|Scientific Name:||Pristis pristis|
|Species Authority:||(Linnaeus, 1758)|
|Infra-specific Taxa Assessed:|
Pristis microdon Latham, 1794
Pristis perotteti Valenciennes, in Müller & Henle, 1841
Pristis zephyreus Jordan & Starks, 1895
|Taxonomic Notes:||In a recent study, Faria et al. (2013) demonstrated that the existing taxonomy of the Pristidae required modification, recognising a total of five species in two genera. Pristis pristis had been recognised previously as consisting of up to three species (Pristis pristis, P. microdon and P. perotteti), but utilising a combination of mitochondrial DNA and morphological characters appears to be one species. While the P. pristis group is best considered a single species, it can be composed of a network of geographical units (subpopulations) that are not genetically distinct, but may be considered ecologically different.
Pristis pristis, has been referred to by many other names throughout its range. It was formerly known as P. perotteti in the Atlantic and sometimes in the Eastern Pacific, and P. microdon in the Indo-West Pacific.
|Red List Category & Criteria:||Critically Endangered A2cd ver 3.1|
|Assessor(s):||Kyne, P.M., Carlson, J. & Smith, K.|
|Reviewer(s):||Harrison, L., Simpfendorfer, C. & Pillans, R.|
The Largetooth Sawfish (Pristis pristis) formerly had a widespread tropical distribution, consisting of four subpopulations (Eastern Atlantic, Western Atlantic, Eastern Pacific and Indo-West Pacific). A recent taxonomic review has shown that P. perotteti (Atlantic) and P. microdon (Indo-West Pacific) are synonymous with P. pristis and this Red List assessment replaces the previous (2006) assessments for those species. The Largetooth Sawfish is a large (6.5+ m total length) euryhaline species, with juveniles occurring in freshwater systems and adults in marine and estuarine environments (although in Lake Nicaragua, individuals spent much, if not all, of their lives in freshwater). All subpopulations have undergone significant population declines and the species is now apparently extinct in many former range states. In most others, recent records are rare (e.g., there have been very few records in the Eastern Atlantic in the last decade). In the Western Atlantic, current records indicate that Largetooth Sawfish can only be regularly encountered today in the Amazon River basin, the Rio Colorado-Rio San Juan area in Nicaragua, and possibly some remote areas of French Guiana, Suriname, and Guyana. In the Indo-West Pacific, northern Australia represents a globally important remaining population centre. Overall, a population reduction based on a reduction in extent of occurrence (EOO) of ≥80% over a period of three generations (i.e., 1960s to present) is inferred. Despite protection in some range states (e.g., Australia, India, Brazil, United States, Mexico; it is possibly extinct in the latter two range states), threats are ongoing and the species is assessed globally as Critically Endangered.
|Range Description:||The Largetooth Sawfish (Pristis pristis) comprises four distinct subpopulations: Eastern Atlantic, Western Atlantic, Eastern Pacific and Indo-West Pacific.
The current distribution of Largetooth Sawfish in the Eastern Atlantic is uncertain due to species identification issues, lack of reporting, and the general contraction of its range. Largetooth Sawfish were historically found along the coast of West Africa from Angola to Mauritania (Faria et al. 2013). Historic records indicate that Largetooth Sawfish were once relatively common in the coastal estuaries of West Africa. Verified records exist from Senegal (1841–1902), Gambia (1885–1909), Guinea-Bissau (1912), Republic of Guinea (1965), Sierra Leone (date unknown), Liberia (1927), Côte d’Ivoire (1881–1923), Congo (1951–1958), Democratic Republic of the Congo (1951–1959), and Angola (1951) (Burgess et al. 2009). Most records, however, lack data and locality and may have been confused taxonomically with other species. Unpublished notes from a 1950’s survey detail 12 Largetooth Sawfish from Mauritania, Senegal, Guinea, Côte d’Ivoire, and Nigeria. The presence of sawfishes in the Mediterranean Sea is still uncertain (Whitehead et al. 1984, Bilecenoğlu and Taşkavak 1999). There have been only two countries with confirmed records for the region in the last 10 years (Guinea-Bissau in 2003, 2004 and 2005; Sierra Leonne in 2003) and unconfirmed records (Pristis sp.) from one other country (Mauritania in 2010). It is likely that areas around Guinea-Bissau represent the last areas where sawfish can be found in West Africa (Mika Diop pers. comm. 2012).
