Bottom trawling is harmful to both the ocean and the climate. •

Bottom trawling is harmful to both the ocean and the climate.  •

In an alarming study released today, scientists focused on a previously overlooked factor in climate change: bottom trawling.

This fishing practice, which involves dragging huge nets across the ocean floor, not only destroys marine life and marine habitats, but also contributes significantly to carbon emissions into the atmosphere.

Bottom trawling and carbonation on the ocean floor

The study, conducted by a global team from institutions including Utah State University, NASA’s Goddard Institute for Space Studies, and National Geographic Pristine Seas, reveals a startling fact.

Between 55% and 60% of the carbon dioxide produced by underwater trawling eventually reaches the atmosphere within nine years.

This revelation is crucial at a time when the world is struggling to reduce emissions from known sources such as fossil fuels and deforestation.

“We’ve known for a long time that dragging heavy fishing nets — some as large as ten 747 planes — across the ocean floor destroys marine life and habitats,” said Dr. Trisha Atwood of Utah State University and National Geographic Pristine Seas.

“We recently discovered that bottom trawling also unleashes plumes of carbon, which would otherwise be safely stored for thousands of years on the ocean floor,” Atwood said.

Surprising extent of bottom trawling emissions

The scale of carbon emissions from bottom trawling is alarming. Annually, it leads to a doubling of emissions resulting from the combustion of fuel in the global fishing fleet, which includes about 4 million vessels.

“Our study is the first to show that more than half of the carbon released by bottom trawling eventually escapes into the atmosphere as carbon dioxide over a period of about ten years, contributing to global warming,” Atwood explains. As with the destruction of forests, seabed dredging causes irreparable damage to climate, society and wildlife.

The study, “Atmospheric carbon dioxide emissions and ocean acidification from bottom trawling,” used advanced data and models to track trawling activities globally from 1996 to 2020.

The University of California Santa Barbara, Columbia University, and James Cook University also contributed to this important research.

The results represent a big leap from previous research, suggesting that the carbon dioxide released into the ocean from this practice is similar to the annual emissions of most countries and similar to emissions from global aviation.

Identify high-risk areas

Particularly affected areas include the East China Sea, Baltic Sea, North Sea and Greenland Sea. There is also concern over Southeast Asia, the Bay of Bengal, the Arabian Sea, parts of Europe, and the Gulf of Mexico.

However, limited data in these areas hinder a comprehensive understanding of the full impact.

“Currently, countries are not taking into account the significant carbon emissions from bottom trawling in their climate action plans,” said Dr. Enrique Sala, National Explorer-in-Residence and Executive Director of Pristine Seas.

“Our research shows that addressing these and other ocean emissions is critical to slowing the planet’s warming, as well as restoring marine life,” Sala continued.

“The good news is that reducing carbon emissions from bottom trawling will deliver immediate benefits. The bad news is that delaying action ensures that emissions from bottom trawling will still leak into the atmosphere a decade from now.”

Interestingly, the study also looks at the fate of carbon that remains in ocean waters after trawling. The results indicate that 40%-45% of this carbon remains in the water, exacerbating local ocean acidification and harming plant and animal life.

Gavin A said: “There are more issues with bottom trawling than just carbon impacts — biodiversity and sustainability, for example,” said Schmidt, director of NASA’s Goddard Institute for Space Studies.

“But this marine deforestation is large enough to be observed and evaluated. Hopefully, this will lead to policy efforts that can try to maximize the benefits across all impacts.”

In sum, this alarming study highlights the hidden impact of bottom trawling on climate change and calls for immediate policy action to mitigate its impacts.

By addressing this neglected issue, there is the potential to make great strides in protecting our oceans and combating global warming.

More about bottom trawling

As discussed above, bottom trawling involves dragging heavy nets across the sea floor, randomly catching everything in its path and causing untold damage.

Mechanics of bottom trawling

Fishermen use bottom trawls to catch a variety of marine creatures. These large nets, weighed down by heavy equipment, scrape along the ocean floor, capturing fish, plants and other marine life.

This method is effective for mass fishing but lacks discrimination, capturing target species and a large amount of bycatch – unwanted marine life.

Environmental impact

The environmental impact of bottom trawling is profound. It destroys complex seafloor habitats, which are home to countless creatures, and upsets the ecological balance.

Coral reefs, which take centuries to form, can be destroyed in a matter of minutes. This destruction leads to the loss of biodiversity, with long-term consequences for marine ecosystems and the fisheries that depend on them.

In addition, recent studies, such as those discussed earlier in this article, have highlighted a troubling aspect of bottom trawling: its contribution to carbon emissions.

Disturbing the seafloor releases carbon stored in ocean floor sediments, dramatically increasing atmospheric carbon dioxide levels. This aspect of bottom trawling contributes to climate change, a threat that extends far beyond the oceans.

An urgent call for change

The global community has become increasingly aware of the need to address bottom trawling.

Conservationists and scientists are calling for stricter regulations, protection of marine areas where trawling is prohibited, and adoption of more sustainable fishing practices.

The goal is to balance the needs of the fishing industry with the urgent need to protect and conserve our ocean environments.

In sum, bottom trawling poses a critical environmental challenge. It depletes fish stocks and destroys marine habitats while also contributing to the broader climate change issue by emitting a huge amount of carbon into the atmosphere.

It is time to act to ensure the health and sustainability of our oceans for future generations.

The full study was published in the journal Frontiers in marine science.


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