one happening on the west coast of the United States that is worth telling.

Two decades after authorities banned their work in large parts of the Pacific Ocean due to species’ depletion, bottom trawler fishermen – those who fish deep-dwelling fish such as bocaccio using nets – are returning by reinventing themselves in a sustainable way.

On January 1st, authorities will reopen a fishing area three times the size of Rhode Island near Oregon and California. Groundfish bottom trawling will again be authorized to work, even with the approval of environmental groups that used to question the activity.

The success story comes after a long collaboration between fishermen and environmental groups. They developed a long-term plan that will allow the groundfish industry to make a comeback, while also protecting large areas of reefs and coral beds that benefit the overfished species.

“It’s really a conservation home run,” said Shems Jud, regional director for the Environmental Defense Fund’s ocean program. “The recovery is decades ahead of schedule. It’s the biggest environmental story that no one knows about.”

The initiative was also celebrated by conservationists focused on the deep-water habitats, an area now not explored by bottom trawlers. According to the agreement between fishermen and environmentalists, there will be an area of the ocean 3.4km deep that will be off-limits to bottom trawling.

“Not all fishermen are rapers of the environment. When you hear the word ‘trawler’, very often that’s associated with the destruction of the sea and pillaging,” said Kevin Dunn, whose trawler Iron Lady was featured in a Whole Foods television commercial about sustainable fishing.

Groundfish refers to dozens of species that live on or near the bottom of the Pacific. Vessels use weighted nets to get as many fish as possible, but by doing so they can harm underwater habitat. Since the 1990s, scientists have been warning over the reduction of fish stocks, with nine of the more than 90 groundfish species in trouble.

Regulators soon took action, assigning quotes to trawlers on the amount of each species they could catch. Fishermen learn which areas to avoid and started innovating to net fewer banned fish. Surveys showed a rebound in groundfish and an 80% decline in accidental trawling of overfished species.

The success of the quota system led to revived conversations between environmentalists and trawlers, as regulators were due to revisit the trawling rules. The two groups met more than 30 times and started working on a proposal, sharing information and knowledge.

This led to a plan being approved last year by regulators to reopen the Rockfish Conservation area near Oregon and California and ban future trawling in extreme-depth waters, also making off-limits certain habitats that are considered essential for fish reproduction.

“A fair number of fishermen thought it was a good deal and if it was going to happen, it was better for them to participate than not,” said Tom Libby, a fish processor who played a big role in the agreement. “It’s right up there with the best and most rewarding things in my career – and I’ve been at it 50 years.“

The fishermen will now have to work to increase consumer demand for a fish that hasn’t been available in grocery stores and restaurant menus for a generation. They will be able to harvest as much as 54 million kilograms per year, according to the new scheme.