Conservation Actions
Through proposals made in 2007 and 2013, all five sawfish species are now listed on Appendix I of the Convention on International Trade of Endangered Species (CITES), which essentially bans commercial international trade in sawfishes and their parts. In 2014, all sawfishes were added to Appendix I and II of the Convention on Migratory Species (CMS), which obligates Parties to act nationally and cooperate regionally to “strictly protect” the species. All sawfishes were added to Annex 1 of the CMS Memorandum of Understanding (MoU) in 2016, which aims to facilitate regional conservation of the species.In 2012, the General Fisheries Commission for the Mediterranean (GFCM) banned retention and mandated careful release for the Largetooth Sawfish listed on the Barcelona Convention Annex II of the Protocol Concerning Specially Protected Areas and Biological Diversity in the Mediterranean. Implementation by GFCM Parties, however, has been very slow. Largetooth sawfish were added to Annex II of the Protocol for Specially Protected Areas and Wildlife (SPAW Protocol) of the Convention for the Protection and Development of the Marine Environment of the Wider Caribbean Region (the Cartagena Convention) in 2017 and 2019, respectively. These listings obligate Parties to grant Largetooth Sawfish strict protections, including through bans on take and trade.
Despite these many binding international treaty mandates, Largetooth Sawfish remain inadequately protected in a great number of countries where basic regulations are lacking and/or poorly enforced. A 2018 analysis identified four priority regions for concerted, international sawfish conservation policy action: the Caribbean, Amazon Delta, Western Indian Ocean, and Australasia (Fordham et al. 2018). Yan et al. (2021) underscored the urgent need for domestic sawfish protections, particularly by nations where Largetooth Sawfish presence is uncertain, low or declining, yet extinction probability is low. Four nations were prioritized for specialized surveys and strong legal protections: Mexico, Panamá, Brazil, Madagascar, and Sri Lanka. Countries where Largetooth Sawfish are still regularly found that fail to apply species-specific prohibitions on killing, retention, sale, and trade (i.e., Papua New Guinea) are also considered priorities for conservation action.
Species-specific protection of Largetooth Sawfish exists in at least 17 countries, that is, Australia, Bangladesh, Brazil, Colombia, Costa Rica, Ecuador, Guinea, India, Indonesia, Malaysia, Mexico, Nicaragua, Pakistan, Panamá, Perú, Senegal, and South Africa (Harrison and Dulvy 2014, Fordham et al. 2018, S. Kelez unpubl. data 2022). However, enforcement of these protection laws is generally poor. Other potential Largetooth Sawfish range states that still lack national protections include Honduras, Perú, Somalia, Madagascar, and Mozambique, as well as the proponent of the CMS and CITES sawfish listing proposals – Kenya (Harrison and Dulvy 2014, Fordham et al. 2018, Lawson and Fordham 2018). Australia, where Largetooth Sawfish are still present and relatively well protected, is considered a “lifeboat” country, but relaxation of key safeguards would immediately threaten these populations.
In addition to species-specific legal protections, Largetooth Sawfish recovery requires minimization of bycatch (and associated mortality) as well as conservation of important coastal habitats (Harrison and Dulvy 2014, Fordham et al. 2018). Effective enforcement of such safeguards requires ongoing educational initiatives, training (including in the area of species identification), and other capacity-building efforts. In these areas, there is room for improvement in every Largetooth Sawfish range state. Better monitoring of Largetooth Sawfish catches, including in artisanal fisheries, and expanded research programs are also needed to help understand population trends and inform management. The multi-lateral environmental agreements that have already listed sawfishes as species warranting strict protections can provide valuable platforms for facilitating sawfish recovery at regional and global scales, but targeted initiatives to do so have not yet been developed. This inaction demonstrates that ongoing public, political, and financial support is also integral to preventing further Largetooth Sawfish extinction.
Location Information
The Largetooth Sawfish has a widespread circumtropical distribution across the Western Atlantic, Eastern Pacific, Eastern Atlantic, and the Indo-West Pacific.Western Atlantic
Historically, Largetooth Sawfish were found from the Gulf of Mexico (and seasonally to the United States), through the Caribbean and Central America to Uruguay (Burgess et al. 2009, Faria et al. 2013, Fernandez-Carvalho et al. 2014). Now, the species is mainly restricted to freshwater and estuarine habitats from Central and South America.
