Noted Halda River researcher Prof Dr Manzoorul Kibria told Dhaka Tribune that different natural factors like the temperature of the water, strong currents and thunderstorms create a congenial atmosphere for the brood fish to lay eggs in the river
Spawn collectors are waiting eagerly for the brood fish (mother fish) of some indigenous species to release eggs in the Halda River, also known as Bangladesh’s largest natural breeding ground for carps.
Usually the brood fish release sample eggs before releasing eggs in full to test the congenial aquatic environment.
Speaking to Dhaka Tribune, Hathazari Upazila Nirbahi Officer (UNO) Ruhul Amin said that three government hatcheries and 60 “kua” were all set for hatching purposes.
After collecting the eggs, the fishermen keep the spawn in the artificial earthen pond or “kua” on the riverbank, where the fry are hatched within 18 hours.
“We have made a list of all spawn collectors. Moreover, we are issuing Halda cards to the spawn and fry collectors for their transportation. We have heightened our vigilance on the river to ensure an undisturbed spawning environment,” said the UNO.
The Halda River researchers and spawn collectors said that the catch would be higher as top polluters like Asian Paper Mills and Hathazari Peaking Power Plant have been shut down for polluting the environment.
On August 18 last year, the Department of Environment (DoE) asked Asian Paper Mills to suspend its operations until it had a proper waste disposal system, amended the faulty Effluent Treatment Plant (ETP) and kept the ETP active round the clock.
On July 17 last year, the DoE ordered the suspension of operations at the state-owned Hathazari 100MW Peaking Power Plant for discharging untreated toxic liquid waste into a waterbody connected to the Halda River.
The plant authorities were asked not to resume operations until they set up and activated an Effluent Treatment Plant (ETP) and an Oil-Water Separator.
Kamal Sowdagor, a veteran spawn collector of the Halda, said that collectors were waiting eagerly for the moment for the brood fish to release eggs on a large scale.
“We hope that the brood fish will lay eggs in the next full moon. The brood fish have already begun to come to the river. This time the catch will be higher as the extent of pollution has fallen. The authorities should strengthen vigilance so that none can catch the brood fish before and after the release of the eggs,” said the spawn collector.
Speaking to Dhaka Tribune, Hathazari Upazila Fisheries Officer Nazmul Huda said: “The movement of brood fish in the ‘kum’ or bow-shaped bends of the river has conspicuously increased. We have taken all-out preparations as the brood fish may release eggs in the next full moon.”
Noted Halda River researcher Prof Dr Manzoorul Kibria told Dhaka Tribune that different natural factors like the temperature of the water, strong currents and thunderstorms create a congenial atmosphere for the brood fish to lay eggs in the river.
“Usually the brood fish first release eggs on a trial basis. The mother fish spawn finally if they find the aquatic environment congenial for laying eggs,” added Prof Kibria.
During the Bangla months of Baishakh and Jaishtha (April and May) every year, different species of mother fish, like Catla (Catla catla), Ruhi (Labeo rohita), Mrigal (Cirrhinus mrigala), and Kalbaoush (Labeo calbasu) start migrating to the spawning ground of the Halda from rivers like Karnaphuli, Matamuhuri and Sangu.
The Halda River, which flows through Hathazari and Raozan upazilas of Chittagong, is considered to be the only natural breeding ground in the world where these species of fish release their eggs at a certain period of the monsoon. Fry-collectors catch the eggs through a unique method to sell them to fish farmers across the country.
According to the Department of Fisheries, there are a total of 588 spawn collectors along the 98-km long river.