This study aimed to test the efficacy of 17 amethyl testosterone (17 a-MT) alone and in combination with letrozole, an aromatase inhibitor, for the induction of sex reversal in protogynous greasy grouper, Epinephelus tauvina. Further, the long-lasting effects of these treatments and spawning performance of sex-reversed males were also investigated. Greasy grouper with oocytes in the perinucleolus stage were implanted with 5 mg 17 a-MT kg À1 body weight (T 1 ), 5 mg 17 a-MT and 0.2 mg letrozole kg À1 body weight (T 2 ) and 5 mg 17 a-MT with 0.4 mg letrozole kg À1 body weight (T 3 ) and no androgens/enzyme inhibitor implanted (C). The 17 a-MT alone and in combination of letrozole-induced sex reversal in greasy grouper, whereas untreated control fish (C) showed normal ovarian development. However, T 2 and T 3 group showed 100% sex reversal and completion of spermatogenesis up to functional male phase in 2 and 3 months, respectively, whereas T 1 group resulted in only 66.67% functional male with motile spermatozoa after 4 months. Sex-reversed males successfully fertilized the eggs during induced spawning. There were significant differences on fertilization and hatching rates between T 2 group (79.00 AE 4.36%; 77.67 AE 2.87%, respectively) and T 1 group (57.67 AE 3.17%; 63.87 AE 2.91%, respectively). The result suggested that 17 a-MT (5.0 mg kg À1 BW) in combination with letrozole (0.2 mg kg À1 BW) has the potential to produce 100% sex-reversed male in short period in greasy grouper, which might greatly help in seed production of greasy grouper.
Beach litter are man-made objects discarded directly or indirectly. This study brings out synoptic picture of status and composition of beach were found in Kerala (17), Maharashtra (12), Tamil Nadu (2), Andhra Pradesh (4), Odisha (7) and West Bengal (3). Whereas extremely littered beaches (>100 g/m 2 ) were found in Karnataka (13), Goa, Gujarat, and Andaman Island. With reference to the coastal population and per capita share of beach debris, Goa registered highest values (40.97 kg/head) and the Odisha coast registered the lowest values (0.005 kg/head).
The present experiment was aimed at studying the conditioning, maturation and natural spawning of orange‐spotted grouper, Epinephelus coioides, in a recirculatory aquaculture system (RAS). Thirty fish (n = 30; 3.35 ± 0.05 kg) were stocked in a circular tank of 125 m3 capacity fitted with an RAS for conditioning and broodstock development. After 15 days, 15 fish were implanted with 17 α methyl testosterone and letrozole at the rate of 5 mg and 0.2 mg/kg body weight, respectively, for conversion from female to male. The gonadal development started after 1 month, and by 90th day, 63.53 ± 3.78% and 2.07 ± 0.84% of the oocytes attained a size of 400–500 μm and 500–600 μm respectively. Natural spawning commenced in the RAS from 4th month onward after stocking and spawning continued round the year. The spawning pair showed courtship behaviour with a typical vertical burst of swimming just before release of gametes. The total number of eggs spawned during 1 year was 47.23 million with spawning frequency varying form 5 to 13 times per month. The association of spawning events with new moon day (lunar cycle) weakened as time progressed. The mean monthly fertilization and hatching rates varied from 77.80 ± 3.34% to 83.70 ± 1.76% and 82.80 ± 4.21% to 88.33 ± 1.39% respectively. The study proved that RAS is an efficient system that provides a stable, controllable and conducive environment for year‐round natural breeding of orange‐spotted grouper.
Present study was undertaken in Godavary Estuary, Andhra Pradesh for evaluation of the effect of three stocking densities on growth performance, survival and production of Lates calcarifer (Bloch, 1790) in floating cages and for optimisation of stocking density in cage farming. Seabass fingerlings having length and weight of 8.36±0.32 cm and 8.10±0.61 g respectively, were stocked in six cages (6 m dia; 3 m net depth) at three different stocking densities of 15, 30 and 45 nos. m -3and their growth performance was monitored every fortnight for five months. All fishes were fed with chopped trash fish @ 8 -12% of body weight. After 150 days of grow-out culture, seabass fingerlings reached 36.0±6.0 cm in length and 690.7±41.3 g in weight at density of 15 nos. m -3 , 33.9±0.4 cm and 633.2±17.9 g at density of 30 m -3 and 30.2±0.4 cm and 465.0±21.2 g at density of 45 nos. m -3 . Growth was allometric and did not differ with stocking density. Survival percentage was comparatively higher at lower (87.3%) and moderate (83.9%) stocking densities, while production was higher at moderate (1363.2 kg) and higher (1258.4 kg) stocking densities (p<0.5). Gain in weight as well as specific growth rate (SGR) were higher at lower and moderate stocking densities (p<0.5). The results of the study indicated that among the three stocking densities tested, 30 nos. m -3 is superior to 15 and 45 nos. m -3, with higher yield.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.