In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.
|EPBC Act Listing Status||Cetacean|
|Adopted/Made Recovery Plans|
|Policy Statements and Guidelines||
Industry Guidelines on the Interaction between offshore seismic exploration and whales (Department of the Environment and Water Resources (DEW), 2007h) [Admin Guideline].
Australian National Guidelines for Whale and Dolphin Watching (Department of the Environment and Heritage, 2005e) [Information Sheet].
|Scientific name||Mesoplodon ginkgodens |
|Species author||Nishiwaki and Kamiya,1958|
This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.
Scientific name: Mesoplodon ginkgodens
Common name: Gingko-toothed Beaked Whale
Other names: Gingko-toothed Whale, Gingko Beaked Whale, Japanese Beaked Whale
The Gingko-toothed Beaked Whale was originally described by 1958 (Nishiwaki & Kamiya 1958). No subspecies have been described. Analysis of nuclear DNA suggests that the Gingko-toothed Beaked Whale is mostly closely related to Gervais' Beaked Whale (M. europaeus), and more distantly, to True's Beaked Whale (M. mirus) (Dalebout 2002).
Gingko-toothed Beaked Whales take their name from the shape of the male's teeth which are similar in shape to the leaf of the Gingko tree which is common in Japan, where this whale was first found. The teeth are about 10 cm wide, which makes them the widest teeth known in beaked whales. They occur as a pair on the lower jaw, towards the middle of the beak and erupt only in mature males (Rice 1998).
Male Gingko-toothed Beaked Whales are dark in colour with white spots and blotches around the belly area. Females are not as dark and have paler bellies. Gingko-toothed Beaked Whales have narrow upper jaws with a sharp point and their lower jaws are highly arched. Their flippers and fins are small and narrow. Like other Mesoplodon species, Gingko-toothed Beaked Whales have a small, triangular dorsal fin, unnotched tail flukes and a single pair of external throat groves positioned between the mandibles to assist in suction feeding (Pitman 2002). Unlike many of the other beaked whales Gingko-toothed beaked whales are not usually scarred (Bannister et al. 1996).
Maximum known sizes of Gingko-toothed Whales are 4.9 m (females) and 5.1 m (males) (MacLeod 2006). The maximum weight is about 1.5 tonnes. It is thought that Gingko-toothed Beaked Whales probably behave like many of the other beaked whales, occurring in small groups and spending much of their lives at depth. The lack of scarring suggests that there is little aggression between males.
The Gingko-toothed Beaked Whale has only recently been confirmed as occurring in Australia through four stranding events: three in southern NSW (two of which probably comprise a cow and calf pair initially identified as Andrews' Beaked Whale (M. bowdoini) (Tidemann 1980); and one stranding in western Victoria (Bannister et al. 1996; Ross 2006). Increasing observer awareness and activity in northern Western Australia, Northern Territory, Queensland and NSW are likely to yield further information.
The current extent of occurrence for Gingko-toothed Beaked Whale is estimated to be greater than 20 000 km² (based on the Australian EEZ 200 nm, north of 37° S and generally deeper than 200m) (Peddemors & Harcourt 2006, pers. comm.). Increasing ocean temperatures predicted by climate change scenarios could potentially increase the extent of occurrence, with warmer water extending southwards beyond 37° S.
The area of occupancy of Gingko-toothed Beaked Whale is likely to be greater than 2000 km² (Peddemors & Harcourt 2006, pers. comm.). Future expansion of high-seas pelagic gillnet fisheries have the potential to result in increased incidental catches of this species, potentially reducing local populations and leading to a decrease in area of occupancy.
Gingko-toothed Beaked Whales are considered to occur in one location as deep water is not a barrier to movement in this species.
Gingko-toothed Beaked Whales are considered to occur in one location as deep water is not a barrier to movement in this species.
No distribution fragmentation is anticipated for Gingko-toothed Beaked Whales in Australian oceanic Antarctic, sub-Antarctic and cold temperate waters.
