A recent publication by scientists and researchers has revealed that 19 Gangetic river dolphins had been rescued from the irrigation canals of the Ganga-Ghagra basin in Uttar Pradesh between 2013 and 2020.
The publication titled ‘Rescuing Ganges river dolphins (Platanista gangetica) from irrigation canals in Uttar Pradesh, North India, 2013–2020‘ not only highlights the capture and relocation methods but also describes the behavioural and demographic details of rescued animals and locations of these canals where the animals had been trapped.
The paper points out that 24 rescue operations had been conducted from 2013 to 2020 and five dolphins had died.
“There were 19 successful rescue operations and 14 dolphins were identified as female and 10 as male. The TBL (total body length) of these dolphins was found to be between 128 cm and 275 cm. The size of male dolphins ranged from 128 cm to 195 cm, whereas the females ranged from 190 cm to 274 cm. Of the five dolphins that died, three had a length over 243 cm,” the paper said.
The publication said dams and barrages had severely affected this habitat as dolphins moved into irrigation canals where they were at a risk of injury or death from a multiple factors, such as rapidly receding waters, heat stroke and human interferences.
The Ganges river dolphin is in Schedule 1 of the Indian Wildlife (Protection) Act 1972, Appendix 1 of the Convention on International Trade in Endangered Species (CITES) and Appendix 1 of the Convention on Migratory Species (CMS).
Endangered species
The species, also considered the national aquatic animal, is listed as “endangered” on the IUCN Red List.
Though the species is not known to be gregarious, the researchers observed and handled at least one adult male and female together on five occasions. “Furthermore, adult females have been seen with a calf on two occasions. These observations suggest that they may prefer to live and/or hunt in the pod. The dolphins may either stray into the canal while following prey upstream or get flushed into the canal by a sudden discharge of water from the barrage gates,” the paper said.
The researchers also pointed out the higher proportion of females to males, and said larger animals and pregnant females look for an easier prey base in the canal system.
Over 70% of entrapments were reported either post monsoon or during peak winter. This suggests straying incidents are directly related to the release of water into canals during or after the monsoon.
“The other 30% of dolphins were rescued during peak summer when water levels fall and the minimum water flow is maintained. Among the rescued dolphins, females were found trapped between September and May with maximum occurrence during peak winter (December to February). In contrast, males were mostly recorded post monsoon and during the summer season, with least occurrence in peak winter,” the paper says.
Shailendra Singh of the Turtle Survival Alliance Foundation India, one of the lead authors of the paper, said that the paper gives data for eight years but from 2013 to 2023, 28 dolphins had been rescued. He explained that the rescue of dolphins required expertise as it was a delicate animal. Keeping them alive after the rescue was also a challenge.
Huge area
“This is a big issue; on an average, we rescue two or three animals and another two or three animals may die in canal network of Gangetic basin every year without timely information. Considering that the dolphins are found in the Ganga-Brahmaputra-Meghna delta, this is a huge problem to monitor this huge area and canal system,” he said.
The other authors of the paper are Arunima Singh, Sreeparna Dutta and Sanjay Srivastava, a senior forest official of the Uttar Pradesh cadre.
The publication states that in 2016, the International Whaling Commission’s (IWC) scientific committee recognised that both Ganges and Indus river dolphins require prompt and coordinated action to protect them from imminent threats.
In 2017, the IWC created the Asian River Dolphin Task Team (AR‐TT) to identify information gaps and research priorities and develop concerted action for the protection of the Ganges and Indus river species in their range.
One of the key recommendations of the scientists is that IWC AR‐TT recognised the issue of canal entrapment and suggested a focused study be conducted to understand the movements of dolphins across barrages in all countries. The publication recommends a pilot scheme using sonic devices or ‘pingers’ at all three barrages in the Ghaghara subbasin to test their efficacy as deterrents, with a view to expanding their use across the range of present species.
