Acoustic detection discovers hotspot for dolphins in the Arabian Gulf and records undocumented species

Gaining knowledge about the biodiversity of an area is a prerequisite to understanding and protecting the inhabiting species. Very little is known about cetacean species and their distribution in Qatar marine waters. The Al Shaheen offshore oil extraction platforms situated in the Arabian Gulf 85 km NE of Qatar mainland have been identified as a hotspot for plankton feeding whale sharks and cetacean species have been sighted consistently in the area during whale shark surveys. Several different species of cetaceans have been sighted but no official records have been published nor has any monitoring been carried out so far. It is important for conservation and management to understand the ecological consequences of human utilisation of marine habitats. Anthropogenic noise in the marine environment is increasing as a consequence of such utilisation and may have a great impact on the behaviour and overall fitness of marine mammals in the vicinity of noise sources (Richardson et al. 1995). A 2 year monitoring project around a Danish Maersk gas production platform initiated in 2013 has indicated that production platforms potentially act as a hotspot for harbour porpoises regardless of the increased noise levels from the ongoing human activities (Balle et al. 2014). It is possible that a similar positive effect is seen with the cetacean species sighted in the Al Shaheen area. Alternatively, Al Shaheen may have a high natural productivity, attracting large fish and cetaceans. Using state of the art marine acoustic technology, 2 passive acoustic monitoring (PAM) stations using Wildlife Acoustic SM3M+ broadband loggers (384 kHz sample rate, 16 bit, -165dB re 1V/µPa single hydrophones) with Sub Sea Sonic AR-60-E acoustic releasers were deployed in August 2014. One station (AlShaheen800) was deployed within 800 m of an operating production platform and a reference station (Alshaheen12800) at 12 kilometres distance within the Al Shaheen area. Here, we will present preliminary diurnal and seasonal variation from the first three deployment periods (Aug-Oct 2014, Feb-Apr 2015 and May-July 2015) and visual identification of 3 species (dwarf spinner dolphin, long-beaked common dolphin and indo-pacific bottlenose dolphin) encountered in the Al Shaheen area. To our knowledge, this is the first time the dwarf spinner dolphin has been sighted in the Arabian Gulf. We also wish to stress the requirement for an ongoing monitoring effort (visually and acoustically) to further understand and document the distribution of cetacean species inhabiting the Al Shaheen area. Balle, Jeppe Dalgaard, Clausen, Karin Tubbert, Mikkelsen, Lonnie, Wisniewska, Danuta Maria & Teilmann, Jonas 2014. Harbour Porpoises and noise around an operating oil and gas production platform in the North Sea – Status report. Nature Agency, Danish Ministry of Environment. Richardson, W.J., Malme, C.I., Green Jr., C.R., Thomson, D.H., 1995. Marine Mammals and Noise. Academic Press, San Diego, CA, USA.