LEAVE BIG FISH AT SEA TO CUT CARBON EMISSIONS: AUSSIE UNIVERSITY

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, Science Daily reported.

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 Gaël Mariani, a PhD student at the University of Montpellier in France.  Mariani led a world-first study showing how ocean fisheries have released at least 730 million metric tons (MT) 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 Center of Excellence for Coral Reef Studies at James Cook University (CoralCoE at JCU) in Townvill, Queensland, Australia 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."