Although Largetooth Sawfish were included in historic faunal lists (Serena 2005), it is still debatable whether sawfishes occurred as part of the Mediterranean ichthyofauna or as a vagrant species as seasonal migrants from areas off West Africa.
In the Western Atlantic, Largetooth Sawfish were widely distributed throughout the tropical and subtropical marine and estuarine waters. Largetooth Sawfish were found from Uruguay through the Caribbean and Central America, the Gulf of Mexico, and seasonally to the United States (Burgess et al. 2009, Faria et al. 2013). Currently, Largetooth Sawfish are thought to primarily occur in freshwater habitats in Central and South America. Largetooth Sawfish have been recorded in locations at least 1,340 km from the ocean in the Amazon River, as well as in Lake Nicaragua and the San Juan River and other east coast Nicaraguan rivers. The species has also been reported in coastal systems in Brazil, French Guiana, Suriname, Guyana and Columbia in South America. In Central America, scattered reports still exist for Largetooth Sawfish in Panama, Costa Rica, Nicaragua, Honduras and Belize. In Mexico, the lack of records may indicate the species is no longer found west of the Yucatan Peninsula (R. Graham pers. comm. 2012). Throughout the Caribbean Sea, the species presence was historically uncertain and early records may have been Smalltooth Sawfish (P. pectinata). Though historically reported in the United States, it appears that Largetooth Sawfish were never abundant and was likely a season migrant. The species has not been reported in the United States since the 1960s (Burgess et al. 2009).
In the Eastern Pacific, the historic range of Largetooth Sawfish was limited by the cooler water currents to the north of its range (California current) and the Humboldt Current in the south (V. Faria pers. comm. 2012). The historic range is thought to occur from Mazatlán, Mexico to Peru (Chirichigno and Cornejo 2001, Cook et al. 2005, Faria et al. 2013). Other references (i.e., Amezcua-Linares 2009) suggest that it occurred south from Topolobampo (some 440 km further north than Mazatlán), highlighting the uncertainty over its historic range. The occurrence of Largetooth Sawfish in Peru may have represented seasonal migration from the species’ core range in Central America. Largetooth Sawfish were historically reported from a number of freshwater systems in the Eastern Pacific (as summarised by Cook et al. 2005).
The Indo-West Pacific subpopulation of the Largetooth Sawfish was formerly wide-ranging from parts of the Western Indian Ocean through India, the Bay of Bengal and Southeast Asia to New Guinea and northern Australia. Its current distribution is now patchy across its range. It had been confirmed from several major river systems of Papua New Guinea, Indonesia and Malaysia (including Borneo), Cambodia, Viet Nam and the Philippines (Roberts 1978, Tan and Lim 1998, Compagno et al. 2005, Stevens et al. 2005). Its occurrence in many of these is now uncertain or non-existent. It may now be extinct in several range states, including South Africa, the Seychelles, Thailand and others; elsewhere it has been severely depleted.
Northern Australia may be the last viable population stronghold in the Indo-West Pacific, although it may persist in remote parts of the region. It occurs across tropical northern Australia from the northeastern coast of Queensland, across Cape York, the Gulf of Carpentaria, the Northern Territory and the Kimberley region (Western Australia). It has occurred as a vagrant to southwestern Australia (Last and Stevens 2009).
