There is growing concern that man-made noise disturbance during offshore seismic exploration may have an affect on marine life, in particular marine mammals and turtles. It is therefore compulsory that a seismic survey vessel be accompanied by at least one marine mammal observer. The role of the marine mammal observer is to monitor the surrounding area, using either visual and/or passive acoustic monitoring methods, and to act immediately to protect species of concern. The observers will advise personnel onboard to delay or shutdown operations until the animals are at a safe distance and also to record behaviour and sightings at other times. Visual monitoring is conducted using a pair of binoculars whereas passive acoustic monitoring is conducted by deploying hydrophone cables and monitoring in-coming signals with specially designed acoustic software (e.g. PAMGUARD). PAM and MMO approaches are often used simultaneously to provide better coverage.