Some Biological Parameters of the Red Porgypagrus Pagrus in Benghazi Coast (Eastern Libya) (Published)
Commercial fish samples from Benghazi coast were studied during December 2014 to November 2015.The number of sample collected was 254 fish, number male fishes 81 and female 143, and 30 immature, the sex ratio male to female was 1:1.8:Age groups estimated, 4 years groups determined from scales reading. The von Bertalanffy growth equation fitted to the most recent, back-calculated lengths from all the samples Lt = 31.4*(1-e(-0.237*(t+1.04)), For male= Lt= 35.04*(1-e(-0.2*(t+0.643)), and for female was Lt=33.5*(1-e(-0.19*(t+0.239)). Growth performance index was, 2.1, 2.4, and 2.3 for whole sample, male and female, respectively. Total mortality ( Z) equal 0.9 per year. Natural mortality (M) about 0.3 per year. Fishing mortality (F) is therefore 0.6 per year. The survival rate value of P.pagrusin Benghazi coast was found to be 0.4, while the exploitation ratio was 0.7. Age at first capture Tc = 1.4 year at length at first capture Lc = 13.9cm, while length at recruitment (Lr) was 9.6 cm and the corresponding age at recruitment (tr) was 0.5 year, the value of Yield per recruit equal 29.8 gm at fishing mortality 0.6 per year, Fmax found to be 0.5 at maximum Yield per Recruit 30.23 gm, lower than ours result 0.6 .