Native:Australia (Northern Territory, Queensland, Western Australia); Bangladesh; Belize; Brazil; Colombia; French Guiana; Guinea-Bissau; Guyana; Honduras; India; Madagascar; Mozambique; Nicaragua; Pakistan; Panama; Papua New Guinea; Sierra Leone; Somalia; Suriname
Possibly extinct:Angola (Angola); Benin; Cambodia; Cameroon; Congo; Congo, The Democratic Republic of the; Côte d'Ivoire; Ecuador; Equatorial Guinea; Gabon; Gambia; Ghana; Guatemala; Guinea; Lao People's Democratic Republic; Liberia; Malaysia; Mexico; Nigeria; Peru; Senegal; Seychelles; Singapore; South Africa; Thailand; Togo; United States; Uruguay; Venezuela, Bolivarian Republic of
|FAO Marine Fishing Areas:||
Atlantic – eastern central; Atlantic – southeast; Atlantic – southwest; Atlantic – western central; Indian Ocean – eastern; Indian Ocean – western; Pacific – eastern central; Pacific – southeast; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
The population size of this species in the Western Atlantic remains unknown. There are no data or information on trends in abundance, thus the population status is inferred from reports of capture records. Its abundance has been continuously declining over the past few decades to the point that it can now be considered rare or even extirpated in some areas where it was previously considered a common species. Burgess et al. (2009) reported on recent records of Largetooth Sawfish in the Western Atlantic. Over the last 10 years, records have only been consistently found in Brazil (Burgess et al. 2009). Records of fishermen still catching sawfish in Panama, Nicaragua, Honduras and Belize have been reported but are scarce (R. Graham pers. comm. 2012). While the species is protected in some areas, illegal fishing and bycatch landings continue to occur which indicates the population still may be in decline except in the most remote areas.
The population size of this species in the Eastern Atlantic remains unknown. There are no data or information on trends in abundance, thus the population status is inferred from reports of capture records. Its abundance has been continuously declining over the past few decades to the point that it can now be considered rare or even extirpated in some areas where it was previously considered a common species. While records of the species still exist (Burgess et al. 2009), in many areas, the time between records is long indicating the population is still declining. Historic records of Largetooth Sawfish include most countries from Angola to Mauritania (Faria 2007, Burgess et al. 2009). However, there have been only two countries with confirmed records for the region in the last 10 years (three animals in Guinea-Bissau in 2003, 2004 and 2005; one animal in Sierra Leonne in 2003). There are unconfirmed records (Pristis sp.) from two countries (three animals in Guinea-Bissau in 2011, and one animal in Mauritania 2010). It is likely that areas around Guinea-Bissau represent the last areas where sawfish can be found in West Africa (Mika Diop pers. comm. 2012). Given many areas still have artisanal gillnet fisheries with little or no regulation, it is likely the population will continue to decline.
The population size of this species in the Eastern Pacific remains unknown. There are no data or information on trends in abundance, thus the population status is inferred from reports of capture records. While historically found from Peru to Mexico, the only recent records (within the last 10 years) are from Columbia, Nicaragua, and Panama (R. Graham pers. comm. 2012). Costa Rica’s Osa Peninsula, which encompasses the Corcovado National Park’s Rio Sirena and the Térraba-Sierpe Wetland are thought to host a remnant population of sawfish, based on fisher interviews of recent but unconfirmed sightings (I. Zanella pers. comm. 2011). However, in the contiguous Golfo Dulce (Costa Rica), artisanal hook and line and net fishers interviewed in 2004 reported that they had not seen a sawfish in decades (R.T. Graham pers. comm. 2012).
Largetooth Sawfish existed in Panama’s Pacific-draining man-made Lake Bayano in 1982 (Montoya and Thorson 1982), but there are no recent records from that site or other parts of Panama or nearby Colombia, based on an IUCN Shark Specialist Group (SSG) survey of members and researchers sent out by the SSG in 2011–2012. The species may now possibly be extinct in several countries such as Mexico, Guatemala, Ecuador and Peru; there are no confirmed records in many parts of the region for the past decade. This represents a significant contraction in the species’ extent of occurrence in the Eastern Pacific. There are some poorly studied parts of the region with suitable sawfish habitat (e.g., the Darien, Panama), suggesting that surveys are required to locate any remnant populations.
Given the degree of mangrove loss and the level of artisanal net fishing, it is likely that the remnant population is still in decline.
There are almost no data on population status of Largetooth Sawfish across the Indo-West Pacific; all populations are, however, probably severely depleted.