In Mexico, the last known records of the Largetooth Sawfish were in 1997–1998 (Bonfil et al. 2017, Bonfil et al. 2018); although there have been unconfirmed sightings in the Usumacinta River (southeastern Mexico) since 2010 based on Local Ecological Knowledge (LEK) (R. Bonfil unpubl. data 2022). In Central America, there are scattered reports of the Largetooth Sawfish in Belize, Guatemala, Honduras, and Panamá, yet most of these are historical records from over 20 years ago (López-Angarita et al. 2021, A. Hacohen pers. comm. 6 January 2022). In Costa Rica, there are only a few recent confirmed records in the south Caribbean coast; most records of the species, including both juveniles and adults, are from freshwater habitats in the north Caribbean (Barra del Colorado) and San Juan River basin (Thorson 1982, Valerio-Vargas and Espinoza 2019). Throughout the Caribbean Sea, the species presence was historically uncertain and early records may have been of the Smalltooth Sawfish (P. pectinata).
The Largetooth Sawfish is still present in several countries from the northern coast of South America (Amazonian Coast), which is likely one of the last strongholds for the species (Feitosa et al. 2017, López-Angarita et al. 2021, P. Charvet pers. comm. 28 January 2022). In addition to its known presence in some of the countries, unconfirmed records of the species have also been recently reported by fishers in coastal areas of Colombia, Guyana, Suriname, French Guiana, and Brazil (López-Angarita et al. 2021, P. Charvet unpubl. data 2022); however, these records are rare. In Brazil, the Largetooth Sawfish is known from as far south as the Parnaíba River delta, in the State of Piauí, Brazil, while further south its presence is uncertain (P. Charvet unpubl. data 2022). The Largetooth Sawfish has also been recorded up to 1,340 km from the ocean in the Amazon River (Feitosa et al. 2017).
Eastern Pacific
Historically, the Largetooth Sawfish was considered to occur from either Topolobampo or Mazatlán, Mexico to northern Perú (Chirichigno and Cornejo 2001, Cook et al. 2005, Faria et al. 2013, Mendoza et al. 2017). In the Pacific coast of Mexico, there is one confirmed and three unconfirmed records of the Largetooth Sawfish in the past 19 years (Bonfil et al. 2017, Bonfil et al. 2018, R. Bonfil unpubl. data 2022). In El Salvador and Guatemala, the last known reports of the species were from over 30 years ago (C. Avalos, pers. comm. 15 January 2022.). In Costa Rica, there are several confirmed records of the species between 2010–2018 along the entire Pacific coast with most of these records from the Humedal Nacional Térraba Sierpe in the south Pacific region, one of the largest and most productive wetlands in Central America (Valerio-Vargas and Espinoza 2019). Other recent records of the Largetooth Sawfish in Costa Rica were from the Gulf of Nicoya (central Pacific) in mangrove and estuarine habitats, and from 2019 to 2021, there were several records from the north Pacific coast in rocky reef habitats (M. Espinoza unpubl. data 2022). The proximity of these Costa Rican records to the border of Nicaragua suggest that the Largetooth Sawfish may also be present in the Pacific coast of Nicaragua, however its presence there is uncertain (M. Espinoza unpubl. data 2022). In Panamá, there were records throughout 2020 from Rompío, a marine inlet of the Tuira River in Darién (Lopéz-Angarita et al. 2021). The most recent reports of the Largetooth Sawfish in Colombia were from November 2020 in the mangroves of Coquí, northern Chocó (Lopéz-Angarita et al. 2021). In Ecuador, the species occurs along the entire coast, with 30 sightings reported from 2010 to 2015 based on LEK (Rosas-Luis 2021). In northern Perú, there are three confirmed records of large individuals (350–600 cm total length) that were reported between 2014 and 2017 (Mendoza et al. 2017, Cabanillas-Torpoco et al. 2020), although its occurrence may have represented seasonal migration from the species’ core range in Central America.
Eastern Atlantic
In the Mediterranean Sea, Largetooth Sawfish have been historically reported to occur with 13 catch records from 1573 to prior to 1966 from mainly the western Mediterranean (Spain, France, and Italy) (Ferretti et al. 2016). These records included 10 juveniles which implies the species was historically resident. However, it is unknown how juveniles could survive the cold winter sea surface temperature of the northern Mediterranean Sea (Ferretti et al. 2016). The scarcity of records, long exploitation history of the Mediterranean Sea, questions on juvenile survival together with large knowledge gaps on the ecology, biology, and baseline distribution ranges of the species globally have led to continued debate on whether this species occurred as part of the Mediterranean ichthyofauna, as a vagrant species, or as a seasonal migrant from areas off West Africa. In the scenario of Mediterranean sawfish populations, extinction analyses suggested that the Largetooth Sawfish went extinct in the Mediterranean Sea between 1975 and 1979 (Ferretti et al. 2016).
Historically, Largetooth Sawfish occurred from Mauritania to Angola and were abundant in coastal estuaries (Burgess et al. 2009, Faria et al. 2013). The current distribution of Largetooth Sawfish in the eastern Atlantic remains uncertain due to the lack of surveys and reporting in most countries; additionally, species identification issues that have not improved over the last decade. The lack of confirmed observations in the past few years suggests that sawfishes are now extremely rare or 'possibly extinct' throughout most of the eastern Atlantic. Interviews conducted in Senegal in 2004 (Robillard and Séret 2006), Liberia and The Gambia in 2014 (Leeney 2015, Leeney and Downing 2016, respectively), Guinea‐Bissau (Leeney and Poncelet 2015), and Mauritania (R.W. Jabado unpubl. data 2021) indicated catches are scarce and have not occurred in many years. The species is likely still extant in five range states where the last known records were in Senegal, in 2013, in The Gambia in 2010, in Guinea Bissau in 2012, in Sierra Leone in 2006, and in Liberia in 2014. In two range states its presence is uncertain, with the last known records in Mauritania in the early 2000s and in Guinea Conarky in 1999 (M. Diop pers. comm. 10 November 2021). Most of these records did not allow species identification, Leeney and Poncelet (2015); however, where there was confirmation from photographs or rostra, it was mostly Largetooth Sawfish rather than Smalltooth Sawfish (P. pectinata), which could suggest that it is Largetooth Sawfish rather than Smalltooth Sawfish that is persisting across the region (R.W. Jabado unpubl. data 2022). There have been no confirmed records of sawfishes in this or other areas of west Africa since 2019 (R. Leeney unpubl. data 2022). The species is 'possibly extinct' in 11 out of 18 range states from this region.
Indo-West Pacific
The Largetooth Sawfish historically occurred from the Western Indian Ocean to northern Australia, but is now patchy across this range. The species is currently present in Mozambique, Madagascar, Oman, Pakistan, India, Sri Lanka, Bangladesh, Indonesia, Philippines, Papua New Guinea, and Australia (Roberts 1978, Tan and Lim 1998, Compagno et al. 2005, Stevens et al. 2005, Moazzam and Osmany 2014, Haque et al. 2020, Tanna et al. 2021, Yan et al. 2021). While they likely would have been historically present, the Largetooth Sawfish presence is now uncertain in Tanzania, Kenya, Somalia, Yemen, Myanmar, Malaysia, Brunei, and Timor Leste (Yan et al. 2021). The Largetooth Sawfish is 'possibly extinct' in South Africa, Thailand, Singapore, Cambodia, Laos, and Viet Nam (Yan et al. 2021). Northern Australia appears to be the most significant stronghold for the Largetooth Sawfish in this region. It is presently considered occurring throughout the northern Australian coastline from the Kimberley region (Western Australia), through to the Lakefield National Park in eastern Queensland (B. Wueringer unpubl. data 2022). There is a single temperate record of this species from the southwest tip of Western Australia (Cape Naturaliste), although this record is considered to be of a vagrant (Chidlow 2007).
Geographic Range
Extant
Australia, Bangladesh, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Gambia, Guinea-Bissau, Guyana, India, Indonesia, Liberia, Madagascar, Mozambique, Nicaragua, Oman, Pakistan, Panama, Papua New Guinea, Peru, Philippines, Senegal, Sierra Leone, Sri Lanka, Suriname, Venezuela, Bolivarian Republic of
Possibly Extinct
Angola, Benin, Cambodia, Cameroon, Congo, Congo, The Democratic Republic of the, Côte d'Ivoire, El Salvador, Equatorial Guinea, Gabon, Ghana, Guatemala, Lao People's Democratic Republic, Nigeria, Singapore, South Africa, Thailand, Togo, Viet Nam
Population Information
The Largetooth Sawfish comprises four distinct subpopulations: Western Atlantic, Eastern Atlantic, Eastern Pacific, and Indo-West Pacific (Faria et al. 2013, Fearing 2020). For all subpopulations, there is limited species-specific time series information on catch rates or abundance trends. Thus, the population status is inferred from a combination of capture records and local ecological knowledge (LEK), which are not always species-specific. Although catch data or landings are not a direct measure of abundance, these can be used to infer population reduction where they have decreased while fishing effort has remained stable or increased.Western Atlantic
The population abundance has continuously declined over the past few decades and the species presence is now uncertain in areas where it was once considered common.
Recent studies from Mexico, Costa Rica, Panamá, and Colombia have all reported declines over the past 20–30 years, with considerably fewer records of the species reported in the last 10–15 years (Bonfil et al. 2017, Bonfil et al. 2018, Valerio-Vargas and Espinoza 2019, López-Angarita et al. 2021). In Mexico, Bonfil et al. (2018) reported a significant decline in Largetooth Sawfish sightings in the Caribbean/Atlantic coast between the 1970s and 2010s, and their analysis showed spatial differences in range contraction of the species along the coast, with individuals last recorded in Quintana Roo (southern Caribbean) in the 1990s. There are a few unconfirmed records of sawfishes in Belize and Honduras, but they are scarce and identification remains an issue (M. Chevis unpubl. data 2022). Along the Caribbean coast of Guatemala, the Largetooth Sawfish is 'possibly extinct' with the last know records from over 30 years ago (C. Avalos pers. comm. 22 January 2022). In the Costa Rican Caribbean, Valerio-Vargas and Espinoza (2019) reported a decline in the number of Largetooth Sawfish records between historic (129 records from 1961–2002) and contemporary (69 records from 2003–2018) periods based on a LEK study conducted throughout the entire country, yet most of the Caribbean records were from freshwater habitats within the San Juan-Colorado River system. Based on recent catch and environmental DNA (eDNA) data, M. Espinoza (unpubl. data 2022) estimated a 78% decline in the EOO (extent of occurrence) and 15% decline in the AOO (area of occupancy) of Largetooth Sawfish within the Costa Rica Caribbean between 1961–2021. Environmental DNA studies in the San Juan River (natural border between Costa Rica and Nicaragua) have confirmed the importance of this entire freshwater system in the connectivity of the sawfish populations occurring in this region (McDavitt 2002, M. Espinoza unpubl. data 2022), which concurs with sawfish tagging studies conducted by Thorson in the 1970s (Thorson 1982). The San Juan River continues to act as one of the last remaining strongholds for this species in Central America, yet overfishing driven by illegal trade, as well as habitat degradation from changes in land use practices and pollution are major threats affecting this population (M. Espinoza unpubl. data 2022).
In Panamá and Colombia, 71% of the sawfish records (n = 188) reported between 1896–2015 were from before the year 2000, while only 9% were from 2010–2015 (López-Angarita et al. 2021). López-Angarita et al. (2021) also noted that sawfish records from the Caribbean of Panamá and Colombia have been particularly scarce for the last 20 years, which is consistent with a recent regional assessment that indicates the Largetooth Sawfish is likely extinct from the Colombian Caribbean (Gómez-Rodriguez et al. 2014). In addition, López-Angarita et al. (2021) reported a decline in the maximum size of captured Largetooth Sawfish over time, which is consistent with increasing fishing pressure and other threats affecting the species (Chasqui et al. 2017).
