Hilsa catches from rivers dwindle as pollution rises

Hilsa catches from rivers are shrinking in spite of a rise in overall production, due to pollution and falling navigability.
In fiscal 2012-13, hilsa catches from inland waters, mainly from rivers, stood at 98,648 tonnes, the lowest in three years and down almost 14 percent year-on-year, according to the Department of Fisheries.
Experts fear hilsa production from rivers might continue to fall unless effective measures are taken to increase the navigability of mainstream rivers Padma and Meghna and stem the flow of industrial and other wastes to rivers.
“We have lost many water bodies that were once habitats for hilsa—many rivers have died. The water flow in major rivers is falling and their bottoms are silted up, affecting movement of hilsa in rivers,” said GC Haldar, a former director of the Bangladesh Fisheries Research Institute (BFRI).
Particularly, the availability of hilsa has slumped in the Ganges-Kobadak area. Huge quantities of hilsa were also found along the entire Padma river a couple of decades ago, but now it is scanty there.
The pollution of river water is another factor for the declining production of fish in rivers, he said.
Hilsa catches have increased from marine waters over the past couple of years, facilitating a spiral in total production, DoF data shows. Hilsa production rose to 3.51 lakh tonnes in fiscal 2012-13 from 3.46 lakh tonnes the previous year.
Md Anisur Rahman, principal investigator for hilsa research at BFRI, linked the recent increase in production of the fish to the government's measures to prevent catches of fries and ban catches of brood-hilsa during the peak spawning season. The declaration of five zones of different rivers as hilsa sanctuaries and enforcement of rules to prevent catches in the area also contributed to the increase in production, he said.
Rahman, however, said similar efforts to increase navigability and water flows in rivers and control discharge of industrial and other wastes to Buriganga and Shitalakhya will contribute to increased availability of hilsa in rivers.
Migration of hilsa is hampered for the rise of char and submerged sandbars in the mainstream rivers, he said, adding that reduced navigability and water flow affects the fish's movement.
The effect of chars is pronounced in the Padma starting from Mawa in Munshiganj to Harinaghat in Chandpur, he said.
In addition, discharge of industrial effluent and other wastes in rivers surrounding Dhaka and Narayanganj create havoc to the liveability of hilsa and other aquatic species, he said.
Polluted waters from Buriganga and Shitalakhya are coming to the Mehgna river as well, he said, adding that the effect of pollution can be seen at Shatnol, Chandpur, from where begins a sanctuary stretching up to Char Alexander in Laxmipur.
“We are very worried about the pollution of Buriganga and Shitalakhya rivers. The quality of water has worsened and there is a shortage of dissolved oxygen. There is also the presence of ammonia, which is harmful for fish.”
Rahman feared that the effect of pollution may spread in rivers unless strict measures are taken to control the discharge of industrial waste. “Therefore, it is essential to ensure establishment of effluent treatment plants and keep those in operation.”
Hilsa accounts for 11 percent of total catches of fish from open water bodies. About 60 percent of the global catches of the fish are from Bangladesh, according to DoF.