Publication

Abstract : Oreochromis niloticus is a widely cultured species because it grows and reproduces in a wide range of environmental conditions and tolerates stress induced by handling. The present studies deals stock assessment and population structure of O. niloticus from the lower stretch of the Yamuna river at Allahabad during August 2011 to July 2012. The fishes of O. niloticus measuring from 10.4 to 44.5 cm. The asymptotic length (L ∞ ∞ ∞ ∞ ∞) and growth coefficient (K) were estimated at 510 mm and 1.61 yr-1 , respectively. The total mortality (Z), fishing mortality (F) and natural mortality (M) were estimated as 4.16 yr-1 , 2.13 yr-1 and 2.03 yr-1 , respectively. Exploitation rate (E) and exploitation ratio (U) were recorded 0.51 yr-1 and 0.50 yr-1. The high value of fishing mortality rates suggests a very intensive exploitation. O. niloticus was exploited at sustainable level in the lower stretch of the Yamuna river at Allahabad. The present investigation clearly showed that the sustainable exploited (E< 0.50) condition of O. niloticus. This type of exploitation is very suitable for heavy recruitment. The population structure of O. niloticus varied from 0+ to 6+ age groups from the Yamuna river at Allahabad. The female population was dominated in 1+ and 2+ age groups.