EXPLOITATION STATUS OF MEGALOBRAMA TERMINALIS BASED ON ANALYSIS OF SBR AND YPR MODELS IN XIJIANG RIVER

In the present study, the growth and mortality parameters of Megalobrama terminalis were analyzed, and the exploitation status of M. terminalis based on analysis of yield per recruit (YPR) and spawning biomass per recruit (SBR) models by using collected samples from Xijiang River (Pearl River) of Zhaoqing from 2009 to 2015. The results showed that the relationship between standard length and weight was expressed as W=1.518×10^–5L^3.051 (R²=0.962, n=2252). The von Bertalanffy growth equation was selected as an optimal growth criteria and was expressed as L_t=419.9891–e^{–0.225(t+0.172)}. The stock of M. terminalis was overfished far beyond the biological target reference points F_40% (0.53/year), F_0.1 (0.27/year), and threshold F_20% (0.94/year) at the current yield effort (F=1.27/year). The mean value of YPR (30.58 g) was far below the target values of YPR_0.1 (36.73 g) and YPR_max (45.89 g) as well. The SBR level was estimated to be 11.50%, which was below the threshold reference point (20%). This indicated that the status of stock of M. terminalis was overexploited and overfished. The implementation of closed fishing in Pearl River played a significant role on recruitment, however, if increase of initial length of fishing would be reached to 250 mm, that is more efficient to recovery the population of Guangdong Bream.