A new study suggests that nearly 90 percent of dolphins in the Indian Ocean have been wiped out by the fishing industry.
The study, which was done by an international group of scientists, claims that nearly 90 percent of the animals have been wiped out by Industrial fishing since the year 1980.
In the study, it suggests that the extraordinary extermination is due to the widespread use of huge gillnets used to catch tuna.
Gillnets are walls of netting that are hung in the water column and are either allowed to drift from floating buoys or can be fixed in one place.
The illegal use of gillnets causes a lot of sea animals to be killed.
The size of the holes in the netting is designed so the tuna fish can only get their head through the netting and not their entire body.
As the fishes in the netting try to free themselves, the netting becomes tighter and tighter.
The nets are designed to target specific species, but smaller fishes can slip through the holes. The nets are made specifically for larger fish.
The nets cause death to sea animals such as sharks, sea lions, whales, dolphins, and even turtles.
Dr. Putu Mustika, from the James University in Australia, who was among the scientists working on the study, said, “We combined results from 10 bycatch sampling programmes between 1981 and 2016 in Australia, Sri Lanka, India and Pakistan to estimate bycatch rates for cetaceans (whales, dolphins and porpoises) across all Indian Ocean tuna gillnet fisheries.”
She added, “The vast majority of the cetacean bycatch is dolphins. Estimated cetacean bycatch peaked at almost 100,000 a year during 2004−2006, but has declined to 80,000 animals a year, despite an increase in the tuna gillnet fishing effort.”
The study indicated that the gillnets that have been deployed in the Indian Ocean have killed nearly 4.1 million small cetaceans between 1950 and 2018 as fishers pursued tuna.
Dr. Putu Mustika said the real numbers can be extremely higher as the available records and data do not take account of factors such as delayed mortality of cetaceans or their mortality that is associated with the nets that are lost at the sea.
Dr. Putu Mustika explained, “The declining cetacean bycatch rates shown by what we can measure suggest current mortality rates are not sustainable. The estimates we have developed show that average small cetacean abundance may currently be 13 per cent of the 1980 levels.”
The current ban of the United Nations on gillnets is hard to enforce as tuna fishers are allowed to use gillnets within the territorial waters of states that are bordering the ocean.
Dr. Putu Mustika said, “Cetacean bycatch in Indian Ocean tuna gillnet fisheries has been a concern for decades but has been poorly studied, reflecting the political reality that hundreds of thousands of relatively poor fishermen and their families rely on gillnet fisheries.”
The countries with the largest current gillnet catch of tuna and to have the largest cetacean bycatch are Iran, Indonesia, India, Sri Lanka, Pakistan, Oman, Yemen, UAE, and Tanzania.
Indonesia and Iran have no national monitoring of the cetacean bycatch.
The study was led by Dr. Charles Anderson, a professional at the Manta marine Organization in the Maldives.