Studies on catch composition and Biology of Etroplus suratensis (Bloch, 1790) and Oreochromis niloticus (Linnaeus, 1758) from Survepalli Reservoir of Andhra Pradesh
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Date
2018-08
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
The present investigation on Etroplus suratensis and Oreochromis niloticus describes the Morphometric and Meristic characters, Length-Weight relationship, Food and feeding habits, Reproductive biology and Age, Growth and Mortality parameters. The maximum length of Etroplus suratensis and Oreochromis niloticus were examined and found to be 23.6 cm and 42.4 cm from Sarvepalli reservoir. The observed ‘b’ values of Etroplus suratensis (Male = 2.912, Female = 3.048, Juveniles = 2.899) and for Oreochromis niloticus (Male = 3.015, Female = 3.056, Juveniles = 3.072) indicates that the growth was isometric, where the value of b can be approximated to ‘3.0’. Etroplus suratensis found to be omnivorous and feeds mainly on Filamentous algae and Oreochromis niloticus found to be herbivorous and feeds on Diatoms. The length at first maturity were observed to be 149 mm and 251 mm for E. suratensis and O. niloticus. Fecundity estimates ranged from 757 - 3715 and 1852 - 3064 for E. suratensis and O. niloticus. Age at zero length (t0) calculated as – 0.14 for E. suratensis and – 0.22 for O. niloticus. Growth parameters such as asymptotic length “L∞” and growth co-efficient “K” were estimated to be 24.8 cm and 0.43 for E. suratensis and 44.2 cm and 0.86 for O. niloticus. The total mortality (Z), natural mortality (M) and fishing mortality (F) calculated for Etroplus suratensis were 1.25, 1.0 and 0.25 and For Oreochromis niloticus were 3.21, 0.11 and 3.10 respectively.
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