In Brazil, the species is likely restricted to the northern coast within the Amazon River and tributaries, which is likely one of the last global strongholds for the species (Feitosa et al. 2017, Fordham et al. 2018, P. Charvet unpubl. data 2022). The presence of large mangrove areas with sand and mud banks, and the high tidal variation of this system is thought to act as a refuge for the species (P. Charvet unpubl. data 2022). However, declines in landings of up to 87% have been reported in Belém (lower Amazon region of Brazil), from the late 1996 to early 2016 (P. Charvet unpubl. data 2022).
While the species is protected in some areas of the Western Atlantic, illegal fishing, incidental catch, and habitat degradation remain a constant threat to the population, and except for some remote localized areas, it is inferred that the population of Largetooth Sawfish has undergone a reduction of >80% over the past three generation lengths (68 years) and is still declining.
Eastern Pacific
In Mexico, the Largetooth Sawfish was a widespread and common species along both coasts, but now the species is exceedingly rare along the Pacific coast with only two recent sightings within the past 15 years. Sightings of the species peaked between 1960s and 1970s, and since then it has experienced a rapid decline with very few records reported in the last decade (Bonfil et al. 2018). In Costa Rica, the number of reported Largetooth Sawfish sightings from a LEK study declined from 129 individuals between 1961–2002 (92 of these records were from 1961–1992) to 69 individuals between 2003–2018, with declines in sightings of 92% in the central Pacific coast, 80% in the north Pacific coast, and 25% in the south Pacific coast of the country (Valerio-Vargas and Espinoza 2019). Historically, the Golfo de Nicoya in the central Pacific of Costa Rica was one of the areas with the highest densities of Largetooth Sawfish in the country due to the presence of suitable mangrove and estuarine habitats inside this large gulf; however, this area was also heavily fished with bottom trawls and gillnets in the 1970s and 1980s (Valerio-Vargas and Espinoza 2019). Yet, based on LEK and recent capture records throughout the Pacific of Costa Rica, the area of occupancy and extent of occurrence of the species has not changed considerably (AOO = no change; EOO = 13% increase) between 1961–2009 and 2010–2021 (M. Espinoza unpubl. data 2022). Lopéz-Angarita et al. (2021) found that 65% and 92% of Largetooth Sawfish records from the Pacific coast of Colombia (n = 51) and Panamá (n = 147), respectively, were reported before the year 2000. Only 9% of the remaining records from both countries were reported from 2010–2015. There was also a significant decline in the maximum size of observed individuals over time (Lopéz-Angarita et al. 2021). The declining frequency of sightings was also corroborated by fishers, who reported fewer catches over the past 20 years. Based on the number of sightings reported during the last 10 years, Lopéz-Angarita et al. (2021) suggest that the Darién region in Panamá and the northern Chocó region in Colombia are likely to be one of the last remaining areas with viable sawfish populations in this region. Moreover, Lopéz-Angarita et al. (2021) estimated reductions in the EOO ranging from 53–86% over the last 100 years for both countries between historic (1900–2009) and contemporary records (2010–2015).
In Ecuador, Largetooth Sawfish sightings peaked between 1985–1996, and since then, the species has gradually declined (Rosas-Luis 2021). However, recent LEK revealed a slight increase in the number of sightings over the full range of sizes between 2010–2015, and along the entire coastline (Rosas-Luis 2021). In 2014, a 506 cm total length (TL) female was captured and released alive in the Santa Elena province (Rosas-Luis 2021). Moreover, 45% of the interviewees mentioned that captured individuals were released alive, and that the species was mainly captured as bycatch using handline, which may increase the probability of post-release survival. In Perú, the Largetooth Sawfish was considered locally extinct for a long time, but recent studies reported landings of several large individuals (350–600 cm TL) in Tumbes and Piura (northern Perú) between 2014–2017 (Mendoza et al. 2017, Cabanillas-Torpoco et al. 2020). Only one of these individuals was released alive, the rest were released dead, which suggests that fishing continues to be a threat for the species in this area (S. Kelez unpubl. data 2022). Despite the increases in sightings in Ecuador, across the remaining eastern Pacific range, it is inferred that the population has undergone a >80% reduction over the past three generation lengths (68 years).
