[ad_1]
Of: TT
Published:
Photo: Itsuo Inouye / TT
When tuna die in the sea, they sink to the bottom and act as a natural carbon sink. Stock Photography.
Large fish in the sea have a hitherto unnoticed ability to remove carbon dioxide from the atmosphere, if allowed to die naturally. But this old cycle has been broken by the fishing industry, a new study shows.
When large fish, such as tuna, mackerel, and swordfish, die a natural death in the sea, they quickly sink to the bottom. The amount of carbon that they have bonded during their lifetime will be stored in sediment for thousands or even millions of years, depending on the depth.
“But if fish are caught, this carbon will be released in the form of carbon dioxide into the atmosphere after a few days or weeks,” Gaël Mariani, a researcher at the University of Montpellier in France, said in a press release.
Just over 700 million tons
Together with French and American colleagues, he has calculated to what extent the fishing industry has influenced this ancient cycle. They have only included fish larger than 30 centimeters, which have been caught in deep water areas.
Their results, published in the journal Nature, show that this capture since 1950 corresponds to emissions of almost 140 million tons of carbon dioxide, which otherwise would have been stored on the seabed for a long time. If fuel from fishing boats is also included, emissions will rise to just over 700 million tons of carbon dioxide.
Since 1950, total emissions have increased tenfold, so that they are now around 24 million tons per year. This corresponds to about half of Sweden’s annual net greenhouse gas emissions.
“Blue coal bomb”
The study shows that just over half of this fish catch has been made and takes place in areas where fishing would not have been profitable without the subsidies.
The researchers note that although the role of fish as a carbon sink is significantly smaller than that of other natural carbon sinks, such as the world’s mangroves and seagrass beds, it is an important part to consider.
“This ‘blue carbon pump’ disturbance needs to be adjusted so that large fish can go back to being a carbon sink rather than an additional source of carbon dioxide. We need to fish better, “said Professor David Mouillot, Gaël Mariani’s partner.
Published:
