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Sperm whales alter the pattern of their vocalisations when they detect nearby ships, suggesting they may change the way they communicate in response to vessel traffic, according to a new study.
Researchers say the whales’ distinctive clicking patterns are so consistent that they can be analysed to determine whether a ship is nearby.
The findings come from a four-year study conducted on 15 sperm whales off the coast of the Caribbean island of Dominica by the non-profit Project CETI (Cetacean Translation Initiative). The research has been published in the scientific journal Ecological Informatics.
According to the researchers, the rhythm of the whales’ short communication signals, known as codas, changes noticeably when ships are in the vicinity.
They found that the duration of the codas becomes shorter and certain vocal patterns become more prominent when whales detect nearby vessels.
David Gruber, founder and chief executive of Project CETI, said the findings raise an important question: whether whales are communicating with one another about ships or whether the presence of ships simply alters the way they vocalise.
“If we can understand what they are saying about ships, it could have significant implications for marine policy and conservation,” he said.
For the study, researchers recorded more than 1,000 codas from groups of 15 sperm whales. Audio tags were attached to the whales using drone technology to minimise disturbance, while the positions of nearby vessels were digitally tracked and compared with changes in the whales’ vocalisations.
Marine animals typically respond to underwater noise pollution by increasing the volume of their calls. However, the researchers found that sperm whales do not simply call louder.
Instead, they modify the structure and timing of their codas, indicating a more sophisticated response to ship noise.