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.
|Scientific name||Pristis pristis |
|Species author||(Linnaeus, 1758)|
|Reference||Faria, V.V., McDavitt, M.T. Charvet, P., Wiley, T.R., Simpfendorfer, C.A. & Naylor, G.J.P. 2012. Zoological Journal of the Linnean Society 167: 146 (also online)|
|Other names||Pristis microdon |
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: Pristis pristis
Common name: Freshwater Sawfish
Pristis microdon is now included with P. pristis, a global species that wasn't previously considered to occur in Australia.
The Freshwater Sawfish is a ray growing to 7 m, having five pairs of gill-openings on the ventral surface of the head; a distinguishing feature of rays. It has less than 20 teeth on each side of its saw (Allen 1989a; Phillips et al. 2008).
The Freshwater Sawfish may potentially occur in all large rivers of northern Australia from the Fitzroy River, Western Australia, to the western side of Cape York Peninsula, Queensland. It is mainly confined to the main channels of large rivers (Allen 2000, pers. comm.).
The species is known from several drainages of northern Australia including the Fitzroy River, Durack River and Ord River in Western Australia; the Adelaide River, Victoria River and Daly River of the Northern Territory; and the Gilbert River, Mitchell River, Norman River and Leichhardt River of Queensland (Last & Stevens 1994). The species is also recorded from the McArthur River, Northern Territory (Merrick & Schmida 1984). In the Fitzroy River catchment it is probably confined to the main Fitzroy River; in the Durack River catchment it probably only occurs in the main Durack River; in the Ord River catchment it occurs only in the Main Ord Channel below Kununurra Dam and in the Pentecost River; and in the Victoria River catchment it is probably restricted to the main Victoria River and possibly Fitzmaurice River (Allen 2000, pers. comm.).
The distribution of the Freshwater Sawfish outside of Australia is uncertain, but it is known to occur in several major river basins of Indonesia and Papua New Guinea (PNG) (Last & Stevens 1994). In PNG waters this species has been recorded from the Digul River, Middle Fly River, Middle and Lower Sepik Rivers, and the Ramu River (Allen 1991). The species is also known from at least one tributary in New Britain (Jenkins 2000, pers. comm.). It is also known from Lake Sentani in Irian Jaya (Allen 1991). The Freshwater Sawfish possibly occurs westwards to India (Last & Stevens 1994) and has a worldwide distribution (Allen 2000, pers. comm.).
Whilst the total population of the Freshwater sawfish is unknown, DNA studies by Phillips and colleagues (2008) has shown that the species, though highly mobile when adult should be considered as 'independent demographic units' (populations), rather than a single panmictic population in Australian waters.
The Freshwater sawfish is suggested to be a long lived (up to 44 years) species that does not reach maturity until approximately seven years of age (Peverell unpublished data, cited in Phillips et al. 2008; Tanaka 1991; Thorburn et al. 2007).
The name Freshwater Sawfish is a misnomer. It is a marine/estuarine species that spends its first threefour years in freshwater growing to about half its adult size (4 m+) (Allen 2000 pers. comm.). Juveniles and sub-adult Freshwater Sawfish predominantly occur in rivers and estuaries, while large mature animals tend to occur more often in coastal and offshore waters up to 25 m depth (Giles et al. 2006; Stevens et al. 2005). A study on the movement patterns of other sawfish species , P. clavata and P. zijsron, showed that the species had a high fidelity to an area, with movements restricted to only a few square kilometres within the coastal fringe, and influenced by tides (Stevens et al. 2008).
In northern Australia, this species appears to be confined to freshwater drainages and the upper reaches of estuaries, occasionally being found as far as 400 km from the sea (Thorburn et al. 2007; Whitty et al. 2008). There are few reports of adult individuals at sea, with only a few records of fish greater than 3 m in total length from the Pilbara coast, and one individual from Cape Naturaliste (south-western Australia) (Chidlow 2007 cited in Whitty et al. 2008).
Freshwater Sawfish occur in fresh or weakly saline water (Last & Stevens 1994). The species tends to move up rivers during flood periods (Allen 2000 pers. comm.). Small specimens, mostly less than 150 cm, have been caught in remote ponds where they have been isolated for several years between floods (Last & Stevens 1994).
The preferred habitat of this species is mud bottoms of river embayments and estuaries, but they are also found well upstream (Allen 1997). They are not found near riparian vegetation (Wilson 1999). They are usually found in turbid channels of large rivers over soft mud bottoms (Allen 1991) more than 1 m deep, but they will move into shallow waters when travelling upstream or while hunting prey (Wilson 1999). Thorburn and colleagues (2003) found Freshwater Sawfish caught as part of their northern Australian distribution study wre most often associated with deeper section of a river adjacent to a sand or silt shallow, such as a sandbar or shallow backwater.
