Seals use signals from acoustic tags to find fish
Michelle Jewell is a Zoologist specialized in predator/prey behaivour and the Scientific Communicator for EDNA Interactive. She has spent the past 4 years studying the behaviour of white sharks and Cape fur seals at Geyser Rock, ‘Shark Alley’, South Africa.
Anyone who has worked with seals knows they are crafty critters that will always find the easiest way to eat fish. Take the rise and fall of acoustic deterrent devices in aquaculture farms that were designed to scare away seals and other predators. They had limited success and resident predators habituated to the sound when they realized there was no immediate danger. These devices have been shown to actually attract more predators over time, especially passing pinnipeds.
Scientists have used acoustic tags to monitor fish movements since the 1950s, and hundreds of species have been implanted with these tags (a ‘few’ studies listed here) throughout rivers, lakes, estuaries, and the ocean. Could marine mammals associate tag signals with food and do they do this in the wild? A recent laboratory study from St. Andrews (free to download here) answers the first half of this question, showing that grey seals Halichoerus grypus were able to use the signals transmitted from Vemco V9–2H tags to identify boxes that contained fish.