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Varghese S.P.,Cochin Base of Fishery Survey of India | Vijayakumaran K.,Fishery Survey of India | Tiburtius A.,Fishery Survey of India | Mhatre V.D.,Fishery Survey of India | Mhatre V.D.,West Marine
Indian Journal of Geo-Marine Sciences | Year: 2015

Diversity and abundance of pelagic shark bycatch in the tuna longline operations in northern Indian Ocean were examined for the period 2004-2010. During the survey 1.2 million hooks were deployed in three regions of seas around India resulting in the catch of 1501 numbers of sharks. Significant variations in the diversity and abundance of pelagic sharks were observed among the three regions of Indian seas. Catches of sharks are prominent in Andaman & Nicobar region contributing 35.15% of the catch by number and 51.46% by weight. In the eastern Arabian Sea, sharks constituted 15.49% and 14.89% of the total catch by number and weight respectively. In western Bay of Bengal, this group contributed 7.74% (by number) and 9.33% (by weight) to the total catch. Alopias pelagicus, Carcharhinus limbatus, Alopias superciliosus and Carcharhinus falciformis were the dominant species of pelagic sharks observed in the Indian seas. Time series analysis of hooking rates revealed drastic decline in the abundance of pelagic sharks in the Arabian Sea as well as Bay of Bengal. © 2015, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.

Varghese S.P.,Cochin Base of Fishery Survey of India | Somvanshi V.S.,A 1 Tower | Gulati D.K.,Fishery Survey of India
Indian Journal of Marine Sciences | Year: 2013

Present study consists the studies on the stomach contents of Indo-Pacific sailfish, Istiophorus platypterus (Shaw, 1792), caught during tuna longline survey conducted in the western Indian EEZ (eastern Arabian Sea) between 2006 and 2009 to investigate the sexual, ontogenetic and seasonal effects in the diet. Stomachs of 290 specimens in the forklength range of 101-261 cm were examined, of which 38 (13.10%) were empty. Prey composition was assessed in terms of occurrence by number, frequency of occurrence, weight and Index of Relative Importance. Quantile regression techniques were used to determine the mean and upper and lower bounds of the relation between prey size and sailfish length. Diet was dominated by teleost fishes, followed by cephalopods while crustaceans were represented in limited instances. Purpleback flying squid, Sthenoteuthis oualaniensis, was the most preferred prey species. Other important prey species identified were Euthynnus affinis, Cubiceps pauciradiatus, Gempylus serpens and Onychoteuthis banksii. Diet did not varied by sex, but the ontogenetic and seasonal variations in diet were significant. The maximum and mean size of prey increased with length of sailfish. However, relatively smaller prey constituted bulk of sailfish diet and even large specimens consumed small prey.

Varghese S.P.,Cochin Base of Fishery Survey of India | Vijayakumaran K.,Fishery Survey of India | Anrose A.,Chennai Base of Fishery Survey of India | Mhatre V.D.,Fishery Survey of India
Turkish Journal of Fisheries and Aquatic Sciences | Year: 2013

Distribution, abundance and biology of swordfish, Xiphias gladius, of the Indian seas were investigated by analyzing the data gathered during tuna longline surveys conducted by the Fishery Survey of India (FSI). Study undertaken during the period from 2004 to 2010 revealed swordfish Catch Per Unit Effort of 0.02 numbers in 100 hooks from the Arabian Sea; 0.01 from Bay of Bengal and 0.02 form the Andaman and Nicobar waters. About 16% of the specimens caught were juveniles and the sex ratio of smaller fishes was in favour of males, whereas, larger specimens were mostly females. Length-weight relationship established indicated slightly positive allometric growth of the species and length based models revealed difference in growth between sexes. The growth parameters estimated for females were: asymptotic length (L∞) = 311.11 cm, growth coefficient (K) = 0.17/yr and age at zero length (t0) = -0.53 yr, whereas, the growth parameters estimated for males were: L∞ = 243.79 cm, K = 0.22/yr and t0 = -0.37 yr. Diet was dominated by finfishes and cephalopods, while crustaceans were recorded rarely. Sthenoteuthis oualaniensis was the dominant prey species, followed by Paralepis sp. Spawning area was identified in the Lakshadweep waters from where mature females with hydrated oocytes were caught during December to April. Size at 50% maturity for females was estimated at 164.03 cm, which is reached at about four years of age. Mean batch fecundity was 4.5 million, while the relative fecundity was 37.5 hydrated oocytes per gram of body weight and the diameters of mature oocytes were in the range of 0.9-1.6 mm. Our results provide preliminary information on the abundance, growth and biology of this species in the Indian seas which should be useful to fishery managers. © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey.

Chembian A.J.,Cochin Base of Fishery Survey of India | Mathew S.,Cochin University of Science and Technology
Indian Journal of Fisheries | Year: 2011

The area west of Kollam (38-51 m depth) and south-west of Cochin (38 - 45 m depth) seems to be the preferred region for spawning of the pharaoh cuttlefish Sepia pharaonis along the south-west coast of India. Juveniles appear to stay for some time in the spawning ground and then undertake offshore migration towards relatively deeper areas of the Wadge Bank in 117-132 m depth range. This migration appears to take place via west of Vizhinjam in the depth range of 60 - 86 m. Fecundity varies from 146 to 1400 eggs, depending upon the size of the animal. S. pharaonis appears to spawn intermittently with group-synchronous ovulation. Spawning appears to be monocyclic and egg-laying occurs in separate batches during the spawning period. Egg capsules are either inserted in to the muddy substratum or fastened on the preferred objects apart from entangling with each other.

Samplings were conducted in fifteen stations in the Wadge Bank (lat. 07°07'N to 07°58'N and long. 76°55' E to 77°54'E) along the south-west coast of India for collecting egg capsules of Raja miraletus. Among the 15 stations covered, egg capsules of R. miraletus were observed only at three stations. A total of 119 egg capsules were collected from the area (lat. 07°21'N to 07°29″N and long. 76°55' E to 77°04'E), at the depth range of 112 -123 m indicating this area as the probable spawning ground of the species along the south-west coast of India. Only two of the egg capsules collected had embyo inside. The ratio of unhatched egg capsules to the number of empty capsules found during the survey indicates that, the terminal period of incubation may be in the month of May.

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