不同采样设计对估计鱼类空间格局指数的影响

查明渔业种群空间格局可为渔业资源的合理利用和管理提供参考依据.在渔业资源调查中,采样设计会影响调查分析结果的准确性和适用性.为查明采样设计对分析种群空间格局的影响,本文根据2016年10月、2017年2月、5月、8月在山东南部近海调查获得的数据,以星康吉鳗(Conger myri-aster)、方氏云鳚(Enedria...

Effects of sampling design on estimation of spatial pattern indices of fish population

The study of spatial patterns of fish populations provides reference for reasonable utilization and management of fishery resources, which depends greatly on the quality of data collected from well-designed surveys. So appropriate sampling designs are essential in fishery-independent surveys, which can greatly affect the accuracy and applicability of the survey results. Computer simulation study is conducted to investigate the effects of sampling design on the spatial pattern of fish populations based on the data collected from bottom trawl surveys in the southern waters off Shandong Peninsula in four seasons from 2016 to 2017 in this study. Four sampling methods, including simple random sampling (SRS), systematic sampling (SYS), stratified random sampling (StRS) and stratified systematic sampling (StSS) with four levels of sample sizes are considered as potential sampling designs in this simulation study. The effects of different sampling designs on the estimation of mean crowding index and poly block index (PBI) for Conger myriaster and Enedrias fangi are examined. Relative estimation error (REE) and relative bias (RB) are used to measure the performances of different sampling designs. The results show that the simulated values of spatial pattern indices from SYS and StSS are closer to the “true” values, and the performances of SRS and StRS are relatively poor. The REE of estimation of spatial pattern indices for target fish populations decreased significantly with sample size. The original spatial pattern of fish populations has a certain effect on the estimation of spatial pattern indices. The precision of estimation of PBI decreased with the increase of the “true” values of spatial pattern indices, with PBI being overestimated when it is high. Different sampling designs have a certain effect on the estimation of spatial pattern indices of fish populations, and the degree of population aggregation also affected the analysis results. Therefore, the spatial pattern indices of target fish populations could be incorporated into the survey goals in sampling designs to improve the fishery-independent surveys with multiple objectives.