Individuals kept in aquaria prefer slightly alkaline waters between 22 ° C and 28 ° C (Wilson 1999).
Merrick and Schmida (1984) noted that no detailed studies had been made on the reproduction of the Freshwater Sawfish. The species possibly breeds in fresh water (Allen 1991). Reproduction is viviparous (the young are nourished by a primitive placenta) and young are born at about 50 cm in length approximately five months after copulation, with litter sizes likely to range between one and 12 (Wilson 1999). In the Mitchell River on western Cape York Peninsula, Queensland, spawning generally occurs at the beginning of the wet season in November or December (Allen 1991). In the Fitzroy River, Western Australia, pupping is correlated to higher water levels in the late wet season (Whitty et al. 2008)
The Fitzroy River has been identfied as a likely important nursery site for the Freshwater Sawfish, as all individuals captured as part of a radio-tagging program were small, immature individuals (Whitty et al. 2008).
Observations of reproductive staging in freshwater sawfish found along the east coast of the Gulf of Carpentaria suggest that pupping occurs through the wet season and continues until the beginning of the dry season in early May (Peverell 2005). Freshwater Sawfish give birth to live young and have a litter size of between 111 offspring (Peverell et al. 2004)
The captures of large numbers of new recruits in the Fitzroy River suggest that there may be synchronisation in timing of parturition (birth) or that there is an instinct of newborns to travel in groups, which would increase an individual's chance of avoiding predation on their journey up river (Whitty et al. 2008).
Different age classes of the Freshwater Sawfish partition habitat, with new recruits remaining in the shallows for much of the day compared to the larger (over one year old) individuals that rarely moved into the extreme shallows. Larger individuals move to deeper water at dawn, and into shallower waters in the afternoon. Similar patterns have been observed in a number of other predatory elasmobranchs. Habitat stratification may be related to foraging activities and/or predator avoidance. The Fitzroy River is also inhabited by Estuarine Crocodiles (Crocodylus porosus) and Bull Sharks (Carcharhinus leucas). Smaller Freshwater Sawfish are potentially more susceptible to predation by these species. Bull Sharks have been shown to predate on Freshwater Sawfish (Thorburn et al. 2004 cited in Whitty et al. 2008; Thorburn 2006 cited in Whitty et al. 2008).
The Freshwater Sawfish feeds on fishes and benthic invertebrates. The saw is used to stun schooling fish, such as mullet, and for extracting molluscs and small crustaceans from the benthic sediment (Allen 1982).
In the Fitzroy River, the Blue Catfish (Arius graeffei), detrital matter and Cherabin (Macrobrachium rosenbergii) were important prey. Bony Bream (Nematalosa erebi) was also eaten (Whitty et al. 2008).
The differences in habitat utilisation by different age classes of Freshwater Sawfish are reflected in differences in diet. Prey available in shallow waters differs significantly day to night, with Cherabin and Bony Bream being more abundant in the shallows at night compared to the day. The diversity of small fish in the shallows at night, such as Spangled Perch (Leiopotherapon unicolor), Prince Regent Hardyhead (Craterocephalus lentiginosus), Barred Grunter (Amniataba percoides), Flathead Goby (Glossogobius giurus) and Blue catfish, also increases substantially. Larger Freshwater Sawfish also utilise deeper waters on nights with greater moonlight, possibly as prey is more visible, or the species may go deeper to avoid predation (Whitty et al. 2008).
The Freshwater Sawfish is highly vulnerable to gillnet fishing. Populations may be threatened in streams where poaching for barramundi is a common practice (Last & Stevens 1994).
Net fishing has been identified as contributing to a rapid decline in sawfish populations (Stevens et al. 2008; Peverell et al. 2004). Also, because of their life history characteristics, over-fishing and bycatch have been identified as being problematic (Stobutzki et al. 2002). Indigenous harvest, habitat modification and recreational 'trophy' fishing have also been identified as threats to the Freshwater Sawfish (Peverell et al. 2004).
Specimens are occasionally taken from the wild for aquarium display purposes (Cook et al. 1995). The high value of sawfish fins (up to A$250 per kg for dried fins) in the shark fin trade is a serious threat to the survival of all sawfish species (Rose & McLoughlin 2001).
Government Funded Grants
Kimberley Land Council (Western Australia) received $23 440 through the Threatened Species Network Community Grants in 200506 for tagging of larger juveniles to identify breeding grounds and determine habitats that are critical and protected; education of the community about Sawfish monitoring; and an incentives program for identification of tag numbers, length of fish and location.
