Ziphius cavirostris (Mediterranean subpopulation)
|Scope: Global & Mediterranean|
|Scientific Name:||Ziphius cavirostris (Mediterranean subpopulation)|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Reviewer(s):||Aguilar, A., Bearzi, G., Birkun, A., Donovan, G., Fortuna, C., Gaspari, S., Hammond, P., Natoli, A., Notarbartolo di Sciara, G., Perrin , W., Reeves, R., de Stephanis, R. & Taylor, B.L.|
Appropriate data on distribution, population structure and abundance in the Mediterranean basin are lacking, except for a very limited areas. Also, the species’ biology is very poorly known. The status of Cuvier’s Beaked Whale in the Mediterranean is therefore impossible to assess on the currently available evidence.
|Range Description:||Cuvier’s Beaked Whales inhabit both the western and eastern basins of the Mediterranean (Notarbartolo di Sciara 2002). Much of the current knowledge of this species in the Mediterranean has come from stranding data. Strandings have been reported in Albania, Algeria, Croatia, Egypt, France, Greece, Israel, Italy, Malta, Spain and Turkey (Podestà et al. 2006). Appropriate data on distribution in the Mediterranean basin are lacking, except for a very limited areas.|
Native:Albania; Algeria; Croatia; France; Gibraltar; Greece; Israel; Italy; Monaco; Spain; Turkey
|FAO Marine Fishing Areas:|
Mediterranean and Black Sea
|Range Map:||Click here to open the map viewer and explore range.|
Strandings have been reported in Albania, Algeria, Croatia, Egypt, France, Greece, Israel, Italy, Malta, Spain and Turkey, totalling 316 animals (Podestà et al. 2006). Twenty-six percent of the total animals recorded stranded in the Mediterranean have been in mass strandings involving three or more animals (Podestà et al. 2006). Strandings have been particularly numerous along the Ligurian and Ionian coasts, but it is important not to infer too much about species distribution or relative abundance from strandings data alone. Strandings data are subject to a variety of types of bias.
Cuvier’s Beaked Whales seem to be relatively abundant in the eastern Ligurian Sea, off southwestern Crete and the Alboran Sea, especially over and around canyons (D’Amico et al. 2003, Frantzis et al. 2003, Ballardini et al. 2005, Scalise et al. 2005). They appear to be regular although less abundant inhabitants of the western Ligurian Sea (41 sightings in 16 years, Tethys Research Institute, unpublished data; 4.2% of 814 sightings during 10,000 km on effort from 1996–2000, Azzellino et al. 2008). Cuvier’s beaked whales have been described as regular inhabitants of the Hellenic Trench (Frantzis et al. 2003), the southern Adriatic Sea based on frequency of strandings (Holcer et al. 2003) and the eastern section of the Alborán Sea (Cañadas et al. 2005). They also occur in the central Tyrrhenian Sea (Marini et al. 1992) and in Spanish Mediterranean waters (Gannier 1999, Raga and Pantoja 2004, M. Castellote pers. comm.). They have been reported both from strandings and sightings in Israeli, Palestinian and Syrian waters (Aharoni 1944; Saad and Othman 2008; D. Kerem, pers. comm.). No information is available for the remaining areas of the Mediterranean.
There are two abundance estimates for this species in small portions of the Mediterranean Sea. In the Gulf of Genova (eastern Ligurian Sea) mark-recapture analysis (2002–2008) yielded an estimate of 96–100 animals (left and right side identifications respectively) from an open population (Rosso et al. 2009). In the northern Alboran Sea, spatial modelling of line transect data (1992–2007) yields an abundance estimate of 102 animals with a CV=32.1% (corrected for availability bias from a D-tagged animal in the Alboran Sea) (Oedekoven et al. 2009). Abundance estimates for the whole Alboran Sea and the northern Tyrrhenian Sea will be available in 2010 after analysis of the Sirena08 and MED09 survey cruises. Therefore, much better information will be available, and a reassessment is recommended for then. Preliminary inspection of the data highlights a relatively high density (compared to other areas of the world) of Cuvier´s Beaked Whales in the Alboran Sea (44 groups, 89 individuals in 846 km on survey effort, for an encounter rate of 19.5 individuals per 100 km of effort; unpublished data).
There are no data on trends for this species in the Mediterranean.
