Marine Mammal Observers (MMOs) are marine professionals, qualified specifically to oversee offshore industrial activities that have potential to impact marine mammals (e.g. seals, porpoises, dolphins, and whales) through physical disturbance or the emission of high amplitude sound. A MMO’s primary role is to ensure activities adhere to legislation via implementation of best practice mitigation measures, which in turn minimise risk of disturbance or injury to marine mammals. MMOs work alongside offshore industry when undertaking, inter alia, projects for seismic surveys, dredging, drilling, decommissioning, defence, explosive detonations (UXO) for military exercises, pile driving for windfarms, pipeline and cable-laying, hydrographic (e.g. multibeam surveys), civil engineering, Government, media (film-making involving explosions), other non-specialist consultancies, academic institutions, or recruitment agencies requiring ad hoc MMO services for construction, aquaculture trials involving Acoustic Mitigation Devices (AMDs), also known as ‘seal scarers’ or Acoustic Deterrence Devices (ADDs). MMOs are used often during rig tows, seen here in this video https://youtu.be/B1BqsSrRqs0.

GUIDELINES AND MITIGATION MEASURES

In the UK, the Joint Nature Conservation Committee (JNCC) has formulated specific guidelines for minimising risk of injury to marine mammals during seismic exploration, piling, and operations using explosives (see JNCC). Similar guidelines have been formulated by other regulatory bodies including Irelands National Parks & Wildlife Service (NPWS), the Bureau of Ocean Energy Management (BOEM), the Bureau of Safety and Environmental Enforcement (BSEE) in the USA, and the Department of Conservation (DOC) in New Zealand. Whilst guidelines surrounding mitigation measures and certification requirements vary between industrial activities and geographical location, all follow similar principles. MMOs typically undertake a pre-watch in which a mitigation zone (usually 500–1000 m) surrounding the physical disturbance or sound source is surveyed visually to assess presence of marine mammals or other protected marine species (e.g. basking sharks, birds, and turtles). If a marine mammal is detected within the mitigation zone, the MMO will advise operatives on the best course of action. In certain circumstances this may involve a short delay or halt to operations until the marine mammal has moved away to a distance at which continuation of activities are deemed to no longer pose significant threat. Guidelines also stipulate that, where possible, the sound source or disturbance is increased gradually over a set period of time to encourage marine mammals to vacate the area prior to initiation of full power.

For additional details on marine mammal mitigation in the UK, please see www.marinemammalmitigationplan.com or www.marinemammalriskmitigation.co.uk

and for New Zealand please refer to www.codeofconductseismicnewzealand.com or www.marinemammalmitigationplans.com.

OPTIMISING EFFECTIVENESS

Whilst MMOs are an invaluable real-time mitigation tool, the effectiveness of visual observation is limited during hours of darkness and unfavourable weather conditions (e.g. high sea state, rain, fog, ice cover). As such, MMOs work often in concert with Passive Acoustic Monitoring (PAM) Operators who utilise underwater hydrophone systems in the form of towed arrays or static moored systems. PAM systems can detect marine mammal vocalisations, from which it can estimate range, bearing, and even species of vocalising individuals in conditions unfavourable to visual observation. When used in conjunction with one another, MMO and PAM Operators provide comprehensive and effective mitigation 24 hours a day, reducing operational downtime significantly.