Recently presented at the Second Workshop on the Biology and ecotoxicology of large marine vertebrates: potential sentinels of Good Environmental Status of marine environment, implication on European Marine Strategy Framework Directive, organised by the Univerity of Siena, Italy.
Lauriano G., Pierantonio N., Donovan G., Panigada S. 2013. Knowledge of Marine Strategy Directive key parameters for the common bottlenose dolphin: a case study in the Western Mediterranean Assessment Area. Biology and ecotoxicology of large marine vertebrates: potential sentinels of Good Environmental Status of marine environment, implication on European Marine Strategy Framework Directive. Siena, Italy, 5-6 June 2013. (Oral presentation)
The common bottlenose dolphin (Tursiops truncatus) from the Mediterranean Sea has been assessed as Vulnerable according to the IUCN Red List Criteria. Moreover, the species is included in several International Agreements, European Regulations and Directives and amongst these a strict protection and identification of special conservation areas are requested from the Habitat Directive.
Despite the above considerations and that the species is the most studied cetacean, to depict the actual conservation status and compare it to the past distribution and abundances throughout the Basin is not possible. In addition, direct takes in the past, bycatch, chemical and acoustic pollution, prey depletion and a general habitat degradation and fragmentation have been indicated as detrimental for the species, but the degree to which they pose an effective population risk is unknown, so far.
From summer to autumn 2010, line transect aerial surveys were conducted in area covering the Ligurian, the Central and the south Tyrrhenian Seas and the Seas of Corsica and Sardinia (fig. 1). A total of 165 parallel line-transects, 15 km apart and totaling 21,189 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 abundance and density estimates using the dedicated software Distance 6. Differences in presences were detected across the study area. The overall abundance estimates resulted in 1,676 animals at surface (CV= 38.25; 95% CI= 804 – 3492) with a density of 0.005 (CV=38.25%) and an encounter rate of 0.000758 groups/km (CV=27.5%). These are the first estimates for the common bottlenose dolphin over a wide portion of the Western Mediterranean Assessment Area (WMAA) and possibly will represent a useful baseline dataset to provide information following the requisites, such as the species distribution and abundances, of the MSFD requirements. The line transect aerial surveys, in conjunction with other study methods (e.g. photo-identification, satellite telemetry) can provide a cost-effective means of fulfilling requirements, under the MSFD and offer a valuable contribution to conservation efforts.