Eastern Atlantic
The population abundance has declined continuously over the past few decades and the species is now considered 'possibly extinct' in 11 of the 18 range states areas where it was once considered common (Faria 2007, Fernandez-Carvalho et al. 2014, Yan et al. 2021). It is suspected that the Largetooth Sawfish population has undergone a >80% reduction over the past three generation lengths (68 years), and given much of this remaining area has artisanal gillnet fisheries with little or no regulation, it is likely the population will continue to decline.
Indo-West Pacific
The presence of the Largetooth Sawfish is either uncertain or it is 'possibly extinct' in half of its former Indo-West Pacific range (Yan et al. 2021). Historical and current fishing pressure (‘actual levels of exploitation’) is high across most of the Indo-West Pacific range of the Largetooth Sawfish and range contractions and ongoing levels of decline are apparent over the past three generation lengths (68 years).
In South Africa, records from anglers in the 1950s and the shark control program in the 1960s revealed large declines over time; the last known record is from 1999 (Everett et al. 2015). The St. Lucia estuary was once an important breeding area for Largetooth Sawfish, but now the species appears to be extinct there mainly due to overfishing and environmental factors (a drought or change in weather patterns that caused the closure of the St Lucia estuary since 2002 which was likely a key habitat in the area) (Everett et al. 2015). Because fishing intensity around the region is high, it is unlikely the species could re-establish even if there were favorable environmental conditions and the estuary remained open in the future (B. Everett unpubl. data 2022). Moreover, an extinction probability analysis using time-series observation data from different sources (1951–2012) suggest that Largetooth Sawfish is no longer present in KwaZulu-Natal waters (Everett et al. 2015). Local ecological knowledge data from Mozambique and Tanzania suggest this species has experienced large-scale declines in both countries, with few confirmed records from the last decade (Leeney 2017, Braulik et al. 2020). In Mozambique, artisanal fisheries remain a major threat as the species continues to be landed in these fisheries along the coast (Leeney 2017). In Madagascar, Largetooth Sawfish were previously common in artisanal landings on the western coast of Madagascar but are now extremely rare along that coast with no records in catch surveys over the past decade; the abundance of the species was already low in the 1960s in Madagascar (Taniuchi et al. 2003, Manach et al. 2011, R. Bennett pers. comm. 15 January 2022). Regular catch surveys in Kenya in the last decade suggest the Largetooth Sawfish is now absent (R. Bennett pers. comm. 15 January 2022). There have been no records of any sawfish species from the Seychelles since the 2000s (Kyne et al. 2013).
Largetooth Sawfish landings are now extremely rare in former range states of the western and northern Indian Ocean (Moazzam and Osmany 2014). Only occasional captures are reported from Pakistan and India; the last reported capture in Pakistan was in January 2016 with an earlier 2009 record in Gwadar, western Balochistan (Moazzam and Osmany 2014). A recent survey using LEK of ~100 fishers showed that there has been a severe decline across Pakistan; fishers suggested that the decline began in the 1950s with the change from cotton to nylon nets in 1955 (M. Khan unpubl. data 2022). In India, fisher surveys in Maharashtra state where sawfishes were commonly harvested historically, indicate a drastic decline in the sawfish fishery from 1985–1990, with only occasional catches in recent years (Kyne et al. 2013). The latest capture of Largetooth Sawfish off Maharashtra was reported in March 2017 (K.V. Akhilesh pers. comm. 26 March 2017). In Sri Lanka, the last verified record of a Largetooth Sawfish is from 2016 with photographic records from the Balapitiya locality in the southern region (Tanna et al. 2021). Sawfishes there appear to have mostly disappeared since the 1990s and have become increasingly rare in landings (Tanna et al. 2021). In Bangladesh, Largetooth Sawfish are still landed in relatively large numbers (over 40 individuals reported between 2016 and 2022, including a young of the year in 2022) (Haque et al. 2020, A. Haque unpubl. data 2022). However, extensive interviews and workshops at landing sites, artisanal fishery surveys, and an overview of historical records have all confirmed that sawfishes have been declining in Bangladesh since the 1970s (Haque et al. 2020). Moreover, there has been over 50% range contraction from historical records (A. Haque unpubl. data 2022). The average annual sawfish encounter rate (observations and catches) in Bangladesh declined from 3.7 individuals using lifetime recall data (~22-years), to 1.5 using 5-year recall data, and further to 0.7 using 1-year recall data (Hossain et al. 2015).
