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||Pseudorca crassidens |
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: Pseudorca crassidens
Common name: False Killer Whale
The False Killer Whale was described by Owen in 1846, based on a sub-fossil specimen, and subsequently recognised as a living species (Rice 1998). No subspecies are currently recognised, although considerable differences exist between groups from Scotland, South Africa and Australia (Bannister et al. 1996; Kitchener et al. 1980). Although skull morphology in this species is similar to that of Killer Whales, False Killer Whales are genetically more similar to Risso's Dolphin, Pygmy Killer Whales and the pilot whales (Globicephala spp.) (Baird 2002).
False Killer Whales have a long slender body, a rounded overhanging forehead and no beak. In males the tip of the upper jaw overhangs that of the lower jaw (Mead 1975b). The dorsal fin is falcate (sickle-shaped) and slender with a somewhat rounded tip. The flippers have a characteristic hump on the leading edge, perhaps the species' most diagnostic character (Jefferson et al. 1993). The body colour ranges from dark grey to black with a blaze of light grey on the ventral (top) surface between the flippers, and occasionally an area of light grey on the sides of the head (Stacey & Baird 1991).
Adult males reach lengths of up to 6 m, while females can reach up to 5 m in length (Baird 2002; Stacey et al. 1994). In addition to these size differences, male and female False Killer Whales may be distinguished by the position of the melon (the oily, fatty lump of tissue at the centre of the forehead). In males, the melon protrudes further forward than in the females (Baird 2002).
False Killer Whales are highly gregarious, occurring in socially cohesive herds of about 2050 animals, in which both sexes are equally represented (Ross 2006). Large aggregations of between 100 to 800 individuals also occur, apparently representing temporary associations of several smaller herds that have congregated to exploit locally abundant prey (Ross 2006).
False Killer Whales are widely recorded in Australia through strandings in each of the coastal states. Strandings have been recorded from Western Australia (17 events), South Australia (3), Victoria (2), Tasmania (15), NSW (11), Queensland (5), and the Northern Territory (2) (Bannister et al. 1996; Chatto & Warneke 2000; Nicol 1987).
The current extent of occurrence for False Killer Whales is estimated to be greater than 20 000 km² (based on the Australian Economic Exclusion Zone (EEZ) 200 nm and north of 35° S) (V.M. Peddemors & R. Harcourt 2006, pers. comm.). Increasing ocean temperatures predicted by climate change scenarios could potentially increase the extent of occurrence, with warmer water extending southwards along both coasts.
The area of occupancy of False Killer Whales cannot be calculated due to the paucity of records for Australia. However, it is likely to be greater than 2000 km² (V.M. Peddemors & R. Harcourt 2006, pers. comm.). Future expansion of high-seas pelagic fisheries could result in increased interactions with False Killer Whales, including increased incidental catches and injury, potentially depleting local populations and possibly leading to a decrease in area of occupancy.
False Killer Whales are currently considered to occur in one location as deep water is not believed to be a barrier to movement or interaction between locations.
False Killer Whales are found worldwide in deep tropical and temperate waters (Odell & McClune 1999). They are distributed circumglobally between 45° S and 45° N, though are not really abundant anywhere (Carwardine 1995). They range north to Maryland, Scotland, southern Japan, Hawaii, and British Columbia and south to Chubut in Argentina, Australia, South Island of New Zealand, Chatham Islands, and Concepción, Chile (Rice 1998).
Most of the distributional records and many of the data available for the species are the result of strandings (Odell & McClune 1999). However, their eastern distribution in the South Pacific and west to between Chile and Easter Islands (112° W and 91° W) is based on sightings (Aguayo et al. 1998).
There are also numerous records of False Killer Whales seen in cool temperate waters, although these appear to be outside the normal range. Wanderers have been recorded as far afield as Norway and Alaska (Carwardine 1995).
