The ocean off India’s Sindhudurg coast hides a tiny, shy creature that most people never see — even though it might be more common than scientists ever imagined.
The Indo-Pacific finless porpoise is one of India’s smallest whale relatives, called cetaceans by scientists. Fully grown, it stretches only 1.5 to 1.9 meters long — about as tall as a human teenager — and weighs roughly 30 to 45 kilograms. But what makes this animal especially hard to find is what it lacks: a dorsal fin, that curved back fin most people picture when they think of dolphins or porpoises. The finless porpoise has a blunt, rounded head and spends its life in shallow, muddy waters, surfacing only briefly before diving again.
These traits made researchers wonder whether visual boat surveys were missing most of the animals. So in 2025, a team of scientists tried something different. They counted porpoises using special sound-recording devices placed in the water — and the results were striking. Acoustic surveys detected finless porpoises four times more often than traditional visual sightings along the Sindhudurg coast, north of Goa.
The reason this matters goes beyond curiosity. The porpoises’ shallow coastal home is becoming dangerous. Boat traffic increases every year, and the animals frequently get tangled in fishing nets — a problem called bycatch. In Goa alone, researchers estimate that 26 porpoises die this way every year along just 100 kilometers of coastline. That number could be even higher in other regions, since visual counts are clearly underestimating how many porpoises are out there.
“Population assessments that only use conventional visual sightings from boats may be capturing only part of the picture,” said Isha Bopardikar, the study’s lead author, who worked on the research through IISER Tirupati and Cornell University’s K. Lisa Yang Center for Conservation Bioacoustics.
Marine mammal researcher Dipani Sutaria explained why bycatch hits porpoises especially hard. “Dolphins can sometimes tear out of nets, but porpoises cannot,” she said. “They get stressed easily and fishers say they cry like human children when entangled.”
The finless porpoise does have one clever trick for survival: it uses high-frequency clicks for navigation and communication, sounds far beyond what human ears can detect. This secret acoustic world helps it avoid larger predators like orcas and dolphins. But that private language is now being drowned out by cargo ships, fishing vessels, and other industrial noise — making it harder for the porpoises to find food and sense danger.
Researchers say shifting toward acoustic monitoring could give conservationists the reliable, long-term data they need to protect these animals. If scientists can finally get an accurate count of how many finless porpoises live in Indian waters, they can push for smarter fishing practices and quieter shipping routes — giving this quiet, finless neighbor of India’s coast a fighting chance.