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Endangered Species Research

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ESR 39:207-220 (2019)  -  DOI: https://doi.org/10.3354/esr00962

REVIEW
Electrofishing as a potential threat to freshwater cetaceans

Peter O. Thomas1,*, Frances M. D. Gulland1, Randall R. Reeves2, Danielle Kreb3, Wang Ding4, Brian Smith5, Muhammad Imran Malik6, Gerard E. Ryan7, Somany Phay8

1Marine Mammal Commission, 4340 East-West Highway, Bethesda, Maryland 20814, USA
2Okapi Wildlife Associates, 27 Chandler Lane, Hudson, Quebec J0P1H0, Canada
3Yayasan Konservasi Rasi, Komplek Pandan Harum Indah, Samarinda, 75124 Kalimantan Timur, Indonesia
4Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, Hubei 430072, PR China
5Wildlife Conservation Society, Asian Coastal Cetacean Program, IUCN SSC Cetacean Specialist Group, Arcata, California 95518, USA
6Indus River Dolphin Conservation Project (IRDCP), WWF-Pakistan, Sukkur 65310, Pakistan
7School of BioSciences, University of Melbourne, Melbourne, Victoria 3052, Australia
8WWFund Cambodia, #21, St. 322, Boeung Keng Kang I, Chamkar Morn, Phnom Penh 12300, Cambodia
*Corresponding author:

ABSTRACT: Electrofishing is an accepted practice for legal fish sampling and surveying, but its use for subsistence food and market fishing has long been illegal in most countries. Illegal use affects freshwater fish populations in many parts of the world, and has been cited as a cause of mortality for endangered freshwater cetaceans in China (Yangtze dolphins and finless porpoises) and Southeast Asia (Ayeyarwady, Mekong, and Mahakam dolphins in Myanmar, Cambodia, and Indonesia, respectively), although the extent of this threat to cetaceans is unclear. Given their threatened status, these populations can ill afford such mortality in addition to the other threats they face (e.g. entanglement in gillnets, habitat deterioration and loss, declines in prey). Here, we review the evidence that electrofishing is a serious threat to freshwater cetaceans. It may alter the behavior of dolphins and porpoises, and contact with electrical currents may even directly kill or injure these animals, although questions remain unanswered concerning the exact nature and scale of the impacts. While other threats may appear more certain and urgent, electrofishing could be playing a significant role in driving the declines of some critically endangered freshwater cetaceans in Asia. Due to ethical and logistical challenges to improving our understanding of the impacts of electrical currents on cetaceans, clear descriptions of lesions in dead animals found stranded are needed to characterize the damage caused by electrofishing, to be more certain about cause and effect beyond spatiotemporal associations, and to determine the extent of this threat. Mortality from electrofishing seems to be uncommon, but in face of the uncertainties and the numerous other threats to these small populations, high priority should be given to enforcing electrofishing bans in the freshwater habitat of dolphins and finless porpoises.


KEY WORDS: Freshwater cetaceans · River dolphins · Finless porpoises · Electrofishing · Cetacean conservation


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Cite this article as: Thomas PO, Gulland FMD, Reeves RR, Kreb D and others (2019) Electrofishing as a potential threat to freshwater cetaceans. Endang Species Res 39:207-220. https://doi.org/10.3354/esr00962

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