Population dynamics of notopterus notopterus (Pallas, 1769) from the Kaptai reservoir of Bangladesh

Abstract

Population parameters of Notopterus notopterus (Pallas, 1769) from length-frequency data collected from Kaptai Reservoir of Rangamati, Bangladesh from January, 2013 to December, 2013 were calculated by using FiSAT software. The asymptotic total length (L_?) and growth coefficient (K) were estimated to be 34.91cm and 0.38 y^?1respectively. The instantaneous rate of natural mortality (M), fishing mortality (F) and total mortality (Z) were estimated to be as 0.91 y^?1, 0.28 y^?1and 1.19 y^?1 respectively. The value of exploitation rate (E) was found to be 0.24 which clearly pointed toward moderate or less fishing pressure (E<0.50) of N. notopterus in the Kaptai reservoir of Bangladesh. The recruitment of the species was found throughout the year with two peaks - one from March-April; and another from May- June. Virtual population analysis (VPA) estimated that the maximum numbers of N. notopterus were caught between 10.50 cm to 32.50 cm with maximum F value (0.80 y^?1) in the mid length of 18.30 cm. During the year 2013 the total catch of N. notopterus was found to be 664.5 MT, which contributed about 7.78% of the total catch of Kaptai Lake. Relative yield per recruit (Y/R) and biomass per recruit (B/R) suggested that the natural mortality should be reduced to 0.91 y^?1 by proper management to obtain a maximum sustainable exploitation rate (E_max= 0.828) for the species in the reservoir.

DOI: http://dx.doi.org/10.3329/sja.v12i2.21923

SAARC J. Agri., 12(2): 112-122 (2014