南海中部海域渔业资源时空分布和资源量的水声学评估

Hydroacoustic assessment of spatial-temporal distribution and biomass of fishery resources in the central South China Sea

2014年3月~2015年2月对南海中部12°N^15°N、111°E^117°E海域进行了4次渔业资源声学调查,其中2014年3月~4月(春季)、11月~12月(秋季)和2015年1月~2月(冬季)利用"南锋"号船载双频分裂波束科学探鱼仪系统(Simrad EK60,38 k Hz、120 k Hz,挪威)进行探测,2014年7月~8月(夏季)利用便携式分裂波束科学探鱼仪(Simrad EY60,70 k Hz,挪威)进行探测。通过鱼类目标强度现场测定,使用回波积分法获得了调查海域内渔业资源的丰度密度空间分布的季节变动特征。结合夏季调查灯光罩网采样数据,分析了调查海域内评估对象种类组成并估算资源总量。结果表明,夏季共捕获鱼类18种,头足类2种,其中鸢乌贼(Sthenoteuthis oualaniensis)为主要渔获种类,声学评估其资源量为2.36×106t,约占评估对象资源总量的73.19%。调查海域内单体目标强度均呈单峰状分布,且主要分布于-56.5^-41.5 d B,4次调查该海域范围内目标强度小于-71.5 d B的单体均分布于100 m以浅水层,而目标强度大于-20.5 d B的单体则均分布于100 m以深水层。

Four acoustic investigations on fishery resources were conducted in 12° N to 15° N,111° E to 117° E in the central South China Sea by＂Nanfeng＂shipborne dual-frequency split beam scientific echosounder system（ Simrad EK60,38,120 k Hz,Norway）during March to April（ spring）,November to December（ autumn） 2014 and January to February（ winter） 2015,as well as by portable split beam scientific echosounder（ Simrad EY60,70 k Hz,Norway） in July to August（ summer） 2014. According to the measurement on fish target strength in situ and with use of echo integration method,we obtained the seasonal variation feature of spatial distribution of fishery resources abundance density in the survey sea area. Furthermore,the species compositions were analyzed and the amount of fishery resources was estimated based on light falling-net sampling data in summer. Eighteen kinds of fish and two kinds of cephalopods are captured in summer and Sthenoteuthis oualaniensis was the main captured species. Acoustic assessment shows that the biomass was 2. 36 × 106 t,accounting for 73. 19% of the total assessing biomass. The single target strength was unimodal distribution in the survey sea area and mainly accumulated from- 56. 5 to- 41. 5 d B. The individuals whose target strengths were less than- 71. 5 d B entirely distributed in 100 m shallow water layer,and those whose target strength over- 20. 5 d B completely distributed under 100 m water layer in the survey sea area.