Resource evaluation, stock, growth and mortality of the Bombay duck (Harpodon nehereus Hamilton, 1822) fishery in the coastal waters of Pakistan

摘要

Bombay duck, Harpadon nehereus (Hamilton, 1822), harvested mainly by dol nets, has been a prolific fishery in the northern Arabian Sea. Monthly length composition data for H. nehereus, landed at the Karachi Fish Harbor (KFH) from July 2014 to June 2015 was used to determine growth, mortality and stock evaluation. Total 2252 specimen with an average of 19.171 +/- 2.659 cm TL (14 to 28 cm total length), an average of 45.254 +/- 23.113 g of 9 to 174 g (total body weight) analyzed. The data used in FiSAT-II applying ELEFAN-I package for estimating population dynamics. The estimated the growth parameters of von Bertalanffy Leo = 29.40 cm, K = 0.610 year(-1) and t(0) =-0.359 year(-1) with a phi phi' = 2.722. The length-weight relationship was W = 0.001L(3.477) (R-2 = 0.918) and b 3 is described as positive allometric growth. Total mortality was calculated at Z = 1.800 year(-1), natural mortality estimated at M = 1.276 year(-1) at 27 degrees C in addition, fishing mortality rate was 0.524 year(-1) is not much higher than the safe level (F-opt = 0.638 year(-1)) and a little below edge (F-limit = 0.850 year(-1)) biological reference points. Due to mortality and exploitation rate (E = 0.291 0.50), the population stock and reserves were underutilized.