Landings of Largetooth Sawfish are now extremely rare in former range states of the Western and Northern Indian Ocean. Although the St Lucia estuary system of South Africa was once an important breeding area, sawfishes (including Largetooth Sawfish) now appear to be extinct in that country. They also now appear to be absent from southern Mozambique (S. Pierce pers. comm. 2012) and while once common in the Zambezi River (Wallace 1967) no recent sightings have been documented. Madagascar, the Seychelles, Pakistan and India, amongst other Indian Ocean range states, have all seen depletions of sawfishes, including Largetooth Sawfish. Sawfish were previously common in artisanal fishing catches on the western coast of Madagascar, but are now extremely rare along that coast (Manach et al. 2011). There are no sawfish records from the Seychelles in the last decade (D. Rowat pers. comm. 2012), and a 2009 record of a Largetooth Sawfish in Gwadar, western Balochistan, Pakistan (A. Rahim pers. comm. 2012) represents a very rare event. Surveys with fishers in Raigad District (Maharashtra state) of India (where sawfishes were commonly harvested historically) indicate a drastic decline in the sawfish fishery from 1985–1990, with only occasional catches in recent years (R. Raut pers. comm. 2012).
In Southeast Asia, localised depletions and extinctions of sawfishes have been reported or inferred from across the region. During some eleven years of market surveys (over 160 visits to 11 market sites) in various parts of Indonesia only two individual sawfish (both Largetooth Sawfish) were recorded which were caught in the Arafura/Banda Sea region (W. White pers. comm. 2012) and possibly came from illegal fishing in Australian waters. Demersal elasmobranchs are intensively targeted in Indonesia (Blaber et al. 2009), and this extremely low occurrence (out of some 60,000 chondrichthyans examined) is indicative of severely depleted populations in Indonesia. In fact, it is thought that sawfishes are extinct from large areas of Indonesia. Despite the presence of sawfish rostra in houses near fishing ports, local Indonesian fishermen indicate that they have not seen sawfishes for more than 20 or 30 years (W. White pers. comm. 2012). Populations in Borneo are thought to be seriously depleted (Last et al. 2010). In Sabah (Malaysian Borneo), fishers and villagers reported sawfish as abundant in the 1970s and declining sharply in the 1980s, with very limited catches since that time (Manjaji 2002). The last known record from the Kinabatangan River was in 1996 (B.M. Manjaji-Matsumoto pers. comm. 2012).
Datasets from as early as 1963–1972 showed the considerable decline in batoids in the Gulf of Thailand (Pauly 1979), which included the virtual disappearance of sawfish (Pauly 1988). Declines in demersal fishes in the Thai Andaman Sea were also documented (Pauly 1979) and these likely included sawfishes. In contrast, historic accounts indicated that sawfishes were ‘common’ and caught in ‘considerable numbers’ in Thailand, including in rivers (Smith 1945). Within the Cambodian Mekong system, numbers of Largetooth Sawfish have reportedly decreased considerably. Historically, they were regularly seen as far upstream as Khoné Falls, and in other areas of the Mekong (Tonlé Sap and Great Lake), none have been seen for ‘several decades’ (Rainboth 1996).
Largetooth Sawfish were considered common in the Philippines by Herre (1953) but none were recorded in more recent surveys and it is thought that the population ‘has greatly declined in the Philippines’ (Compagno et al. 2005).
Largetooth Sawfish had previously been described as common in the middle reaches and large tributaries of the Fly River, Papua New Guinea (Roberts 1978) but its status there requires reappraisal. More recently, the ‘demise’ of the species has been reported in Lake Sentani, West Papua as a result of the change from traditional fishing methods to the use of gill nets (Polhemus et al. 2004).
All sawfish species have undergone significant, albeit largely unquantified, declines in Australia. In places, viable populations persist, representing some of the last viable populations in the Indo-West Pacific, with Australia being one of a limited number of global strongholds for sawfishes (Stevens et al. 2005, DSEWPaC 2011a). Genetic data indicate that Largetooth Sawfish has moderate levels of genetic diversity and male-biased dispersal in Australian waters (Phillips et al. 2011, Phillips 2012). Genetic evidence suggests that females have strong reproductive philopatry (returning to sites previously used for reproduction), with maternal population structuring between Western Australia and the Gulf of Carpentaria, with the northern coast of the Northern Territory and the Queensland east coast populations also potentially forming distinct maternal populations (Phillips et al. 2011). In contrast, males disperse between at least Western Australia, the Northern Territory and the Gulf of Carpentaria (Phillips 2012).
