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Dolphin population in Halda on decline

  • Nur Uddin Alamgir
  • 5 October, 2021 12:00 AM
  • Print news

CHATTOGRAM: The number of freshwater dolphins is decreasing gradually in the Halda River, the lone natural fish spawning centre of the country.

The number of the amazingly intelligent mammal is decreasing mostly due to the manmade reasons.

Halda Researcher Professor Dr Manzoorul Kibria of Chattogram University said they conducted a survey and found existence of a total of 167 dolphins of ‘Platanista Gengetica’ species in the Halda River in 2018.

The number of the endangered species stood at 127 in another survey conducted using technologies two years later in 2020, he said.

But, they found a total of 31 dead dolphins in the river since September 2017 to Monday last, said Manzoorul.

Of them, highest 18 dolphins were found dead in between September 2017 and February 2018. Besides, a total of four dead dolphins were also found this year.

The experts attributed to pollutants from the multi-dimensional sources, absence of sewage treatment plant, dumping of household solid and liquid wastages, movement of mechanised boats and dredgers and use of gill-net by the fishermen for the decrease in number.

The first autopsy on a dolphin was conducted in February, 2018 after deaths of dolphin were being reported frequently.

The Ministry of Fisheries gave responsibility to the Halda River Research Laboratory of Chittagong University to unearth the cause.

The autopsy report revealed hit by propellers of dredgers behind death of the mammals, said the professor. As works of an embankment on the both banks of the river were going on then, a good number of dredgers and boats were plying frequently.

The dolphins died after being hit by their propellers then, said the researcher.

Later, the government cancelled lease for sand-lifting from 17 spots and movement of dredgers in the river following recommendations of the experts, said Manzoorul adding that the initiatives brought the situation under control then.

A committee was also formed following a writ petition filed in this connection. The committee has been working to save the dolphins and fishes in the river.

“But, the dolphins are now basically dying after being trapped in the gill net of the fish-thieves. As the quantity of fishes increased following different measures, the fish-thieves became more active now,” observed Professor Manzoorul.

The dolphins usually get stuck in the net and cannot come to surface for breathing. It caused their death, he said.

The researchers put emphasis on awareness among the locals and coordination among the agencies concerned including Department of Environment, Fisheries, Forest and local administration for an end to the death of the mammals.

He also suggested for forming the ‘Halda Authority’ to ensure coordination among them to save the aquatic animals of endangered species.