基于单位补充量模型的西江赤眼鳟种群资源利用现状评价

赤眼鳟(Squaliobarbus curriculus)是珠江中下游最重要的经济鱼类之一,本研究利用2009—2014年西江肇庆江段渔业捕捞调查监测数据,分析了其生长和死亡参数历史变化,利用单位补充量渔获量(yieldperrecruitment,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赤眼鳟资源利用状况。结果表明,赤眼鳟体长(L)和体重(W)关系为W=2×10^-5L^2.9527(R^2=0.9595,n=2346),生长方程为L_t=725.802[1-e^{-0.110(t+0.613})]。目前西江的捕捞强度(F=0.96/a)和开发状况(E=0.86)远超种群可持续开发水平,赤眼鳟种群处于生长型捕捞过度状态。根据实际情况,建议将西江赤眼鳟开捕年龄提高至3龄(或开捕体长增大至238 mm),则预计单位补充量渔获量可增加175%,在珠江禁渔期制度的协同保护下,种群实际保护效果可能更好。

Exploitation status of Squaliobarbus curriculus in the Xijiang River based on the analysis of the yield per recruit and spawning biomass per recruit models

The Pearl River, the largest river in southern China, historically harbors abundant fishery resources. However, the fishery resources have severely declined in recent decades owning to dam cascade development, overfishing, water pollution, and so on. Therefore, it is necessary to evaluate fishery resource utilization and exploitation, which provides scientific guidance for fishery resource conservation in the Pearl River. Generally, the per recruitment model has been widely applied to the dynamics of single fish populations. The per recruitment models mainly consist of the yield per recruitment model (YPR) and the spawning biomass per recruitment models (SBR). The YPR model prevents overgrowth overfishing and is usually used to determine the fishery management parameters (e.g. mesh size and catch rate). This model could provide management guidance for the development and utilization of fish stocks. The spawning biomass per recruitment model prevents supplemental overfishing. This model is utilized to assess whether parental biological residues and spawning stock are sufficient to maintain the stock of larvae supplementation, and then it estimates the status of resource utilization. The barbel chub (Squaliobarbus curriculus) is an important economic fish inhabiting the middle and lower reaches of the Pearl River. An assessment of the current status of S. curriculus utilization is important for reasonable resource exploitation and maintenance. The data of the present study were collected in the Zhaoqing section of the Xijiang River (an important stem of the Pearl River) between 2009 and 2014. We analyzed the growth and mortality characteristic parameters and evaluated the resource exploitation status by the YPR model, SBR model, and biological reference points. The relationship between standard length and weight was expressed as:W=2×10^-5L^2.9527 (R²=0.9595, n=2346). The von Bertalanffy growth equation was selected as the optimal growth model and was expressed as L^t=725.802[1-e^{-0.110(t+0.613)}]. The present fishing intensity (F^ave=0.96/a) and exploitation rate (E=0.86) have far exceeded the level of sustainable population development. The stock of S. curriculus was overfished in its vegetative form. We suggest to increase the catch age to 3 years old (or to a standard length of 238 mm) for the stock conservation of S. curriculus in the Xijiang River; the yield per recruitment could thus be increased by 175%. The protective efficacy could increase with a fishing moratorium in the Pearl River, and relevant fishery management measurements should be improved at the same time.