Reproductive hormone profile and gonadal maturation of Siganus species
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Date
2020
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Fisheries College and Research Institute, Thoothukudi, Tamilnadu Dr.J.Jayalalitha Fisheries University
Abstract
The representatives of the family Siganidae are popularly called as Rabbitfishes or Spinefoot. There are 30 species recorded the world over, and are distributed in reefs among sea grasses, mangroves, and estuaries and in shallow lagoons of tropical and subtropical coastal environments. The present investigation was undertaken to ascertain the effect of reproductive hormone profile and gonadal maturation of Siganus species. The hormone profile of naturally occurring Siganus species were in the range of Siganus canaliculatus – (Testosterone - 0.012 – 1.88 ng/ml; Estrogen - 0.212 – 1.728 ng/ml; Progesterone - 0.42 – 1.68 ng/ml; Prostaglandin – 0.46 – 1.68 pg/ml and Vitellogenin - 0.258 - 1.776 ng/ml), and Siganus lineatus - (Testosterone - 0.012 – 1.776 ng/ml; Estrogen - 0.212 - 2.18 ng/ml; Progesterone - 0.52 - 1.78 ng/ml; Prostaglandin - 0.56 – 2.58 pg/ml and Vitellogenin - 0.258 - 2.776 ng/ml). The gonadal maturation was observed using two different hormones viz., HCG and Ovatide. Based on four hormone concentrations, the fishes were divided into five groups. First, second, third and fourth groups of fishes were injected intramuscularly with HCG and Ovatide respectively. The fifth group was maintained without any hormone injection as sham control. A duplicate set was also maintained simultaneously. Male and female fishes were socked in separate tanks. Monthly samples of blood and gonads were also collected from control and hormone (HCG and Ovatide) injected fishes during the experimental period to assess the hormone profile and maturation using various reproductive parameters such as Gonadosomatic Index (GSI), fecundity and ova diameter. The hormone profile value of Ovatide hormone injected fishes was higher than that of other hormone and control fishes in most of the sampling period. Changes in the hormone profile like Testosterone, Estrogen, Progesterone, Prostaglandin and Vitellogenin levels were observed from the hormone injected fishes when compared to sham control. Maximum levels of Vitellogenin and Prostaglandin level of 6.62 ng/ml and 6.42 pg/ml was observed in blood serum from Ovatide hormone injected S. canaliculatus, whereas S. lineatus injected with Ovatide hormone shows maximum level of Vitellogenin and Prostaglandin of 6.72 ng/ml and 6.52 pg/ml respectively. S. canaliculatus with maximum Testosterone, Estrogen and Progesterone level of 6.32 ng/ml, 5.68 ng/ml and 5.68 ng/ml were observed in blood serum from Ovatide hormone injected while S. lineatus injected showed maximum level of Testosterone, Estrogen and Progesterone level of 6.42 ng/ml, 5.68 ng/ml and 5.72 ng/ml. With the changes in level of hormones, maximum fecundity of S. canaliculatus (125022 eggs) and S. lineatus (165786 eggs), GSI of S. canaliculatus (male fish - 4.25 and female - 4.41) and S. lineatus (male fish - 3.41 and female - 5.41), average ova diameter of S. canaliculatus (2.526 mm) and S. lineatus (2.65 mm) were observed from Ovatide injected fishes. The above results showed that Ovatide plays a major role in hormone profile and gonadal maturation of S. canaliculatus and S. lineatus when compared to other tested hormones.