[MARMAM] Seasonal flow dynamics exacerbate overlap between artisanal fisheries and imperiled Ganges River dolphins

SHAMBHU PAUDEL spaudel at email.arizona.edu
Mon Nov 2 06:54:58 PST 2020

Hi all:

Please find the recent research outcomes on the interactions between
artisanal fisheries and endangered Ganges River dolphins in Nepalese

Paudel, S., Koprowski, J.L. & Cove, M.V. Seasonal flow dynamics exacerbate
overlap between artisanal fisheries and imperiled Ganges River dolphins. *Sci
Rep* 10, 18798 (2020). https://doi.org/10.1038/s41598-020-75997-4

Here we quantify the effects of artisanal fisheries on the ecology of a
small cetacean, the Ganges River dolphin (*Platanista gangetica gangetica*,
GRD), in a large river system of Nepal. We examine the size-classes of
fisheries’ catches, behavioural changes in GRD in response to fishing
activities, and diel overlap between GRD and fishing activity. We observed
high human exploitation rates (> 60% of the total catch per effort) of
GRD-preferred prey sizes, indicating risks of high resource competition and
dietary overlap, especially during the low water season when resource
availability is reduced. Competitive interactions in the feeding niches
during the low water season, plus temporal overlap between the peak
exploitation and critical life-history events (e.g., reproduction), likely
have ecological consequences. Furthermore, we detected 48% (95% CI 43–52%)
increase in the chance of behavioural changes among dolphins exposed to
anthropopressure (fishing activity), risking social behaviour impairment in
exposed dolphins. The higher diel overlap and increased diel coefficient as
the surveys progressed towards the monsoon season suggest temporal shifts
in GRD socio-behavioural states and seasonal effects on resource
partitioning, respectively. This work identifies drivers of small
cetaceans-fisheries interactions and their consequences, and can be used to
help reduce biologically significant fishing impacts on small cetaceans.
Mitigation strategies, together with river sanctuary and distanced-based
approaches, should be urgently included in a framework of ecosystem-based



*Ph.D. Candidate / **Russell E. Train Fellow (EFN/WWF-USA) *

School of Natural Resources & the Environment

Wildlife Conservation and Management

Environment & Natural Resources 2

University of Arizona

Tucson, Arizona  85721 USA

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