Passive acoustic monitoring of sound characteristics and vocalisation patterns of Brown croaker

Passive acoustic monitoring (PAM) is an observation method for detecting
and characterising ocean soundscapes, and it has recently been used to
observe underwater marine life. The brown croaker (Miichthys miiuy) is an
important fish species in the Northwest Pacific Ocean that produces
biological sounds. In this study, the sounds of 150 adult brown croakers
were recorded continuously for 3 weeks using a self-recording hydrophone.
The acoustic parameters of their calls, choruses, and vocalisation
patterns were analysed using environmental factors from the ocean. The
brown croaker`s call sound with zero peak sound pressure level was 150.8
dB, but the chorus sound was relatively high at 161.3 dB. The vocalisation
of the sounds occurred daily around sunset and dusk and was associated
with decreased spawning activity when the water temperature decreased
below approximately 25 °C. The acoustic characteristics of the brown
croaker`s sounds will help improve ocean soundscape management to protect
the marine ecosystem and identify spawning and fishing grounds.