Rigs may provide vital habitat for endangered marine mammals and their prey Scientists from Scotland-based Ocean Science Consulting (OSC) were the first in the world to eavesdrop on the acoustic activity of marine mammals around the legs of North Sea offshore oil and gas installations. From 2004 to 2010, OSC used autonomous underwater echolocation click-detectors called T-PODs and C-PODs to monitor acoustic activity of harbour porpoises (Phocoena phocoena) around oil and gas installations in the German sector of the North Sea. Under the supervision of Dr Victoria Todd and Ian Todd, OSC initially assessed the underwater noise regime of rigs, to determine if drilling and operational sounds were likely to be audible to porpoises. The next stage of the research was to find out if porpoises were present around rigs, and to what extent.