Studies on catch composition and Biology of Oreochromis niloticus (Linnaeus, 1758) from Nellore and Kanigiri Reservoirs of Andhra Pradesh
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Date
2017-02
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
The present investigation was carried out on Catch composition, Morphometric & Meristics, Length-Weight relationships, Food and feeding, Reproductive biology, Age and growth, Mortality. Length-frequency data of Nile tilapia was collected from fish landing centres of Nellore and Kanigiri reservoirs of Andhra Pradesh from August, 2015 to July, 2016. The catch composition of two reservoirs was investigated and higher annual yield was reported from Nellore reservoir (639.03 kg/ha/yr) than Kanigiri reservoir (334.70 kg/ha/yr). In both the reservoirs, catches of O. niloticus was dominant followed by O. mossambicus and Rohu species (L.rohita, L. calbasu, L. fimbriatus). Basically Nile tilapia is herbivorous followed by omnivorous. Length at first maturity was observed at 189.5
mm and 164.5 mm from Nellore and Kanigiri reservoirs. The absolute fecundity of Nellore and Kanigiri ranged from 1854 to 2371 eggs for 180 to 335 g fish and 368 to 568 eggs for 70 to 190 g fish at each reservoirs respectively. Riped ovaries observed highest during September followed by December from Nellore Reservoir where as March followed by November in case of Kanigiri reservoir. The Von Bertalanffy’s growth parameters for O. niloticus from Nellore reservoir worked out as L = 43.48 cm, K=0.71 per year and to = 0.11. Based on these values the growth at the end of I-IV years of its life worked out to be 23.71, 33.76, 38.7 and 41.13 cm respectively. The Von Bertanlanffy’s growth parameters for O. niloticus in Kanigiri reservoir were L = 29.12 cm, K= 0.69 per year and to = 0.07 and based on these values the growth at the end of I - IV years were 15.2, 22.13, 25.61 and 27.36 cm respectively. The mortality co-efficient (Z, M and F) for Nellore reservoir were estimated as 5.32, 1.70 and 3.62 and for Kanigiri reservoir 5.09, 1.50, 3.59 respectively.
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