Scientists studying sperm whales off the Caribbean island of Dominica have discovered that the whales change how they communicate when ships are nearby. The whales do not just speak louder to be heard over the engine noise. They actually change the speed and the patterns of their clicks, according to findings published in the journal Ecological Informatics. The study is based on four years of data collected from a group of 15 whales using drone-deployed audio tags, with ship locations confirmed through digital tracking (The Guardian, 2026-07-22; Ecological Informatics).

Sperm whales communicate using clicks grouped into short patterns called codas. Think of a coda as a brief word made of clicks. The researchers recorded more than 1,000 codas from this whale group, known as the Dominica clan. Under quiet conditions, a whale they named Atwood produced a five-click coda in a pattern called 1-1-3: two clicks at a steady pace, then three faster ones. That 1-1-3 pattern is unique to this clan and helps identify them, the way a regional accent identifies where a person is from.

When ships were close, Atwood produced the same 1-1-3 pattern but faster, with shorter gaps between clicks. Across all the data, the whales produced shorter click sequences when shipping noise was present. They did not simply raise their volume, which is what some other ocean animals do. Instead, they changed both the speed and the types of click patterns they used.

Gašper Beguš, the linguistics lead at Project CETI, said that researchers can tell whether ships are nearby just by listening to the whales' clicks. That is how consistent the changes are.

In earlier research reported in April 2026, the same team found that when clicks are packed tightly together, they create continuous sounds that resemble two human vowels: "aaaa" and "iiii." In this new study, the whales used the "aaaa" type more often when ships were noisy. That means the whales are not just adjusting volume but are shifting the building blocks of their communication system.

Project CETI had previously identified 156 distinct click patterns in the sperm whales' sound system, which they described as a "sperm whale phonetic alphabet" with vowel-like sounds serving as building blocks of their speech (UC Berkeley, 2025-11-12; National Geographic Society). David Gruber is the founder and leader of the initiative.

The broader context here is a clash between busy shipping lanes and a species that relies entirely on sound to communicate, navigate, and stay connected with its group. Sperm whales live in deep, dark water where sound matters far more than light. Their 1-1-3 coda is not just a call. It is a cultural identity marker passed down within the clan. If shipping noise is compressing the structure of these codas and changing which sound building blocks the whales use, the open question is whether that degrades the information they share or whether the whales are adapting in a way that keeps their communication working despite the interference.

The study cannot yet answer that question. It shows a clear, predictable link between vessel noise and coda changes, but the effects on group bonds, mother-calf communication, or the passing down of culture over time remain untested. What the data do show is that the changes are not random. The whales are picking specific coda types and adjusting their timing in a way that tracks with noise exposure, which points to a deliberate response to the interference rather than a simple stress reaction.

That distinction matters for policy. Shipping noise is already recognized as a problem under several international agreements, but the rules have mostly focused on how loud the noise is. If whales are reorganizing the internal structure of their communication rather than just shouting louder, then regulations aimed only at decibel levels may be missing the point. Measures like slowing ships down or rerouting them away from whale areas could matter as much as or more than making the vessels themselves quieter.

Dominica has declared a sperm whale sanctuary in its waters and sits at a natural bottleneck for Caribbean shipping traffic. That combination of protected habitat and busy shipping lanes makes the island's eastern waters a natural laboratory for studying this kind of acoustic competition, and Project CETI's long-term dataset is among the most detailed available for this work.

The next phase of research will need to examine whether these changes last across generations or whether the whales revert to their normal patterns once the noise fades. The answer to that question will shape how scientists and policymakers judge the long-term consequences of human noise intruding into a culturally structured communication system.