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ESR 22:99-114 (2013)  -  DOI:

Impacts of fisheries on the Critically Endangered humpback dolphin Sousa chinensis population in the eastern Taiwan Strait

Elisabeth Slooten1,*, John Y. Wang2,3, Sarah Z. Dungan2,3, Karin A. Forney4, Samuel K. Hung2,5, Thomas A. Jefferson6, Kimberly N. Riehl2,3, Lorenzo Rojas‑Bracho7, Peter S. Ross8,9, Ashley Wee3, Robin Winkler10, Shih-Chu Yang11, Chaolun A. Chen12

1Otago University, Dunedin 9016, New Zealand
2FormosaCetus Research & Conservation Group, Thornhill, Ontario L4J-7X1, Canada
3Trent University, Peterborough, Ontario K9J 7B8, Canada
4Protected Resources Division, Southwest Fisheries Science Center, NMFS, NOAA, Santa Cruz, California 95060, USA
5Hong Kong Cetacean Research Project, Lam Tin, Kowloon, Hong Kong 999077, SAR
6Clymene Enterprises, Lakeside, California 92040, USA
7Coordinación de Investigación y Conservación de Mamíferos Marinos, Instituto Nacional de Ecología y Cambio Climático (INECC), Ensenada, Baja California 22860, Mexico
8Fisheries and Oceans Canada, Institute of Ocean Sciences, Sidney, British Columbia V8L 4B2, Canada
9Eastern Taiwan Strait Sousa Technical Advisory Working Group (ETSSTAWG), Sidney, British Columbia V8L 3Y3, Canada
10Winkler Partners, Attorneys at Law, Taipei 100, Taiwan
11FormosaCetus Research & Conservation Group, Hualien City, Hualien County 970, Taiwan
12Biodiversity Research Centre, Taiwan International Graduate Program (TIGP) Biodiversity, Academia Sinica, Nangang, Taipei 115, Taiwan

ABSTRACT: Biological and fisheries data were analysed to assess the impact of fisheries mortality on a Critically Endangered subpopulation of <100 humpback dolphins Sousa chinensis in the eastern Taiwan Strait (ETS). Substantial interactions between ETS S. chinensis (hereafter Sousa) and fishing gear are known to cause dolphin mortality. In 2009, a total of 6318 motorised fishing vessels were operating from ports within Sousa habitats. An average of 32 fishing craft per kilometre was observed along a 200 km stretch of Sousa habitat. Based on a photo-identification catalogue, >30% of the ETS Sousa subpopulation exhibited injuries caused by fishing gear. Three individuals were photographed with fishing gear attached to their bodies, and 1 dolphin was found dead with fresh injuries caused by fishing gear. To ensure recovery of ETS Sousa, mortality due to human causes should be reduced to <1 individual every 7 yr. Fisheries bycatch is the most serious threat to these dolphins and needs to be eliminated as soon as possible to avoid extinction. Preventing the use of trammel nets, other gillnets and trawling throughout their habitat would be the single most effective conservation measure for ETS Sousa in the short term. Other fishing methods are available, and using the most selective, sustainable fishing methods available will benefit not only dolphins but also fish stocks, seabirds and other species, as well as the fishing industry, which depends on these species for its long-term viability. However, in the short term, there are costs associated with switching to more selective fishing gear.

KEY WORDS: Fisheries impacts · Eastern Taiwan Strait · Critically Endangered · Bycatch · Indo‑Pacific humpback dolphins

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Cite this article as: Slooten E, Wang JY, Dungan SZ, Forney KA and others (2013) Impacts of fisheries on the Critically Endangered humpback dolphin Sousa chinensis population in the eastern Taiwan Strait. Endang Species Res 22:99-114.

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