|Scientific Name:||Pristis pectinata (Eastern Atlantic subpopulation)|
|Taxonomic Notes:||Faria et al. (2013) state that both morphology and genetics support the current specific status of the Smalltooth Sawfish (Pristis pectinata) and propose modification of the distribution of the species to an Atlantic only range. No geographical structure of Smalltooth Sawfish populations is present and Western and Eastern Atlantic populations of Smalltooth Sawfish represent separate units for conservation purposes.|
|Red List Category & Criteria:||Critically Endangered A2cd ver 3.1|
|Assessor/s:||Carlson, J., Wiley, T. & Smith, K.|
|Reviewer/s:||Diop, M. & Böhm, M.|
The Smalltooth Sawfish (Pristis pectinata) were once a common component of the marine fauna in the Eastern Atlantic in western Africa but now have been nearly extirpated primarily by fishing (trawl and inshore netting). The lack of records infers a population reduction of ≥80% over a period of three generations (i.e., 1962 to present) based on a reduction in extent of occurrence (EOO). There has been only one confirmed record for the region in the last 10 years (Sierra Leone in 2003) and it is not known if the population is recovering. There are unconfirmed records (Pristis sp.) from only two other countries (Guinea Bissau in 2011, and Mauritania 2010). It is likely that areas around Guinea-Bissau represent the last areas where sawfish can be found in western Africa. Threats to Smalltooth Sawfish are ongoing from inshore netting and habitat modification (mangrove removal).
|Range Description:||The current distribution of Smalltooth Sawfish in the Eastern Atlantic Ocean is uncertain due to species misidentification, lack of reporting, and the general contraction of its range. Smalltooth Sawfish were historically found along the coast of western Africa from Angola to Mauritania (Faria et al. 2013). There has been only one confirmed record for the region in the last 10 years (Sierra Leone in 2003). There are unconfirmed records (Pristis sp.) from only two other countries (Guinea-Bissau in 2011, and Mauritania 2010).
The presence of sawfishes in the Mediterranean Sea is still uncertain (Whitehead et al. 1984, Bilecenoğlu and Taşkavak 1999). Although Smalltooth Sawfish were included in historic faunal lists (Serena 2005), it is still debatable whether sawfishes occurred as part of the Mediterranean ichthyofauna or are a vagrant species as seasonal migrants from areas off western Africa. Reports of Smalltooth Sawfish outside of the Atlantic Ocean are likely misidentifications of other sawfish species (Faria et al. 2013).
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:||There are no data on population size of the Smalltooth Sawfish in the Eastern Atlantic and the only information on trends in the population can be inferred from capture records. Smalltooth Sawfish were once common in western African waters, but today records are sparse. Early records of this species include most countries from Angola to Mauritania. Specific records on length and sex of individuals come from Cameroon, the Republic of the Congo, Mauritania, Senegal, Gambia and Guinea-Bissau (Faria et al. 2013). However, there has been only one confirmed record for the region in the last 10 years (Sierra Leone in 2003). There are unconfirmed records (Pristis sp.) from only two other countries (Guinea-Bissau in 2011, and Mauritania 2010). It is likely that areas around Guinea-Bissau represent the last areas where sawfish can be found in western Africa (M. Diop pers. comm. 2012).|
|Habitat and Ecology:||
There is no life history information available for Smalltooth Sawfish in the Eastern Atlantic. However, life history information is available for the Western Atlantic and it assumed that life history parameters would be similar for conspecifics throughout the Atlantic Ocean. This species is lecithotrophic viviparous and litter size is thought to be 15–20 pups (Simpfendorfer 2005) born every other year, but there is little supporting data for this. Demographic analysis using early reports of life history and estimates from other pristids indicated that Smalltooth Sawfish intrinsic rate of increase ranged from 0.08 to 0.13 yr−1, and population doubling times from 5.4 to 8.5 yrs (Simpfendorfer 2000).
There is still some question regarding age and size at maturity for Smalltooth Sawfish. Simpfendorfer (2005) reported maturity at 360 cm TL for females. However, females of 300-400 cm stretched total length (STL) necropsied from the US were immature, with the smallest mature female examined being 415 cm STL (J.K. Carlson unpublished data). Males were thought to be mature about 270 cm TL (Simpfendorfer 2005). However, a recently necropsied male Smalltooth Sawfish that was 308 cm TL was found to be immature (J.K. Carlson unpublished data). The smallest mature male from field-collected specimens was 371 cm STL (J.K. Carlson unpublished data). Back-transforming these lengths into ages using the von Bertalanffy growth model of Scharer et al. (2012) indicates that males mature around 7.5 years and females 10–12 years. As these data indicate much faster growth and earlier maturation than previously determined, any updated demographic model will likely indicate higher productivity and rebound potential.Moreno Iturria (2012) constructed a deterministic model based on standard life table techniques using growth estimates from Simpfendorfer et al. (2008) and calculated demographic parameters for Smalltooth Sawfish for US waters. Intrinsic rates of increase were estimated as 0.07 per year, generation time 17 years and population doubling time 9.7 years.
