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First record of the pelagic thresher shark Alopias pelagicus (Pisces: Alopiiformes: Alopiidae) from the Lakshadweep Sea, India

Published online by Cambridge University Press:  27 March 2012

K.V. Aneesh Kumar ,
S. Paresh Khanolkar ,
P. Pravin ,
B. Meenakumari  and
E.V. Radhakrishnan
K.V. Aneesh Kumar*
Affiliation:
Central Institute of Fisheries Technology, CIFT Junction, Matsyapuri PO, Cochin-682029, India
S. Paresh Khanolkar
Affiliation:
Central Institute of Fisheries Technology, CIFT Junction, Matsyapuri PO, Cochin-682029, India
P. Pravin
Affiliation:
Central Institute of Fisheries Technology, CIFT Junction, Matsyapuri PO, Cochin-682029, India
B. Meenakumari
Affiliation:
Indian Council of Agricultural Research, Krishi Anusandhan Bhavan-II, New Delhi-110012, India
E.V. Radhakrishnan
Affiliation:
Central Marine Fisheries Research Institute, Cochin-682018, India
*
Correspondence should be addressed to: K.V. Aneesh Kumar, Central Institute of Fisheries Technology, CIFT Junction, Matsyapuri PO, Cochin-682029, India email: menoncift@gmail.com

Abstract

The pelagic thresher shark Alopias pelagicus is a large, wide-ranging Indo-Pacific Ocean pelagic shark. In this paper, the first record of the pelagic thresher shark, caught from the Lakshadweep Sea is reported. The shark 275 cm in total length was caught by drift longline operation at depth of 60 m in the Lakshadweep Sea (10°52N latitude 72°13E longitude).

Keywords

Alopias pelagicusLakshadweep Sea
Type
Research Article
Information
Marine Biodiversity Records , Volume 5 , August 2012 , e16
Copyright
Copyright © Marine Biological Association of the United Kingdom 2012

INTRODUCTION

Family Alopiidae includes three species of thresher sharks viz., pelagic thresher Alopias pelagicus (Nakamura, 1935), bigeye thresher, A. superciliosus and thresher shark A. vulpinus. Distribution of pelagic thresher is largely restricted to the Indian and Pacific Oceans (Compagno, Reference Compagno2001). The pelagic thresher is highly migratory inhabiting in both coastal and oceanic waters in temperate and tropical seas. It can grow very large in size (Lmax = 365 cm total length (TL)) and the growth rate is comparatively very low (K = 0.10 year−1) showing late sexual maturity (8.0–9.2 years for females and 7.0–8.0 years for males) and usually producing about two embryos per litter (Liu et al., Reference Liu, Chen, Liao and Joung1999).

The occurrence of this species in the Indian Ocean has been documented by Pillai & Honma (Reference Pillai and Honma1978), John & Varghese (Reference John and Varghese2009), Huang & Liu (Reference Huang and Liu2010), Romanov et al. (Reference Romanov, Bach, Rabearisoa, Rabehagasoa, Filippi and Romanova2010) and others. Shark distribution is said to be high in the north of the equator (Pillai & Honma, Reference Pillai and Honma1978). This species is reported from the Indian Exclusive Economic Zone by Vijayakumaran (Reference Vijayakumaran1994), Pillai & Parakkal (Reference Pillai and Parakkal2000), Bhargava et al., (Reference Bhargava, Somvanshi, Varghese, Pillai, Menon, Pillai and Ganga2002), Manojkumar & Pavithran (Reference Manojkumar and Pavithran2006), Kizhakudan et al. (Reference Kizhakudan, Rajapackiam and Rajan2007) and Joshi et al. (Reference Joshi, Balachandran and Raje2008), and contributes considerably to the elasmobranch fishery of India. Alopias vulpinus is the only species of thresher shark previously reported from the Lakshadweep Sea (Jones & Kumaran, Reference Jones and Kumaran1980). In this paper, evidence of the occurrence of Alopias pelagicus in the Lakshadweep Sea is presented.

MATERIALS AND METHODS

A male pelagic thresher shark Alopias pelagicus was landed during longline operation in the Lakshadweep Sea by fishermen from Agatti Island on 4 April 2011 (Figure 1). The shark was caught on the 3.4 Sun Japanese tuna hook and the location of capture was recorded as 10°52N latitude; 72°13E longitude. The morphometric measurements of the shark were made with a measuring tape to the nearest millimetre (Compagno, Reference Compagno1984) and weight was measured to the nearest gram. The species identification was carried out based on Compagno (Reference Compagno1984).

Fig. 1. Pelagic thresher shark, Alopias pelagicus.

RESULTS

The morphometric measurements of the specimen are given in Table 1. The TL of the specimen was 275 cm and standard length was 160 cm. The size of the shark was bigger than earlier reported from the Arabian Sea by Joshi et al. (Reference Joshi, Balachandran and Raje2008).

Table 1. Morphometric measurements of Alopias pelagicus.

The species has moderately large eyes reaching up to the dorsal surface of the head. Head is convex and the forehead is moderately convex in the lateral view. An inconspicuous horizontal groove is present on each side of the head above the gills. Labial furrows are absent. Snout is moderately long and conical. Pectoral fins are not falcate and the tips are broad and straight. Terminal lobe of the caudal fin is very small. Ventral side is white in colour and is not extending beyond the pectoral fin bases.

DISCUSSION

The pelagic thresher shark is a large, wide-ranging Indo-Pacific Oceanic species, which is highly migratory, with low fecundity and a low annual rate of population increase. The thresher sharks are listed as ‘Vulnerable’ globally because of their declining populations (IUCN, 2011). Our study presents the first record of Alopias pelagicus from the Lakshadweep Sea.

ACKNOWLEDGEMENTS

The authors are grateful for the encouragement given by the Director, CIFT, Cochin and Mr Mark, Department of Conservation, UK for help in species identification. The financial assistance received from NAIP, ICAR, and the Government of India is gratefully acknowledged.

References

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Figure 0

Fig. 1. Pelagic thresher shark, Alopias pelagicus.

Figure 1

Table 1. Morphometric measurements of Alopias pelagicus.