Dhaka, March 27 -- For nearly two decades, Bangladesh's second UNESCO-recognised natural heritage site, Tanguar Haor has witnessed an ecological collapse: half its native fish species have vanished.

"The number of birds visiting in winter has drastically decreased," notes local environmentalists. Migratory patterns are disrupted, and the wetland's delicate balance teeters on the brink.

Former dean of Fisheries at Sylhet Agricultural University Prof Mrityunjoy Kunda, recounts a recent 2024 study: "We recorded 76 species of fish in Tanguar Haor. But not all species are common or evenly distributed. In some areas, only 35 to 40 species appear regularly. The rest are rare."

He adds that previous studies in 2022 noted 93 species, and the IU...