渔业声学数据后处理中积分阈的选择与优化Ⅰ:目标离散分布状态下积分阈的确定

Definition and optimization of integration threshold in the post-processing of fisheries acoustic data Ⅰ: Determination of integration threshold for scattered distribution

积分阈是渔业声学数据后处理中对回声信号进行积分的临界值,是参与积分的最弱回声信号的体积反向散射强度。通过合理设置积分阈,能在保留目标信号的同时有效地消除噪音和非目标回声信号,从而提高渔业资源声学评估的准确性。为研究目标离散分布状态下选择和优化积分阈的方法,推导了单体目标体积反向散射强度与目标强度之间的函数关系,提出了利用鱼类目标强度-体长经验公式和目标强度现场数据确定积分阈的两种方法,并以黄海鳀的调查为例,对上述两种积分阈确定方法进行了应用探讨,为渔业资源声学评估数据处理中目标离散分布状态下积分阈的选择与优化提供了有效参考。

Integration threshold is the critical signal level that governs whether or not an echo signal will be included in the echo integration during the post-processing of fisheries acoustic data.It is the Volume Backscattering Strength（VBS） of the weakest echo signal that will be involved in the echo integration process.An appropriate integration threshold may effectively remove noise and non-target signals while keep the signals from target species intact,thus improve the accuracy of acoustic estimation of fishery resources.In order to study the methods for the selection and optimization of the integration threshold for a scattered target distribution,the functional relationship between the VBS and the Target Strength（TS） was derived based on basic concepts and formulas in fisheries acoustics,and two methods,namely the TS-Length empirical relationship method and the in situ TS data method,were proposed for the determination of integration threshold.The application of both methods was then demonstrated in the anchovy Engraulis japonicus survey in the Yellow Sea.It provides an effective reference for the definition and optimization of integration threshold in the post-processing of fishery acoustic data with the scattered target distribution.