Toxic wastes killing Halda biodiversity

Ayub Ali, Ctg: In the last one week, five big mother fish and a dolphin have died in the Halda river of Chittagong, the only natural fish breeding center in the country. Last Sunday afternoon, another mother Katla fish was found dead at Azim Ghat of West Gujra Union on the Raujan side of the river. The weight of the fish is 19 kg 300 grams. Halda river researchers call fish dying one after another as an unusual event.
The District Fisheries Department formed a five-member investigation committee on Sunday to find out the cause of death of these fish and dolphins.
Talking to the District Fisheries Department and Haldar volunteers, it is known that last Friday at noon, while floating through the Kumarkhali Ghat area of Hathajari North Madarsha Union, the volunteers of the river brought two dead mother Katla fish to the river. In the afternoon, upazila fisheries department, local public representatives and volunteers buried a fish. The other was sent to the laboratory of Chittagong University.
Last Tuesday afternoon, a large dolphin weighing 90 kg floated dead from the Gardwara Sipaighat area of the Hathazari section of the river. Last Wednesday afternoon, a 12 kg dead cotton fish floated in Bakar Ali Chowdhury Ghat area of Urkirchar Union of Raujan.
A week ago, when a dead catla fish floated in the same ghat, it was picked up and buried in the ground.

When asked why the fish are dying one after another, Halda researcher and head of biology department of Chittagong Cantonment Public School and College said. Md. Shafiqul Islam told, “The death of five mother fish and one dolphin in the Halda river in the last one week is an ominous sign.” Currently, the picture of river pollution has become dire. Apart from this, human-made pollution is responsible for the destruction of Halda fish breeding grounds.
There are numerous branch canals connected with the Halda river. Shafiqul Islam said, “The biggest one has 16 branch canals. Through which various polluted wastes of the factories are constantly falling into the Halda. Especially the pollution of three canals from Madunaghat to Mohra has become dire. Polluted waste is coming to Halda through Katakhali canal, Brahmanshahi canal and Khandakia canal. Chemical-laden water and effluents used in many factories are coming directly into the river. Also, tannery toxic waste, industrial waste, poultry waste, household and human waste are also entering the river. Apart from this, illegal fishing with nets, spears and poisons and illegal sand mining have affected the Halda and Shakha canals. These can also cause death of fish.
This researcher also said, “Last Friday, water samples from Katakhali section of Haldar Madunaghat were tested. Tests showed that the amount of dissolved oxygen in the water dropped to 3.6 milligrams per liter. Its ideal value is 5 mg. The level of free carbon dioxide in the water increased to 20 grams per liter compared to normal (5-10 mg per liter). Again, the pH value is very close to the normal minimum limit (6.5). Which is responsible for the death of fish.
If you want to know about this, Halda River Research Laboratory Coordinator Professor Dr. Manjurul Kibria told, “The disappointing thing is that after 2016, fish have laid the least number of eggs in Halda river this year. Now the death of the mother fish has started again. This is due to river pollution.
Stating that environmental damage and fish deaths have increased due to pollution of Halda’s branch canals, he said, “There is no opportunity to take the matter lightly to protect Halda.” To prevent this disaster, I demand that an investigation committee be formed quickly through the Ministry of Fisheries and Livestock to find out the reason.
In this regard, Chittagong District Fisheries Officer Shribas Chandra Chand told, “The fact that five mother fish and one dolphin died in Halda in a week is a matter of concern. A five-member committee has been formed to find out why so many mother fish and dolphins died in a week. Farooq Mayduzzaman, Senior Fisheries Officer of Hathajari Upazila, has been convened in the committee. The committee has been asked to report within a week. Necessary action will be taken after receiving the report.
According to the sources of Department of Environment Chittagong Metropolitan Office, the organization has formed a separate investigation committee to investigate the cause of death of fish and dolphins in Halda. The committee has been working for the past one week.
Halda river has been declared as Bangabandhu Fisheries Heritage by the government in 2020. According to the promise of Mujib year, the Ministry of Fisheries and Livestock issued a notification in this regard on December 22 of that year.
According to the notification, with the aim of ensuring the safety of rui national fish and preserving the habitat of Gangetic dolphins through conservation of natural environment and development of environmental standards, Halda river flowing through Ramgarh and Manikchari upazilas of Khagrachari district, Fatikchari, Raujan, Hathajari upazila and Panchlaish police station of Chittagong district and the river bank 93 23 thousand 422 acres of 1 thousand 612 spots have been declared as Bangabandhu Heritage. According to the government gazette, 12 conditions are mentioned in the Bangabandhu Fisheries Heritage Area. One of the conditions is that residential houses, industrial establishments and other establishments around the river cannot discharge sewage and liquid waste. But till now 12 conditions have not been implemented.
Halda is one of the largest natural fish breeding areas in South Asia. This river is a center of free movement of various species of carp including roe. Here every year from April to June, the mother fish lay eggs.
According to Halda Research Laboratory sources, 41 endangered Gangetic dolphins have died in Halda since September 2017. The 40th dolphin died on November 3, 2022. About 30 mother fish died at the same time. Most of these dolphins and mother fish died due to injuries, breathing problems and pollution, according to the Halda Research Laboratory.