The Gingko-toothed Beaked Whale is known only from tropical and warm temperate waters in the Pacific and Indian Oceans. They occur on either side of the equator to 37° S, including Sri Lanka, the Strait of Malacca, Taiwan, Kyushu, Honshu, Chatham Is., southern California, Baja California and the Galapagos Is. (Baker 1990; Leatherwood & Reeves 1983; Mead 1989; Nishiwaki et al. 1972; Rice 1998). This species is thought to be more common in the western North Pacific than elsewhere (Ross 2006).
It is unlikely that Australian Gingko-toothed Beaked Whales are a distinct population, as no subspecies are currently recognized. As Gingko-toothed Beaked Whale is a deep water species primarily living off the continental shelf, incidental bycatch of animals in neighbouring countries and/or international waters may affect the Australian population.
World-wide, the Gingko-toothed Beaked Whale is not well surveyed. Their distribution is primarily assumed from limited cetacean surveys and incidental sightings, plus beach-cast animals, for all areas (Bannister et al. 1996).
No information is available on the population size of the Gingko-toothed Beaked Whale in Australian waters (Bannister et al. 1996). Gingko-toothed Beaked Whales are not considered abundant as sightings and strandings are rare.
All cetaceans are protected within the Australian Whale Sanctuary under the EPBC Act. The Sanctuary includes all Commonwealth waters from the 3 nm State waters limit out to the boundary of the EEZ (200 nm and further in some places). Gingko-toothed Beaked Whales are also subject to International Whaling Commission (IWC) regulations and protected within the Indian Ocean Sanctuary and Southern Ocean Sanctuary.
Gingko-toothed Beaked Whales prefer temperate (1020 °C) and tropical (2232 °C) deep oceanic waters (Bannister at al. 1996). No information on habitat is available, although these whales are presumed to feed at depth on mid- and deep-water squid and fish (Baker 1990; Bannister et al. 1996). Shipboard surveys of beaked whales (Mesoplodon spp. and Ziphius cavirostris) from 19911998 along the shelf edge and Gulf Stream waters off the northeast United States showed that these species frequent shelf-edge habitats (Waring et al. 2001). Beaked whales were present mostly along the colder shelf edge and associated significantly with canyon habitats (Waring et al. 2001). However, a more recent survey of the same area found that this previously proposed definition of beaked whale habitat may be too narrow, suggesting that beaked whales may be found from the continental slope to the abyssal plain, in waters ranging from well-mixed to highly stratified (Ferguson et al. 2006). It is likely that such habitats are utilised by beaked whales along much of Australia's extensive coastline, particularly along the more southern shores that support populations of Andrews' Beaked Whale (Ross 2006).
The habitat of Gingko-toothed Beaked Whale is oceanic, but, as for many species of beaked whale, it may also be found close to undersea features such as submarine escarpments and sea mounts where prey are believed to aggregate (Balcomb 1989). In the eastern tropical Pacific, beaked whales were sighted an average of 1000 km offshore, with a range of approximately 403750 km. The mean water depth of Mesoplodon beaked whale sightings in this region was just over 3.5 km, with a maximum depth of approximately 5.75 km (Ferguson et al. 2006).
Sexual maturity in Gingko-toothed Beaked Whales is attained before males reach 4.8 m in length, and before females reach 4.5 m (Bannister at al. 1996). The life expectancy of the Gingko-toothed Beaked Whale is unknown, although the maximum recorded age for Baird's Beaked Whale (Berardius bairdii) is 84 years, and for all other beaked whales recorded age is between 27 and 39 (Mead 1984, in MacLeod & D'Amico 2006). Natural causes of mortality are poorly understood, but are thought to include predation, disease and effects associated with 'old age' (MacLeod & D'Amico 2006).
Areas and habitats used for breeding are unknown for Gingko-toothed Beaked Whales, but are presumed to be oceanic. Due to the lack of scarring in Gingko-toothed Beaked Whale males it is believed that there is minimal physical competition for partners. Females give birth to a single calf, which is thought to be born about 2.02.5 m in length (Pitman 2002). A calving interval of three to four years leads to a slow reproductive capacity (Bannister at al. 1996).