In Myanmar, fisheries surveys in 2016–2017 in Rakhine State did not report the species, and fishers indicated they had not seen sawfishes in the past five years; further, it was not detected in targeted eDNA surveys in the Myeik Archipelago and Ayeyarwady River (M. Mizrahi pers. comm. 21 February 2022). In Peninsular Malaysia, there are historic accounts of the species in the Perak River (e.g., Smith 1931). However, subsequent riverine elasmobranch surveys conducted in 1976 did not report it (Taniuchi 1979). In Thailand, the formerly common Largetooth Sawfish had disappeared from catches by the 1980’s (Pauly 1988, Kyne et al. 2013). In the Mekong River (Cambodia, Laos and Vietnam), by the 1990s, the species had not been seen for several decades (Rainboth 1996, Tanaka and Ohnishi 1998). In Sabah, Malaysia, targeted surveys of elasmobranchs found Largetooth Sawfish were common in the 1970’s, declined sharply in the 1980’s, and were uncommon by the 1990’s (Manjaji-Matsumoto 2002). Subsequent surveys in Sabah in 2015–2016 did not record any Largetooth Sawfish and fishers made no reports of any sawfish captures over the past 20 years (Manjaji-Matsumoto et al. 2017). In Sarawak, surveys in 2017–2019 did not record any sawfishes (Booth et al. 2021). In the Philippines, Largetooth Sawfish were historically reported as common on Luzon and Mindoro Islands, however declines were noted in the 1950s (Herre 1953, 1958), and it was not reported during a freshwater elasmobranch survey in Lake Naujan, Mindoro in 1976 (Taniuchi 1979, Compagno et al. 2005). It was observed in the Philippines in 2014 (M. McDavitt via R.W. Jabado pers. comm. 25 May 2017).
In Indonesia, there are extensive historical records of the Largetooth Sawfish. Recent elasmobranchs studies in Sumatran rivers have not reported any Largetooth Sawfish (Iqbal et al. 2018, M. Grant unpubl. data 2022), although survey effort has been limited since observations of the species in 1976 and 1996 (Taniuchi 1979, Tan and Lim 1998). In Java, two individuals were recorded in 2002 from fisheries operating in either the Arafura or Banda Sea (D’Alberto et al. 2022). In Sulawesi, rostra from two Largetooth Sawfish caught in 1991–2000 have been observed (B. Simeon unpubl. data 2022). In Papua Province, recent LEK surveys at Lake Setani indicate that sawfishes were present until at least 1975, and there is anecdotal evidence that they are still present in Asmat and Mamberamo Districts (S. Silalahi pers. comm. 14 June 2021). Sawfish LEK surveys conducted with local fishers in Merauke indicate that while most fishers (186 out of 245) have seen sawfishes, only 104 had reported captures since 2010, with 60 of these interviewees reporting declines in sawfishes during their lifetimes (Y. Wakhida unpubl. data 2022). In Papua New Guinea (PNG), fisheries and LEK surveys revealed that Largetooth Sawfish of a wide range of size classes are still relatively common in some areas of southern PNG and this area appears to be a stronghold for the species (Grant et al. 2021a, Grant et al. 2021b). However, the population is currently declining and at high risk from fishing pressure (Grant et al. 2021b). Historically, the species was widespread and common until the 1970’s–80’s with declines reported during the 1990’s and 2000’s in a range of areas including the Kikori, Fly, Sepik, and Ramu Rivers (Haines 1979, Storey et al. 2009, White et al. 2017, Leeney et al. 2018, Grant et al. 2021b).
