Scientists have demonstrated that undersea optical fibres, typically used for data communication, can be employed as a new tool to track whales, even when they are not vocalizing. This advancement, based on distributed acoustic sensing (DAS) technology, opens up the possibility of passively monitoring cetacean activity on a large scale, providing crucial data for their conservation and the study of their behaviour.

The DAS technique transforms fibre optic cables into a network of thousands of seismic sensors. By sending laser pulses through the fibre and analysing the backscattered light, minute deformations in the cable caused by acoustic vibrations can be detected. In this instance, vibrations generated by the movement of whales through the water were sufficient to be picked up by the system. This method offers an alternative to traditional hydrophones, which require specific deployments and have a more limited range.

The ability to detect silent whales is particularly significant, as many cetacean species do not vocalize constantly, or do so at frequencies not easily detectable by conventional methods. This new application of undersea telecommunications infrastructure could transform how marine life is studied and protected, enabling continuous, low-impact monitoring across vast oceanic expanses. The collected data could help to better understand migratory routes, feeding patterns, and the impact of human activities on these marine mammals.