Species-specific data to accurately ascertain the status of Australian sawfishes is generally lacking and the evidence for decline and range contraction is largely anecdotal. Data from the Queensland Shark Control Program, which operates ‘bather protection’ fishing gear along the Queensland east coast, shows a clear decline in sawfish catch (non species-specific) over a 30 year period from the 1960s and the complete disappearance of sawfish in southern Queensland (Stevens et al. 2005). All Pristis species are now extremely rare along the Australian east coast (the area in which human population and habitat modification is greatest) where they have undergone a considerable range contraction. Although populations across northern Australia have undergone significant reduction and their status is uncertain, Australian populations are considered some of the highest in the world.
While specific management measures are now in place in Australia, including full species protection, education of fishers about safe release practices, and fishery-specific management, threats are ongoing and there is no information to suggest that the population is recovering from previous declines.
Across the Indo-West Pacific, a population reduction of ≥80% is inferred based on a reduction in extent of occurrence (EOO) over a period of three generations (i.e., 1969 to present). Declines and continuing threats (much of the species’ Indo-West Pacific range, with the exception of northern Australia, is subject to intense human pressure, particularly through generally unregulated and unmanaged fisheries, and habitat loss and degradation in critical sawfish habitats) are resulting in the continual declines of remnant populations. The Australian population of Largetooth Sawfish likely comprises a high proportion of the global population (Stevens et al. 2005).
|Habitat and Ecology:||
Available life history information on Largetooth Sawfish comes from in Lake Nicaragua in Central America (Thorson 1976; 1982) and from northern Australia.
Largetooth Sawfish are generally restricted to shallow (<10 m) coastal, estuarine, and fresh waters, although they have been found at depths of up to 26 m in Lake Nicaragua. Largetooth Sawfish move across salinity gradients freely and in northern Australia, parturition probably occurs in brackish or saltwater and juveniles spend ~4–5 years in the freshwater reaches of rivers and floodplain waterholes before migrating to estuarine and marine waters (Thorburn et al. 2007, Peverell 2008, Whitty et al. 2008, Whitty et al. 2009, P. Kyne unpublished data). In Lake Nicaragua, individuals spent much, if not all, of their lives in freshwater with reproduction of the population occurring primarily in the lake (Thorson 1982).
The life history of Largetooth Sawfish, like many elasmobranchs, is characterised by slow growth, late maturity, and low fecundity, which generally contributes to a low intrinsic rate of increase. The maximum reported size of Largetooth Sawfish is 656 cm TL, although it has been estimated up to 700 cm TL (Compagno and Last 1999). Very large individuals are now rarely seen anywhere in the Indo-West Pacific.
The reproductive method of sawfishes is most likely lecithotrophic viviparity. The only known reproductive study of Largetooth Sawfish was from Lake Nicaragua in the 1970s (Thorson 1976) with other observations from northern Australia. Thorson (1976) found that both ovaries appeared to be functional, though the left seemed to be larger and carry more ova. Litter sizes in Lake Nicaragua were 1–13 (mean 7.3) following a gestation period of about five months. While the reproductive cycle is possibly biennial in the Western Atlantic (Thorson 1976), it appears to be annual in northern Australia (Peverell 2008).
Size at birth ranges 72–90 cm TL (Peverell 2008). Size at maturity is ~300 cm TL for females and ~280–300 cm TL for males (Thorburn et al. 2007, Peverell 2008, Whitty et al. 2008). Age at maturity in Queensland, northern Australia, has been estimated at 8–10 years (Peverell 2008). Peverell (2008) using a preliminary vertebral growth ring analysis estimated a maximum age of 35 years in northern Australia.
Using life history information from populations in Central America, Simpfendorfer (2000) estimated an intrinsic rate of increase of 0.05 to 0.07 per year and population doubling times of 10.3–13.6 years. These rates were estimated under ideal conditions (i.e. no fisheries, no population fragmentation, no habitat modification and no inbreeding depression). Moreno Iturria (2012) estimated an intrinsic rate of population increase of 0.12 yr-1, a population doubling time of 5.8 yrs and a generation time of 14.6 yrs for Indo-West Pacific Largetooth Sawfish, and an intrinsic rate of population increase of 0.03 yr-1, a population doubling time of 23.3 yrs and a generation time of 17.2 yrs for Western Atlantic Largetooth Sawfish.
|Use and Trade:||
While international trade sawfishes is banned under the species’ listing on Appendix I of the Convention on International Trade of Endangered Species (CITES), illegal international trade may still exist due to the high value of their products.
