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Endangered Species Research

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ESR 28:11-17 (2015)  -  DOI:

The legendary hump-backed mahseer Tor sp. of India’s River Cauvery: an endemic fish swimming towards extinction?

Adrian C. Pinder1,2,*, Rajeev Raghavan1,3,4, J. Robert Britton

1Mahseer Trust, c/o The Freshwater Biological Association, East Stoke River Laboratory, Wareham, Dorset BH20 6BB, UK
2Faculty of Science and Technology, Bournemouth University, Fern Barrow, Poole, Dorset BH12 5BB, UK
3Conservation Research Group (CRG), St Albert’s College, Kochi, Kerala, 682 018, Kerala, India
4Laboratory of Systematics, Ecology and Conservation, Zoo Outreach Organization (ZOO), Coimbatore, 641 035, Tamil Nadu, India
*Corresponding author:

ABSTRACT: The Western Ghats region of India is an area of exceptional freshwater biodiversity and endemism. Mahseer of the genus Tor are considered prized sport fishes of great cultural significance; nevertheless, they are threatened as a result of increasing anthropogenic stressors. In the River Cauvery, the mahseer community comprises a ‘blue-finned’ and an orange-finned, ‘hump-backed’ fish. Whilst it is not yet known whether these are distinct species or 2 different phenotypes, evidence suggests that the hump-backed phenotype is endemic to the river, whereas the blue-finned phenotype was introduced in the 1980s. Angler-catch data from a managed fishery on the River Cauvery, gathered between 1998 and 2012 and comprising 23620 h of fishing effort, revealed that captured individuals ranged in size from 0.45 to 46.8 kg, with the blue-finned phenotype comprising 95% of all captured fish and the remainder being hump-backed. The catch per unit effort (CPUE) of the blue-finned phenotype significantly increased over the study period, while the mean weight of individual fish significantly declined. By contrast, the CPUE of the hump-backed phenotype declined significantly over the period, with individual mean weights significantly increasing. These data suggest a recent recruitment collapse in the hump-backed phenotype resulting in an ageing population that may be headed towards extinction. The introduced blue-finned phenotype, however, continues to recruit strongly, suggesting that the mahseer community of the River Cauvery has undergone considerable shifts in the last 30 yr.

KEY WORDS: Western Ghats · Tor khudree · Tor mussullah · Catch and release · Endemic · Recruitment · Recreational fisheries

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Cite this article as: Pinder AC, Raghavan R, Britton JR (2015) The legendary hump-backed mahseer Tor sp. of India’s River Cauvery: an endemic fish swimming towards extinction?. Endang Species Res 28:11-17.

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