Short Conversations: The Destructive Impact of Vessel Noise on Sperm Whale Communication
A study from the University of Haifa reveals that sperm whales alter their 'coda' click sequences when near vessels. Researchers found that these sounds become shorter and change in acoustic structure, providing the first systematic proof that ship noise directly impacts whale behavior.
Sound is the primary means by which marine mammals communicate, navigate, and locate food. Sperm whales maintain social bonds through 'codas' — structured sequences of clicks that vary in rhythm, timing, and acoustic characteristics.
While previous studies have linked human-made marine noise to changes in the intensity and frequency of calls, a direct causal link between vessel noise and sperm whale communication had not been proven until now. Research conducted at the University of Haifa and published in the journal Ecological Informatics has provided the first systematic evidence of this impact.
When vessel noise was detected in their environment, the click sequences emitted by the whales were shorter, and their acoustic characteristics were altered. Remarkably, machine learning models were able to identify the presence of nearby vessels with over 90% accuracy, based solely on the analysis of the whales' own sounds.
"The connection to noise is not expressed only in the question of whether the whales make more or fewer sounds, but also in the way the sound sequence itself is built. This means the first systematic proof that noise from vessels affects the behavior of sperm whales," said Prof. Roee Diamant of the Leon H. Charney School of Marine Sciences at the University of Haifa, who led the study.
As part of the international Project CETI, researchers analyzed 1,398 codas recorded from 15 sperm whales in the Dominica area of the eastern Caribbean. The recordings were captured using temporary tags attached to the whales, allowing scientists to correlate whale sounds with ship noise data obtained via the Automatic Identification System (AIS).
The findings show that in the presence of vessel noise, codas were not only shorter but also exhibited changes in acoustic patterns. Furthermore, researchers observed an increase in codas where individual clicks failed to match the acoustic profile of the rest of the sequence.
Prof. Diamant noted that these findings align with broader research on the extensive impact of ship-radiated noise on the marine environment, including fish, sea turtles, and crustaceans. He emphasized that Israel has the potential to lead in marine regulation to mitigate these impacts, particularly in areas surrounding marine nature reserves.
