Passive Acoustic Monitoring is an important part of the work carried out by OSC Ltd. Currently we have a number of operators working in the field to put mitigation measures in to practice on board seismic vessels. Hydrophones towed behind the vessel are used to detect the sounds of marine mammals; this week our observers have been listening to the whistles of dolphins.
Set up with headphones, two laptops and a Data Acquisition Unit (DAU), which receives signals from the hydrophones, PAM operators work throughout the night, and sometimes during the day, to ensure marine mammals are not within close proximity to a sound source before it is activated.
Viewing a visual representation of the vocalisation on a spectrogram, Passive Acoustic Monitoring operators are able to identify species, and in some cases the distances and bearing from the hydrophone.