Target strength of northern whitefish Coregonus peled by using Kirchhoff ray mode methods
SUN Yang1, TANG Yong1*, XING Binbin1, LI Hongquan1, BI Fuyang2, MA Zhuang2
1.College of Marine Technology and Environment, Dalian Ocean University, Dalian 116023, China; 2.Xinjiang Uygur Autonomous Region Saihu Fishery Science and Technology Development Company Limited, Bortala Mongol Autonomous Prefecture 833500, China
Abstract: In order to use the target strength to evaluate the stock of northern whitefish Coregonuspeled in Sayram Lake, Xinjiang Uygur Autonomous Region, the target strength was determined in 19 individuals sampled from traps from June 2017 to July 2018 using Kirchhoff ray mode methods with the attitude inclination at the commonly used fishery acoustic survey frequencies of 70, 120, and 200 kHz, and then the fitting equations were established at different frequencies corresponding to the northern whitefish according to the directivity pattern and the probability density distribution of the attitude inclination, to establish empirical formula of target strength with body length and body length squared. The results showed that the northern whitefish had similar frequency characteristics to that of general swim bladder fish in directivity pattern of target attitude inclination, that is, the main lobe was obvious in the lower frequency band and the side lobes were less, without the obvious main lobe in the high frequency band and with the relatively large side lobes. The maximum target strength was observed at the attitude inclination angle from -3° to -5°, basically consistent with the angle between the swim bladder and the fish body (average value 2.8°). Assuming that the attitude of the northern whitefish was -5°±10° under the condition of 10° Gaussian distribution, the relationship between average target strength and body length corresponding to the three frequencies was expressed as fitting equation TS=16.4 lgL-59.2 at 70 kHz, TS=21.3 lgL-64.3 at 120 kHz and TS=23.7 lgL-65.3 at 200 kHz. The relationship between the average target strength and the square of the body length(which is the common logarithmic value of body length squared) was described as fitting equation TS=20 lgL-63.6 at 70 kHz, TS=20 lgL-62.6 at 120 kHz and TS=20 lgL-60.7 at 200 kHz. The findings indicated that there was 3-5 dB larger average target strength, elevated with the increase in frequency, in the northern whitefish than that in conventional single-chamber swim bladder fish, which is similar to the previous research results of target strength in other whitefish Coregonus.
孙扬, 汤勇, 邢彬彬, 李泓泉, 毕福洋, 马壮. 基于基尔霍夫射线模型法的高白鲑目标强度研究[J]. 大连海洋大学学报, 2021, 36(2): 310-316.
SUN Yang, TANG Yong, XING Binbin, LI Hongquan, BI Fuyang, MA Zhuang. Target strength of northern whitefish Coregonus peled by using Kirchhoff ray mode methods. Journal of Dalian Ocean University, 2021, 36(2): 310-316.
2021, Vol. 36 
