Page 198 - 《水产学报》2025年第5期

唐浩，等 水产学报, 2025, 49(5): 059716

Effects of the simulated catch weight on the hydrodynamic and
oscillation characteristics of the codend

1
1
1,2*
TANG Hao 1,2,3,4,5 , ZHANG Feng , LIU Wei , YE Xuchang ,
6
HU Fuxiang , XU Liuxiong 1,2,3,4,5
1. College of Marine Living Resource Sciences and Management, Shanghai Ocean University, Shanghai 201306, China;
2. National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai 201306, China;
3. Key Laboratory of Oceanic Fisheries Exploration, Ministry of Agriculture and Rural Affairs,
Shanghai Ocean University, Shanghai 201306, China;
4. Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources,
Ministry of Education, Shanghai Ocean University, Shanghai 201306, China;
5. Scientific Observing and Experimental Station of Oceanic Fishery Resources, Ministry of Agriculture and Rural Affairs,
Shanghai Ocean University, Shanghai 201306, China;
6. Faculty of Marine Science, Tokyo University of Marine Science and Technology, Tokyo 108-8477, Japan

Abstract: To investigate the relationship between hydrodynamic characteristics and catch weight inside the mid-water trawl
codend, this study examined the effects of catch weights (0.00, 1.68, 3.36 and 5.04 kg) on the drag force, shape, and oscillation
of codend under five different flow velocities (0.5, 0.6, 0.7, 0.8 and 0.9 m/s) using flume tank experiment. The results show
that: ① the drag force of the codend increased with increasing flow velocity and catch weight. At lower flow velocities, the
drag force of the codend with a catch weight of 1.68 kg was 30% greater than that of empty codend; ② the shape of the codend
structure tended to constrict with increasing flow velocity, while it expanded with increasing catch weight. However, the fish
guiding area tightened and took on a "waist drum"; ③ the codend volume was directly proportional to the catch weight. When
the catch weight increased to 5.04 kg, the codend volume was approximately 0.8 times that of the empty codend, indicating that
the empty codend has the greatest volume. Under different catch weight, the periodicity and the amplitude of codend position
oscillations decreased with increasing flow velocity. The codend position oscillations were fitted using a third-order Fourier
series, yielding satisfactory results. These findings are expected to contribute to the optimization of the codend structure and
provide relevant information for improving the hydrodynamic characteristics, geometric shape, and selectivity of the mid-water
trawl codend.

Key words: codend; drag characteristic; oscillation characteristic; catch weight; shape
Corresponding author: YE Xuchang. E-mail: xcye@shou.edu.cn
Funding projects: National Natural Science Foundation of China (32373187); Shanghai Natural Science Foundation
(23ZR1427000)

中国水产学会主办 sponsored by China Society of Fisheries https://www.china-fishery.cn
13