Meals on Wheels? A Decade of Megafaunal Visual and Acoustic Observations from Offshore Oil & Gas Rigs and Platforms in the North and Irish Seas

Abstract

A decade of visual and acoustic detections of marine megafauna around offshore Oil & Gas (O&G) installations in the North and Irish Seas are presented. Marine megafauna activity was monitored visually and acoustically by Joint Nature Conservation Committee (JNCC) qualified and experienced Marine Mammal Observers (MMO) and Passive Acoustic Monitoring (PAM) Operators respectively, with real-time towed PAM in combination with industry standard software, PAMGuard. Monitoring was performed during routine O&G industrial operations for underwater noise mitigation purposes, and to ensure adherence to regulatory guidelines. Incidental sightings by off-effort MMOs and installation crew were also reported. Visual and acoustic monitoring spanned 55 non-consecutive days between 2004 and 2014. A total of 47 marine mammal sightings were recorded by MMOs on dedicated watch, and 10 incidental sightings of marine megafauna were reported over 10 years. Species included: harbour porpoise (Phocoena phocoena), Atlantic white-sided dolphin (Lagenorhynchus acutus), white beaked dolphin (Lagenorhynchus albirostris), common dolphin (Delphinus delphis), minke whale (Balaenoptera acutorostrata), common seal (Phoca vitulina), grey seal (Halichoerus grypus) and, basking shark (Cetorhinus maximus). Passive Acoustic Monitoring was conducted on two occasions in 2014; 160 PAM hours over 12 days recorded a total of 308 individual clicks identified as harbour porpoises. These appear to be the first such acoustic detections obtained from a North Sea drilling rig whilst using a typically configured hydrophone array designed for towing in combination with real-time PAMGuard software. This study provides evidence that marine megafauna are present around mobile and stationary offshore O&G installations during routine operational activities. On this basis, Environmental Impact Assessments (EIAs) for decommissioning O&G platforms should be carried-out on a case-by-case basis, and must include provisions for hitherto overlooked marine megafauna.

Ecological Role of an Offshore Industry Artificial Structure

“…Artificial structures in the marine environment alter ecological structure and functioning. They provide habitat for threatened species (Bell and Smith, 1999), contribute reef habitat (Fowler et al, 2018), enhance recruitment of overfished species (Love et al, 2006), increase connectivity (Henry et al, 2018), often produce considerable fish biomass (Claisse et al, 2014) and provide foraging areas for large predators (Todd et al, 2016). These factors may vary over time, relating to environmental conditions and stage of ecological succession (Fujii, 2015).…”

Enhancing the Scientific Value of Industry Remotely Operated Vehicles (ROVs) in Our Oceans

“…Linking between industry and science can alleviate recovery of long-term moorings through the use of acoustic release systems. Todd et al, 2009Todd et al, , 2016Erbe et al, 2015 Multibeam/imaging sonar Low: Imaging sonar systems can detect "targets" at greater ranges than visual techniques, reducing effect of ROV presence and noise; however, target identification is limited. Becker et al, 2013;Parsons et al, 2013Parsons et al, , 2014Lieber et al, 2015 Fish abundance, behavior and composition Archive (historical) video of structures High: Use of historical video imagery of structures to quantify associated fish.…”

“…Linking between industry and science can alleviate recovery of long-term moorings through the use of acoustic release systems. Rountree et al, 2002Rountree et al, , 2003Erbe et al, 2015;McCauley and Cato, 2016;Parsons et al, 2016;Todd et al, 2016 Acoustic telemetry High: Potential for ROV to carry receiver unit and opportunistically detect tagged fauna or carry and acoustic tag and provide opportunistic performance testing. ROV can deploy acoustic receivers along maintenance routes or in dedicated trips to produce an array.…”

“…ROV recordings of sound around O&G structures provides information on soniferous (sound producing) species present, anthropogenic noise and how the latter impacts the former (Williams et al, 2015;Todd, 2016). Moreover, underwater noise pollution is a serious issue, and the introduction of further anthropogenic noise, such as that generated by O&G activities (during exploration, construction or operation), often requires permits and use of Marine Mammal Observers (MMOs) and PAM to determine potential effects on marine fauna (Todd et al, 2015(Todd et al, , 2016. Such activities add significant cost and operational constraints on offshore projects and are increasingly important components of Environmental Impact Assessments (EIAs), whether for an individual activity or under shared sector and cross sector "noise budgets."…”

Observation of a porbeagle shark Lamna nasus aggregation at a North Sea oil platform

“…Far less is known about the behaviour of pelagic predators around oil platforms although they are known to aggregate tuna and plankton feeding whale sharks Rhincodon typus (Smith 1828) in some locations (Robinson et al ., ). In the North Sea, one basking shark Cetorhinus maximus (Gunnerus 1765) has been observed, along with several marine mammal species, in the vicinity of operational oil platforms (Todd et al ., ).…”