Building a Cetacean Passive Acoustic Network in Belgian marine waters

Left: a C-POD anchored to a shipwreck. Photo: VLIZ. Right: Harbour porpoises (Phocoena phocoena) are often spotted in Belgian marine waters. Photo: Kustfotografie.be/Misjel Decleer.
 
Harbour porpoises and dolphins (belonging to the toothed whales or Odontoceti) use echolocation to extract information from their surroundings. Dolphins produce clicks in a wide frequency range and are typically short and loud, while harbor porpoises are producing rather longer, but weaker clicks in a narrow frequency range (120 - 145 kHz, mode 132 kHz).
 
These clicks can be recorded by the passive acoustic device, C-POD (Chelonia Limited), when a marine mammal is swimming in the vicinity of the recorder. The C-POD can record clicks between 20 and 160 kHz including ambient background noise, sonar and other biotic underwater sound. The key to the performance of the C-POD is detection and classification of series of clicks, so-called click trains. Click trains have distinctive features which are used by the classification algorithms to identify the occurring cetacean species.
 
Currently (August 2016) eight C-PODs are attached to buoys, anchored to ship wrecks or to artificial hard structures positioned along an east-west gradient covering coastal, midshore and offshore zones of the Belgian part of the North sea.
 
More information: Elisabeth Debusschere, VLIZ (elisabeth.debusschere@vliz.be or +32-(0)59-34 01 81)