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Biological aspects of silky shark Carcharhinus falciformis in the eastern Arabian Sea

Published online by Cambridge University Press:  21 October 2015

Sijo P. Varghese ,
D.K. Gulati ,
N. Unnikrishnan  and
A.E. Ayoob
Sijo P. Varghese*
Affiliation:
Cochin Base of Fishery Survey of India, Kochangadi, Kochi, India
D.K. Gulati
Affiliation:
Cochin Base of Fishery Survey of India, Kochangadi, Kochi, India
N. Unnikrishnan
Affiliation:
Cochin Base of Fishery Survey of India, Kochangadi, Kochi, India
A.E. Ayoob
Affiliation:
Cochin Base of Fishery Survey of India, Kochangadi, Kochi, India
*
Correspondence should be addressed to:S.P. Varghese, Cochin Base of Fishery Survey of India, Kochangadi, Kochi, India email: varghesefsi@hotmail.com
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Abstract

Reproduction, diet and growth of silky shark Carcharhinus falciformis in the eastern Arabian Sea are described based on 473 specimens collected from the gillnet-cum-longline landings at the Cochin fisheries harbour during 2012–2014. The reproductive biology of 215 males and 258 females was examined while 113 stomachs were sampled to study the diet. The von Bertalanffy growth parameters estimated using length-based models were asymptotic length (L ∞) = 309.80 cm, growth coefficient (K) = 0.10 year−1 and age at zero length (t 0) = −2.398 year. The sex ratio was significantly skewed to females. Seasonality in reproduction was not evident and in males, sexual maturity was attained at 201–223 cm total length (L T) with the size at maturity (L T50) occurring at 217.0 cm, whereas in females sexual maturity was attained at 224–231 cm L T and L T50 occurs at 226.5 cm. In total 114 embryos, in the length range of 12.2–65.1 cm were recovered from 15 pregnant females. Numbers of embryos in females were in the range of 3–13, averaging 7.6. Silky sharks of the eastern Arabian Sea feed primarily on swimming crab Charybdis smithii, with juveniles feeding principally on swimming crabs, while adults feed on actively swimming prey like squids and teleost fishes. This preliminary information on the reproduction, diet and growth should be useful to identify management strategies for silky sharks in the eastern Arabian Sea.

Keywords

Elasmobranchswestern Indian Exclusive Economic Zonegillnet-cum-longline fisherymaturitystomach contentsgrowth parameters

Information

Type
Research Article
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 96 , Issue 7 , November 2016 , pp. 1437 - 1447
Copyright
Copyright © Marine Biological Association of the United Kingdom 2015 

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