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Susceptibility of sharks, rays and chimaeras to global extinction

Field, Iain Craig, Meekan, Mark G., Buckworth, R. and Bradshaw, Corey J. A. (2009). Susceptibility of sharks, rays and chimaeras to global extinction. Advances in Marine Biology,56:275-363.

Document type: Journal Article
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Title Susceptibility of sharks, rays and chimaeras to global extinction
Author Field, Iain Craig
Meekan, Mark G.
Buckworth, R.
Bradshaw, Corey J. A.
Journal Name Advances in Marine Biology
Publication Date 2009
Volume Number 56
ISSN 0065-2881   (check CDU catalogue open catalogue search in new window)
Start Page 275
End Page 363
Total Pages 89
Place of Publication US
Publisher Academic Press
HERDC Category C1 - Journal Article (DEST)
Abstract Marine biodiversity worldwide is under increasing threat, primarily as a result of over-harvesting, pollution and climate change. Chondrichthyan fishes (sharks, rays and chimaeras) have a perceived higher intrinsic risk of extinction compared to other fish. Direct fishing mortality has driven many declines, even though some smaller fisheries persist without associated declines. Mixed-species fisheries are of particular concern, as is illegal, unreported and unregulated (IUU) fishing. The lack of specific management and reporting mechanisms for the latter means that many chondrichthyans might already be susceptible to extinction from stochastic processes entirely unrelated to fishing pressure itself. Chondrichthyans might also suffer relatively more than other marine taxa from the effects of fishing and habitat loss and degradation given coastal habitat use for specific life stages. The effects of invasive species and pollution are as yet too poorly understood to predict their long-term role in affecting chondrichthyan population sizes. The spatial distribution of threatened chondrichthyan species under World Conservation Union (lUCN) Red List criteria are clustered mainly in (1) south-eastern South America; (2) western Europe and the Mediterranean; (3) western Africa; (4) South China Sea and Southeast Asia and (5) south-eastern Australia. To determine which ecological and life history traits predispose chondrichthyans to being IUCN Red-Listed, and to examine the role of particular human activities in exacerbating threat risk, we correlated extant marine species' Red List categorisation with available ecological (habitat type, temperature preference), life history (body length, range size) and human-relationship (whether commercially or game-fished, considered dangerous to humans) variables. Threat risk correlations were constructed using generalised linear mixed-effect models to account for phylogenetic relatedness. We also contrasted results for chondrichthyans to marine teleosts to test explicitly whether the former group is intrinsically more susceptible to extinction than fishes in general. Around 52% of chondrichthyans have been Red-Listed compared to only 8% of all marine teleosts; however, listed teleosts were in general placed more frequently into the higher-risk categories relative to chondrichthyans. IUCN threat risk in both taxa was.
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