The False Killer Whale is generally poorly known. No global abundance estimates are available, but judging by the large group sizes and regular reports, it was originally assumed that this species is fairly abundant (Stacey & Baird 1991). However, as abundance estimates in the large area of the eastern tropical Pacific Ocean indicate a population in the low tens of thousands, the species may be less abundant than originally thought (Reeves et al. 2003). Population estimates of 16 000 have been reported for the coastal waters of China and Japan (Odell & McClune 1999)
There are no estimates of False Killer Whale population size, either globally or for Australia, so the proportion of the global population in Australian waters is unknown. Substantial differences in cranial characters have been reported between False Killer Whales from Australia, Scotland, and South Africa (Kitchener et al. 1980), although recognition of any subspecies has not yet been made (Rice 1998).
Large-scale movements of False Killer Whales have been reported, prompting Stacey and Baird (1991) to postulate that it would be unlikely that distinct stocks would exist within ocean basins. However, genetic research is required to ascertain whether Australian False Killer Whales could be divided into east and west coast stocks. Considering the potential for long-range movements (Tomilin 1957), it is possible that mortalities in neighbouring countries and/or international waters may affect the Australian population.
False Killer Whales are not well surveyed within Australian waters. Their distribution is primarily assumed from incidental sightings, plus beach-cast animals.
No population estimates are available for False Killer Whales in Australian waters, however, they occur in low abundance (Reeves et al. 2003). It is therefore likely that the total number of mature False Killer Whales within Australian waters is less than 10 000 (V.M. Peddemors & R. Harcourt 2006, pers. comm.), considering an average group size of about 100 individuals in the recorded strandings within Australia (Ross 2006).
All cetaceans are protected under state legislation to three nautical miles offshore and under Australian legislation within the Australian EEZ out to 200 nautical miles offshore. False Killer Whales are also subject to International Whaling Commission (IWC) regulations and protected within the Indian Ocean Sanctuary and Southern Ocean Sanctuary.
False Killer Whales show a preference for tropical (i.e. 2232 °C) to temperate (i.e. 1020 °C) oceanic waters. Although they seem to prefer warmer temperatures (Carwardine 1995), they have been sighted in water temperatures as low as 9 °C (Stacey & Baird 1991).
False Killer Whales prefer deep, offshore waters (and some semi-enclosed seas such as the Red Sea and the Mediterranean) and sometimes deep coastal waters (Culik 2005). They approach close to land only where the continental shelf is narrow, possibly attracted to zones of enhanced prey abundance along the continental slope (Bannister et al. 1996). However, off Hawaii, both shallow (less than 200 m) and deep water (greater than 2000 m) habitats have been reported for the species (Culik 2005).
The age at sexual maturity of False Killer Whales appears to vary between populations, but is generally between eight and 14 years (Perrin & Reilly 1984; Stacey et al. 1994). Length at sexual maturity is between 44.5 m in males, and approximately 3.5 m in females (e.g. a record from Tasmania: Nicol 1986) (Perrin & Reilly 1984). The maximum age is not known (Stacey et al. 1994), but has been estimated at about 57 years in males and 62 years in females (these estimates should be viewed with caution, however, as growth layers in the teeth have yet to be chronologically calibrated) (Baird 2002).
The False Killer Whale is prone to mass stranding, which can result in the death of whole herds. Mass strandings on Australian coasts occur relatively frequently, on average one per 2.5 years since 1970, and have involved from between 20 and 250 whales, with an average of about 100 (Ross 2006). A mass stranding in Tasmania in about 1868 also included Long-finned Pilot Whales and Killer Whales, but the circumstances leading to this event are unclear (Nicol 1987).
Although various parasites have been discovered in stranded False Killer Whales, they are generally not considered to cause mortality under normal circumstances (Stacey & Baird 1991). No documented cases of predation by Killer Whales or sharks have been reported (Stacey & Baird 1991). While scars and wounds on some strandings in Victoria indicate attacks by Cookie-cutter Sharks (Isistius sp.), these are not considered to have been the cause of death (Ross 2006).
