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Fin whales in the Pelagos Sanctuary
Fin whales in the Mediterranean congregate in highly productive localities to feed. High whale densities comparable to those found in rich oceanic habitats are found in the Ligurian-Corsican-Provençal Basin, and particularly within the Pelagos Sanctuary, where their presence is particularly noticeable during the summer. In this subregion, where sighting reports are abundant, fin whales rank second after striped dolphins in sighting frequency.
The abundance of fin whales in the area can be explained by its well-known productivity, due to a permanent frontal structure. This productivity sustains a large biomass of krill Meganyctiphanes norvegica, the fin whales’ main prey in the region.
Extensive observations confirm the presence of large numbers of fin whales in the Ligurian Sea during the summer months. The early summer increase in the Ligurian-Corsican-Provençal Basin coincides with the well-known seasonal migration pattern towards feeding grounds observed in oceanic whales. Likewise, the decline of whale abundance in early autumn is suggestive of a seasonal migration away from the Ligurian Sea feeding ground.
While in the Ligurian Sea, fin whales show significant site fidelity, as evidenced by the numerous re-sightings of identified individuals.
A fin whale breaching in the Pelagos Sanctuary. Photo © Tethys Research Institute.
Active feeding in this region has been confirmed by frequently observed defecation episodes. Conversely, direct observations of fin whales engaging in feeding, frequent on many feeding grounds in the world, are absent in the Ligurian-Corsican-Provençal Basin, in spite of the wealth of direct observation time collectively spent by many investigators on these feeding grounds. This is likely related to the vertical distribution and movement pattern of the whales’ main prey in the area.
Fin whales in the Ligurian Sea perform the deepest dives known for the species, exceeding 470 m.
A fin whale at risk of collision with a ferry in the Pelagos Sanctuary. Photo © Tethys Research Institute.
Ship strikes are a significant source of fin whale mortality in the Mediterranean, and represent an important threat in the Pelagos Sanctuary.
In addition, other human activities may generate potentially high levels of disturbance which is known to induce short-term avoidance reactions in whales. These include intense maritime traffic, a burgeoning and currently unregulated whale-watching industry, and loud noise production by oil and gas prospecting and military activities.
Cetacean Alliance investigators:
For more information on fin whales in the Ligurian-Corsican-Provençal Basin see:
