Abstract

 Ganga River basin, which was comparatively free from anthropocentric activities until the 1940s, became a disposal site for agricultural, industrial and sewerage wastes after independence of India in 1947. Discharge of wastes generated due to developmental activities including irrigation projects, river course modifications and demographic explosion in the basin, have ecologically impaired the river system, so that water quality is degraded, and fish yield as well as biodiversity has decreased. Amongst these, irrigation projects and flood control measures have almost destroyed flood plains, sloughs, inundation zones and oxbow lakes, all of which are the breeding and nursing grounds of the prized Indian major carp. This led to decline of the major carp population, while less economic fishes (minor carps and small catfishes) are increasing in relative abundance. The hydraulic structures have destroyed the anadromous fisheries (Tenualosa ilisha, Pangasius pangasius) of the riverine stretch of the Ganga. However, launching of the Ganga Action Plan phase-1 by the Central Government in the mid 1980s for cleansing the river has resulted in amelioration of some water quality parameters (increased DO and decreased HOD) to the level of the 1960's in the riverine stretch. However, some fisheries remain in decline. This is mainly due to reduction in water volume in the river due to siltation of the riverbed and increased water abstraction. However, improvement of fisheries in general and that of Tenualosa ilisha in particular in the estuarine zone, on account of release of water from the Farakka barrage in the estuary is also observed. The present paper discusses the impact of environmental aberrations on the fisheries of the Ganga River.

Keywords: Biodiversity, macrozoobenthos; plankton; Tenualosa