Inland Fisheries

Impacts of Dams on Fisheries in India

Dams have had negative impact on river fisheries in various systems throughout the region. Sharp declines in catches of Hilsa ilisha were noticed as a result of dams, barrages, weirs and anicuts on the Hooghly, Godavari, Krishna and Cauvery rivers (India), and that mahseer Tor putitora and T. tor no longer are found above Nangal and Talwara dams. Fish ways constructed in conjunction with dams are used as fish traps by local fishers.

In addition to impacts on hilsa and mahseer stocks and their associated fisheries, formation of reservoirs in India has had negative impact on snow trout (Schizothorax), and rohu (Labeo) in Himalayan streams, and catadromous eels and freshwater prawns in all major river systems. One of the earliest known impacts to river fisheries in India occurred as a result of construction of Mettur Dam (1935) on the Cauvery River, which formed Stanley Reservoir and completely stopped runs of the Indian shad Tenualosa ilisha. Within the reservoir itself, water level changes, recruitment failures and predation resulted in reduced stocks of Indian major carps.

Reservoirs in Punjab region have resulted in good fisheries, with more than 1,800 t/year landed annually at Bhakra Dam and Pong Dam, collectively. In the reservoirs formed by these dams high yield fisheries have evolved, primarily through development of stocks of exotic fishes (eg, the fishery for the exotic silver carp, Hypophthalmichthys molitrix contributes more than 30% to the catch from Gobindsagar Lake).

However, river fisheries have been negatively impacted, particularly with regard to migratory fishes. Construction of barrages at Ropar, Harike, and Ferozepur has restricted migration of Indian major carps, in spite of fishways. During most of the year, little water is released into the river below the dams from the reservoirs, and fish are concentrated in pools where they are more easily captured by fishers. Fishways designed to promote fish passage past dams are used by fishers to capture fish. Dams in India’s Punjab region have reduced flooding, but in so doing they have also negatively impacted production of Indian major carps, resulting in reduced total fish production for the region.

Persons linked to river fisheries through culture, tradition and economics incorporate these fisheries as dominant components of their human identities. Reorientation of their values and activities after impacts to or loss of the foundation for their identities can generate considerable socio-economic stress to these people, their communities and their cultures.