Mesoplodon europaeus (Gervais,
English: Gervais' beaked whale
Spanish: Zifio de Gervais, ballena picuda de Gervais
French: Mésoplodon de Gervais, baleine à bec de Gervais
Mesoplodon europaeus © Wurtz-Artescienza (see links).
Gervais' beaked whales are generally dark grey, with pale grey
on the undersides. The triangular teeth of the male are found one
third behind the tip of the beak on the lower jaw (Norman and Mead,
2001; Jefferson et al. 2008). M. europaeus measures 3.7 -
5.2 m and reaches a body mass of at least 1,200 kg (Reidenberg and
Gervais' beaked whale occurs mainly in the North Atlantic from
Cape Cod to Ireland and the English Channel south to southern Brasil,
Guinea Bissau and as far south as Angola (Norman and Mead, 2001;
Jefferson et al., 2008, Macleod, 2000).
Distribution of Mesoplodon europaeus (Jefferson
et al. 2008; Taylor et al. 2008; © IUCN;
map). Gervais' beaked whale prefers warm temperate and tropical
in the North Atlantic but also somewhat south of the equator.
While the distribution is inferred mainly from 54
strandings (Mead, 1989), newer records seem to indicate a larger
distribution in the temperate waters of the North Atlantic, not
only near Florida and on the eastern coast of central America, but
also in the Gulf Stream, the Canary Islands and in currents north
of the equator. According to Robineau (1995) European seas seem
to mark the end of the distributional area, but stranded specimens
are reported from the Canary Islands (Martin et al., 2001), the
Azores (Reiner et al. 1993), Guinea Bissau (Reiner, 1980) and Mauritania
(Robineau and Vely, 1993) which confirms the wider distributional
range. Moore et al. (2004) report on a stranded specimen in Cape
Cod Bay, which in the western North Atlantic seems to mark the northernmost
limit of the distribution.
3. Population size
4. Biology and Behaviour
Mead (1989) suggests that Gervais' beaked whale prefers deep waters,
which is deduced from lack of sightings nearshore. However, there
are few observations at sea to test this hypothesis. Strandings
suggest that the species prefers tropical and subtropical waters.
There are only a few sightings in the wild (Jefferson et al. 2008).
According to Jefferson (1993) Gervais' beaked whale seems to feed
on squid. However, Santos et al. (2007) report that a stranded animal
from the Canary Islands had eaten both fish and cephalopod prey.
The most numerous prey remains belonged to viperfish (Chauliodus
sp.). These results are consistent with the limited published data
on diet in Mesoplodon species which suggest a relatively
higher proportion of fish in their diet whereas Ziphius
caviristris specialises on cephalopods.
There is a record of one specimen having been taken in a pound
net off New Jersey and others may have been taken in Caribbean small
cetacean fisheries (Jefferson et al., 1993).
From 1992 to 1998 a total of 49 beaked whales stranded along the
US Atlantic coast between Florida and Massachusetts (NMFS unpublished
data). This included 28 Gervais' beaked whales, which was therefore
the most frequently affected species (Waring et al. 2001). Furthermore,
several unusual mass strandings of beaked whales, including also
Gervais' beaked whales, were associated with naval activities: Mid
to late 1980's on the Canary Islands (Waring et al. 2001), and again
in September 2002 during a naval NATO manoeuvre involving low frequency
sonar around the Canaries (Vidal, pers. comm.).
Cook et al. (2006) confirm, that M. europaeus is most sensitive
to high frequency signals between 40 and 80 kHz, but produced smaller
evoked potentials to 5 kHz, the lowest frequency tested. The beaked
whale hearing range and sensitivity are similar to other odontocetes
that have been measured.
Evidence from stranded individuals of several species, including
M. europaeus, indicates that they have swallowed discarded
plastic items, which may eventually lead to death (e.g. Scott et
al. 2001 ).
Known and inferred Range states (Taylor et al. 2008):
Bahamas; Brazil; Cape Verde; Cuba; France; Guinea-Bissau; Ireland;
Jamaica; Mauritania; Saint Helena; Spain; Trinidad and Tobago; United
Kingdom; United States of America.
Categorised as "Data Deficient" by IUCN. Gervais' beaked
whale is not listed by CMS but is listed in Appendix II of CITES.
8. Sources and further information
Mesoplodon - Beaked whales: Introduction and Sources"
© Boris Culik (2010) Odontocetes.
The toothed whales: "Mesoplodon europaeus". UNEP/CMS
Secretariat, Bonn, Germany. http://www.cms.int/reports/small_cetaceans/index.htm
© Illustrations by Maurizio Würtz, Artescienza. ©
Maps by IUCN.