By Salam Rajesh
The Manipur Paradox
Since its inception in the early 1970s and its existence from the early 1980s, the Ithai Barrage for the 105 megawatt Loktak hydroelectric power project in Manipur has been the nemesis for myriad issues including habitat degradation and sharp decline in migratory freshwater fish populations that earlier used to spawn upstream of the Manipur River.
Migratory freshwater fishes which are among the highly relished food fishes in the State, and elsewhere, provide sources of food and economy for thousands of wetland fishery dependent local communities.
The decline in migratory freshwater fish populations has considerably hit the resources of the marginalized fisher families living within the Loktak wetland complex during these past decades since the commissioning of the barrage in mid 1983.
The barrage, meant as a development mechanism, ironically has been the prime factor for depriving the local population settled in the Manipur floodplains of their primary diet which is freshwater fish, and that, too, highly relished food fishes like Bangana devdevi, Osteobrama belangiri, Labeo bata and Wallago attu amongst others.
The Manipur River system connects with the Chindwin-Irrawaddy river system in Myanmar and it is through this connectivity that important migratory fishes like Bangana devdevi, Osteobrama belangiri, Labeo bata, Wallago attu, Anguilla bengalensis and other species migrate upstream to spawn in wetlands dotting the Manipur floodplains.
The blockage of their migratory passage by the Ithai Barrage, which is constructed over the Manipur River at its confluence with Khuga River near Ithai Khunou village in Bishnupur District of Manipur, had almost completely wiped out the presence of these migratory freshwater fishes.
So much so that today, Osteobrama belangiri is listed as ‘extinct in the wild’ in the Manipur region, with other migratory freshwater fish listed either as Vulnerable or Near Threatened (Anguilla bengalensis) as per the CMS listing.
CMS Prioritization on Migratory Freshwater Fishes
It is for such discerning reason that the United Nation’s Convention on the Conservation of Migratory Species of Wild Animals (CMS) states that freshwater fishes are among the most imperiled vertebrates, and many migratory species now face decline driven by loss of connectivity, flow alteration, habitat degradation, exploitation, pollution, and interacting pressures across borders.
Freshwater fishes occur on every continent except Antarctica and occupy nearly all inland aquatic habitats, from headwater streams and springs to large rivers, floodplains, lakes and wetlands.
CMS notes that migratory behavior is widespread across freshwater fishes and cuts across major lineages, and freshwater fishes may be (a) exclusively freshwater, (b) occur in fresh and brackish waters, or (c) occur in fresh, brackish and marine waters.
Dr Zeb Hogan, CMS Scientific Councilor for Fish, the lead author for the CMS report ‘Global Assessment of Migratory Freshwater Fishes 2025’, notes that CMS Parties, recognizing the importance of migratory freshwater fishes and the multiple threats to their populations and ecosystems, have called for strengthened measures for their protection.
CMS has sought stronger, coordinated action for inland fishes that move across national jurisdictions, Dr Zeb adds.
With reference to the freshwater fishes mentioned in the CMS suggested listing, few of the freshwater fishes found in Manipur finds mention, for instance, Anguilla bengalensis (Indian mottled eel/Ngarin-laina, IUCN status: Near Threatened), Bagarius bagarius (Ngarel, IUCN status: Vulnerable), Chanda nama (Ngamhai, IUCN status: Least Concerned), Mystus cavasius (Ngasep, IUCN status: Least Concerned), Ompok bimaculatus (Ngaten, IUCN status: Near Threatened), Osteobrama belangiri (Pengba, IUCN status: Near Threatened), and Tor putitora (Mahseer/Ngara, IUCN status: Endangered).
The IUCN Red List coverage of freshwater fishes has since expanded from 3,000 to nearly 15,000 assessed species, enabling a much more complete picture of status and trends across identified regions.
Transboundary Priority Regions
In consistent with the global assessment and the numerous case studies in field, the CMS report notes that several transboundary systems emerge as priority areas requiring international cooperation to protect freshwater fish species from decline and loss.
One of these priority regions is the Amazon and La Plata–Paraná–Paraguay region in South America providing habitat for long-distance catfishes and characids, and needing floodplain nursery protection, coordinated seasonal closures and high-gain barrier retrofits.
Another of the priority region is the Danube connecting European basins providing habitat for potamodromous cypriniforms (that is, fish that migrates wholly within freshwater), sturgeon and lamprey runs, and requiring sediment continuity and passage across multiple countries.
The other priority region is the Congo, Niger-Lake Chad, and Nile in Africa with issues of drought sensitivity and habitat fragmentation.
The fourth priority region is the Mekong in Southeast Asia, and the Ganges-Brahmaputra-Meghna in South Asia with high biomass of migrants, and with issues of dams and hydro-peaking. These regions require passage standards, life-stage fishery regulation and shared recruitment indices as per the CMS finding.
The Pathways Ahead
The Mekong River Basin supports globally significant freshwater biodiversity and numerous migratory species, including several that are Critically Endangered. Interestingly, there are species sharing the transboundary space of the Mekong and the Ganges-Brahmaputra-Meghna regions, as for instance Wallgo attu which is found in both the spaces.
For Manipur and the other northeastern States that have inter-connectivity in the natural systems via the passages of the transboundary migratory freshwater fish populations, it becomes a priority to formulate strategic action plans on ground and to engage in international cooperation amongst South Asian and Southeast Asian countries for species protection and conservation as per the IUCN and CMS guidelines.
In Manipur’s specific case, the re-designing or restructuring (or, decommissioning) of the man-made structure Ithai Barrage over Manipur River becomes essential in this crucial dialogue on migratory freshwater fish species loss, and decline in populations, by what the CMS says “loss of connectivity” induced by anthropogenic influences, in specific the barrage in question which has caused substantial ecological and environmental changes much of which are negative in character and in nature.
{The author is member of IUCN CEESP (Commission on Environmental, Economic and Social Policy)}
