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

Abstract

Bombay duck, <em>Harpadon nehereus</em> (Hamilton, 1822), harvested mainly by dol nets, has been a prolific fishery in the northern Arabian Sea. Monthly length composition data for <em>H. nehereus</em>, 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 L∞ = 29.40 cm, K = 0.610 year^-1 and t₀= -0.359 year^-1 with a phi φ’ = 2.722. The length-weight relationship was W = 0.001L^3.477 (R²= 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 °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 (Fl_imit= 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.