Balearic Islands Shelf and Slope IMMA
22 708 km2
Qualifying Species and Criteria
Sperm whale – Physeter macrocephalus
Criterion A; C (1, 2)
Marine Mammal Diversity
Stenella coeruleoalba, Tursiops truncatus, Grampus griseus, Globicephala melas, Delphinus delphis
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The deep-water shelf and slope areas of the eastern Balearic archipelago contain a high density of Mediterranean sperm whales (Physeter macrocephalus). Both social units and mature males are consistently observed here. This ecologically important area thus also has an important role as one of the known breeding grounds for the species in the Mediterranean. The species is distributed from the deeper continental shelf to waters of 2000-2500m depth. The Mediterranean sperm whale subpopulation is Endangered and is threatened in the area mainly by net entanglement and ship strikes.
Description of Qualifying Criteria
Criterion A – Species or Population Vulnerability
The IUCN Red List classifies the Mediterranean subpopulation of sperm whale as Endangered and infers that their numbers are declining from significant anthropogenic threats. These whales are likely to be genetically isolated from the Atlantic population. The principal threats are from ship strikes and entanglement in driftnets, followed by ingestion of plastic debris, anthropogenic noise, chemical pollution, and disturbance by poorly managed whale watching operations.
Criterion C: Key Life Cycle Activities
Sub-criterion C1: Reproductive Areas
The area is one of the few regions in the western Mediterranean basin in which sperm whale social groups and singleton males are both sighted regularly – indicating it is an important area for contact between mature males and reproductive females. Calves are also regularly sighted within female groups.
Sub-criterion C2: Feeding Areas
Bathymetric features and the hydrodynamic processes in the area act to concentrate prey for sperm whales and evidence suggests that the south-face continental shelf slopes are an important foraging habitat for this population. Acoustic data confirm the activity of feeding. Sperm whales in the area concentrate in areas where the bottom aspect is approximately between 0° and 210°, i.e. where the shelf wall is oriented north-eastward, eastward or southward. Depth might be associated with the bathymetric zonation of cephalopod assemblages, while slope aspect likely interacts with north-flowing Atlantic water drawn by the Balearic Current to determine the downwelling/upwelling movements that are believed to influence the availability and concentration of sperm whale prey.
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