No data are available on Gingko-toothed Beaked Whale feeding, but the diet of these whales is assumed to be mid- and deep-water squid and fish, as is recorded for other members of this family (Bannister et al. 1996; Pitman 2002).
Gingko-toothed Beaked Whales are active predators and presumed to be strong swimmers capable of deep dives in pursuit of prey, but the mode of capture is not known. Only adult males have erupted teeth, consisting of a single pair of flattened tusks that barely break the gum-line behind the middle of the lower jaw. It thus seems unlikely that these teeth are used for prey capture, but rather that prey are seized and disabled between the hard edges of the mandibles and the rostral palate (Ross 2006). The pair of V-shaped throat grooves typical of this family may enable distension of the throat creating a sucking pressure allowing larger whole prey to be swallowed whole (Baker 1990; Pitman 2002).
Very little information is available on the social structure of the Gingko-toothed Beaked Whale. However, other Mesoplodon species have been recorded as having group sizes of one to 15 individuals, with an average of 2.9 individuals per group. Group composition is also largely unknown, but incidental sightings of groups with two or more adult males have been made for some Mesoplodon species (MacLeod & D'Amico 2006). In the eastern tropical Pacific Ocean, Mesoplodon beaked whales had a mean density of 2.96 individuals per 1000 km² (Ferguson et al. 2006).
The uniform dark pigmentation, small posteriorly placed teeth, and paucity of characteristic ziphiid (beaked whales) scarring may allow a tentative classification of adult male Gingko-toothed Beaked Whales. Otherwise, this species will be virtually indistinguishable from other species of Mesoplodon when viewed at sea (Jefferson et al. 1993).
Gingko-toothed Beaked Whales are generally slow, sluggish animals, spending little time at the surface and therefore making individuals difficult to identify or find (Jefferson et al. 1993; Reeves et al. 2002). In addition, they, like other beaked whales, spend much of their time at depth, surface without a visible blow or splash, and are relatively silent when they are within 200 m of the surface (Ferguson et al. 2006).
Cetacean surveys are constrained by several important factors including weather (e.g. sea state and light conditions), area to be covered, aim of the survey (abundance estimate versus ecological studies), the activities of the animals themselves (e.g. travelling, resting, surface versus deep feeding), and the type of craft used for the survey. Additionally, beaked whales are notoriously difficult to identify at sea due to their propensity to spend little time at the surface, breathing only a few times before submerging for extensive periods.
Surveys for oceanic cetaceans such as beaked whales have primarily been boat-based transects. There are almost no dedicated cetacean surveys conducted in Australian waters likely to be the range of Gingko-toothed Beaked Whale. Participation of observers on petro-chemical exploration surveys could assist in enhancing knowledge of cetacean distribution and abundance. During such non-dedicated surveys, a minimum requirement is to record all cetacean sightings encountered with corresponding GPS position, environmental data (sea conditions and habitat) and behavioural observations. From fishing vessels, all incidentally caught animals should be recorded with corresponding GPS position, plus attempts should be made to obtain basic biological information from dead animals (Peddemors 2006, pers. comm.).
Historically, low numbers of Gingko-toothed Beaked Whales were taken in coastal fisheries off Japan (Jefferson et al. 1993). The current threats to this species include occasional incidental capture in net fisheries and possible entanglement in drift nets and other nets set, lost or discarded in international waters (Bannister et al. 1996).
