Rapid in situ range testing for acoustic telemetry in Leizhou Bay, South China Sea.

Acoustic telemetry is widely used to study the movement and habitat use of marine animals, but its effectiveness depends greatly on the appropriate receiver spacing and the local environmental context. In practice, when time or logistical resources are limited, short-term range tests, if carefully planned and interpreted, can provide rapid and valuable deployment guidance. Here, we conducted a 24-h in situ range test in a subtropical bay as a practical case study and reference workflow for planning receiver deployment before animal tracking studies. Two transmitters with different power outputs were deployed, and a generalized additive mixed model was applied to assess how environmental factors influenced detection proportion. The results showed that the effective detection range (50% detection proportion) was 170.4 m for the high-power transmitter and 114.3 m for the low-power transmitter. Mean detection proportion at nighttime was significantly higher than at daytime for both transmitter types. Distance to transmitter and water temperature significantly affected both transmitter types, while other factors, such as hour of day, wind, water depth, dissolved oxygen, background noise, and tilt angle, showed transmitter-specific effects. This study was not intended to develop universal predictive models from the 24-h dataset, but rather to determine appropriate receiver spacing and demonstrate how environmental variables can be incorporated to interpret rapid range test results under local conditions. The workflow provides a replicable and efficient approach for short-term range testing and data interpretation, offering practical guidance for optimizing acoustic telemetry deployment in similar environments.