死亡因素对放流明对虾群体资源变动及生物学参考点影响的量化评估

为评估环境突变、被捕食、纳潮、非法捕捞和交尾死亡对资源量和渔获量的影响,及5种死亡因素和与生长有关的参数引入不确定性对估算生物学参考点(Fmax和F0.1)的影响,基于发展的可应用于研究放流增殖渔业的YPR(yield per recruitment)模型,模拟5种死亡因素不同水平下放流中国明对虾的资源变动规律。结果显示,环境突变、被捕食、纳潮、非法捕捞和交尾死亡水平越高,单位放流资源量和渔获量越少,交尾死亡尤其对累计单位放流渔获量的影响明显;在未引入不确定性时,作用于开捕前的环境突变、被捕食、纳潮和非法捕捞死亡的不同水平对生物学参考点无影响,与生长有关的参数及5种死亡因素引入不确定性可能存在低估F0.1和Fmax的现象。研究表明,减小与放流技术有关的环境突变、被捕食、纳潮和非法捕捞死亡水平对提高放流中国明对虾渔业效果有明显的作用,交尾死亡发生的时间及死亡水平对放流中国明对虾渔获有直接的影响,当参数引入不确定性时进行放流中国明对虾资源评估,生物学参考点的中位数较均值抗不确定性干扰能力更强。

Impacts of mortality factors and uncertainty on the population and biological reference points in stock Chinese shrimp fishery

In order to evaluate the factors affecting the yield of released fishery resources and impact of their uncertainty on the amount of resources and catch, as well as on biological reference points (F_max and F_0.1), The uncertainty was introduced into the parameters about growth and mortality, and based on the developed yield per recruit (YPR) model, and the dynamics of released Chinese shrimp was simulated, and difference index was applied to evaluate the difference between based scenario and other scenarios. Four factors influencing mortality, i.e., environment change, predation, intake sea water and illegal fishing, were shown to have similar influence on resource biomass. They had greater impacts on resource reduction when the mortality was high. At the same mating death rate, the impact on catch quantity was greater when the mating occurred earlier. Contrast to scenario 1, when four factors influencing mortality are at low level and the mating death occurred later, the BPR at the beginning and end of fishing, and accumulated YPR at the end of fishing increased by 14.38%, 24.88% and 17.28%, respectively. In the absence of uncertainty, the level of mortality factors occurring before fishing did not impact the biological reference points; after the introduction of uncertainty to mortality factors and the parameters in length-weight relationship, as well as VBGF, although F_0.1 and F_max did not display the certain specific trend with the uncertainty increasing, they were possibly underestimated when the age-structure YPR model was used. And the effects of introduced uncertainty on the mean and median of biological reference points are different, the mean and median of F_max, and the median of F_0.1 did not change obviously with the uncertainty, and the max mean of F_0.1 is 3.52 times the min mean. Additionally, the C.V. F_0.1 is between 392.15% and 630.28% at the three levels of uncertainty, and then the C.V. F_max is from 24.99% to 48.48% under the same conditions. So, the better technigues were applied to improve the effect of stock Chinese shrimp fishery, and the impact of mating must be taken into consideration in formalating the fishing strategy. Compared with mean of BRP, the median has an advantage in resisting disturbance of uncertainty introduced into mortality and parameters of VBGF when stock assessment was made.