Recently, there have been a number of studies investigating the impacts of anthropogenic noise on beaked whales, particularly activities that transmit sounds into the water column. These studies have, in part, been driven by mass strandings of beaked whales coinciding temporally and spatially with naval manoeuvres (MacLeod & D'Amico 2006). For example, necropsies (autopsies) of stranded Blainville and Cuvier's Beaked Whales following low frequency acoustic sonar tests have revealed tissue trauma associated with an acoustic or impulse injury that caused the animals to strand (Frantzis 1998). It has been noted that beaked whales with group sizes of less than 20 (including the Mesoplodon spp.), and particularly groups composed primarily of immature, juvenile or cow-calf pairs, may be more susceptible to strandings associated with anthropogenic noise, although it is not known why. Anthropogenic sounds may disrupt or interfere with the sounds produced by beaked whales, including disruption of navigation, and/or interfere with social communication. While data is limited, where there is data beaked whales appear to use relatively high frequency echolocation (up to 120 kHz or more) and non-echolocation sounds in the region of 116 kHz (MacLeod & D'Amico 2006).
Competition for food resources from expanding commercial fisheries in higher latitudes, particularly on pelagic squids in temperate waters also represents a potential threat. In addition, pollution leading to accumulation of toxic substances in body tissues (likely to be low), and ingestion of plastic, represent potential risks to populations of Gingko-toothed Beaked Whales (Bannister et al. 1996; MacLeod & D'Amico 2006; Reeves et al. 2003; Ross 2006).
Although little is known about reproduction in beaked whales, it is likely that Gingko-toothed Beaked Whales have a low reproductive rate, producing one offspring every three to four years. This means that population recovery is a slow process.
Bannister and colleagues (1996) and Ross (2006) recommended the following measures be undertaken to better understand the threats to Gingko-toothed Beaked Whales:
- Determine the distribution and monitor abundance of Gingko-toothed Beaked Whale in Australian waters, especially in sub-Antarctic and cold temperate waters, to assess the possible impact of threats including the effect of direct and indirect fishing activities. This should be done via a sighting program to monitor numbers.
- Obtain information on Gingko-toothed Beaked Whale diet to determine their trophic level and assess any possible impact of the fishing industry on beaked whale food resources.
- Obtain basic biological information (including diet and pollutant levels) from incidentally-caught and stranded Gingko-toothed Beaked Whales, and ensure specimens are made available to appropriate scientific museums to enable collection of life history data and tissue samples for genetic analysis.
- Ensure adequate protection for the species, and its resources, in Australian and nearby waters.
Disentanglement workshops have also been recommended, particularly for offshore fishers, and suitable action plans developed (Bannister et al. 1996).
Current projects initiated to address these threats include a requirement to report all incidental catches made within the Australian EEZ (Bannister et al. 1996).
The Action Plan for Australian Cetaceans (Bannister et al. 1996) and the Review of the Conservation Status of Australia's Smaller Whales and Dolphins (Ross 2006) provide brief biological overviews and management recommendations of this species. In addition, Industry Guidelines on the Interaction between offshore seismic exploration and whales (DEWHA 2007h), and Australian National Guidelines for Whale and Dolphin Watching (DEH 2005c) have been published.
No threats data available.
Baker, A. (1990). Whales and Dolphins of Australia and New Zealand: An Identification Guide. Page(s) 133 pp. Wellington, New Zealand: Victoria University Press.
Balcomb, K.C. (1989). Baird's Beaked Whale Berardius bairdii Stejnegeri, 1833: Arnoux's Beaked Whale Berardius arnuxii Duvernoy, 1851. In: Ridgway, S.H. & R. Harrison, eds. Handbook of Marine Mammals Vol. 4: River Dolphins and the Larger Toothed Whales. Page(s) 261-288.
Bannister, J.L., C.M. Kemper & R.M. Warneke (1996). The Action Plan for Australian Cetaceans. [Online]. Canberra: Australian Nature Conservation Agency. Available from: http://www.environment.gov.au/coasts/publications/cetaceans-action-plan/pubs/whaleplan.pdf.
Dalebout, M.L. (2002). Species identity, genetic diversity and molecular systematic relationships among the Ziphiidae (beaked whales). Ph.D. Thesis. University of Auckland, New Zealand.
Department of the Environment and Heritage (2005e). Australian National Guidelines for Whale and Dolphin Watching. [Online]. Available from: http://www.environment.gov.au/coasts/publications/whale-watching-guidelines-2005.html.
