Estimation of growth, mortality and exploitation of lesser tiger toothed croaker Otolithes cuvieri (Trewavas. 1974) in Pakistan

摘要

Four demersal trawl surveys were carried out in Pakistani marine waters in 2009-2010. Length frequency data of 3219 individuals were used to estimate growth, mortality and exploitation, whereas data of 671 individuals were used to estimate length weight relationship in Otolithes cuvieri (Trewavas, 1974). Length ranges from 3 - 35cm and weight ranges from 1 - 208g. Length weight relationship parameters were computed as a = 0.014, b = 2.870 and R-2 = 0.952. Using the ELEFAN routine of the FiSAT computer package, the calculated von Bertalanffy growth function parameters were L infinity = 36.75cm, K= 0.300/year. Total mortality were computed using length-converted catch curve analysis at Z=1.26/year, whereas natural mortality M=0.740/year and fishing mortality F=Z-M= 0.52/year were calculated. The exploitation ratios (E) were computed as E-max =0.412, E-10 = 0.355, E-50=0.278.The yield per recruit analysis showed that when t(c) was 1, F-max was calculated at 0.5 and F-0.1 at 0.4. When biological reference point of F-opt was 'M (0.740), current fishing mortality rate of 0.52 is smaller than the target biological reference point.