(Day, 1877) (Pisces: Actinopterygii) in the north-western Persian Gulf

Length composition data of thinspine sea catfish, Plicofollis tenuispinis (Day, 1877), landed between April 2009 and March 2011, off Persian Gulf along the coast of Iran, were used to estimate the population parameters and to assess the stock of the species. Based on length frequency analysis, growth parameters of von Bertalanffy equation were calculated as L = 58 cm; K = 0.22 yr-1; t0 =-0.63 year for P. tenuispinis. The estimated total mortality (Z), natural mortality (M), fishing mortality (F) and exploitation rate (E) were 1.97, 0.5, 1.47, and 0.75, respectively. Relative yield per recruitment (Y’/R) of 0.010, relative biomass per recruitment (B’/R) 0.1, maximum sustainable yield (MSY) 0.88, exploitation rate at maximum sustainable yield (Emax) 0.45, precautionary average target (Fopt) of 0.25 and its limit (Flimit) of 0.33 were estimated for the local stock of thinspine sea catfish. The results of this study indicated that the thinspine sea catfish stock is overfished and exploitation rates should be regulated