Tropical northern Australia is considered one of the last viable population strongholds in the Indo-West Pacific for Largetooth Sawfish. However, this species was recently assessed as Vulnerable under Australian environmental legislation, due to ongoing population declines (Kyne et al. 2021a). There is evidence of large declines from the East Queensland Shark Control Program (QSCP) from 1962–2016 (Wueringer 2017). For example, standardized catch rates of sawfishes in two areas, Townsville and Rockhampton, declined by 72% and 93% from the 1970s to 1990, respectively. Although no specific data on the Largetooth Sawfish could be extracted from the QSCP data, a decline in this species in Queensland also coincided with a significant range contraction along this coast. Up until the 1960s, large specimens were caught along Queensland's east coast (e.g., Brisbane River, 1950s; Bowling Green Bay near Townsville, 1966) (B. Wueringer unpubl. data 2022). An ongoing campaign to report public sightings of sawfishes both recent and historic, failed to produce any sightings of Largetooth Sawfish on Queensland’s east coast since then, except for within Lakefield National Park (B. Wueringer unpubl. data 2022). Moreover, an analysis of sightings compiled for the entire Australian range revealed a 67% decline in EOO and 22% decline in AOO between historic (before the year 2000) and recent years (after the year 2000) (K. Lear unpubl. data 2021). Western Australia is the only region where the population is not inferred to have recently declined; monitoring of the Fitzroy River since 2002 showed stable and fluctuating recruitment linked with environmental conditions such as flow rates and temperature (Lear et al. 2019, Lear et al. 2020, Lear et al. 2021), indicating that the productivity of the population likely remains high. However, water resource development and climate change in the region pose major and ongoing threats to this important refuge population (e.g., Petheram et al. 2017). Sightings of this species also remain fairly common along the northern coast of Western Australia and in the Northern Territory, albeit in far lower numbers than the Fitzroy River. Low levels of fishing, human population density, and habitat modification suggests threats to the species are low in this region. Across its entire Australian range, it is suspected that the population has undergone a >80% reduction over the past three generation lengths (68 years) (Kyne et al. 2021a). Over its Indo-Pacific range, the population is suspected to have undergone a >80% reduction over the past three generation lengths.
Across the entire global range of the Largetooth Sawfish, severe declines have been documented. Australia and PNG may provide the last viable populations owing to some refuge from intense fishing pressure as a result of low human population density. However, declines are also evident in those regions. Overall, it is inferred that the Largetooth Sawfish populations have undergone a >80% reduction over the past three generation lengths (68 years) due to actual levels of exploitation, habitat degradation, and a decline in extent of occurrence.
Threats
The Largetooth Sawfish is subject to intense fishing pressure that is poorly managed or unregulated across much of its range. The species is taken as bycatch in commercial and small-scale fisheries (including artisanal, cultural, and subsistence) with a variety of fishing gears including gillnet, trawl, and line, where it is often retained for at least its fins and meat (Dulvy et al. 2016, Yan et al. 2021). The toothed rostra of sawfishes make them highly susceptible to entanglement particularly in gillnets and trawls. Fishing effort has increased over the past decades across the species’ range with the fin and meat trade driving increasing demand and exploitation of many elasmobranchs (Okes and Sant 2019). The difficulty of removing the species from fishing gear and returning it alive combined with the exceedingly high first point of sale and final point of sale value (>USD$14,000 per individual) means that there is a high likelihood of retention even though the species are captured infrequently (Chen 1996, Jabado et al. 2017, Yan et al. 2021).The freshwater and inshore estuarine, mangrove, and coastal habitats used by the species are threatened by habitat loss and degradation (CITES 2007). For example, in Southeast Asia, mangrove areas have been reduced by an estimated 30% since 1980 (FAO 2007, Polidoro et al. 2010). There is also global concern for declines of freshwater species (e.g., Tickner et al. 2020), with large-bodied species showing the largest declines (He et al. 2019). The primary threats in freshwater include fisheries (e.g., Funge-Smith 2018, Ainsworth et al. 2021) and habitat degradation (e.g. Ramsar Convention on Wetlands 2018, Grill et al. 2019, Maus et al. 2020). These pressures are likely to be exacerbated by climate change (Lennox et al. 2019), to which Largetooth Sawfish is considered to be highly exposed (Chin et al. 2010, Lear et al. 2021). For example, in the Fitzroy River (Western Australia), recruitment of the Largetooth Sawfish population depends on large flood events; in years with a long dry season that result in low volumes of wet season flooding, the Largetooth Sawfish had significantly poorer body condition (Lear et al. 2021). The compounded exposure of Largetooth Sawfish to both marine and non-marine pressures collectively make this species highly susceptible to a range of pressures throughout its life history (Grant et al. 2019).
Partners
