Researchers listening off the Caribbean island of Dominica found variations in the mammals’ audible clicks when marine traffic was close Sperm whales produce a specific pattern of…

Researchers listening off the Caribbean island of Dominica found variations in the mammals’ audible clicks when marine traffic was close Sperm whales produce a specific pattern of clicking noises when they hear the noise of boats, researchers have found. The pattern is so distinct that the scientists who identified it said they can now use it to predict when ships are nearby. Researchers from Project Ceti (the Cetacean Translation Initiative), a non-profit research organisation working to decode sperm whale communication, spent four years tuning in on the calls of 15 sperm whales off the coast of Dominica. They discovered specific differences in sperm whale “codas”, the discrete and distinctive patterns of clicks that this species utters to communicate when those whales encountered shipping. Individual click sequences became shorter, and one type became more prominent than another. Their findings are published in the journal Ecological Informatics. “This research begs the question: are whales talking about the ships, or is it an impact on their voices because the ships are around?,” said David Gruber, the founder and chief executive of Project Ceti. “And then if we’re able to discern what they’re saying about the ships, how might that impact policy and laws?” Under normal conditions, recordings from one of the whales, named “Atwood”, picked up one type of coda comprising five clicks in a 1-1-3 pattern (two clicks preceding three quicker ones), which, Gruber explained, is unique to this specific clan of sperm whales off the Caribbean coast of Dominica. With the background hum of a ship, Atwood issued the same 1-1-3 click rhythm but noticeably faster, with the whale reducing the intervals between each click. The association was so strong that “in general, from their vocalisations alone, we can predict whether ships are around,” said Gašper Beguš, linguistics lead at Project Ceti. For the study, Beguš and colleagues recorded more than 1,000 codas from the 15-strong sperm whale pod, using audio tags attached to whales by drones to be minimally invasive. Where background shipping noise was detected, it was verified using digital geolocation data to confirm that vessels were in the whale’s vicinity when the recording was made.