There are areas, especially in the southern portions of the basin, where Cuvier’s Beaked Whales have not been recorded from either strandings or sightings. However, it must be borne in mind that their long dive times, usually inconspicuous appearance at the surface and typical avoidance of vessels make them difficult to spot (Heyning 1989). In addition, sighting effort and the efficiency of stranding networks vary throughout the Mediterranean: many areas have little or no effort to make and record sightings or to detect strandings. Therefore, a comprehensive basin-wide survey and an efficient basin-wide stranding network are needed before reaching firm conclusions about presence and absence. It is nevertheless possible, based on available data, to identify at least some areas as good habitat, and probably hot-spots, for Cuvier’s Beaked Whales, such as the eastern Ligurian Sea, the eastern Alborán Sea and the Hellenic Trench. The species is probably also common in several other unexplored areas.
|Current Population Trend:||Unknown|
|Habitat and Ecology:|
Cuvier’s Beaked Whale is a predominantly oceanic species often associated with steep slope habitat and a marked preference for submarine canyons and escarpments (D’Amico et al. 2003, MacLeod 2005, Podestá et al. 2006). In the Alborán Sea, Cuvier’s Beaked Whales are encountered in areas of 600 m depth and 40 m km-1 of slope, especially around the 1,000 m isobath in an area of steep canyons off southern Almería, SE Spain (Cañadas et al. 2002, Cañadas et al. 2005). In the Hellenic Trench, Cuvier’s Beaked Whales are sighted in areas of between 500 and 1,500 m depth; it is not known if they are also present farther offshore over the abyssal plain (Frantzis et al. 2003). They seem to be present over all steep topographic features of the Aegean Plateau (Frantzis et al. 2003). In the eastern Ligurian Sea (Gulf of Genoa) they are especially abundant around canyons (D’Amico et al. 2003). In this area, Scalise et al. (2005) reported a mean depth at encounters of 1,358 m (range = 641–2545, se = 514) and a mean slope of 77.1 m km-1 (range = 3–256.5, se = 57). In the same area, cruises organised by SACLANTCEN encountered Cuvier’s Beaked Whales in waters 500–2,600 m deep, with a peak encounter rate in waters 1,000–1,500 m deep over steep slopes (M. Carron, pers. comm.). In the western Ligurian Sea, sightings have been in waters of an average of 1,722 m deep (range = 795–2,500, se = 276) (Azzellino et al. 2008).
Mean group size is fairly constant across the whole basin where data have been collected, ranging from 2.2 to 2.6 individuals (Cañadas et al. 2005, Ballardini et al. 2005, Scalise et al. 2005), except in the western Ligurian Sea with a mean of four (sd = 2) (Azzellino et al. 2008). Social organization is unknown, although the intermediate levels of mtDNA diversity observed in Cuvier’s Beaked Whales suggest that social groups are unlikely to be strongly matrifocal (Dalebout et al. 2005).
Owing to their offshore occurrence and tendency to feed on deep-sea squid, Cuvier’s Beaked Whales are probably little exposed to human activities that occur in coastal waters (tourism, many types of fisheries, etc.). However, the few studies carried out on this species highlight one main threat: certain forms of man-made underwater noise. This threat affects the species world-wide and it has been responsible for some of the observed mortality in the Mediterranean. Military sonars and possibly high-energy sounds from other anthropogenic sources have repeatedly resulted in the stranding and death of Cuvier’s Beaked Whales. The implications of this mortality at the population level are uncertain. Two other concerns are bycatch in drift gillnets and the ingestion of plastic debris (e.g. Kovacic et al. 2009).
