Detection of infrasound by the Atlantic cod

Area of Science:

• Marine Biology
• Bioacoustics
• Oceanography

Background:

• Ambient ocean noise increases at lower frequencies, particularly in the infrasound range.
• Infrasound propagates long distances with minimal attenuation, creating directional patterns in the sea.

Purpose of the Study:

• To investigate the sensitivity of Atlantic cod (Gadus morhua) to infrasound.
• To determine if cod can detect infrasound levels present in the marine environment.

Main Methods:

• Utilized a standing-wave acoustic tube to expose cod to infrasound down to 0.1 Hz.
• Employed the cardiac conditioning technique to measure auditory thresholds.

Main Results:

• Cod exhibited a decline in threshold values towards lower frequencies below 10 Hz.
• Sensitivity reached approximately 10(-5) ms-2 at 0.1 Hz, sufficient to detect ambient infrasound levels.
• Measured ambient infrasound levels at 0.1 Hz range from 120 to 180 dB (re 1 microPa).

Conclusions:

• Cod possess the auditory sensitivity to detect naturally occurring infrasound in the ocean.
• Hypothesize that cod may utilize infrasound patterns for orientation during migration, potentially alongside other sensory inputs.