After approximately a 15 month gestation period, False Killer Whales are born at lengths between 1.2 m (recorded in Tasmania) and 1.9 m (Perrin & Reilly 1984), and weaning at between 18 to 24 months. The calving interval averages 6.9 years (in Japan) and increases with age (Bannister et al. 1996), suggesting considerable maternal investment. Mating and calving occurs throughout the year, with no known seasonal pattern, and no calving areas are known for Australian waters (Baker 1990; Bannister et al. 1996; Purves & Pilleri 1978; Stacey et al. 1994).
False Killer Whales primarily eat fish and cephalopods, but have been known to attack other small cetaceans in the eastern tropical Pacific during chase and back-down operations of tuna purse seine fishing (Perryman & Foster 1980) and, on one occasion, even attacked a humpback whale calf (Hoyt 1983). Depending on location, stomach contents have included salmon (Oncorhynchus sp.), squid (Berryteuthis magister or Gonatopsis borealis) sciaenid and carangid fishes, bonito (Sarda sp.), mahi mahi or dolphin-fish (Goryphaena), yellowfin tuna (Thunnus albacares), yellowtail (Pseudosciana spp.), perch (Lateolabrax japonicus), mackerel, herring and smelt (Odell & McClune 1999). The most important prey species identified in stomachs of False Killer Whales from the coasts of the Strait of Magellan, Chile were the oceanic and neritic-oceanic squids, Martialia hyadesi and Illex argentinus, followed by the neritic fish, Macruronus magellanicus. These prey species were subantarctic, with two Antarctic species, abundant over the Patagonian shelf and adjacent oceanic waters around Tierra del Fuego (Koen-Alonso et al. 1999).
False Killer Whales appear to be opportunistic feeders, consuming a large size range and wide variety of prey. Considering the extensive distribution of False Killer Whales, and the large variety of habitats that they would utilise during foraging, it can be assumed that this species would exhibit adaptable foraging behaviours. False Killer Whales have been seen travelling in line formation and one large herd of about 300 individuals was distributed over an area approximately 5 km long and 800 m wide (Culik 2005). Such formations are considered to be associated with foraging in pelagic cetaceans (Gaskin 1985). Unfortunately, little else is known of the foraging behaviour of False Killer Whales, but their propensity to steal bait and catch from longlines and sport fishing gear are behaviours that would make them vulnerable to harmful interactions with fisheries.
Migration is not well documented for False Killer Whales, although it has been suggested that closely related globicephalid whales including Globicephala, Pseudorca and Grampus species in the western North Pacific move from warmer, southern waters in winter to cooler, northern waters in summer, possibly in response to prey distribution (Culik 2005). North-south and inshore seasonal movements of False Killer Whales have been observed in the north-eastern Pacific and other areas, apparently associated with warm currents and seasonal availability of prey (Ross 2006).
The movement patterns of False Killer Whales off Australia are primarily inferred from stranding patterns. The trends in strandings suggest there may be a seasonal movement inshore or along the continental shelf on the southern and south-eastern coasts between May and September (Bannister et al. 1996; Nicol 1987).
The False Killer Whale is reported to have travelling speeds of around three to six knots, and as high as 10 knots (Odell & McClune 1999).
The False Killer Whale resembles the Pygmy Killer Whale, but is much larger (maximum 5.5 m versus 2.7 m), and can be distinguished at close range by the lack of white colouration around the lips and ventrum. False Killer Whales may also be confused with Melon-headed Whales, although again, False Killer Whales are much larger (almost twice the length). It is also possible to confuse False Killer Whales with Pilot Whales and Killer Whales, although both these species lack the characteristic hump on the forward margin of the flipper of the False Killer Whale. Additionally, Pilot Whales have extremely bulbous foreheads and a thick broad low profiled dorsal fin, while Killer Whales have taller dorsal fins (especially males) and striking regions of white colouration (Jefferson et al. 1993; Leatherwood & Reeves 1983).
