Wetlands of Assam undergoing rapid degradation in the face of anthropogenic pressure and climatic change, revealed a latest study.
The study conducted by ICAR-Central Inland Fisheries Research Institute through its Guwahati Regional Centre on the vulnerability of beels of the State found that the degradation was affecting spawning and reproductive behaviour of fishes.
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The study, conducted in the beels of Dhubri district during 2018-19, was done under a research project ‘Impact of climate change in inland fisheries and development of adaptation strategies’ by a team comprising Dr BK Bhattacharjya, BK Das, UK Sarkar, D Debnath and Sona Yengkokpam.
“The study focused on vulnerability of beels, their users and the fishes in them. It showed that due to natural factors like climate change, siltation and encroachment, Sara Beel was converted into a seasonally open beel from a perennially open one. This beel had a connection with the Gaurang river 20 years ago,” The Assam Tribune quoted BK Bhattacharjya, principal scientist and head (acting) at ICAR-CIFRI Guwahati Regional Centre as saying.
The study revealed that over the past 30 years, about 70 per cent of the beels experienced reduction in water-spread area.
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High level of siltation, encroachment, detachment of marginal areas due to construction of roads, etc., caused reduction in the water-spread area from the original area, mostly in the dry season.
“As a result, spawning and reproductive behaviour of the Indian major carps have been impacted. Flood in Assam during the rainy season is as severe a problem for the fisheries sector as waterless-ness during the dry season, which makes a wetland all the more vulnerable.
“As per information available, most of beels of Assam experienced major flood in 1988, 2014, 2017 and 2019,” he said.
To cope with the impact of climate change and for promoting sustainable wetland fisheries, various adaptation strategies were identified by the scientists.
These are temporary pre-summer enclosures, deep-pool refuge, autumn stocking, submerged branch pile refuge, and floating aquatic macrophyte refuge (jeng/katal).
“Enclosure aquaculture in the form of pens and cages can not only prevent fish from escaping during flood, these structures can be shifted to deeper areas of the wetlands in case of reduced water depth during the dry season, making these technologies climate-resilient. Enclosure culture technologies are simple but useful tools for producing stocking material (advanced fingerlings) and table fish that potentially can improve socio-economic condition of beel fishers,” he said.
Bhattacharjya said introduction of exotic fishes in natural water bodies from nearby ponds and culture fisheries could take place due to natural disasters like flood, which potentially can affect icthyofaunal biodiversity in those water bodies.
“Majority of the beels of Assam reported exotic fishes like Cyprinus carpio (common carp), Ctenopharyngodon idella (grass carp), Hypophthalmichthys molitrix (silver carp), Hypophthalmichthys nobilis (bighead carp) and Piaractus brachypomus (pacu).
“Surprisingly, Pacu, a highly invasive species locally known as ‘Rupchanda’, was reported in a few beels (like Hakama beel) that threatened small indigenous fishes of that wetland,” Bhattacharjya added.
Worryingly, there has been a decrease in fish catch per person per day in a majority of the beels as compared to the past 30 years.
“With increase in population, the number of fishermen has also increased causing reduced catch per capita. But the phenomenon could also be attributable to the degrading nature of the fish habitats in terms of reduced water-spread area, pollution, loss of riverine connection, etc., and reduced number of fish species in the beels studied,” he said.