两种鲤科经济鱼类水声目标强度的实验测定与应用评估

THE EXPERIMENTAL DESIGN AND APPLICATION OF HYDROACOUSTICAL TECHNIQUES FOR TARGET STRENGTH OF TWO COMMERCIAL CYPRINIDAE FISH SPECIES

鱼类目标强度(Target Strength,TS)及其与鱼体长度的关系是渔业声学技术研究和应用的核心内容之一。本文以我国广泛分布的鲤科经济鱼类鲤(Cyprinus carpio)和鳙(Aristichthys nobilis)为研究对象,选择湖北省宜昌市隔河岩水库的一处僻静库湾作为实验地点,于2017年5月1—20日采用绳系实验法和Simrad EY60型(频率120 kHz)分裂波束回声探测仪,在环境干扰小的实验网箱里逐一测量单体实验鱼游动状态下的目标强度,由此构建2种鱼的目标强度与个体大小关系式。用于实验的鲤和鳙均为26尾,其全长分别为19.9—29.6 cm和49.2—74.2 cm,体重分别为175—461 g和1200—4700 g,实验所测TS值分别为–59.35—–45.20 dB和–34.22—–17.49 dB。回归得到实验鱼目标强度(TS,dB)与全长(TL,cm)关系式(1)鲤: TS = 29.84×lgTL – 95.23(R^2 = 0.74,P<0.01),(2)鳙: TS = 35.88×lgTL – 90.33 (R^2 = 0.83,P<0.01)。同时选择一个小型封闭水体(盐龙湖)“赶、拦、刺、张”联合渔法捕捞之前的鱼探仪调查数据作为分析实例,通过本文鳙TS-TL关系式估算全湖鱼类资源总量为89360 kg,折合40.1 g/m^2,捕捞产量(73610 kg)与之较为接近,在一定程度上反映了实验目标强度测定及其与体长关系式的合理性,有助于丰富我国内陆水域鱼类资源水声学评估技术的基础参数。

The target strength (TS) of fish and its relationship with body length is one of the core contents of research and application in fishery acoustic technology.The current study measured target strengths of two widespread commercial cyprinid fish species,Cyprinus carpio and Aristichthys nobilis with hydroacoustics experiment with tethering method and Simrad EY60 echosounder (120 kHz) under swimming status (26 individuals of C.carpio and 26 of A.nobilis) in an undisturbed cage in the Geheyan Reservoir (Yichang City,Hubei Province) from 1 May-20 May,2017.The total length of C.carpio and A.nobilis were from 19.9 to 29.6 cm and 49.2 to 74.2 cm,respectively.The body weight of them were from 175 to 461 g and 1200 to 4700 g,and their TS were from –59.35 to –45.20 dB and –34.22 to –17.49 dB,respectively.The regression relationship between target strength (TS,dB) and total length (TL,cm) for the two species were TS = 29.84×lgTL – 95.23 (R^2 = 0.74,P < 0.01) for C.carpio,and TS = 35.88×lgTL – 90.33 (R^2 = 0.83,P < 0.01) for A.nobilis.The TS-TL equation of A.nobilis was used to assess the total fish biomass of a small enclosed water body (Lake Yanlong) to 89.36 ton (i.e.40.1 g/m^2),which is close to the real total catch (73.61 tons) of this area,supporting the rationality of in method to evaluate fish target strengths and their relationship with body length.Exploring target strength for the two most common fish should benefit the development of hydroacoustics techniques in China’s inland waters.