加利福尼亚湾茎柔鱼(Dosidicus gigas)渔场声学调查方法

Acoustic Investigation Methods for Dosidicus gigas Fishery in Gulf of California

声学方法已成为海洋生物资源评估的重要手段,水声学调查与数据分析作为海洋生物资源声学评估的关键,直接影响渔业资源评估结果。通过对数据处理过程中的目标强度、噪声剔除、物种判别问题进行分析,探究墨西哥加利福尼亚湾的茎柔鱼(Dosidicus gigas)资源水声学调查方法,进而为系统了解和掌握加利福尼亚湾渔场经济品种的资源量打下基础。调查所用数据由加利福尼亚湾中墨海上联合调查船“BIP-XI”安装的单波束回声测深仪Simrad EK60采集,并利用水声学数据处理软件与相关方法进行分析,采用标准球方法对38、120 kHz频率换能器进行了校正。通过积分阈值和信噪比估算方法剔除背景噪声发现,对于高频信号噪声剔除效果良好,120 kHz回波映像的变化比38 kHz更明显,前者噪声去除整体效果优于后者。将虚拟变量剔除背景噪声与优化积分阈方法相结合可剔除大部分噪声数据,减少数据复杂程度。经过海底与海表信号剔除、噪声剔除、频差法识别之后,调查区域内大部分无关噪声信号被剔除,最后使用频差法提取到了目标鱼种的信号。通过加利福尼亚湾茎柔鱼渔场声学调查方法,取得了大洋性鱿鱼类声学评估的初步进展,为后期资源调查奠定了基础。

Acoustic method has become an important mean for marine biological resources assessment.The analysis method of acoustic data is the key in the qualification and quantification of fisheries resources.Based on the analysis of target intensity,noise elimination and species discrimination during data processing,the method of hydroacoustic investigation of Dosidicus gigas resources was explored in the Gulf of California,Mexico,and a foundation for systematically understanding and grasping the amount of economic species resources was laid in the Gulf of California fisheries.The survey was carried out by the boat R.V.BIP-XI in the cruise of China-Mexico joint survey and the data were collected by the Simrad EK60 system in the Gulf of California.Transducers were all precomputed using the standard sphere method before the cruise.After the background noise was removed by integrating threshold and SNR estimation method,it was found that the noise removal effect of high frequency signal was effective and the image variation of 120 kHz echo was more obvious than that of 38 kHz.The overall noise removal effect of the former was better than that of the latter.Combined with the method of subtracting background noise from dummy variables and optimizing integral threshold,most noise data were eliminated and data complexity was reduce.After the elimination of sea bottom and sea surface signals,noise elimination and frequency difference identification,most of the irrelevant noise signals in the survey area were eliminated,and finally the signal of target fish species was extracted by frequency difference method.Through the analysis of the acoustic survey method in the Gulf of California,the preliminary progress in the acoustic assessment of oceanic squid had been made,and the direction and foundation for the later resource investigation had been pointed out.