How Fishing May Contribute to Climate Change

From coral bleaching to ocean acidification, there is lots of discussion about how the climate crisis harms marine life. But is it possible that the loss of undersea animals could actually worsen the impacts of climate change?

A study published in Science Advances last year found that the amount of carbon sequestered as fish dung in the ocean had declined by nearly half since commercial fishing began in earnest a little more than a century ago.

“It’s sort of demonstrating that fish matter for the big carbon cycle in the ocean and other biogeochemical cycles,” study lead author and University of California, Los Angeles oceanographer Daniele Bianchi told EcoWatch.

The carbon cycle describes how carbon travels from the atmosphere to plants to animals and the soil and back into the atmosphere when animals exhale (or when humans burn fossil fuels), according to the University Corporation for Atmospheric Research. In the oceans, a similar process occurs with phytoplankton, which convert carbon dioxide into the sugars that form the basis of the marine food web, according to the Woods Hole Oceanographic Institute. This carbon ends up sequestered in the deep ocean or the seafloor when animals die and sink.

Carbon dioxide is also traded back and forth between surface water and the air. However, when considering the living drivers of this and other biochemical processes in the ocean, scientists have largely looked at phytoplankton or bacteria rather than animals like fish, Bianchi said. This study marks “the first time that I think someone [has tried] to do these calculations and show that biological processes that have to do with animals in the ocean matter for these chemical processes,” he said.

Lead Image: Atlantic bluefin tuna in a net. Antonio Busiello / Moment / Getty Images.

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