Seals can home in on acoustic tags routinely attached to fish by marine scientists.
These small, sound-emitting devices are often used to track fish populations. Vincent Janik at the University of St Andrews, UK, and his colleagues allowed 10 captive grey seals (Halichoerus grypus; pictured) to explore 20 boxes in a pool. One box was baited with an untagged fish, another contained a tagged fish and the rest were empty.
In a series of tests, the seals found the tagged fish with increasing speed, and homed in on it faster than on the untagged fish. In later experiments in which no fish bait was used, the animals still generally visited tagged boxes faster than untagged boxes.
This adds to evidence that marine mammals can use human-generated sounds to find prey in the wild.