Abundance and distribution of Tursiops truncatus in the Western Mediterranean Sea: an assessment towards the Marine Strategy Framework Directive requirements.
The Mediterranean Sea common bottlenose dolphin population has been assessed as Vulnerable according to the IUCN Red List Criteria. The species is also included in several International Agreements, European Union Regulations and Directives. Amongst them, a strict protection and identification of special conservation areas are requested by the EU Habitats Directive. Despite direct takes, by-catch, chemical and acoustic pollution, and prey depletion, general habitat degradation and fragmentation have been indicated as detrimental for the species, the degree to which these threats pose population risk is still largely unknown. At present it is thus not possible to depict the actual status of the population and to assess prospective trends. To address this gap in the current knowledge, line transect distance sampling aerial surveys were conducted in a wide portion of the Western Mediterranean Sea between the summer of 2010 and winter 2011. A total of 165 parallel transects equally spaced at 15 km were designed providing homogeneous coverage probability. Overall, 21,090 km were flown on effort and 16 bottlenose dolphin sightings were recorded and used for the analysis. The surface abundance and density estimates resulted in 1676 animals (CV = 38.25; 95% CI = 804-3492) with a density of 0.005 (CV = 38.25%). These results represent the first ever estimates for the common bottlenose dolphin over a wide portion of the Western Mediterranean Sea Subregion, with the potential to be useful baseline data to inform conservation. Specifically, they could be used as indicators under the Marine Strategy Framework Directive requirements, in conjunction with other study methods.
Institute for Environmental Protection and Research (ISPRA), Via V. Brancati 60, 00144 Roma, Italy. Electronic address: giancarlo.lauriano@isprambiente.it.
Giancarlo
G
Lauriano
Tethys Research Institute, Viale G.B. Gadio 2, 20121 Milano, Italy.
Nino
N
Pierantonio
The International Whaling Commission, The Red House, 135 Station Road, Impington, Cambridge, Cambridgeshire CB24 9NP, UK.
Greg
G
Donovan
Tethys Research Institute, Viale G.B. Gadio 2, 20121 Milano, Italy; Institute for Environmental Protection and Research (ISPRA), Via V. Brancati 60, 00144 Roma, Italy.
Simone
S
Panigada
D063147:Animal Distribution; D000818:Animals; D050681:Bottle-Nosed Dolphin / Q000502:physiology*; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring; D005062:European Union; D007558:Italy; D008522:Mediterranean Sea; D011156:Population Density
Abundance; Aerial survey; Common bottlenose dolphin; Distance sampling; Marine Strategy Framework Directive; Marine mammals; Mediterranean Sea