Silver, bighead, and common carp orient to acoustic particle motion when avoiding a complex sound

Area of Science:

• Aquatic Ecology
• Bioacoustics
• Invasive Species Management

Background:

• Invasive carp pose significant ecological and economic threats to freshwater ecosystems.
• Understanding their sensory mechanisms for detecting and avoiding threats is crucial for effective management.

Purpose of the Study:

• To investigate the phonotactic responses of silver carp, bighead carp, and common carp to complex, broadband sounds in the absence of visual cues.
• To determine the relative roles of sound pressure and particle motion in mediating these behavioral responses.

Main Methods:

• Behavioral experiments were conducted in a dark, featureless enclosure with groups of three fish.
• Fish proximity to speakers and swimming trajectories were analyzed relative to sound pressure and particle acceleration during sound playback.
• Sound levels and fish orientation relative to sound sources were quantified.

Main Results:

• All three carp species exhibited negative phonotaxis, actively avoiding the sound source during initial exposures.
• Fish significantly reduced time spent near the speaker, with median percentages decreasing substantially across species.
• Oriented avoidance behavior was strongly correlated with particle acceleration, suggesting it mediates sustained responses.
• Fish avoided sound fields exceeding 140 dB (ref. 1 μPa).

Conclusions:

• Invasive carp demonstrate a capacity to avoid complex underwater sounds, particularly in low-visibility conditions.
• While sound pressure may initiate responses, particle motion appears to be the primary cue for directed avoidance.
• This research provides critical insights for developing novel acoustic deterrents targeting invasive carp in dark, turbid waters.