The Challenge of Studying Finless Porpoises
The Indo-Pacific finless porpoise is one of the smallest cetaceans in India, inhabiting murky coastal waters and lacking a dorsal fin, which makes this species difficult for researchers to spot. Recently, research suggests that these animals are much more prevalent in Indian waters than visual sightings suggest, however, they may be disappearing before they can be accurately counted.
What We Know About Finless Porpoises
A fully developed Indo-Pacific finless porpoise measures 1.5-1.9 meters in length and weighs about 30-45 kilograms. It is highly inconspicuous, with a rounded head, no dorsal fin, and occupies shallow, muddy waters, surfacing only briefly. However, the finless porpoise can be "heard". It navigates murky waters by echolocation, emitting high-frequency pulses that are unique to the species and far beyond human hearing range, but detectable by specialized sound recording devices.
The Importance of the Acoustic Approach
In 2025, a study counted finless porpoises using both visual and acoustic surveys off the coast of Sindhudurg, north of the state of Goa. The acoustic surveys detected finless porpoises four times more frequently than the visual surveys. The lead author, Isha Bopardikar, from the Indian Institute of Science Education and Research (IISER) Tirupati and the K. Lisa Yang Center for Conservation Bioacoustics at Cornell University, said that relying on visual estimates in Indian waters is a significant drawback due to limited visibility and the animal's brief surface time.
Implications and Challenges
This means that population assessments using only conventional visual boat-based sightings may be capturing only part of the picture. Understanding population trends is crucial for the conservation of these animals. The acoustic approach offers a clearer perspective on the presence and distribution of finless porpoises, allowing conservationists to develop more effective strategies to protect them.
Broad Context and Future Perspectives
Conservation of finless porpoises is part of a broader effort to protect marine biodiversity. Habitat loss, pollution, and overfishing are just some of the challenges these animals face. As we continue to learn more about these incredible cetaceans, it is essential that we also take concrete steps to mitigate human impacts on their habitats and ensure the longevity of these species.
Next Steps and Open Questions
The next steps include expanding acoustic studies to other regions, developing evidence-based conservation strategies, and raising awareness about the importance of protecting these animals. Additionally, it is crucial to address the broader issues affecting marine conservation, such as sustainable management of marine resources and reduction of environmental impacts.
Source / Reference
This article was originally published on Mongabay.