Kimberley Land Council (Western Australia) received $24 000 through the Threatened Species Network Community Grants in 200304 for the survey of populations on the Fitzroy River to determine whether the fish utilise the area for breeding and/or as a nursery habitat, as well as the evaluation of overall population characteristics.
Marine bioregional plans have been developed for four of Australia's marine regions - South-west, North-west, North and Temperate East. Marine Bioregional Plans will help improve the way decisions are made under the EPBC Act, particularly in relation to the protection of marine biodiversity and the sustainable use of our oceans and their resources by our marine-based industries. Marine Bioregional Plans improve our understanding of Australia's oceans by presenting a consolidated picture of the biophysical characteristics and diversity of marine life. They describe the marine environment and conservation values of each marine region, set out broad biodiversity objectives, identify regional priorities and outline strategies and actions to address these priorities. Click here for more information about marine bioregional plans.
The Freshwater Sawfish has been identified as a conservation value in the North-west (DSEWPaC 2012y) and North (DSEWPaC 2012x) marine regions. See Schedule 2 of the North-west Marine Bioregional Plan (DSEWPaC 2012y) for regional advice. Maps of Biologically Important Areas have been developed for Freshwater Sawfish in the North-west (DSEWPaC 2012y) Marine Region and may provide additional relevant information. Go to the conservation values atlas to view the locations of Biologically Important Areas. The "species group report card - sharks and sawfishes" for the North-west (DSEWPaC 2012y) Marine Region and the "species group report card - sawfishes and river sharks" for the North (DSEWPaC 2012x) Marine Region provide additional information.
Whitty and colleagues (2008) studied habitat associations and movements of the Freshwater Sawfish in the Fitzroy River (Western Australia). Phillips and colleagues (2008) analysed the genetic diversity and population structure of this species in Australian waters.
The Freshwater Sawfish is included in the North Marine Bioregional Plan: Bioregional Profile (DEWHA 2008).
The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.
|Threat Class||Threatening Species||References|
|Biological Resource Use:Fishing and Harvesting Aquatic Resources:Collection for the aquarium trade||Pristis microdon in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006uo) [Internet].|
|Biological Resource Use:Fishing and Harvesting Aquatic Resources:Commercial harvest||Pristis microdon in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006uo) [Internet].|
|Biological Resource Use:Fishing and Harvesting Aquatic Resources:Harvest by gill netting||Sharks and Rays of Australia (Last, P.R. & J.D. Stevens, 1994) [Book].|
|Biological Resource Use:Fishing and Harvesting Aquatic Resources:Mortality due to capture, entanglement/drowning in nets and fishing lines||Pristis microdon in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006uo) [Internet].|
|Biological Resource Use:Gathering Terrestrial Plants:Commercial harvest||Status of the largetooth sawfish Pristis perotteti Muller and Henle, 1841. Shark News Newsletter of the IUCN Shark Specialist Group. 4:5. (Cook, S., L. Compagno & M. Oetinger, 1995) [Journal].|
Allen, G.R. (1982). A Field Guide to Inland Fishes of Western Australia. Perth, Western Australia: University of Western Australia Press.
Allen, G.R. (1989a). Freshwater Fishes of Australia. Brookvale, NSW: T.F.H. Publications.
Allen, G.R. (1991). Field Guide to the Freshwater Fishes of New Guinea.:268. Madang: Christensen Research Institute.
Allen, G.R. (1997). Marine Fishes of Tropical Australia and South-East Asia - A field guide for anglers and divers. Third Revised Edition. Perth, Western Australia: Western Australian Museum.
Allen, G.R. (2000). Personal communication.
Cook, S., L. Compagno & M. Oetinger (1995). Status of the largetooth sawfish Pristis perotteti Muller and Henle, 1841. Shark News Newsletter of the IUCN Shark Specialist Group. 4:5.
Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC) (2011i). Survey guidelines for Australia's threatened fish. EPBC Act survey guidelines 6.4 . [Online]. EPBC Act policy statement. Canberra, ACT: DSEWPAC. Available from: http://www.environment.gov.au/epbc/publications/threatened-fish.html.
Department of the Environment, Water, Heritage and the Arts (DEWHA) (2008). The North Marine Bioregional Plan: Bioregional Profile: A Description of the Ecosystems, Conservation Values and Uses of the North Marine Region. [Online]. Canberra: DEWHA. Available from: http://www.environment.gov.au/resource/north-marine-bioregional-plan-bioregional-profile-description-ecosystems-conservation.