The exploitation of elasmobranchs is high in many parts of the Largetooth Sawfish’s global range, and there is no doubt that it is still caught, landed and traded.
McDavitt (2005) reviewed all available information related to sawfish trade and identified six sawfish parts, derived mostly from sawfish captured as bycatch in fisheries, which were historically or currently found in trade. These sawfish parts identified in trade are: fins, whole rostra, rostral teeth, meat, organs and skin.
The fins of sawfish are used to produce shark fin soup and sawfish fins are highly favored in Asian markets (NMFS 2009). Because of their large fins with high fin needle content, fins of species in the family Pristidae are highly valued for shark fin soup (CITES 2007).
Sawfish rostra are often traded as curios, ceremonial weapons, or for use in traditional medicines (NMFS 2009). Rostra have long been a favorite marine curio (Migdalski 1981), with large rostra commanding impressive prices (McDavitt 1996). Organized curio trade in rostra of species in the family Pristidae has recently been reported in Brazil (Charvet-Almeida 2002, McDavitt and Charvet-Almeida 2004). It was estimated that 90–180 large rostra are purchased annually by Asian buyers from the main fish market in northern Brazil, presumably for the curio trade (McDavitt and Charvet-Almeida 2004). Local artisans in Brazil sometimes decorate medium-sized pristid rostra (usually Largetooth Sawfish) for sale to tourists. Overall, an estimated 1,000–1,500 small- to medium-sized rostra are sold per year from this same market for a variety of purposes (McDavitt and Charvet-Almeida 2004). The use of rostra in traditional medicine includes some use in Mexico and Brazil (NMFS 2009).
Rostral teeth of species in the family Pristidae have been the preferred material used to manufacture artificial spurs on Peruvian fighting cocks (Cogorno Ventura 2001). The rostral teeth are mostly obtained from Brazil, Ecuador, Panama and various Caribbean countries (CITES 2007). Charvet-Almeida (2002) and McDavitt and Charvet-Almeida (2004) determined that rostra find their way into the international cockfighting market from Brazil.
Sawfish are regularly used for their meat; however, most of the consumption is local and so they appear to be only occasionally traded beyond local markets (NMFS 2009). In the north of Brazil, Charvet-Almeida (2002) reported a limited market for meat, rostra and rostral teeth of fish in the family Pristidae.
Chinese traditional medicine also uses other sawfish parts, including liver, ova and gall bladder (NMFS 2009).
Sawfish skin has been used to produce leather, which, like shark leather, is considered of very high quality (NMFS 2009). The leather is used to make belts, boots, purses, and even to cover books (NMFS 2009).
Sawfishes are highly prized as display animals in public aquariums due to their large size, bizarre shape, and shark-like features (McDavitt 1996, NMFS 2009). Prior to the uplisting of ‘Pristis microdon’ to CITES Appendix I at the 16th Conference of Parties in 2013, it was listed on Appendix II (in 2007) ‘for the exclusive purpose of allowing international trade in live animals to appropriate and acceptable aquaria for primarily conservation purposes’. This legal international trade in Largetooth Sawfish for aquaria originated only from Australia and involved a small number of Largetooth Sawfish. In 2011, Australia determined that it was not able to issue a Non-Detriment Finding, ruling that ‘it is not possible to conclude with a reasonable level of certainty that any harvest of P. microdon for export purposes would not be detrimental to the survival or recovery of the species’ (DSEWPaC 2011b). As such, there has been no export since 2011. Domestic harvest for aquariums in ongoing in Australia with juveniles periodically collected in the Northern Territory and Queensland.
