On the stock assessment of Parailia pellucida (Schilbeidae)in the Cross River Nigeria

Abstract

The growth, mortality rates and the fisheries yield of Parailia pellucida (Schilbeidae) caught from Cross River at Obubra were studied. The seasonalized von Bertalanffy growth equation fitted to the length frequency data gave the following parameters: Loo= 18.0cm TL,K=0.47yr^-1 , C=0.4, WP=0.86 and t₀= -0.389yr with R_n=0.56. The instantaneous total mortality coefficient estimated from the seasonalized length converted catch curve, was Z = 1.57yr^-1 The instantaneous natural mortality coefficient was M = 1.28yr^-1 while the instantaneous fishing mortality coefficient was F = 0.03yr^-1 the estimated current exploitation rate was E = 0.19. The  probability of capture of each size class showed that the length at first capture was L_c = 7. 82cm TL. The Beverton and Holt's relative yield per recruit and relative biomass per recruited predicted a maximum exploitation rate E_max =0.52. The stock is not over exploited since E<E_max The analysis of recruitment pattern shows the existence of two recruitment regimes.

Keywords: Stock Stock assessment, Parailia pellucida, Cross River, Nigeria