Estimated beam pattern and echolocation characteristics of clicks recorded from a free-ranging Ganges river dolphin

Author(s):  
Tamaki Ura ◽  
Rajendar Bahl ◽  
Harumi Sugimatsu ◽  
Junichi Kojima ◽  
Tomoki Inoue ◽  
...  
Author(s):  
Rajendar Bahl ◽  
Harumi Sugimatsu ◽  
Junichi Kojima ◽  
Tamaki Ura ◽  
Sandeep Behera ◽  
...  

2006 ◽  
Vol 120 (5) ◽  
pp. 3228-3228 ◽  
Author(s):  
Tamaki Ura ◽  
Harumi Sugimatsu ◽  
Tomoki Inoue ◽  
Rajendar Bahl ◽  
Junichi Kojima ◽  
...  

Mammalia ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Shakti Prajapati

AbstractPopulations of endangered Ganges and Indus river dolphins have been under severe threat from diversion of river water by dams, barrages, and canal networks across the Indus and Ganges–Brahmaputra river basins. River dolphins prefer deep water and might enter irrigation canals in the dry-season, getting stranded there. Stranding can cause mortality and local population declines, and poses an emerging challenge to river dolphin conservation efforts. In Pakistan’s Indus river basin, stranding rates of Indus dolphins in irrigation canals are high, and well-coordinated rescue-release operations are undertaken. Despite commendable river dolphin rescue efforts in some parts of India, stranding cases are not always reported. From open-access media reports (2007–08 to 2017–18), I found 26 stranding cases of Ganges river dolphins from the Ghaghara–Sharada canal network across seven districts of Uttar Pradesh, India. Of these, 62% reports were from 2015 to 2016. Most cases occurred in secondary and tertiary canal branches. Interviews with fishers, farmers, and government officials revealed low awareness of stranding cases. Stranded dolphins might have no chance of returning to their source habitat, unless rescued. From my results, I discuss how current barrage-canal operations could influence dolphin stranding risk, and their implications for flow management in the Ghaghara–Sharada river basin.


Mammalia ◽  
2012 ◽  
Vol 76 (4) ◽  
Author(s):  
Tawqir Bashir ◽  
Afifullah Khan ◽  
Sandeep Kumar Behera ◽  
Parikshit Gautam
Keyword(s):  

AMBIO ◽  
2014 ◽  
Vol 43 (8) ◽  
pp. 1029-1046 ◽  
Author(s):  
Ravindra K. Sinha ◽  
Kurunthachalam Kannan

2018 ◽  
Author(s):  
Gabriel Melo-Santos ◽  
Angélica Lúcia Figueiredo Rodrigues ◽  
Rodrigo Hipólito Tardin ◽  
Israel de Sá Maciel ◽  
Miriam Marmontel ◽  
...  

The recent discovery of the Araguaian river dolphin (Inia araguaiaensis) highlights how little we know about the diversity and biology of river dolphins. In this study, we described the acoustic repertoire of this newly discovered species in concert with their behaviour in free-ranging, human-habituated individuals. We analysed 393 signals that we classified into 13 types of tonal sounds (n=15) and 66 types of pulsed calls (n=378). The most common sounds were short two-component calls. Thirty-five percent (n=140) of these calls were emitted by calves as they reunited with their mothers suggesting a key role in mother-calf communication. Our findings show that the acoustic repertoire of river dolphins is far from simple. Furthermore, the calls described here are similar in acoustic structure to those produced by social delphinids, such as orcas and pilot whales. Uncovering the context in which these signals are produced may help understand the social structure of this species and contribute to our understanding of the evolution of acoustic communication in whales.


2015 ◽  
Author(s):  
Shambhu Paudel ◽  
Juan C Levesque ◽  
Camilo Saavedra ◽  
Cristina Pita ◽  
Prabhat Pal

The Ganges River dolphin (Platanista gangetica gangetica) (GRD) is classified as one of the most endangered of all cetaceans in the world and the second scarcest freshwater cetacean. The population is estimated to be less than 2,000 individuals. In Nepal’s Narayani, Sapta Koshi, and Karnali river systems, survival of GRD continues to be threatened by various anthropogenic activities, such as dam construction and interactions with artisanal fisheries. A basic description of the geographic scope, economics, and types of gear used in these fisheries would help managers understand the fishery-dolphin interaction conflict and assist with developing potential solutions to reduce interactions between GRD and local fisheries in Nepal. The main purpose of the study was to collect fishery and socio-economic information by conducting interviews with local fishermen in the Narayani, Sapta Koshi, and Karnali river systems. Based on interviews (n = 163), 79 percent of Nepalese fishermen indicated fishing for local species (e.g., mullet [Rhinomugil corsula] or siloroid catfish [Bagarius bagarius]) was their primary form of income. Fishermen reported fishing effort was greater in summer than winter; greatest in the afternoon (1430 hrs ± 0.27) and during low water level conditions; and gear was set 4.8 ± 0.2 days/week. Fishermen reported using eight different types of monofilament nets (gillnets and cast nets). Sixty percent used gillnets less than 10 m long, and less than one third preferred gillnets between 10 and 100 m long; a few used gillnets longer than 100 m. Fishermen usually set their gear close to their village, and about 50 percent preferred to fish in tributaries followed by the main channel behind sandbars and islands, and the main channel near a bank. Fishermen reported seeing more GRD in the main river stem in winter. In summer, fishermen spotted more GRD in tributaries. Most fishermen told us they believed education, awareness, and changing occupations were important for GRD conservation, but they indicated that occupational options were currently limited in Nepal. Nepalese fishermen acknowledged that fisheries posed a risk to GRD, but they believed water pollution, and dam/irrigation development were the greatest threats.


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