Halda River, the lone breeding ground for natural spawning of carp fish in South Asia, has seen second spawning within a month after having first laying of eggs by brood fish on May 22.
The spawning is assumed to have occurred thanks to an increase in brood fish stock. Around 150 to 200kg of eggs were collected early yesterday at Baroighona and Chayarchar, two points adjacent to Halda.
Manzoorul Kibria, noted Halda researcher and professor of zoology at Chittagong University, said it is truly a promising sign for the river, which he thinks was enriched with stock of brood fish following a drop in pollution and other manmade hazards.
"When a waterbody has a large amount of brood fish, some of them take time to get matured enough to release eggs. This is what exactly happened in Halda" he said, adding that this is the first time he had seen such second spawning.
Half of the egg collectors did not go to the river as they could not sense the spawning, Prof Kibria said. Halda has around 500 egg collectors.
Egg collectors told The Daily Star that in their early days, they would see spawning thrice a year.
Seasoned egg collector Elias Hossen of Hathazari upazila said as pollution started wreaking havoc, spawning was reduced to once. "This is first time I have seen second spawning, which is really positive for the river and those of us who depend on it," he said.
Chattogram district fisheries officer Lovely Akther told The Daily Star that they were all excited over the second spawning and it raises hopes.
During the first spawning in May, egg collectors were delighted by the huge haul of eggs in the river. A few factors played a role in the high egg yield this year, said Prof Kibria.
First stopping of tobacco farming, then the shutdown of two polluting factories near the river and third the quick response of Hathazari upazila administration, surveillance by IDF, an NGO working to protect Halda, and nationwide shutdown helped the river detoxify itself, he added.
All of the above helped create a better environment for fish to lay eggs, he said.