In the Eastern Pacific, Largetooth Sawfish were used for human consumption (meat) (McEachran 1995), or for ornamental purposes (Amezcua-Linares 2009), as well as the other uses outlined above. Sawfish have been historically highly valued for fins, meats and liver oil in the Indo-West Pacific. India has traditionally been a regional hub in the shark fin trade, collecting fins from around the Western Indian Ocean (e.g., Red Sea, Persian (Arabian) Gulf, Indian subcontinent), and shipping these to the main markets of Singapore and Hong Kong (M.T. McDavitt pers. comm. 2012). Trade in shark fin is significant throughout Southeast Asia.
In northern Australia, the meat of sawfish is sometimes utilised by Indigenous communities but the extent to which Indigenous Australians harvest and utilise Largetooth Sawfish is unknown; it is likely localised and at a low rate.
See CITES (2007) for a comprehensive overview of trade in sawfishes.
The principal threats to this species are from fishing; it was formerly targeted, but is now mostly taken incidentally in broad-spectrum fisheries (CITES 2007). The long toothed rostrums of sawfishes make them extraordinarily vulnerable to entanglement in any sort of net gear, gillnetting and trawling in particular. The exploitation of elasmobranchs is high in many parts of the Largetooth Sawfish’s range, particularly in coastal areas and freshwater systems. Unregulated and unmanaged fisheries, and habitat loss and degradation all threaten sawfishes across large parts of its range.
For at least part of its life cycle, the Largetooth Sawfish relies on a variety of specific habitat types including freshwater systems, estuaries and mangroves; these are all affected by human development (CITES 2007). Agricultural and urban development, commercial activities, dredge-and-fill operations, boating, erosion, and diversions of freshwater runoff as a result of continued coastal and catchment development has caused substantial loss or modification of these habitats (CITES 2007). Mining activities, in northern Australia, New Guinea (e.g., the Fly River) and elsewhere, pose a risk to Largetooth Sawfish through freshwater habitat alteration or potential pollution events. Alterations to river courses are a realised threat to Largetooth Sawfish which migrate upstream in early life stages. These range from smaller barrages and road crossing in northern Australia to large-scale river alterations in Southeast Asia.
In West Africa, shark fishing increased significantly in the past several decades and ‘the intensive exploitation of sharks over the past thirty years has completely decimated the most vulnerable populations…’ (Diop and Dossa 2011). The disappearance of sawfish in the region was thought to have begun in the 1970s when new fishers entered the region and new fishing gear was developed (Diop and Dossa 2011). Threats are ongoing in the region and given that many areas still have artisanal gillnet fisheries with little or no regulation, it is likely the population will continue to decline.
In the Western Atlantic, the main threats are region-wide gillnets used effectively in rivers, at river mouths, estuaries and nearshore waters (up to 200 km out in case of Amazon-Orinoco estuaries; P. Almeida pers. comm. 2012), and trawling. In the Eastern Pacific, Largetooth Sawfish were caught by gillnets, longlines and trawl nets.
In Australia, datasets indicate that net fisheries account for the greatest bycatch of sawfish (all species) across northern Australia (80.2%) followed by trawling (16.6%), line fishing (9.2%) and recreational fishing (0.3%) (Stevens et al. 2005). Largetooth Sawfish are captured by all these fishing activities (Giles et al. 2004) and declines in Largetooth Sawfish are suspected based on potential levels of exploitation (Larson et al. 2006). A survey across northern Australia from Western Australia to Queensland appears to support the assertion that fishing is responsible for declines, as it found greater numbers of sawfish in areas of lower fishing pressure (both commercial and recreational) (Thorburn et al. 2003). The sustainability of Largetooth Sawfish populations in northern Australia is considered to be at high risk due to the cumulative effects of all fisheries, and the species’ low biological productivity and susceptibility to gillnets (Salini et al. 2007).
A number of Queensland, Northern Territory and Western Australian inshore net fisheries continue to catch Largetooth Sawfish incidentally. Despite requirements to release these, there is no doubt a continuing level of bycatch-associated mortality.
The extent to which recreational fishers interact with Largetooth Sawfish across northern Australia is unknown, but in some areas where the species has been recorded, recreational fishing is a popular activity, which is increasing in popularity and could pose a threat to the species. In the Fitzroy River (WA), recreational fishers have been reported killing incidentally caught Largetooth Sawfish for the ‘trophy’ rostrum and for retrieval of fishing tackle (Thorburn et al. 2003).
