嘉陵江下游江段蛇种群动态及利用现状

为分析嘉陵江下游江段蛇资源量的动态变化规律,探讨和研究其种群资源开发现状,于2015和2016年在嘉陵江下游江段共收集256尾蛇,运用FistaⅡ软件对蛇的生长参数及种群的资源量进行估算。结果显示,嘉陵江下游蛇体长(L)和体质量(W)的关系式为W=7.5×10~(-5)×L~(2.58)(R~2=0.731 1,n=256),通过体长变换渔获曲线法,计算出Von Bertalanffy生长方程的参数分别为渐进体长L_∞=173.81 mm,生长系数K=0.73,起点年龄t_0=-0.23;生长方程的表达式为L=173.811-e~(-0.73(t+0.23))]。相对单位补充量渔获量(Y'/R)分析结果显示,2015和2016年蛇种群的实际开发率(68%和69%)均超过理论最大开发率(42%),种群资源处于过度开发状态。研究表明,嘉陵江下游江段蛇偏向r选择类型,为负异速生长型鱼类,其种群为单峰补充,补充高峰在4—6月;当前蛇种群结构呈现出显著的小型化、低龄化趋势,过度捕捞和种群自然补充量减少是蛇资源量下降的两个主要原因。

Population dynamics and stock status of Saurogobio dabryi in the lower reaches of the Jialing River

A total of 256 individuals of Saurogobio dabryi were collected in the lower reaches of the Jialing River (Hechuan section) from 2015 to 2016. Growth parameters and stock status of the S. dabryi population were estiamted by using Fista II software. The length-weight relationship was W=7.5×10-5×L2.58 (R2=0.7311,n=256), the Von Bertalanffy growth equation was fitted as L=173.81(1-e-0.73(t+0.23)), where Loo=173.81mm, K=0.73, t0=-0.23. The exploration rates of the S. dabryi population were 68% and 69% in 2015 and 2016 respectively, exceeding the theoretical maximum development rate (42%) which suggested by Yield per Recruit model (YPR), and indicating that the population resources of S. dabryi were overexploited. This study demonstrated that the S. dabryi in the lower reach of the Jialing River was more biased towards the r-selection type, which showed the growth pattern of S. dabryi was allometric. The mode of population replenishment was unimodal, with one main peak period from April to June. The population structure of S. dabryi revealed a significant trend of miniaturization and lower age, and overfishing and recruitment decrease of natural population were the two main reasons for the decline in the resources of the S. dabryi.