After a three-month hiatus, mother carp fishes (Rui, Katla and Mrigel carp) have started to lay eggs in the Halda River in Chattogram following heavy rains and thunderstorms.
Fishermen and fish farmers on Thursday (16 June) started collecting eggs at various points of the Halda, the sole natural spawning ground for carp-like fishes in South Asia.
They said the quantity of eggs is higher this year due to a favourable environment for the mother fish to lay eggs.
"The long wait is over. A suitable environment for laying eggs has been created in the Halda river due to flash floods," Manjurul Kibria, coordinator of Halda River Research Laboratory and a professor of zoology at the University of Chittagong, told The Business Standard (TBS).
"Since last night, fishermen in about 200 boats have been collecting eggs at various points of Halda- Azimer ghat, Garduara, Madunaghat, and Ramdash Munsirhat," he added.
Md Shafiqul Islam, Halda researcher and head of the biology department at Chattogram Cantonment Public College, said, "After observing the rain pattern and nature of river currents, we predicted on Thursday that the mother fishes will lay eggs and that is exactly what happened."
"Each boat collected around 1-1.5 kg of carp eggs last night," he added.
Mohammad Dulal, a fisherman from Hathazari's Garduara area, told TBS, "I have been spending my nights on the banks of the Halda for the last three months. The quantity was very small when sample eggs were laid a few times."
"But last night the catch was very good. So far we have been able to collect 1.5 kg of carp eggs," he added.
According to researchers, if it rains with thunder on full moon nights between the Bangla months of Chaitra and Ashar, there are flash floods in Halda. If the temperature is favourable, the carps lay eggs. The mother fish usually lays eggs in the Halda between mid-April and June.
But in recent years, precipitation has declined with rising temperatures due to climate change. Salinity is also increasing in Halda due to the sea level rising. Under these conditions, the mother fishes are not laying eggs as usually expected.
In May, fishermen got only 3,500 kg of eggs. At that time, per kilogram of eggs sold at a record price of Tk2 lakh due to high demand.
According to the Halda River Research Laboratory of Chittagong University, only 8,500 kg of eggs and 105 kg of carp fish fry were collected from Halda in 2021. In 2020, some 25,000 kg of eggs were collected from Halda, the highest in 12 years up until 2020.