Marine mammal sightings around oil and gas installations in the central North Sea

• Published in: Journal of the Marine Biological Association of the United Kingdom
• Main Authors: Delefosse, Matthieu, Rahbek, Malene Louise, Roesen, Lars, Clausen, Karin Tubbert
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: Anthropogenic; Cetacean; Diversity; Harbour porpoise; Minke whale; Offshore; Pinniped; Platform; Volunteer programme; Balaenoptera acutorostrata; Killer Whale; Lagenorhynchus albirostris; minke whale; Orca; Orcinus orca; Phoca vitulina; Phocoena phocoena; White-beaked dolphin; Killer whale
• Online Access: https://pure.au.dk/portal/da/publications/marine-mammal-sightings-around-oil-and-gas-installations-in-the-central-north-sea(517ffa48-3681-4010-8a22-9e9c232a2a60).html; https://doi.org/10.1017/S0025315417000406; https://pure.au.dk/ws/files/118499311/marine_mammal_sightings_around_oil_and_gas_installations_in_the_central_north_sea.pdf

Relatively little is known about the distribution and diversity of marine mammals around offshore anthropogenic structures. Wepresentresultsobtainedfromincidentalsightings ofmarinemammalsaroundoilandgasinstallationslocated200 kmoff the Danish coast. A total of 131 sightings corresponding to about 288 animals were reported between May 2013 and May 2016. A total of seven marine mammal species were identified, five cetaceans: harbour porpoise (Phocoena phocoena), minke whale (Balaenoptera acutorostrata), white-beaked dolphin (Lagenorhynchus albirostris), killer whale (Orcinus orca), pilot whales (Globicephala spp.) and two species of pinnipeds: harbour (Phoca vitulina) and grey seals (Halichoerus grypus). The most sighted species were harbour porpoise (41%) and minke whale (31%). Relative counts and biodiversity of marine mammals observed around installations corresponded well with the expected distribution in the central North Sea. Several taxon-specific correlations were identified between number of sightings and environmental parameters (depth and latitude) or installation characteristics (installation aerial footprint). Furthermore, 85% of sightings were made during spring and summer and it is unclear whether the pattern observed reflected a natural seasonal occurrence ofmarine mammalsintheareaoraneffect ofreducedeffort during autumnandwinter. Despitethe potentialcaveats,results obtained during this programme provide an insight into the relationship between marine mammals and oil and gas offshore installations in the North Sea.