Mesoplodon ginkgodens Nishiwaki
and Kamiya, 1958
English: Ginkgo-toothed beaked whale
German: Japanischer Schnabelwal
Spanish: Zifio de Nishiwaki, Ballena picuda de Nishiwaki
French: Mésoplodon de Nishiwaki, baleine à bec de
Mesoplodon ginkgodens © Wurtz-Artescienza (see links).
The species has almost never been identified in the wild (Pitman
2009). Adult males are dark grey but females are lighter with pale
undersides. The teeth on the lower jaw are found towards the middle
of the beak, posterior to the mandibular symphysis, and barely break
the gumline in mature males. Thus, the teeth are not involved in
fights (Nishiwaki and Kamiya, 1958; Jefferson et al. 2008). This
is reflected by a lack of scarring in males, which may not stem
from a lack of aggression between males as suggested earlier (Carwardine,
1995). It is unclear whether females share the pale beak. Adults
show white spots on the back and ventral surfaces, presumably marks
of parasitic fishes (lampreys, cookie-cutter sharks). Maximum known
sizes are 5.3 m for both males and females (Jefferson et al. 2008).
Ginkgo-toothed whales are found in the tropical and warm temperate
waters of the Indopacific; they have been recorded from Sri Lanka,
the Strait of Malacca, Taiwan, Kyushu, the Pacific coast of Honshu,
New South Wales, the Chatham Islands, southern California, the west
coast of northern Baja California Sur, and the Galapagos Islands
Distribution of Mesoplodon ginkgodens
(Taylor et al. 2008; © IUCN; enlarge
map). The species
occurs in tropical and warm temperate waters of the Indian and Pacific
Oceans (Pitman, 2002).
Palacios (1996) summarised that M. ginkgodens
is only known from 15 stranding records. Of these, eight are from
the western North Pacific (Japan and Taiwan), three from the South
Pacific (one from the Chatham Islands and two from Australia), and
two from the Indian Ocean (Sri Lanka and Indonesia). The remaining
two records are from the eastern North Pacific: a female stranded
at Del Mar, California, US, in 1954 and a skull collected on 30
December 1980 at Playa Malarrimo, outside Laguna Ojo de Liebre (Scammon's
Lagoon), Baja California, Mexico. There is an additional record
of a specimen from the Galapagos Islands, Ecuador, eastern tropical
Pacific (Palacios, 1996).
Furthermore, Anderson et al. (1999) report on recent strandings
on the Maldives in the Indian Ocean. However, Baker and van Helden
(1999) showed that a tooth collected from the Chatham Islands that
was considered to be M. ginkgodens was in fact M.
grayi. And a specimen from White Island (New Zealand) thought
to be M. ginkgodens was subsequently shown to be M.
traversii (van Helden et al. 2002).
Nevertheless, two strandings of M. ginkgodens have occurred
in New Zealand, the first at Onaero Beach, Taranaki, in 2003 and
the second at Puponga, Golden Bay, in 2004. Both animals were mature
males measuring 4.8m (A. van Helden, pers. comm.).
3. Population size
4. Biology and Behaviour
The Ginkgo-toothed beaked whale is very poorly known. Nothing is
known about its behaviour, but it is likely to be unobtrusive. Probably
M. gingkodens occurs in small groups. Confusion is most likely with
other beaked whales, such as Blainville's, Andrews', Hubbs', Stejneger's
and Cuvier's beaked whales (Carwardine, 1995).
Food presumably consists of squid and fish (Jefferson et al. 2008).
A few animals have been taken off the coast of Japan (Jefferson
et al. 1993) by Japanese and Taiwanese whalers (Taylor et al. 2008)
and some have been taken in deep water drift gillnets (Jefferson
et al. 2008).
Liu et al (2009) report that blubber samples from one specimen of
M. ginkgodens collected from Honghai Bay, Guangdong Province,
China, showed high PCB toxicity equivalent quantities in comparison
to cetaceans from other marine areas. The mean composition of PCBs
in this whale was similar to the chemical Acroclor1254 found in
industrial products, which might root in the illegal demolition
and stacking of abandoned paint, transformer or electronic equipment.
Wang and Yang (2006) report on several unusual stranding events
in Taiwan in early 2004 and in 2005 during large-scale naval exercises
in nearby waters. Results of gross post-mortem examination were
suggestive that nearby naval exercises may have contributed to or
caused the death of at least one cetacean in this region and that
species other than beaked whales may also be susceptible to such
activities. With an increasing number of military exercises in this
region, more attention to the impacts of such activities on cetaceans,
as well as prevention measures such as passive acoustic beaked whale
detection (e.g. Moretti el at. 2006) followed by acoustic alerting
and temporal displacement is needed.
For recommendations on south-east Asian stocks, see also Perrin
et al. (1996) in Appendix
Confirmed and inferred range states (Taylor et al. 2008):
American Samoa; Australia; Chile; China; Colombia; Cook Islands;
Ecuador; Fiji; French Polynesia; India; Indonesia; Japan; Kenya;
Kiribati; Marshall Islands; Mexico; Micronesia, Federated States
of; Nauru; New Caledonia; New Zealand; Niue; Northern Mariana Islands;
Palau; Papua New Guinea; Peru; Philippines; Pitcairn; Samoa; Sri
Lanka; Taiwan; Tanzania; Tokelau; Tonga; Tuvalu; United States of
America; Vanuatu; Wallis and Futuna.
IUCN status: "Data Deficient". Not listed by CMS. Listed
in Appendix II of CITES.
8. Sources and further information
Mesoplodon - Beaked whales: Introduction and Sources"
First version kindly reviewed by Anton van Helden, Museum of
New Zealand, Wellington
© Boris Culik (2010) Odontocetes.
The toothed whales: "Mesoplodon ginkgodens". UNEP/CMS
Secretariat, Bonn, Germany. http://www.cms.int/reports/small_cetaceans/index.htm
© Illustrations by Maurizio Würtz, Artescienza.
© Maps by IUCN.