T-PODS (Timing Porpoise Detectors)

To complement the land based effort related survey, T-PODS (Timing Porpoise Detectors) are being used to monitor cetaceans under the water on the North coast of Devon.

What is a T-POD?

A T-POD consists of a hydrophone which listens for cetacean clicks under the water. They log the times and duration of clicks resembling the echo-location clicks produced by these animals.

The T-POD software then identifies and classifies trains of clicks within the logged data. This process of click train recognition filters out non-cetacean clicks and gives reliable data on the presence of the animals and some indication of their behaviour.

The hydrophone is encased in a robust water-tight tube and the T-POD secured to a lobster pot and weighted rope connecting the T-POD to two buoys at the surface.

North Devon survey

In August 2009, DBRC deployed two T-PODs off Baggy and Capstone point on the North Devon coast. The T-PODs were set to scan for harbour porpoise and bottlenose dolphin clicks. Baggy and Capstone Point are particular hotspots for harbour porpoise and are regularly surveyed by volunteers, so these two locations seemed the most sensible for T-POD deployment.

We know cetaceans are in the areas we are using so the aim of collecting the data is to give us a clearer picture of their behaviour, how they use the area and at what time of day. By comparing surface sightings and underwater activity, we can pull this information together to gain more of an insight into what’s going on.  
They can also begin to indicate the activity of these animals at night when volunteers are no longer able to continue watching.