基于单位补充量模型的西江广东鲂种群资源利用现状评价

广东鲂(Megalobrama terminalis)是珠江中下游最重要的经济鱼类之一, 但由于过度捕捞和栖息地破坏, 资源日趋衰退, 科学评估其资源利用现状, 对合理开发与科学养护具有重要意义。利用2009—2015年西江肇庆江段渔业资源调查监测数据, 分析了广东鲂生长与死亡相关特征及参数变化; 利用单位补充量渔获量(Yield per recruitment, YPR)模型、单位补充量产卵群体生物量(Spawning biomass per recruitment, SBR)和生物学参考点评估了西江肇庆江段广东鲂资源利用状况。结果表明: 西江广东鲂体长(L)和体重(W)关系为W=1.518×10–5L3.051(R2=0.962, n=2252), 生长方程为L_t=419.9891–e–0.225(t+0.172)]; 现有捕捞强度(F平均1.27/年)远超过种群开发可承受水平(F_40%=0.53, F_0.1=0.27, F_20%=0.94); YPR_ave=30.58 g, 远低于YPR_0.1(36.73 g)和YPR_max(45.89 g); SBR=11.5%, 低于20%的下限临界参考点。西江广东鲂种群资源已过度开发, 处于补充型捕捞过度和生长型捕捞过度状态。目前珠江禁渔期制度的实施对广东鲂资源补充起到了良好作用, 但提高开捕体长至250 mm资源恢复效果将更明显。

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=1.518×10–5L3.051 (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.