Researchers have cautioned that existing levels of tuna fishing are unsustainable after scientists discovered that global catches have risen over 1,000% in the past 60 years.
A study in the journal Fisheries Research evaluated that 6m tonnes amounts of tuna are caught every year, a rate that "risks driving tuna populations to unsustainable levels and possible extinction".
“Tuna fisheries have expanded into every region that we can exploit. There are no new fishing grounds to explore and we are catching fish at the highest rate we can,” said Angie Coulter, a researcher with the Sea Around Us initiative at the University of British Columbia.
The international study is the first to estimate the volume of tuna removed from the sea, where the fish are being gotten and the measure of bycatch – tuna got unintentionally and discarded into the ocean.
Booming demand for tinned fish since the second world war has fuelled a second extension of modern fisheries, the examination said. The scientists pointed out that technological advances, for example, mechanization and refrigeration have tremendously expanded the ability to fish, driving gigantic overfishing.
The decline of tuna populations could threaten food supply chains and employment around the globe, just as conceivably destabilizing the submerged food web, Coulter said. “Tuna are both predators and prey. They eat smaller fish and invertebrates and are a food source for larger marine life, such as sharks and whales."
“If we lose tuna due to overexploitation, we break those links in the food web and disrupt the function of the ecosystem. This means that the survival of other species in the ecosystem is also threatened,” she said.
Specialists found that 67% of the world's tuna catches are made in the Pacific Ocean by Japanese and American fleets, 12% in the Indian Ocean, and 12% in the Atlantic. The investigation estimated that, between 1950 and 2016, 5.7m huge amounts of bycatch from various shark species were discarded in the Pacific Ocean alone.
Tuna fishing has hugely influenced shark populations: 23% of "other" fish got accidentally during tuna fishing were blue sharks.
“Unlike tuna, sharks take many years to mature and do not produce many offspring,” said Coulter. “This makes their populations particularly vulnerable to these fishing pressures. And the worst part is that many of these sharks are not brought to land so their meat can be used as food. They have their fins removed and [are] sold in shark fin markets, or are simply thrown overboard as discards.”