Shahadat Hossain Sazzad, Raozan (Chattogram)

The Halda River is one of South Asia’s significant freshwater natural fish breeding grounds. It is famous for the natural spawning of major carp species (Rui, Katla, Mrigel, and Kalibaush). 

The peak egg-laying season is ongoing. Every year, between April and June, during the new moon and full moon phases, if there are thunderstorms, heavy rain, and upstream mountain runoff, carp species (Rui, Katla, Mrigel, and Kalibaush) release eggs in this river. Two such tidal surges already passed in April. However, egg collectors hope that mother fish may release eggs in the upcoming full moon tides.

The mother fish that were in the river’s connecting canals have now moved into the Halda River for spawning. Their presence has increased. Collectors believe that with thunder and sufficient rain plus mountain runoff, the mother fish will first release sample eggs, followed by full spawning.

An on-site visit shows egg collectors are ready with nets and boats. Some are repairing boats by the riverside, while others are waiting with nets and boats by the riverbank. Hundreds of local egg collectors gather these eggs and hatch them in traditional clay pits or hatcheries to produce high-quality fry. According to the collectors, there are six government hatcheries on both sides of the river to hatch eggs into fry. However, none of them have staff. Among the three hatcheries in Rauzan, two are inactive and abandoned. While the Kagatia and Paschim Gohira hatcheries are abandoned, only the Mobarakkhil hatchery is operational.

Due to the abandonment of two hatcheries, the collectors are not benefiting from the multi-crore-taka installations. As a result, despite the risk of egg spoilage, most collectors still rely on age-old clay pits. These clay and concrete pits have already been repaired and prepared. Md. Nurul Alam, an egg collector, said, “We’ve been collecting eggs for 50 years. We’ve prepared everything, including boats. Now we wait, wondering when the fish will release eggs in the river.”

It is known that every year between the months of Chaitra and Shraban, mother fish spawn in the Halda River. When there is heavy rainfall and thunder, the water depth in the river increases. As the intensity of mountain runoff grows and the river water turns turbid, depth develops, which is ideal for egg laying.

Meanwhile, to ensure the free and safe movement of fish in the Halda River, the administrations of Rauzan, Hathazari, Chattogram District, the Department of Fisheries, and Halda’s River Police have strengthened patrols. Key spots along the river are now under CCTV surveillance to protect the mother fish.

Rauzan Upazila Senior Fisheries Officer Alamgir Hossain said that egg collectors in Halda are ready. Hatcheries are prepared. If the environmental conditions are favorable, mother fish may lay eggs during the first full moon tide.

After testing water samples from Halda’s spawning grounds, Halda researcher Dr. Md. Shafiqul Islam said that the river’s physical and chemical water properties are within ideal ranges. However, the temperature, a crucial parameter for carp spawning, is slightly higher than ideal. Observing the various preparations by government hatcheries and egg collectors, it’s clear that preparations for egg collection are in the final stage.

If the environment is favorable—meaning thunder, enough rain, and mountain runoff occur—then during this month’s full moon tidal surge (May 10–14) or the new moon tidal surge (May 25–29), there is a possibility that major carp species will lay eggs in the Halda River. He further said that due to climate change and destructive human activities, the number of eggs collected from Halda has drastically decreased over the past few years. However, he hopes that if the natural environment supports it this year, the number of eggs collected from Halda will increase.