Leaving more big fish in the sea reduces CO2 emissions


Share post:

An international team of scientists has found leaving more big fish in the sea reduces the amount of carbon dioxide (CO2) released into the Earth’s atmosphere.

Leaving more big fish in the sea reduces CO2 emissions
Leaving more big fish in the sea–especially where fishing is not economically profitable in the
Central Pacific, South Atlantic, and North Indian Oceans –reduces the amount of
carbon dioxide (CO2) released into the Earth’s atmosphere [Credit: Enric Sala]

When a fish dies in the ocean it sinks to the depths, sequestrating all the carbon it contains with it. This is a form of ‘blue carbon’–carbon captured and stored by the world’s ocean and coastal ecosystems.

“But when a fish is caught, the carbon it contains is partly emitted into the atmosphere as CO2 a few days or weeks after,” said Gael Mariani, a PhD student at the University of Montpellier in France.

Mr Mariani led a world-first study showing how ocean fisheries have released at least 730 million metric tons of CO2 into the atmosphere since 1950. An estimated 20.4 million metric tons of CO2 was emitted in 2014–equivalent to the annual emissions of 4.5 million cars.

Co-author Professor David Mouillot from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (CoralCoE at JCU) and the University of Montpellier said the carbon footprint of fisheries is 25 percent higher than previous industry estimates.

“Fishing boats produce greenhouse gases by consuming fuel,” Prof Mouillot said. “And now we know that extracting fish releases additional CO2 that would otherwise remain captive in the ocean.”

Large fish such as tuna, sharks, mackerel and swordfish are about 10 to 15 percent carbon.

“When these fish die, they sink rapidly,” Prof Mouillot said. “As a result, most of the carbon they contain is sequestered at the bottom of the sea for thousands or even millions of years. They are therefore carbon sinks–the size of which has never been estimated before.”

He says this natural phenomenon–a blue carbon pump–has been increasingly and greatly disrupted by industrial fishing.

The authors also say the phenomenon has not only been overlooked until now, but it happens in areas where fishing is not economically profitable: in the Central Pacific, South Atlantic, and North Indian Oceans.

“Fishing boats sometimes go to very remote areas–with enormous fuel consumption–even though the fish caught in these areas are not profitable and fishing is only viable thanks to subsidies,” Mr Mariani said.

For the authors of the study, the new data strongly supports more reasoned fishing.

“The annihilation of the blue carbon pump represented by large fish suggests new protection and management measures must be put in place, so that more large fish can remain a carbon sink and no longer become an additional CO2 source,” Mr Mariani said. “And in doing so we further reduce CO2 emissions by burning less fuel.”

“We need to fish better,” Prof Mouillot said.

The study is published in Science Advances.

Source: ARC Centre of Excellence for Coral Reef Studies [October 28, 2020]

Support The Archaeology News Network with a small donation!



Related articles

Caribbean bats need 8 million years to recover from recent extinction waves

It will take at least eight million years to restore species recently lost to extinction, according to research...

Research reveals the scale at which Earth’s mantle composition varies

New research by Brown University geochemists provides new insights on the scale at which Earth's mantle varies in...

Earth’s magnetic field is not about to reverse

A study of the most recent near-reversals of the Earth's magnetic field by an international team of researchers,...

Explosion in number of known life forms

A remarkable effort from University of Queensland researchers has helped increase the number of known genomes by almost...

New findings explain synchronous deglaciation that occurred 17,700 years ago

New findings published in the Proceedings of the National Academy of Sciences by Desert Research Institute (DRI) Professor...

Native biodiversity collapse in the Eastern Mediterranean

The coastline of Israel is one of the warmest areas in the Mediterranean Sea. Here, most marine species...

Ancient humans impact African island environment

Humanity's impact on the environment is often framed in the context of the post-industrial era but new archaeological...

The moon controls the release of methane in Arctic Ocean

It may not be very well known, but the Arctic Ocean leaks enormous amounts of the potent greenhouse...