The Genoa Canyon, located in the westernmost part of the Ligurian Sea, has been identified as a high-density area for a resident population of Mediterranean Cuvier’s beaked whales (Ziphius cavirostris). A high correlation was also observed between the presence of Cuvier’s beaked whales and the underlying canyon area; this has been validated by modelling studies. The area extends to the 1000m isobath.
Description of Qualifying Criteria
Criterion A: Species or Population Vulnerability
The subpopulation of Cuvier’s beaked whale in the Mediterranean Sea is listed as Vulnerable (VU) C2a(ii) IUCN Red List of Threatened Species, with a decreasing population trend (Cañadas and Notarbartolo di Sciara, 2018).
Criterion B: Distribution and Abundance
Sub-criterion B1: Small and Resident Populations
This area is indicated to contain the highest density of Cuvier’s beaked whale in the Mediterranean Sea. This fact is supported by other studies that indicate the the Ligurian Sea is a high-density area with high site fidelity for the species. Mark recapture analysis conducted on a long-term dataset report an abundance estimate of about 100 individuals and pattern of high residency within the Genoa Canyon.
Sub-criterion B2: Aggregations
his area is indicated to contain the highest density of Cuvier’s beaked whale in the Mediterranean Sea. A combination of acoustic and predictive modelling studies to map high density areas for beaked whale at Mediterranean level indicate the importance importance of the Genoa Canyon area, and wider Ligurian Sea, for Cuvier’s beaked whale as the areas with the highest predicted density and acoustic encounter rates.
Criterion C: Key Life Cycle Activities
Sub-criterion C1: Reproductive Areas
Long term photo-identification studies have shown the presence of both juveniles and calves in the Ligurian Sea. At least 2 newborns, showing fetal folds, have been photographed in 2016. Maturity results indicate that 19 groups were mixed herds (with both immature and mature individuals), 17 groups were herds of only immature animals and 4 groups were herds of only mature animals. The 19 mixed herds were composed mainly of 4.0±2.2 individuals (range=2–8) and were made up of 58% mature individuals. The 17 immature groups were composed of 2.1±0.9 individuals. Mature animals were usually found alone.
Sub-criterion C2: Feeding Areas
Evidence of feeding has been reported research conducted in the Ligurian Sea. Stomach contents from stranded animals in the confirm that the animals feed on mesopelagic cephalopod in the area. It is widely known that beaked whales are deep diving species, performing deep foraging dives to feed on deep water food resources. Cuvier’s beaked whale diving profiles in the Ligurian Sea showed foraging activity in mesopelagic to bathypelagic water depths (613–1297 m). The stomach contents of 3 Cuvier’s beaked whales stranded along the Ligurian coast consisted of digested mesopelagic cephalopod beaks principally of the Histioteuthidae family, specifically Histioteuthis reversa and H. bonnellii and other cephalopods species.
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