The endangered short beaked common dolphin (Delphinus delphis) - once one of the commonest cetacean species in the Mediterranean Sea - has faced a dramatic decrease in the last few decades. No specific management measures have been taken to protect the few remaining groups of common dolphins in Mediterranean even though it is well known that dolphins are exposed to direct disturbance by vessel traffic, by catch in fishing gear, and habitat degradation.

Since 1997, relatively large groups were consistently encountered off the island of Ischia, Italy. Photo-identification studies suggested high levels of site fidelity.

 

Striped dolphin (Stenella coeruleoalba), is the commonest species in Mediterranean Sea.

Every year we could observe, in the area of the canyon, large groups of 200 individuals. Striped dolphins were often sighted in association with common dolphins. Feeding and mating behaviours were observed for both species. Newborns were sighted in July and August.

Our data showed a relevant overlap in the distribution of common and striped dolphins in the study area, suggesting the possible existence of antagonism between them in the habitat use.

 

A residential group of 20 common bottlenose dolphins (Tursiops truncatus) has been photo-identified and has been studied since 1993. The home range of this group is extended from Ischia to Ponza, but the most frequent observations have been recorded around Ventotene and Ischia Island.

Bottom gillnets are used in the area only by artisan fishermen. Every year, in the months of March, May and September dolphins were observed preying from nets: dolphins made long dives around the nets, and produced large rips to catch their preys.

 

Risso's dolphins (Grampus griseus) appeared to be seasonally "resident" in the study area, a group of about 20 individuals was regularly resighted, based on photo-identification data collected between 1998-2000. Newborns were sighted in July and August.

A dramatic harassement event had been recorded on Sunday 27 August 2000.

.

 

A single stable pod of long finned pilot whales (Globicephala melas) has been monitored since 1995.

During the years whales' number decrease from six to two.

 

 

 

Sperm whale (Physeter macrocephalus) sightings are off of the canyon area, in the slope environment. Whales are monitored acoustically, following their signals (clicks), which are emitted continuously during the diving.

Since 2002 we recorded the presence of social groups of sperm whales, composed by females and their relatives. Although females and immature sperm whales spent most of their time diving, members of the group clustered at the surface for periods of an hour or more. During these phases a number of different activities were seen from above the water surface.

 

 

The area is used as feeding ground by fin whales (Balaenoptera physalus), the most common species in the canyon.

The analysis of faecal material, according to what had been already observed, has revealed the presence of crustacean exoskeletons belonging to the euphasiacean Meganyctiphanes norvegica, a key species in the trophic web.

 

 

The strong impact of the boats on cetaceans is becoming everyday routine especially in summertime: distress and disorientation, collisions and deaths by a propeller strike.

Timely management measures to protect cetaceans in this key area are clearly needed, regardless of its inclusion in the area proposed for the Marine Protected Area.

 

 

 

Notwithstanding the EU band on the driftnetting fishery, started on January 1st, 2002, illegal fishing with drftnets is still a problem around the Island of Ischia. By catch events were documented for several cetaceans' species.