Growth,mortality and optimum catchable size of small yellow croaker (Larimichthys polyactis Bleeker) in the Southern Yellow Sea

Based on the biological data collected from the trawl fishery survey in the southern Yellow Sea from 2008 to 2009,growth and mortality parameters of small yellow croaker( Larimichthys polyactis( Bleeker,1877)) were estimated by the FiSAT II software,and status of stock and optimal first capture size were assessed by Beverton-Holt model. Optimum catchable size was determined by comparing the critical size and the length of point of inflection. The result showed that:(1) the relationship between body length and body weight can be expressed as W = 0.0268× L2.814(;2) Growth parameters can be described by the von Bertalanffy growth equation,the parameters were estimated to be L∞ = 27.00 cm ,k = 0.45 a-1 and t0 = - 0.47 a;(3) Mortality coefficients were estimated to be Z = 2.40,M = 0.77, F = 1.63 and exploration rate E = 0.68;(4) Under the actual fishing mortality coefficient F = 1.63,Yw/R can get maximum when the first capture age and size were 1.41a and 15.42 cm. It was suggested that the optimum catchable size of small yellow croaker in the Southern Yellow Sea was 14.83 cm.