The use of C-pods (continuous porpoise detectors) is currently the preferred method to monitor the habitat use of harbour porpoises over longer periods.
C-pods are used as standard in effect studies. It is not yet possible to translate the number of clicks into numbers of individuals.IMARES is an expert in the area of C-pods and has all the necessary hardware and software to collect, analyse, interpret and report data. In recent years C-pods (the successor to T-pods ) have been successfully used in various monitoring programmes for offshore wind parks.
Porpoises continuously emit clicks used for echolocation. C-pod allows for these sounds to be recorded; they are fully automatic, static, passive monitoring systems that recognise the click trains of porpoises, dolphins and other toothed whales (sounds that these sea mammals use to detect prey, orient themselves and communicate). C-pods can be used in various environments and for a wide variety of purposes.
Although C-pods have limited spatial coverage, they have the great advantage of being able to collect data for months. The C-pods are installed in the North Sea in the desired location with a ship from Rijkswaterstaat (the Dutch department of waterways and public works). To prevent collisions with C-pods they are attached to a structure with large marker buoys. The C-pod data are collected on memory cards for about four months; when the battery is empty or memory card is full, a C-pod can be quickly serviced at sea.