Department of the Environment and Water Resources (DEW) (2007h). Industry Guidelines on the Interaction between offshore seismic exploration and whales. [Online]. Available from: http://www.environment.gov.au/epbc/publications/seismic.html.
Ferguson, M.C., J. Barlow, B. Reilly, S.B. & T. Gerrodette (2006). Predicting Cuvier's (Ziphius cavirostris) and Mesoplodon beaked whale population density from habitat characteristics in the Eastern Tropical Pacific Ocean. Journal of Cetacean Research and Management. 7(3):287-299.
Frantzis, A. (1998). Does acoustic testing strand whales?. Nature. 392:29.
Jefferson, T.A., S. Leatherwood & M.A. Webber (1993). FAO species identification guide. Marine Mammals of the World. [Online]. Rome: United Nations Environment Programme, Food and Agricultural Organization. Available from: ftp://ftp.fao.org/docrep/fao/009/t0725e/t0725e00.pdf. [Accessed: 15-Aug-2007].
Leatherwood, S. & R.R. Reeves (1983). The Sierra Club Handbook of Whales and Dolphins. San Francisco: Sierra Club Books.
MacLeod, C.D. (2006). How big is a beaked whale? A review of body length and sexual size dimorphism in the family Ziphiidae. Journal of Cetacean Research and Management. 7(3):301-308.
MacLeod, C.D. & A. D'Amico (2006). A review of beaked whale behaviour and ecology in relation to assessing and mitigating impacts of anthropogenic noise. Journal of Cetacean Research and Management. 7(3):211-221.
Mead, J.G. (1989). Beaked Whales of the Genus Mesoplodon. In: Ridgway, S H & R. Harrison, eds. Handbook of Marine Mammals Vol. 4: River Dolphins and the Larger Toothed Whales. Page(s) 349-430. Academic Press, London.
Nishiwaki, M., T. Kasuya, K. Kureha & N. Oguro (1972). Further comments on Mesoplodon ginkgodens. Scientific Reports of the Whales Research Institute, Tokyo. 24:43-56.
Peddemors, V.M. (2006). Personal Communications. Sydney: Graduate School of the Environment, Macquarie University.
Peddemors, V.M. & R. Harcourt (2006). Personal Communication. Sydney: Graduate School of the Environment, Macquarie University.
Pitman, R.L. (2002). Mesoplodont Whales Mesoplodon spp. In: Perrin, W.F., Wursig, B. & Thewissen, J.G.M., eds. Encyclopedia of Marine Mammals. Page(s) 738-742. London, Academic Press.
Reeves, R., Stewart, B., Clapham, P. & Powell, J., eds. (2002). Sea Mammals of the World. London: A & C Black.
Reeves, R.R., B.D. Smith, E.A.Crespo, & G. Notarbartolo di Sciara, eds. (2003). Dolphins, Whales and Porpoises: 2002-2010 Conservation Action Plan for the World's Cetaceans. Switzerland and Cambridge: IUCN/SSC Cetacean Specialist Group. IUCN, Gland.
Rice, D.W. (1998). Marine mammals of the world. Systematics and distribution. Special publication number 4. Kansas: Society for Marine Mammalogy.
Ross, G.J.B. (2006). Review of the Conservation Status of Australia's Smaller Whales and Dolphins. Page(s) 124. [Online]. Report to the Australian Department of the Environment and Heritage, Canberra. Available from: http://www.environment.gov.au/coasts/publications/pubs/conservation-smaller-whales-dolphins.pdf.
Tidemann, C. (1980). Mesoplodon bowdoini Andrews (Ziphiidae): a new whale record for New South Wales. Victorian Naturalist. 97:64-65.
Waring, G.T., J.M. Quintal & S.L. Swartz (2001). U.S. Atlantic and Gulf of Mexico marine mammal stock assessments - 2001. NOAA Technical Memorandum. NMFS-NE168.
This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.
Citation: Department of the Environment (2013). Mesoplodon ginkgodens in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Fri, 13 Dec 2013 09:04:42 +1100.