A preliminary study on the acoustic deterrence system at Xianghe fishway in Xiang River, a tributary of the Yarlung Zangbo River

Acoustic deterrence system (ADS) are pivotal for fish attraction and protection, holding considerable value in fish conservation efforts. Despite this, Chinese research on ADS has predominantly centered on identifying sounds sensitive to fish in laboratory settings, with a dearth of practical engineering studies. This study aimed to determine if sound-driven fish technology could augment fish passage in field conditions. Underwater speakers were strategically positioned at upstream river channel near the entrance of fishway 2^# in the Xianghe River, a Yarlung Zangbo River tributary, broadcasting alligator sinensis predator sounds (Alligator sinensis) on a continuous 24-hour loop. The negative phonotaxis behavior of target fish species (Schizopygopsis younghusbandi; Ptychobarbus dipogon and Triplophysa stoliczkai) was monitored as they traversed the Xianghe River's hydrological hub, employing a Passive Integrated Transponder (PIT) system. To account for the influence of hydrological and environmental factors on this behavior, a multiple-factor logistic regression model was developed. The optimal model was selected based on Akaike Information Criterion (AIC), pinpointing the critical factors influencing fish negative phonotaxis. Findings indicated that: ① the experimental group's fishway entry rate significantly exceeded that of the control group (P<0.05); ② sound exposure and the discharge at fishway entrance 2^# were pivotal in affecting fishway passage rate (P<0.05); ③ post-sound activation, the entry rates for S. younghusbandi and P. dipogon markedly surpassed that of T. stoliczkai (P<0.05); ④ during the study, the flow rate at the fishway entrance 2^# between 0.81-1.32 m³/s, with a negative correlation observed between flow rate and fishway passage rate (P=0.007). Excessive flow rate were found to diminish fishway passage rates. decreased with the increase of fishway flow rate. This research demonstrates that ADS can deter fish from hazardous zones like power station tailwaters while enhancing the likelihood of fish entering fishways in practical engineering applications. This study seeks to offer scientific foundation and reference for the engineering implementation of ADS and the refinement of ecological dispatching at hydroelectric stations.