This study assessed the impact of an acoustic stimulus on the behavioral responses and physiological states of the large yellow croaker (Larimichthys crocea). The test fish, with an average body weight of approximately 352.81 ± 70.99 g, were exposed to one hour of acoustic stimulation at seven different frequencies: 100 Hz, 125 Hz, 160 Hz, 200 Hz, 500 Hz, 630 Hz, and 800 Hz. The aim was to delineate the specific effects of acoustic stimulation on the behavior and physiological indices. The results show that acoustic stimulation significantly altered the behavioral patterns of the large yellow croaker, predominantly manifested as avoidance behavior towards the sound source. At a stimulus frequency of 630 Hz, the test fish exhibited continuous irregular motion and erratic swimming. Physiologically, one hour of exposure to acoustic stimulation notably affected the endocrine system. The levels of Epinephrine and thyroxine were significantly elevated at 200 Hz, while the cortisol levels did not show significant differences. Additionally, the lactic acid content significantly increased at 800 Hz, and the blood glucose content peaked at 630 Hz. This study discovered that sound frequencies of 200 Hz, 630 Hz, and 800 Hz led to a significant increase in the levels of Epinephrine, glucose, thyroid hormones, and lactate in large yellow croaker, consequently affecting their behavior. The changes in these physiological indicators reflect the stress response of the large yellow croaker in specific sonic environments, providing crucial insights into the physiological and behavioral responses of fish to acoustic stimuli.

The construction of marine ranches can enrich and conserve the fishery resources and improve the marine ecosystem, which helps realize the sustainable utilization of these resources. Sebastes schlegelii is a major breeding and releasing fish species in the marine ranches of North China. Its behavioral characteristics can be understood better by researching its vocalization, which will provide data support for constructing acoustic taming marine ranches with S. schlegelii as the target fish species. However, there are few studies focusing on its sounds and behaviors. Therefore, based on the passive acoustic monitoring technology, the audios of underwater noises made by S. schlegelii were extracted using an AQH hydrophone. The high-definition internet protocol camera was used to monitor the behavior change of S. schlegelii. Then, by collating and replaying the collected audios and videos, the feeding behavior and biological noises of S. schlegelii were matched to analyze their relationship. Results are as follows: (1) The noise of chewing settling granular baits (Φ5.0 mm) has a main frequency band and sound pressure level of 2000~4500 Hz and 96.53 ± 0.65 dB, respectively; in this feeding process, the main frequency band and sound pressure level of the swimming noise are 25~400 Hz and 95.63 ± 0.38 dB, respectively; the values are 500~700 Hz and 97.34 ± 4.91 dB, respectively, for the noise of flapping the water with the tail. (2) The sound signals emitted by S. schlegelii are mostly presented as single pulses during normal habitation or ingestion of baits on the surface of the water tank. However, S. schlegelii will attack and fight against each other when scrambling for baits, during which these signals are presented as continuous pulses. To sum up, the vocalization of S. schlegelii is closely related to feeding activities, and the sounds produced under different behaviors have specific biological significance.

To understand the behavior of the large yellow croaker (Larimichthys crocea) in a pen aquaculture setting, three individuals in each of two experimental groups were telemetered in meter scale by four cable-synchronized hydrophones. The ultrasound pinger system was applied to track the motion of six L. crocea for 24 h using two fixation methods, i.e., implanting tags in the abdomen (the in vivo implantation group) and hanging tags on the dorsal fin (the dorsal fin suspension group). Pingers repeated unique 62.5 kHz coded signals at 5 s intervals along with a pressure signal. The results showed that fish tagged with internal pingers took approximately 3 h longer than externally tagged fish to stabilize in their behavior, as measured by depth utilization; the horizontal movements of the test fish were mostly found outside of the fence, where the test fish performed round-trip swimming, with the least probability of appearing near the production platform and more frequent activities in the feeding areas.

Corrigendum: Study on feeding behavior and biological sound of Sebastes schlegelii

In this study, passive acoustic technology was used to obtain sound signals indicative of feeding in individual rainbow trout (Oncorhynchus mykiss). Feeding signals were separated from background signals to characterize their acoustic parameters, in order to quantify feeding activity. The audio and video data of rainbow trout during feeding were synchronized to determine the signal category and mark it, and the time-domain features and frequency-domain features of fish swallowing feed were extracted. This not only has important theoretical value for in-depth understanding of fish growth, reproduction, and other life activities, but also provides data support and technical recommendations for future research on this topic.