|Scientific Name:||Pristis pectinata (Western Atlantic subpopulation)|
Faria et al. (2013) state that both morphology and genetics support the current specific status of the Smalltooth Sawfish (Pristis pectinata) and proposed modification of the distribution of the species to an Atlantic only range. No geographical structure of Smalltooth Sawfish populations has been detected, but the Western and Eastern Atlantic populations of the Smalltooth Sawfish represent separate units for conservation purposes.
|Red List Category & Criteria:||Critically Endangered A2cd ver 3.1|
|Assessor/s:||Wiley, T., Carlson, J. & Smith, K.|
|Reviewer/s:||Grubbs, D. & Böhm, M.|
The Smalltooth Sawfish (Pristis pectinata) has been wholly or nearly extirpated from large areas of its former range in the Western Atlantic Ocean by fishing (trawl and inshore netting) and habitat modification. Negative records from scientific surveys, anecdotal fisher observations, and fish landings data over its historic range infer a population reduction ≥95% over a period of three generations (i.e., 1962 to present). While the population found in the United States appears to have stabilised with some evidence of increase, information from other areas is lacking. The remaining populations are inferred to be small and fragmented based on the lack of records. The species can only be reliably encountered in the Bahamas (where suitable habitat is available) and the United States (Georgia south to Louisiana). It is rare but present in Honduras, Belize, and Cuba. While historic threats to Smalltooth Sawfish have been reduced in places like the US, threats still exist today from areas where sawfish are unprotected and habitat modification and inshore netting still occurs.
Smalltooth Sawfish were widely distributed throughout the tropical and subtropical marine and estuarine waters of the Western Atlantic Ocean. Smalltooth Sawfish were found from Uruguay through the Caribbean and Central America, the Gulf of Mexico, and the Atlantic coast of the United States (Faria et al. 2013). However, this range has contracted and Smalltooth Sawfish have been likely extirpated from large areas of its former range. The species is currently known to occur in the southeastern United States, Bahamas, Cuba, Honduras and Belize. Reports of Smalltooth Sawfish outside of the Atlantic Ocean are likely misidentifications of other sawfish species (Faria et al. in 2013).
Native:Bahamas; Belize; Cuba; Honduras; United States
Possibly extinct:Anguilla; Antigua and Barbuda; Aruba; Barbados; Cayman Islands; Dominica; Grenada; Guadeloupe; Jamaica; Martinique; Montserrat; Netherlands Antilles; Puerto Rico; Saint Kitts and Nevis; Saint Lucia; Saint Vincent and the Grenadines; Trinidad and Tobago; Turks and Caicos Islands; Uruguay; Virgin Islands, British; Virgin Islands, U.S.
|FAO Marine Fishing Areas:||
Atlantic – northwest; Atlantic – southwest; Atlantic – western central
|Range Map:||Click here to open the map viewer and explore range.|
At the end of the 19th century the Smalltooth Sawfish was common in inshore waters of the Western North Atlantic (e.g., Goode 1884, Henshall 1895, Jordan and Evermann 1896, Bigelow and Schroeder 1953). In the United States, the Smalltooth Sawfish population appears to have declined dramatically during the middle and later parts of the 20th century (Simpfendorfer 2002). Based on the contraction of the range and declines in landings, it is likely that the US population at the end of the 20th century was less than 5% of its size at the time of European settlement (Simpfendorfer 2002). Based on genetic sampling, estimates of the current effective population size range of the US population of Smalltooth Sawfish were from 269.6–504.9 individuals (95% Confidence Interval 139.3–1,515) (Chapman et al. 2011). Outside US waters, no data on population size or trends in abundance exist and the only information on trends in the population can be inferred from capture records. While early records of this species include most countries throughout Central and South America, records and reports indicate the Smalltooth Sawfish can only be reliably encountered in the Bahamas (where suitable habitat is available), Honduras, Belize, and Cuba (R. Graham pers. comm. 2012).
The population of Smalltooth Sawfish may have stabilised in the United States. Carlson and Osborne (2012) reported the relative abundance of sawfish increased at an average rate of about 3–5% per year since 1989 based on of voluntary dockside interviews of sport fishers. Despite a low population size in the US, the Smalltooth Sawfish population will probably retain >90% of its current genetic diversity over the next century (Chapman et al. 2011).
Data outside US waters are not available to determine the size or status of remaining populations.
|Habitat and Ecology:||
Currently, life history information for the Smalltooth Sawfish is only available for the Western Atlantic and it assumed that life history parameters are 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 are 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 3 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). There have been some large-scale fisheries targeting the species, including in the southeastern US in the 19th and early 20th centuries, and possibly in Brazil from the 1960s to 1980s (CITES 2007).
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.
National protections for Smalltooth Sawfish have been adopted in the United States. Smalltooth Sawfish are listed as Endangered under Endangered Species Act, 2003 which makes it illegal to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect or to attempt to engage in any such conduct with Smalltooth Sawfish. ‘Critical Habitat’ has also been established for Smalltooth Sawfish in the US (Norton et al. 2012), which is a key conservation objective, designed to facilitate recruitment into adult sawfish population by protecting juvenile nursery areas.
Outside US waters, Nicaragua imposed a permanent ban on targeted sawfish fishing in Lake Nicaragua. In Brazil, Smalltooth Sawfish is protected (no take) by the Ministry of Environment and in Mexico the take of all sawfishes is banned.
|Citation:||Wiley, T., Carlson, J. & Smith, K. 2013. Pristis pectinata (Western Atlantic subpopulation). In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 20 April 2014.|
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