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Towards better management of Australia’s shark fishery: genetic analyses reveal unexpected ratios of cryptic blacktip species Carcharhinus tilstoni and C. limbatus

Ovenden, J.R. and Morgan, J. and Kashiwagi, T. and Broderick, D. and Salini, J. (2010) Towards better management of Australia’s shark fishery: genetic analyses reveal unexpected ratios of cryptic blacktip species Carcharhinus tilstoni and C. limbatus. Marine and Freshwater Research, 61 (2). pp. 253-262.

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Article Link(s): http://dx.doi.org/10.1071/MF09151

Publisher URL: http://www.publish.csiro.au/

Abstract

The common blacktip shark (Carcharhinus limbatus) and the Australian blacktip shark (C. tilstoni) are morphologically similar species that co-occur in subtropical and tropical Australia. In striking contrast to what has been previously reported, we demonstrate that the common blacktip shark is not rare in northern Australia but occurs in approximately equal frequencies with the Australian blacktip shark. Management of shark resources in northern Australia needs to take account of this new information. Species identification was performed using nucleotide sequences of the control, NADH dehydrogenase subunit 4 (ND4) and cytochrome oxidase I (COI) regions in the mitochondrial genome. The proportion of overall genetic variation (FST) between the two species was small (0.042, P < 0.01) based on allele frequencies at five microsatellite loci. We confirm that a third blacktip species (C. amblyrhynchoides, graceful shark) is closely related to C. tilstoni and C. limbatus and can be distinguished from them on the basis of mtDNA sequences from two gene regions. The Australian blacktip shark (C. tilstoni) was not encountered among 20 samples from central Indonesia that were later confirmed to be common blacktip and graceful sharks. Fisheries regulators urgently need new information on life history, population structure and morphological characters for species identification of blacktip shark species in Australia.

Item Type:Article
Corporate Creators:DEEDI, CSIRO
Additional Information:© CSIRO
Keywords:Blacktip shark; COI; control region; cytochrome oxidase I; fisheries; Indonesia; NADH dehydrogenase subunit 4; ND4; species identification.
Subjects:Aquaculture and Fisheries
Science > Biology > Genetics
Deposited On:28 Apr 2011 07:01
Last Modified:28 Apr 2011 07:01

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