Growth Parameters and Stock Assessment of Carangoides bajad Forsskal, 1775 (Carangiformes: Carangidae) in Jeddah Fisheries

Abstract

Abstract The current status of Carangoides bajad population in Jeddah fisheries was assessed by estimating the growth parameters, based on age determination using vertebrae as hard structures, and current levels of fishing mortality and size at first capture, then applying the results to estimate the current levels of yield and biomass per recruit. The length-weight relationship could be described by the power equation: W = 0.012 L3.003 (R2 = 0.99) for males, W = 0.011 L3.031 (R2 = 0.99) for females, and W = 0.011 L3.019 (R2 = 0.99) for combined sexes, and the exponent values for both sexes were not significantly different from the value ‘3’ of the isometric growth. Von Bertalanffy Growth parameters (L∞, K and t0) for sexes combined (pooled data) were estimated and found to be L∞ = 71.53 cm, K = 0.224 year− 1, and to = -0.52 year. The total ‘Z’, natural ‘M’, fishing ‘Fcur’ mortality coefficients and current exploitation ‘Ecur’ were calculated to be Z = 0.72 year− 1, M = 0.337 year− 1, F = 0.383 year− 1, and E = 0.53 year− 1. Beverton and Holt (1957) model was used to estimate the yield (Y) and biomass (B) per recruit (R) at the current levels of fishing mortality and age at first capture and found to be Y/R = 291 g and B/R = 759 g. Compared with the two yield-based biological reference points Fmax = 0.56 year− 1 and F0.1 = 0.346 year− 1, the current fishing mortality was very close to the value of F0.1 required to get the optimum yield per recruit. The current spawning potential ratio ‘SPR’ was estimated to be 28.3% of the virgin (unfished) spawning stock biomass per recruit ‘SSBR’, which can sustain sufficient recruitment to the fishery. We recommend avoiding any increase in the current level of fishing mortality, and at the same time increasing the age at first capture from 1.94 to 3.0 years to increase the biomass per recruit from 759 g (SPR = 28.3%) to 793 g (SPR = 33.1%), which increase probability of sustaining sufficient recruitment to the fishery of C. bajad in Jeddah fisheries.