BANGLADESH AGRICULTURAL UNIVERSITY, (Mymensingh), May 11, 2025 (BSS) – A new carp breeding ground has been discovered in Kaptai Lake, which is located near Maladwip Point in the Kassalong Channel under Longadu Upazila.

Bangladesh Fisheries Research Institute (BFRI) scientists have discovered the new carp breeding ground near Maladwip Point under Longadu Upazila (Latitude 23.00341438, Longitude 92.194337061), BFRI Publication Officer S M Sariful Islam shared the information today.

“The spawning success rate at the new site was found to be around 90–95%,” he said.

Senior Scientific Officer Md. Istiaque Haidar, along with Scientific Officers B. M. Shahinur Rahman, Md. Khaled Rahman, and Md. Lipon Mia, played key roles in identifying the new breeding site and collecting fertilized eggs during the research.

During the spawning season, water depth in the Kassalong Channel is ranged from 1.8 to 2.4 meters. Other recorded physico-chemical conditions include water temperature (26.62–27.1°C), salinity (0.01–0.02 ppm), pH (7.28–7.40), and dissolved oxygen levels (5.2–6.6 mg/L)—all of which are favorable for carp spawning.

However, the depth of the spawning grounds has been diminishing due to delayed rainfall and sedimentation caused by climate change. This is affecting the migration routes of brood carp and gradually shrinking their natural breeding grounds.

Kaptai Lake, the largest inland open water reservoir in Bangladesh, is a vital natural resource. It contributes significantly to the country's fish production. In the fiscal year 2022-23, the lake produced 17,056 metric tons of fish, and approximately 26,688 fishermen and their families depend directly on it for their livelihoods.

Sariful Islam noted that natural reproduction is one of the major factors contributing to increased fish production in open water bodies. The primary research activities of the BFRI Riverine Sub-Station in Rangamati include fish production, conservation, carp maturation and spawning season monitoring, identification of breeding sites and migration routes, and the collection, quantification, and species identification of eggs and embryos from natural reproduction, he added.

In Kaptai Lake, carp typically breeds during the monsoon season (June to July), especially during periods of heavy rainfall and thunderstorms. The strong currents and water eddies created by upstream mountain runoff promote natural spawning. Carp traditionally breeds in the Kassalong, Barkal, Chengi, and Rinkhiang channels.

Research on natural breeding grounds in Kaptai Lake dates back to 1986, with further studies conducted between 2001 and 2004. In 2016–17, scientists from the BFRI Riverine Sub-Station, Rangamati, again found carp eggs in the Kassalong Channel. Recently, BFRI researchers identified fertilized carp eggs at a new breeding site near Maladwip Point, in addition to the four previously known breeding sites.