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 Nishiwaki

Family Ziphiidae

Mesoplodon ginkgodens © Wurtz-Artescienza (see links).

1. Description

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).back to the top of the page

2. Distribution

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 (Rice, 1998).

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.).back to the top of the page

3. Population size

Unknown.back to the top of the page

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).back to the top of the page

5. Migration

Unknown.back to the top of the page

6. Threats

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 2.back to the top of the page

7. Remarks

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.back to the top of the page

8. Sources and further information

see "Genus 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.
© Illustrations by Maurizio Würtz, Artescienza.
© Maps by IUCN.

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