Browsing by Author "V.K. Venkataramani"
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ReprintItem Open Access Population dynamics of siboga squid Doryteuthis sibogae (Cephalopoda/Teuthoidea) in Thoothukkudi (Tuticorin) coast, southeast coast of lndia(2002) N. Neethiselvan; V.K. VenkataramaniStudy on the poputalion dynamics of siboga squid Doryteuthis sibogae in Thoothukkudi coast revealed that the seasonal change has define impact on the growth of this species.The. study infers that the cod end mesh size of the trawls of Thoothukkudi has to be increased from 10 to 25 mm to increase the yield per recruit. Further the effort should be reduced and maintained at the exploitation ratio of 0.45 to get maximum yield per recruit.ReprintItem Open Access Reproductive biology of the siboga squid Doryteuthis sibogae (Adam) from Thoothukkudi (Tuticorin) coast, southeast coast of India(Indian journal of marine sciences, 2001-12) N. Neethiselvan; V.K. Venkataramani; B. SrikrishnadhasStudies on the seasonal occurrence of maturity stages of Doryteuthis sibogae revealed that it is a prolonged breeder as matured and spent specimens of both the sexes were recorded almost round the year. Two peak spawning periods, one from August to September and another from'December to January were observed. Matured animals were represented by a wider length range inferring non semelparous nature of the species. However, dominance of males during peak spawning season as evidenced fionr sex ratio studies do confirm existence of a minor degree of post spawning mortality in females. The weight of gonad and nidamental glands increased during maturation and proved as good indices of maturation. Females attained maturity earlier than males. Fecundity showed a significant correlation with dorsal mantle length. Doryteuthis sibogae form regular fishery in Thoothukkudi coast on commercial scale. Since this species is a continuous spawner as evidenced in the present study and is intensively exploited at Thoothukkudi bay, an in depth study on stock assessment of this species is an urgent need to sustain the fishery.ReprintItem Open Access Sepia prabahari sp. nov. (Mollusca/Cephalopoda), a new species of Acanthosepion species complex from Tuticorin bay, southeast coast of India(Indian journal of marine sciences, 2002-03) N. Neethiselvan; V.K. Venkataramaninew cuttlefish Sep,a prabahari sp. nov. collected from Tuticorin bay(8"47'N, 78"9'E) is described with a comparison of the closely related species Sepia pharaonis. Sepia prabahari sp. nov. shows a clear-cut sexual dimorphism with respect to length and shape of arms. ln males, first and fourth pair of arms distinctly extended and whip like. However, in females, first and fourth arms are neither distinctly extended nor whip like. Sepia prabahari sp. nov. closely resembles the juvenile of Sepia pharaonis of both of them have distinct tiger-stripe pattern on the dorsal side of the mantle. However,.sepia prubahari sp. nov. can easily be distinguished from the closely related spicies ,S. pharaonis based on the arrangement of suckers in the tentacular club. The tentacular club ofs. prabalrari sp. nov. is with minute suckers of equal size without any entarged suck, ers, in contrast to that of .S. pharaonis with big suckers, of which about 6 suckers in medial rows are much enlarged. In S -prabahari sp. nov. the left ventral arm of male is hectocotylised with 8 hansverse series of normal basal suckers fol-Iowed by 7 series of modified suckers, in contrast to 10-12 basaltransverse series of normal suckers followed by 7 series of modified suckers in S-pharaonis. Further, S prabaha sp. nov belongs to Acanthosepion species complex (Rocheburne, 1884) as its inner cone ofthe cuttlebone is distinct, forming rounded and cap-like cavity in contrast to that of plate like callosity in S.pharaonis and hence belongs to Sep ia sensu stricto species complex. The diagnostic characters of the species belong to the Acalthosepion species complex of the genus Sepla of Indian waters with that of S- prabahari sp. nov. are also discussed.ReprintItem Open Access Use of Fermented Fish Ensilage in the Diets of Etroplus suratensis (Bloch)N. Neethiselvan; G. Indira jasmine; D. Manikandavelu; V.K. VenkataramaniA feeding experiment was conducted to assess the ability of Etroplus suratensis (Bloch) to utilize diets containing fish ensilage as a major protein source' Attempt was also made to find out whether the neutralization of the fermented ensilage influenced the growth of E. suratensis or not. No significant difference in the survival rate of fish fed with various feeds was noticed (P(0.05). However, significant difference could be observed in specific growth rate,(p<0.01), food conversion efficiency and protein efficiency ratio (P<0.05) The study revealed that the diets containing fish ensilage, either neutralized with calcium hydroxide or without neutralization could yield better wait gains(86.25% and 89.08% respectively ) than other feeds. E. suratensis could utilize the diets containing fish ensilage as the as hydroxide protein recorded lower wait gain (80.87%)the effect was more adverse when potassium hydroxide was used as the neutralizating agent (56.18%)