[Estimation of growth and mortality parameters of Argyrosomus argentatus in northern South China Sea].

ABSTRACT

In this paper, Argyrosomus argentatus in northern South China Sea was grouped into the colony in continental shelf of northern South China Sea and that in Beibu Gulf. Based on the trawl survey data during 1960s and 1990s, and by using ELLEFAN technique, the growth and mortality parameters of Argyrosomus argenrtatus in northern South China Sea were estimated. The estimated parameters for Von Bertalanffy growth equation were Linfinity = 382 mm, K = 0.42 and t0 = -0.16 for the colony in Beibu Gulf, and Linfinity = 315 mm, K = 0.35 and t0 = -0.23 for that in continental shelf of northern South China Sea. The turning point for body weight growth curve of the stock was situated at t = 2.44 in Beibu Gulf, and t = 2.87 in continental shelf. Accordingly, the instantaneous total mortality (Z), natural mortality (M) and fishing mortality (F) were 3.55, 0.93 and 2.62, and 3.12, 0.85 and 2.27, respectively. The exploitation rates in recent years were 0.74 and 0.73, and the stock was on the status of over-exploitation. According to Beverton-Holt dynamic model, the optimum fishing age of Argyrosomus argenrtatus should be larger than 1.90 and 1.95 years old, and the optimum body-length should be above 211 mm and 168 mm, respectively.