False Killer Whales are often seen with other cetaceans, such as Bottlenose Dolphins, Tursiops species, off Japan (Tsutsumi et al. 1961). This very fast and athletic species will approach vessels and bow-ride, and is capable of high leaps well clear of the water.
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.
Surveys for oceanic cetaceans such as False Killer Whales have primarily been boat-based transects. There are almost no dedicated cetacean surveys conducted in continental Australian waters. During 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 (V.M. Peddemors 2006, pers. comm.).
False Killer Whale interactions with fisheries, particularly their tendency to remove bait and fish from longlines and sport fishing gear, have made them targets of culling efforts (Reeves et al. 2003). More than 900 False Killer Whales were killed in drive fisheries in Japan between 1965 and 1980, and they continue to be taken opportunistically in Japanese harpoon and drive fisheries (Kishiro & Kasuya 1993). They are also hunted in Indonesia and the West Indies, and they are killed incidentally in various fisheries. They were taken incidentally in Taiwanese pelagic gillnet fisheries off northern Australia, although this threat has largely receded (Bannister 1977; Harwood & Hembree 1987). Additionally, some False Killer Whales were captured for oceanaria in southern Queensland (Ross 2006).
Current and future threats to False Killer Whales include hunting to protect the finfish fishery off western Japan, along with mortalities through incidental entanglement in tuna purse seine and other net and longline fisheries elsewhere in Pacific Ocean (Bannister et al. 1996). Entanglement in driftnets set outside Australian Territorial Waters and in lost or discarded netting should be considered a potentially increasing threat.
There are reports on the presence of high levels of mercury and hydrocarbon residues, including DDE, in tissues of False Killer Whales from British Columbia (Stacey & Baird 1991), suggesting that increasing levels of pollution (including increasing amounts of plastic debris at sea, oil spills and dumping of industrial wastes into waterways and the sea) could lead to bio-accumulation of toxic substances in body tissues. This may lead to immunosuppression and increased mortalities of False Killer Whales (Bannister et al. 1996).
Although little is known about reproduction in Australian False Killer Whales, it is likely that they have a low reproductive rate, producing one offspring every several years. This means that population recovery is a slow process.
Bannister and colleagues (1996) and Ross (2006) recommended the following measures be taken to better understand the threats to the False Killer Whale:
- Determine the distribution and monitor abundance of False Killer Whales in Australian waters to assess the possible impact of threats, particularly the effect of direct and indirect fishing activities. This should be done via a sighting program to monitor numbers, particularly in subtropical and tropical waters. There should be consideration to pool existing sightings and strandings data to locate possible concentration areas.
- Obtain information on False Killer Whale diet to determine their trophic level and assess any possible impact of the fishing industry on Odontocete food resources.
- Obtain basic biological information (including diet, pollutant levels and tissue samples for genetic analysis) from incidentally-caught and stranded False Killer Whale specimens.
- Ensure adequate protection of the species and its resources in Australian and nearby waters.
Current projects initiated to address these threats include a requirement to report all incidental catches made within the Australian EEZ (Bannister et al. 1996). Disentanglement workshops have also been initiated, and may be particularly relevant for offshore fisheries.
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 overviews of this species, and some management recommendations. In addition, Australian National Guidelines for Whale and Dolphin Watching have been prepared (Department of the Environment and Heritage 2005e) as have Industry Guidelines on the Interaction between offshore seismic exploration and whales (DEW 2007h).
No threats data available.
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Baker, A. (1990). Whales and Dolphins of Australia and New Zealand: An Identification Guide. Page(s) 133 pp. Wellington, New Zealand: Victoria University Press.
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.
Carwardine, M. (1995). Whales, Dolphins and Porpoises. Page(s) 257 pp. London, UK: Dorling Kindersley.
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Citation: Department of the Environment (2013). Pseudorca crassidens in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Thu, 19 Dec 2013 09:52:26 +1100.