Sperm whales alter vowel-like clicks near boats, study finds

Sperm whales appear to adjust the structure of their communication when boats are close, according to new research from Project CETI off the Caribbean island of Dominica. The study adds to growing evidence that marine traffic can affect the way marine mammals communicate and suggests that these vocal shifts may be distinctive enough for scientists to use as a signal that ships are nearby.

Sperm whales change vowel-like clicks near boats

Project CETI, the Cetacean Translation Initiative, spent four years listening to the calls of 15 sperm whales in waters off Dominica. According to the researchers, the animals did not simply continue clicking in the same way regardless of conditions. Instead, their codas, the patterned sequences of clicks sperm whales use to communicate, changed when shipping noise was present.

The team identified two kinds of changes. First, individual click sequences became shorter when marine traffic was close. Second, the prevalence of two vowel-like sounds shifted in noisy conditions. The supplied source material does not give the technical details of those sound categories, but it does show that the researchers observed a consistent change in the whales' audible output in the presence of boats.

The scientists said the pattern was clear enough that it could be used to predict when ships are nearby. That point matters because it moves the finding beyond a simple observation of noise exposure. It suggests that sperm whale communication may carry information about the surrounding environment in a measurable way, giving researchers another possible tool for monitoring human activity at sea.

Why the finding matters

Sperm whales are known for producing codas, which are discrete and distinctive patterns of clicks used for communication. The new work adds to the understanding of how those vocalizations behave under pressure from marine traffic. Rather than remaining fixed, the whales' sounds appear to vary in tempo and in the relative prominence of certain vowel-like components when ships are in the area.

That matters for two reasons. First, it offers a possible window into how whales respond to noise in their habitat. Second, it may help scientists studying whale communication separate natural patterns from those influenced by boats and shipping lanes. In other words, the environment itself may be changing what researchers hear when they record whale vocal behavior.

The research was carried out in waters off Dominica, a setting that has become important for long-term listening projects focused on sperm whales. The four-year study period and the sample of 15 whales provide a specific look at one population rather than a broad global survey, so the results should be read in that context. Even so, the findings are notable because they connect animal communication directly with nearby marine traffic and offer a practical prediction tool based on the whales' own clicks.

What the researchers found

The key result is not that sperm whales make sounds near boats, but that the shape of those sounds changes. The codas became shorter, and two vowel-like sounds appeared in different proportions under noisy conditions. That combination gave the researchers a pattern distinct enough to stand out in their recordings.

The source material says the findings were published in the journal Ecological., but it does not provide the full journal title or additional methodological detail. What is clear is that Project CETI sees the result as part of a broader effort to decode sperm whale communication.

For marine science, the study adds another piece to the puzzle of how large whales adapt to a world with more vessel traffic. For communication research, it suggests that the whales' clicks may be influenced by more than the social situation alone.

As scientists continue listening to sperm whales off Dominica and elsewhere, work like this may help determine how much of what they hear reflects the animals themselves and how much reflects the noise of the human activity around them.