A study on the present status of fish in a perennial wetland (Beel) of Central Assam, India

Abstract

The permanent wetlands of Assam, known as Beels, are crucial in regulating the functions of natural ecosystems and harbor coveted Bioresources such as fish.  On the majority of occasions, these wetlands provide essential nutrition in the form of varieties of fish species while generating primary and secondary sources of employment and income to sustain the livelihood of large socio-economically vulnerable sections of society. However, fish diversity is slowly decreasing in most wetlands over time, primarily due to anthropogenic stresses. For conservation measures, ichthyofaunal diversity is a good indicator of the health of the aquatic ecosystem. We studied the Ichthyofaunal diversity and its prospectus in one such wetland of central Assam (Morigaon), known as Kuji Beel. We recorded a total of 35 inhabited fish species the Beel and most of them belong to the order Cypriniformes followed by Siluriformes, Channiformes, and Perciformes. We also identified certain invasive species, particularly common carp, which become the dominant species in a short period at the cost of the drastic exhaustion of three native fish species, such as Barali, Pabda, and Chitala, falling into the IUCN classification of vulnerable to near-threat. The Mahaldar of the Beel and local fishermen also confirmed a significant decline in fish diversity and availability over the last decade, regardless of species. This reduction in diversity and availability can be attributed mainly to four reasons: (i) Destructive fishing like indiscreet fishing and killing of juvenile and brood species during the peak breeding season,  (ii) The use of different types of fishing gear, the mesh of which is small enough to hold fry, (iii) Loads of sediment deposition and siltation along with pollution (agro-chemical) from cultivation practices in the vicinity, and (vi) Uncontrolled growth of aquatic plants such as water hyacinth and increased biological oxygen demand, hampering the growth of fish species. Finally, we have suggested appropriate conservation measures to maintain fish diversity whilst preserving the rich fish population of Kuji Beel and other similar permanent wetlands of Assam.