Impact of flood control schemes on river fish migrations and species assemblages in Bangladesh

A mark‐recapture programme at the Pabna Irrigation and Rural Development Project (PIRDP) site in NW Bangladesh showed that Catla catla, Channa striata and Wallago attu migrated through the sluice gates, both with and against prevailing currents in different season, while the smaller Anabas testudineus, Glossogobius giuris and Puntius sophore did not. Species assemblages were significantly different inside and outside the flood control, drainage and irrigation (FCDI) schemes, with up to 25 species absent or less abundant inside compared to outside. The majority of these species were large predators or conspicuous members of the highly prized migratory ‘whitefish’ category, including silurid catfish, Indian major carps, mullets and clupeids. In their absence, species inside FCDI schemes were dominated by much smaller resident…