Sawfish (non species-specific records) have been recorded in derelict fishing nets in northern Australian waters; the Gulf of Carpentaria is a particular hotspot for these ‘ghost nets’ (Gunn et al. 2010) and capture in these may result in sawfish mortality. Because of their toothed rostrum, sawfish may be exceptionally susceptible to entanglement in other types of marine debris, and entanglement has been reported in a number of types of marine debris (Seitz and Poulakis 2006). Entanglement in discarded or lost recreational fishing line may occur on occasion, as has been documented for Largetooth Sawfish in Western Australia (Thorburn et al. 2004).
All species of sawfish are listed on Appendix I of the Convention on International Trade of Endangered Species (CITES), which effectively bans commercial international trade in sawfish or their parts.
Sawfish are protected in the Exclusive Economic Zone in Guinea and Senegal and in Marine Protected Areas in Mauritania and Guinea-Bissau (S.V. Fordham pers. comm. 2012).
Largetooth Sawfish are protected in Brazil. The commercial fishery for both shark and sawfish is banned in Lake Nicaragua and all take of Largetooth Sawfish is banned in Mexico (where it already appears to be extinct). Largetooth Sawfish are also listed as Endangered under the US Endangered Species Act.
All take of Largetooth Sawfish is banned in Mexico (where it already appears to be extinct). Elsewhere throughout the Pacific range of Largetooth Sawfish, there are no conservation or management measures, and these are urgently needed.
Within Australia, Largetooth Sawfish has the following conservation and protected status listings: Australian Commonwealth waters, Vulnerable (Environment Protection and Biodiversity Act 1999); Queensland, Protected (Fisheries Act 1994); Northern Territory (NT), Vulnerable (Territory Parks and Wildlife Conservation Act 2000); Western Australia (WA), Totally Protected (Fish Resources Management Act 1994). The take of the species is therefore prohibited within Australian Commonwealth, state and territory waters.
In addition to the above legislated regulations, the Commonwealth, Queensland, NT and WA all have fisheries management plans in place for interactions with protected species, including Largetooth Sawfish. These include mandatory reporting of interactions with these species, release of live animals, observer coverage of most of the fisheries (although this is very low in state and territory fisheries which are likely to interact with Largetooth Sawfish) and education programmes for fishers on identification and ways to minimise interactions with this species. The Queensland Government has published a guide to the safe release of sawfish for commercial fishers (DEEDI 2010) and NT shark fishers have a Code of Practice for the release of live sawfish from gillnets (Salini et al. 2007).
Several spatial closures in riverine, estuarine and coastal waters in the NT Barramundi Fishery offer Largetooth Sawfish some refuge from commercial gillnet fishing activities in the NT. Closed areas within the Great Barrier Reef Marine Park and the closure of rivers in Princess Charlotte Bay to gillnetting may also afford some protection. Seasonal spawning closures for the take of Barramundi (Lates calcarifer) (mostly during the summer wet season) throughout much of the range add a level of protection to the species, however, information on Largetooth Sawfish long-term movement patterns and habitat use are required in order to assess the benefits of closed areas and seasons not specifically designed for sawfish.
In northern Australian prawn trawl fisheries, the use of turtle exclusion devices (TEDs) and bycatch reduction devices (BRDs) is mandatory, though the benefit of these devices on sawfish is poorly quantified. In one study, they have been shown to reduce the catch of Narrow Sawfish (Anoxypristis cuspidata), however, they and other sawfish species are still being caught as their rostra become tangled in the body of the net (Brewer et al. 2006).
Outside of Australia, awareness needs to be raised, and regulations put in place to protect all sawfishes and promote population recovery. While sawfishes (including Largetooth) are theoretically protected in India (Indian Wildlife (Protection) Act), threats continue with little beneficial management, although increasing awareness of sawfishes in India is encouraging. Largetooth Sawfish are also protected in Bangladesh, Malaysia and Indonesia. Although protected in these range states, the lack of enforcement or specific fisheries regulations, and ongoing gillnet and trawl fisheries, means that the threats are ongoing.
|Citation:||Kyne, P.M., Carlson, J. & Smith, K. 2013. Pristis pristis. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 02 September 2014.|