Recent atypical mass strandings of beaked whales have been linked to high-powered navy sonar and seismic exploration (e.g. Frantzis 1998, Jepson et al. 2003, Fernández et al. 2005). Deployment of military sonar has led to strandings of beaked whales suffering from chronic and acute tissue damage due to the in vivo formation of gas bubbles, possibly the result of decompression sickness (Jepson et al. 2003, Fernández et al. 2005). Cuvier’s Beaked Whale is the species most commonly involved in these atypical mass strandings (Brownell et al. 2005). Of 224 recorded stranding events of Cuvier’s Beaked Whales in the Mediterranean, 15 involved two animals (9.8% of the total) and 12 involved three or more animals (totalling 80 animals; 26.1% of the total) (Podestà et al. 2006). Four of these strandings were definitely associated with naval activity so far: 1) Valencia, Spain in February 1996 (Filadelfo et al. 2009), 2) Kyparissiakos Gulf, Greece in May 1996 (Frantzis 1998), 3) Ionian Islands, Greece in October 1997 (Frantzis 2004, Filadelfo 2009), 4) Algerian coasts, in 2001 (Filadelfo et al. 2009). In the other cases, either no appropriate data were collected or the analyses were inadequate for assessing the potential association (Podestà et al. 2006). An atypical mass stranding of four Cuvier’s Beaked Whales occurred in SE Spain in January 2006. This event was coincident in time and space with military manoeuvres of NATO (Draft EIS/OEIS 2007), and necropsies of the animals showed “Gas and Fat Embolic Syndrome”, previously associated with anthropogenic acoustic activities, most probably anti-submarine active mid-frequency sonar used during the military naval exercises (Jepson et al. 2003; Fernandez et al. 2004, 2005; Cox et al. 2006). The Mediterranean Sea is a militarily strategic area and is also of increasing interest for hydrocarbon exploration and exploitation. All military or geological or oceanographic activities involving high-intensity noise carried out in the proximity of Cuvier’s Beaked Whales are of concern.
Although the population-level implications of the use of military sonar are uncertain, there is evidence suggesting that they could be at least locally significant. A photo-identification study that preceded and followed the Bahamas mass stranding showed that previously photo-identified, resident beaked whales either left the area or died, since they were never re-captured (photographically) after the event (Balcomb and Claridge 2001). In the Mediterranean Sea, no surveys had been conducted in the Kyparissiakos Gulf before the mass stranding following a naval military sonar exercise (Frantzis 1998). However, strandings of Cuvier´s beaked whales had been common in that area (average rate of one per semester) and have become extremely rare (none or only one) in the nine years since the event. Two international surveys that covered the Kyparissiakos Gulf (IFAW 2003 and MVO in 2004) as well as a survey that has crossed the same area twice yearly since 2002 have failed to record any sightings of Cuvier´s Beaked Whales.
Cuvier’s Beaked Whales are occasionally taken incidentally in driftnets in the Mediterranean Sea. DUring the MED09 survey in the Alboran Sea, a Cuvier´s Beaked Whale was found alive recently (probably) entangled in a driftnet (and two Moroccan driftnetters were spotted a few miles away). After several hours of attempts, it was not possible to approach the animal close enough to release it from the net.
In a study of cetacean by-catch by the Spanish Mediterranean long-lining fleet, only one unidentified beaked whale was found entangled (released alive) out of 798 sets (CPUE).
Fourteen Cuvier’s Beaked Whales were reported as having been captured intentionally between 1972 and 1982 – 11 in French and three in Spanish waters, all shot and one also harpooned (Northridge 1994). No pingers are in use in this area to avoid beaked whales bycatch.
With regard to plastic debris, two stranded animals in Greece had stomachs full of pieces of plastic bags (A. Frantzis, pers. comm.), as did a stranded animal in Croatia (Holcer et al. 2003). Poncelet et al. (1999) described a considerable amount of plastic debris in the stomach of a Cuvier’s Beaked Whale washed ashore on the French Atlantic coast. Together with pilot whales (and some other teuthophagous species), Cuvier’s Beaked Whale seems to be attracted by plastic debris that may be mistaken for squid.
One probable hot-spot for Cuvier’s Beaked Whales in the Mediterranean, the eastern section of the Ligurian Sea, is included within the Pelagos Sanctuary created by Italy, France and Monaco. However, no management or conservation measures have been taken as yet specifically for this species.
A SPAMI (Specially Protected Area of Mediterranean Importance) under the Barcelona Convention has been proposed for the northern half of the Alborán Sea and Gulf of Vera in southern Spain (Cañadas et al. 2005), but it has not yet been designated or even evaluated by the Spanish administration. This proposed area includes another of the probable hot-spots for Cuvier’s beaked whales: the deep waters off southern Almería. The Hydrographic Office of the Spanish Navy has agreed not to use active sonar in that area (C. Gamundi, Subdirector of the Hydrographic Office of the Spanish Navy, pers. comm.).
|Citation:||Cañadas, A. 2012. Ziphius cavirostris (Mediterranean subpopulation). The IUCN Red List of Threatened Species 2012: e.T16381144A16382769.Downloaded on 25 September 2018.|
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