Recent information on tag-recaptured juvenile Smalltooth Sawfish collected in Florida, USA, indicates substantially faster growth than previously assumed for this species. Simpfendorfer et al. (2008) found that growth was rapid during the first two years after birth.
Using data from reported encounters from 1998 to 2008, Wiley and Simpfendorfer (2010) evaluated Smalltooth Sawfish habitat use patterns in the US. There was an inverse relationship between sawfish size and extent of northern distribution, with animals less than 200 cm having a wider latitudinal distribution and occurring farthest north, and animals greater than 200 cm reported mostly in southern Florida (Wiley and Simpfendorfer 2010). Most encounters occurred in estuarine and nearshore habitats, and their locations were not randomly distributed, having a positive association with inshore mangrove and seagrass habitats. While sawfish were reported in depths to 73 m, there was a significant relationship between size and depth, with smaller animals occurring in shallower waters (Wiley and Simpfendorfer 2010).
Data from acoustic telemetry and tag-recapture information indicates Smalltooth Sawfish (less than 100 cm) had the smallest home ranges, low linearity of movement, and a preference for very shallow mud banks (Simpfendorfer et al. 2010). Juveniles greater than 100 cm demonstrated larger home ranges, preference for shallow mud/sand banks, and remained close to mangrove shorelines. Tide was found to be the main factor influencing movement on short time scales. Sawfish <150 cm STL spend the majority of their time in water <0.5 m deep, while larger juveniles spend most of their time in water 0.5–1.0 m deep. Juveniles >130 cm had high levels of site fidelity for specific nursery areas for periods up to almost three months, but the smaller juveniles had relatively short site fidelity to specific locations (Simpfendorfer et al. 2010).
Based on data from catch-per-unit effort (CPUE), Poulakis et al. (2011) found that most juvenile Smalltooth Sawfish had an affinity for water less than 1.0 m deep, water temperature over 30ºC, dissolved oxygen over 6 mg/L, and salinity between 18 and 30. Greater catch rates for sawfish over age one were associated with shoreline habitats with overhanging vegetation such as mangroves (Poulakis et al. 2011).
Simpfendorfer et al. (2011) conducted a long-term tracking study and found mean daily activity space was 1.42 km of river distance. The distance between 30-minute centres of activity was typically 0.1 km, suggesting limited movement over short time scales. Salinity electivity analysis demonstrated an affinity for salinities between 18 and at least 24, suggesting movements are likely made in part, to remain within this range (Simpfendorfer et al. 2011).
The US National Marine Fisheries Service designated critical habitat for the US distinct population segment of Smalltooth Sawfish (Norton et al. 2012). The nursery habitats essential to the conservation of the species were identified as those adjacent to red mangroves (Rhizophora mangle) and euryhaline habitats with water depths less than or equal to 0.9 m (Norton et al. 2012).
For adult sawfish, unpublished data from pop-off archival satellite transmitting (PAT) tags indicate Smalltooth Sawfish spend the majority of their time in shallow waters (<10 m deep) and prefer temperatures between 22°C and 28°C (J.K. Carlson unpublished data). The maximum recorded depth for Smalltooth Sawfish is 88 m.
The principal threats to Smalltooth 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 Smalltooth 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). The Smalltooth Sawfish relies on a variety of specific habitat types including 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 of Guinea and Senegal and in Marine Protected Areas in Mauritania and Guinea-Bissau (S.V. Fordham pers. comm. 2012).
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Simpfendorfer, C.A., Yeiser, B.G., Wiley, T.R., Poulakis, G.R., Stevens, P.W., and Heupel, M.R. 2011. Environmental influences on the spatial ecology of juvenile smalltooth sawfish (Pristis pectinata): results from acoustic monitoring. PLoS ONE 6(2): e16918.
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|Citation:||Carlson, J., Wiley, T. & Smith, K. 2013. Pristis pectinata (Eastern Atlantic subpopulation). In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 09 March 2014.|
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