Paris - Sound-emitting tags fitted to fish to track their survival may, paradoxically, be alerting predator seals to their whereabouts, said scientists on Wednesday who warned of a “dinner bell” effect.
Tests with captive grey seals showed that they learned quickly to associate the tag's sound with the presence of an easy meal, British researchers reported in the journal Proceedings of the Royal Society B.
Ten juvenile seals who had not been exposed to acoustic tags before, were put to the test in a concrete pool with twenty boxes into which fish, tagged and untagged, were randomly placed for them to eat in 20 trials.
“The seals found the tagged fish in fewer box visits than the untagged fish in later trials, demonstrating the learned use of the acoustic tag to locate food,” the researchers found.
With each consecutive test, seals needed about five percent less time to find the box with the tag inside. And they visited the boxes with tagged fish much more frequently than empty boxes or those with non-tagged fish.