|Scientific Name:||Pristis pristis (Eastern Atlantic subpopulation)|
See Pristis pristis
Pristis perotteti Müller & Henle, 1841 (Eastern Atlantic)
|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.
Largetooth Sawfish (Pristis pristis), formerly known as P. perotteti in the Atlantic, has been referred to by many other names throughout its range. For instance, it has been called P. antiquorum (as cited in Bigelow and Schroeder 1953), P. zephyreus (Beebe and Tee-Van 1941), P. pristis (McEachran and Fechhelm 1998), or P. microdon (Garman 1913, Fowler 1941, Chirichigno and Cornejo 2001, Heymans and Vakily 2002).
|Red List Category & Criteria:||Critically Endangered A2cd ver 3.1|
|Assessor/s:||Carlson, J. & Smith, K.|
|Reviewer/s:||Simpfendorfer, C. & Harrison, L.|
|Facilitator/s:||Harrison, L. & Kyne, P.M.|
Eastern Atlantic Largetooth Sawfish (Pristis pristis) were once commonly found from Angola to Mauritania but now have been nearly extirpated primarily by fishing (trawl and inshore netting). The lack of recent records infers a population reduction based on a reduction in extent of occurrence (EOO) of ≥80% over a period of three generations (i.e., 1961 to present). There are recent unconfirmed records (Pristis sp.) from only two countries (Guinea-Bissau in 2011, Mauritania in 2010) and there have been few individual records of Largetooth Sawfish in the last decade (three reported in Guinea-Bissau in 2003, 2004 and 2005, and one in Sierra Leone in 2003) and in general, few captures over the last three generations. The region has been subject to intense trawl fisheries in offshore waters from international fleets since at least the 1950s, combined with intense fishing pressure due to rapid coastal population growth and the rise in artisanal fisheries throughout the region. Declines and continuing threats result in a Critically Endangered assessment for this subpopulation.
|Range Description:||The current distribution of Largetooth Sawfish in the Eastern Atlantic is uncertain due to species identification, 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), Cote 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 1950s survey detail 12 Largetooth Sawfish from Mauritania, Senegal, Guinea, Cote d’Ivoire, and Nigeria. 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).
The presence of sawfishes in the Mediterranean Sea is still uncertain (Whitehead et al. 1984, Bilecenoğlu and Taşkavak 1999). 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.
Native:Guinea-Bissau; Sierra Leone
Possibly extinct:Angola (Angola); Benin; Cameroon; Congo; Congo, The Democratic Republic of the; Côte d'Ivoire; Equatorial Guinea; Gabon; Gambia; Ghana; Guinea; Liberia; Nigeria; Senegal; Togo
|FAO Marine Fishing Areas:||
Atlantic – eastern central; Atlantic – southeast
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The population size of this species in the Eastern Atlantic remains unknown. There is 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.|
|Habitat and Ecology:||
There is no ecological or life history information available for Largetooth Sawfish in the Eastern Atlantic. Life history information is available from conspecifics in the Indo-West Pacific and Central American regions.
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 are often found in brackish water near river mouths and large bays, preferring partially enclosed waters, lying in deeper holes and on bottoms of mud or muddy sand (Bigelow and Schroeder 1953). This species, like the Smalltooth Sawfish (P. pectinata) is, in parts of its range, highly mangrove-associated (Burgess et al. 2009). Largetooth Sawfish move across salinity gradients freely and appear to have more physiological tolerance of freshwater than Smalltooth Sawfish (see Thorson 1982). 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). 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 Whitty et al. 2008, Whitty et al. 2009, P. Kyne pers. comm. 2013).
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). Indeed, unpublished notes from a 1950’s survey detail 12 Largetooth Sawfish from Mauritania, Senegal, Guinea, Cote d’Ivoire, and Nigeria, which ranged in size from 89–700 cm TL. Maximum size in Lake Nicaragua appeared to be smaller with Thorson (1982) recording females to 429 cm TL and males to 384 cm TL.
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. The breeding season in Lake Nicaragua probably extended from May to July, with parturition taking place from early October into December (Thorson 1976). Litter sizes were 1–13 (mean 7.3) following a gestation period of about five months. The reproductive cycle is possibly biennial in the Western Atlantic (Thorson 1976) but annual in the Indo-West Pacific (Peverell 2008). Size at birth ranges 72–90 cm TL (Thorson 1976, Thorburn et al. 2007, Peverell 2008).
Age at maturity has been estimated at 8–10 years (Queensland, northern Australia; Peverell 2008) and ~10 years (Lake Nicaragua, Thorson 1982). Size at maturity is ~300 cm TL for females and ~280–300 cm TL for males (Thorson 1976, Thorburn et al. 2007, Peverell 2008, Whitty et al. 2008). Peverell (2008) using a preliminary vertebral growth ring analysis estimated a maximum age of 35 years in northern Australia. Thorson (1982) determined a life span of over 30 years in Lake Nicaragua.
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 a generation time of 17.2 years for Atlantic Largetooth Sawfish.
The principal threats to Largetooth Sawfish are from fishing; it was formerly targeted, but is now mostly taken incidentally in broad-spectrum fisheries (CITES 2007). The long toothed rostrum of sawfish makes them extremely vulnerable to entanglement in any sort of net gear, gillnetting and trawling in particular. Depleted populations mean that commercial targeting of most stocks is no longer cost-effective and bycatch mortality is now the primary threat to Largetooth Sawfish (CITES 2007). However, there are indications that sawfish are at times targeted opportunistically for the shark fin trade (CITES 2007).
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.
Habitat degradation and loss also threaten sawfishes throughout their range (CITES 2007). 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).
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).
|Citation:||Carlson, J. & Smith, K. 2013. Pristis pristis (Eastern Atlantic subpopulation). In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 10 March 2014.|
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