Ireland — SCIENTISTS are anchoring listening devices deep in the Shannon Estuary to eavesdrop on the “conversations” of dolphins as part of a major study on the cetaceans.

Special electronic microphones called T-pods will record the mammals as they click and whistle at each other at the mouth of the country’s great river.

It is part of a study which will gather data on the population of more than 200 dolphins in the estuary.

The team has spent years photographing the population of dolphins and is now able to recognise individuals by battle scars on their dorsal fins and other markings.

Dr Simon Berrow, co-ordinator of the Shannon Dolphin and Wildlife Foundation, said that the recording of the mammals’ noises will help them learn more about their behaviour. “We put the T-pods down on the ocean floor and they can detect the echo-location click of porpoises and dolphins.

“They work day and night and in all sorts of weather so they are a brilliant way of finding out where dolphins go. They could determine foraging noises and distinguish between dolphins and porpoises. We will be able to find out where their important feeding areas are and where they go in different seasons.”

Dr Berrow said there are four T-pods in place and they expect to have 10 by next year. The marine biologist said it would provide vital information to scientists about important conservation areas for the much-loved mammals.

He said: “For instance, if they want to put a gas terminal in the ocean we will know whether it is an important dolphin site by the use of the acoustic devices.

“Sometimes the dolphins will only go somewhere for the winter or the summer, so we can tell developers they can work on the site when the dolphins are gone.

“It’s a great way of determining exactly where they go and establishing patterns.”

He said the Shannon Estuary has the largest resident group of dolphins in the country and is one of the most important sites in Europe.

“It’s been here hundreds or even thousands of years. The dolphins are in the estuary all year around. It has an abundance of food, areas for resting and areas for calving.

“It has all the requirements dolphins need. It’s not just somewhere for feeding, it’s somewhere for mating and calving. It’s a sheltered area too, so they can avoid predators like killer whales.”