Giles, J., R.D. Pillans, M.J. Miller & J.P. and Salini (2006). Sawfish Catch Data in Northern Australia: A Desktop Study. Internal CSIRO Report for FRDC. 2002/064:74.
Jenkins, A.P. (2000). Personal Communication.
Last, P.R. & J.D. Stevens (1994). Sharks and Rays of Australia. Melbourne, Victoria: CSIRO.
Merrick, J.R. & G.E. Schmida (1984). Australian Freshwater Fishes - Biology and Management. Netley, South Australia: Griffin Press.
Peverell, S. (2005). Distribution of Sawfishes (Pristidae) in the Queensland Gulf of Carpentaria, Australia - with notes on sawfish ecology. Environmental Biology of Fishes. 73:391-402.
Peverell, S., N. Gribble & H. Larson (2004). 'Sawfish'. In: National Oceans Office, Description of Key Species Groups in the Northern Planning Area. [Online]. Hobart, Tasmania: Commonwealth of Australia. Available from: http://www.environment.gov.au/coasts/mbp/publications/north/pubs/n-key-species.pdf.
Phillips, N.M., J.A. Chaplin, D.L. Morgan, S.C. Peverell & D.C. Thorburn (2008). Genetic diversity and population structure of the Freshwater Sawfish (Pristis microdon) in Australian Waters. Whitty, J.M., N.M. Phillips, D.L. Morgan, J.A. Chaplin, D.C. Thorburn & S.C. Peverell, eds. Habitat associations of Freshwater Sawfish (Pristis microdon) and Northern River Sharks (Glyphis sp. C): including genetic analysis of P. microdon across northern Australia. [Online]. Centre for Fish & Fisheries Research (Murdoch University)- Report to the Department of the Environment, Water, Heritage and the Arts, Australian Government. Available from: http://www.environment.gov.au/coasts/publications/pubs/freshwater-sawfish-northern-river-shark.pdf.
Rose, C. & K. McLoughlin (2001). A Review of Shark Finning in Australian Fisheries. Final report to Fisheries Resources Research Fund. Canberra, ACT: Bureau of Rural Sciences. Department of Agriculture, Fisheries and Forestry-Australia.
Stevens, J.D., R.D. Pillans & J. Salini (2005). Conservation Assessment of Glyphis sp. A (Speartooth Shark), Glyphis sp. C (Northern River Shark), Pristis microdon (Freshwater Sawfish) and Pristis zijsron (Green Sawfish). [Online]. Hobart, Tasmania: CSIRO Marine Research. Available from: http://www.environment.gov.au/coasts/publications/pubs/assessment-glyphis.pdf.
Stevens,J.D., R.B. McAuley, C.A. Simpfendorfer & R.D. Pillans (2008). Spatial distribution and habitat utilisation of sawfish (Pristis spp) in relation to fishing in northern Australia. A report to the Department of the Environment, Water, Heritage and the Arts. [Online]. CSIRO and Western Australia Department of Fisheries. Available from: http://www.environment.gov.au/coasts/publications/pubs/sawfish-report.pdf.
Stobutzki, I.C., J.M. Miller, D.S. Heales & D.T. Brewer (2002). Sustainability of Elasmobranches Caught as By-catch in a Tropical Prawn (Shrimp) Fishery. Fishery Bulletin. 100:800-821.
Thornburn, D.C., S. Peverell, S. Stevens, J.D. Last & A.J. Rowland (2003). Status of Freshwater and Estuarine Elasmobranches in Northern Australia. Report to Natural Heritage Trust, Canberra, Australia.
Whitty, J.M., D.L. Morgan, D.C. Thorburn, T. Fazeldean & S.C. Peverell (2008). Tracking the movements of Freshwater Sawfish (Pristis microdon) and Northern River Sharks (Glyphis sp. C) in the Fitzroy River. Whitty, J.M., N.M. Phillips, D.L. Morgan, J.A. Chaplin, D.C. Thorburn & S.C. Peverell, eds. Habitat associations of Freshwater Sawfish (Pristis microdon) and Northern River Sharks (Glyphis sp. C): including genetic analysis of P. microdon across northern Australia. [Online]. Centre for Fish & Fisheries Research (Murdoch University) report to the Department of the Environment, Water, Heritage and the Arts, Australian Government. Available from: http://www.environment.gov.au/coasts/publications/pubs/freshwater-sawfish-northern-river-shark.pdf.
Wilson, D. (1999). Freshwater sawfish Pristis microdon. Australia New Guinea Fishes Association A-Z Notebook of Native Freshwater Fish (Australia New Guinea Fishes Association Bulletin). 41.
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Citation: Department of the Environment (2014). Pristis pristis in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Sun, 31 Aug 2014 18:51:51 +1000.