Brood fishes (mother fishes) of some indigenous sweet water fish species released eggs in the Halda River for the second time of spawning of the current season at 1:30am yesterday. To test the aquatic environment, the brood fishes spawned for the first time on April 21. This time, soon after the release of spawns, around 300 egg collectors, with their boats and nets, started collecting the eggs in a festive mood. However, egg collectors have said that this time the quantity of collected eggs was slightly lower than the previous year. Different natural factors like temperature of the water, strong currents and thunderstorms create a congenial atmosphere for the mother fish to lay eggs in the river.
During the Bangla months of Baishakh and Jaishtha (April and May) every year, different species of mother fish, like the catla (Catla catla), Ruhi (Labeo Rohita), Mrigal (Cirrhinus Marigala) and Kalbaoush (Labeo Calbasu) start migrating to the spawning ground of the Halda from rivers like the Karnaphuli, Matamuhuri and Sangu.  The mother fishes have started releasing spawn in strong currents at different points, covering around 10 km area of the Halda. The points include Napiterghona, Ankurighona, Azimerghat, Garduara and Ram Das Ghat, Baruapra, Machhuraghona and Garduara.
Ashu Barua, a spawn collector, told this reporter that he could collect 10 buckets of eggs amounting to 40 kg.
While talking to The Independent, Md Manzoorul Kibria, an expert on the Halda river, said this time the catch of spawn was a bit poor.
The Halda which flows through Hathazari and Raozan upazilas of Chittagong, is considered as the only natural breeding ground in the world where these species of fish release their eggs at a certain period of the monsoon and fry-collectors catch those eggs through a unique method to sell it to fish farmers across the country.
At the beginning of April, indigenous fish species migrate from different rivers, including the Karnaphuli and Sangu, out into the Halda to spawn.
After collecting the eggs, fishermen nurture those in mud pots and also in cisterns of eight hatcheries established by the fisheries department, said spawn collectors. After 96 hours, the eggs transform into fries which are then sold to the fry collectors or hatchery owners at Tk. 50,000 to Tk. 80,000 per kg, said a local fisherman.
“This time, the quantity of eggs released is quite poor. I have seen 300 boats collecting spawns from different spots of the river. The decreasing trend is a negative sign for us. We should think about it with all seriousness to protect the natural breeding ground,” said Kibria.
 “Construction of rubber dams and unplanned sluice gates for irrigation, discharge of industrial wastes and catching of brood fishes are destroying the environment for spawning in the river,” added Kibria, who is also Associate Professor of the Zoology Department, Chittagong University.
The Halda River wore a festive look when the egg collectors and local fishermen on-boarding several hundreds boats started collecting eggs from different points of the river including Kagtia, Kashemnagor, Mobarakkhal, Ajimer Ghat, Onkurighona, Dakkhin and Paschim Gahira, Abur Khil, Khalifarghona, Paschim Binajuri, Urkir Char and Napiter Ghat of Raojan upazila and Garduara, Amtoa and Madrasa area of Hathajari upazila.