Egg collectors in the Halda river have been delighted by what is this decade's record haul of eggs in the lone natural breeding ground of carp-like fish in South Asia.

Around 25,536 kgs of eggs were collected from the river yesterday. The number was just 7,000 last year.

The eggs will be hatched in fisheries. The local administration buys a portion of the hatched fry which are then released in the Halda every year to increase the fish stock.

Ruhul Amin, upazila nirbahi officer of Hathazari upazila, told The Daily Star that he released one lakh fries into the Halda last year, adding they planned to do the same this year.

Broodfish started laying eggs early today and a full spawn occurred at 7:30 am at five points along the river.

Around 616 egg collectors took position at various point of the river since Thursday night following a moderate downpour. They first come across the sample eggs at 3:00am earlier yesterday.

Mohammad Elias, a seasoned egg collector of Halda River at Ramdasmunsir Hat of Hathazari upazila, told The Daily Star that few eggs were seen in the morning.

"With tide on the river, the amount of eggs began to increase giving us the record haul in recent years," he said.

Egg collectors descended on the river with 280 boats and got seven to eight buckets of eggs each, he said.

"Halda River has given us hope for better days," he added.

Eminent Halda researcher Professor D Manzoorul Kibria told The Daily Star that few factors played a role in the high egg yield this year.

First stopping of tobacco farming, then the shutdown of two polluting factories near the river and third the quick response of Hathazari upazila administration and surveillance by IDF, an NGO working to protect Halda River all combined to create a better environment for fish to lay eggs.

He said the last big haul was in 2006. That year the amount was 32,000kgs, but this year's amount was the highest in 14 years.

"If there was heavy shower with gusty wind and thunder, there would have been more eggs," he said.

Ruhul Amin, upazila nirbahi officer of Hathazari upazila, told The Daily Star that throughout the years his administration seized illegal nets, dredgers and boats.

"Halda finally paid off. Our effort and labour finally found meaning," he said.