Related Experiment Video
Updated: Aug 26, 2026

Optical Trawl Surveys of Groundfish: A Video Trawl Survey of Western Gulf of Maine Atlantic Cod (Gadus morhua)
Published on: March 20, 2026
Click sounds produced by cod (Gadus morhua)
Heike I Vester1, Lars P Folkow, A S Blix
1Department of Arctic Biology and Institute of Medical Biology, University of Tromsø, NO-9037 Tromsø, Norway.
Abstract:
Conspicuous sonic click sounds were recorded in the presence of cod (Gadus morhua), together with either harp seals (Pagophilus groenlandicus), hooded seals (Cystophora cristata) or a human diver in a pool. Similar sounds were never recorded in the presence of salmon (Salmo salar) together with either seal species, or from either seal or fish species when kept separately in the pool. It is concluded that cod was the source of these sounds and that the clicks were produced only when cod were approached by a swimming predatorlike body. The analyzed click sounds (n = 377) had the following characteristics (overall averages +/- S.D.): peak frequency = 5.95 +/- 2.22 kHz; peak-to-peak duration = 0.70 +/- 0.45 ms; sound pressure level (received level) = 153.2 +/- 7.0 dB re 1 microPa at 1 m. At present the mechanism and purpose of these clicks is not known. However, the circumstances under which they were recorded and some observations on the behavior of the seals both suggest that the clicks could have a predator startling function.
Related Concept Videos
The Auditory Ossicles
The aptly named stapes look very much like a stirrup. The three ossicles are unique to mammals, and each plays a role in...
Hair Cells
Sound Waves
Sound waves are longitudinal in most fluids because fluids cannot sustain any lateral pressure. In solids, however, shear forces help in propagating the disturbance in the lateral direction as well. Hence,...
Korotkoff Sounds
During blood pressure assessment, inflating the cuff 30 millimeters of mercury above the patient's systolic blood pressure...
The Cochlea
Perception of Sound Waves
The pitch of a sound depends on the frequency and the pressure amplitude of the source. Two sounds of the same frequency...

