Preliminary study on the blocking efficacy of acoustic barriers against Schizothorax prenanti under varied acoustic parameters and hydraulic conditions

As To investigate whether acoustic deterrence technology can enhance fish passage efficiency at fishway entrances under hydrodynamic conditions, this study established a 1∶50 scaled physical model of the Xianghe Hydraulic Complex in a laboratory flume. Underwater speakers were deployed upstream of the fishway entrance in the river channel to evaluate the efficacy of predator vocalizations and pulsed sounds in obstructing upstream migration and improving fishway entrance passage rates, using Schizothorax prenanti as the test species. The results demonstrated that: ① Tested acoustic signals experienced waveform distortion under hydrodynamic conditions, yet retained spectral characteristics exceeding ambient noise levels while remaining within the frequency reception range of cyprinids. ② All acoustic stimuli induced significant negative phonotaxis in test fish, with the sound field exhibiting a “central amplification-peripheral attenuation” pattern characterized by faster lateral attenuation than longitudinal dissipation. ③ Optimal deterrence effects were achieved with 130 dB pulsed sounds at river current velocity 0.15 m/s and fishway entrance velocity 0.4 m/s, whereas 130 dB Chinese alligator (Alligator sinensis) vocalizations showed superior efficacy at 0.15 m/s river flow and 0.6 m/s fishway entrance velocity. ④ At 0.4 m/s fishway entrance velocity, both 130 dB alligator vocalization and pulsed sound experimental groups demonstrated significantly higher passage rates compared to the control (P<0.05). Two-Way ANOVA revealed significant main effects of sound type (P<0.05) and fishway entrance velocity (P<0.05), with a significant interaction between these factors (F=3.273, P=0.04). This study confirms that acoustic deterrence technology can effectively impede upstream migration in fluvial environments under specific hydrodynamic conditions. The findings provide scientific evidence and technical references for engineering applications of acoustic fish guidance systems and optimization of ecological operations in hydropower facilities.