Gharials, Gavialis gangeticus, are freshwater Crocodilians found only on the Indian Subcontinent. Modification of river systems by damming and water extraction has fragmented the Gharial population into a series of isolated subpopulations, leading to a steady decline in their available habitat and total number of Animals, for which reason Gharails are now considered to be Critically Endangered under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species.
In 1976 the construction of a irrigation barrage on the Girwa–Kaudiyala Rivers led to the isolation of a population of Gharials on the Girwa River within the Katerniaghat Wildlife Sanctuary in Uttar Pradesh, with the species disappearing from the Karnali River upstream of the sanctuary and the Ghaghara River downstream. The Girwa River population is monitored by the Katerniaghat Wildlife Division, with 72 individuals and 36 nests recorded in February 2020, but there is no regular monitoring of the Ghaghara River. The number of juvenile Gharials reaching adulthood in the Girwa River is surprisingly low, and it has been suggested that hatchlings might be being swept into the Ghaghara River when the gates of the barrage are opened in the monsoon season.
In a paper published in the journal Oryx on 22 December 2023, Gaurav Vashistha of Sri Guru Nanak Dev Khalsa College at the University of Delhi, and the Gharial Conservation Programme, Vivek Ranjan of the Wildlife Institute of India, Devvrat Singh and Shantanu Ugemuge, also of the Gharial Conservation Programme, Akash Deep Badhawan of the Katerniaghat Wildlife Division, and Pulkit Gupta, again of the Gharial Conservation Programme, present the results of a survey of the upper stretch of the Ghaghara River, from the Girijapuri Barrage in Katerniaghat Wildlife Sanctuary downstream to Chahlari Ghat.
The Ghaghara River carries 21% of the total volume of water entering the Ganga, making it the river's largest tributary. Water flow within the Ghaghara is controlled by the Girijapuri Barrage on the Girwa River and the Sharda Nagar Barrage on the Sharda River, both of which are opened three times a year. The opening of the barrages allows large quantities of sediment to be carried downstream, allowing the formation of braids in the Ghaghara River. Vashistha et al. surveyed a 100 km section of the river by boat from the Girijapuri Barrage to Chahlari Ghat between 9.00 am and 5.00 pm on 26 and 27 February 2023, travelling 50 km each day.
Observed Gharials were recorded, and placed in four size classes based upon their estimated lengths, these being yearlings under 1 m in length, juveniles 1-2 m in length, subadults 2-3 m in length, and adults more than 3 m in length. Vashistha et al. also searched for spoor marks on the riverbanks.
Vashistha et al. observed 84 Gharials at 29 locations, the majority of which were young Animals less than 2 m in length, including 16 yearlings presumed to have hatched in 2022. No adult males (which can be identified by the presence of a nasal protuberance called a 'ghara') were observed, although three adult females had bulging abdomens, which is a possible sign of pregnancy. No trace was found of 40 tagged Gharials released into the river by the Uttar Pradesh Forest Department in 2020, although a 2021 survey of the lower part of the river observed eight of these Animals.
Based upon the results of their survey and the survey of the lower part of the river carried out the year before, Vashistha et al. estimate that the Ghaghara River has a population of 258. This is almost four times as high as the estimated population of the Girwa River in Katerniaghat Wildlife Sanctuary. Vashistha et al. believe that this confirms the hypothesis that Gharials are dispersing from the Girwa River into the Ghaghara when the barrage is open. The presence of three females with bulging abdomens suggests that they are breeding on the Ghaghara River, although this cannot be proved. Eight adult males were spotted during the survey of the lower river, and females are known to move some distance between seasons.
There are long stretches of undisturbed, free-flowing water on the Ghaghara River, with plenty of sandy banks suitable for nesting. The river is known to be a sink for Animals dispersing downstream from the Girwa and Kaudiyala rivers, and as well as a population of Gharials, is home to Endangered Ganges River Dolphins, Platanista gangetica, Vulnerable Indian Flapshell Turtles, Lissemys punctata, Indian Softshell Turtles, Nilssonia gangetica, and Indian Tent Turtles, Pangshura tentoria, as well as a wide range of aquatic Birds.
Much of the suitable Gharial nesting habitat on the Girwa River has been degraded by vegetational succession, following a channel shift in 2010, although conservationists are currently working on a project to build artificial sand banks, in order to create more suitable nesting sites. The population of Gharials on the Ghaghara River is considered to be threatened by flow regulation on the barrages, development of riverbank environments for agriculture, and fishing activities on the river.
Vashistha et al. recomend that a system of monitoring is developed for Gharails on the Ghaghara River, as well as the development of a co-operative program involving government agencies and local communities to conserve these Animals on both protected and unprotected rivers in the region.
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