|Scientific Name:||Anoxypristis cuspidata|
|Species Authority:||(Latham, 1794)|
Pristis cuspidatus Latham, 1794
|Taxonomic Notes:||Although there are records of Australian specimens of Narrow Sawfish (Anoxypristis cuspidata) with broader triangular rostral teeth than normal, the analysis of genetic data from this region did not produce any evidence that there is more than one species present (D’Anastasi 2010).|
|Red List Category & Criteria:||Endangered A2cd ver 3.1|
|Assessor/s:||D'Anastasi, B., Simpfendorfer, C. & van Herwerden, L.|
|Reviewer/s:||Böhm, M., Kyne, P.M. & Pillans, R.|
The Narrow Sawfish (Anoxypristis cuspidata) is an Indo-West Pacific species occurring from the northern Persian (Arabian) Gulf to Australia and north to Japan. It is a bentho-pelagic species that occurs from inshore and estuarine areas to offshore habitats in depths of up to 100 m. It is the most productive sawfish species, reaching maturity early (2–3 yr) and having intrinsic rates of population increase >0.27 yr-1, making it less susceptible to fishing pressure than other sawfish species. However, it does have the highest post release mortality of all sawfish species. While the current population size and its historic abundance are unknown, it persists in most of its range states, but in substantially lower numbers than historically. Like other sawfishes, the toothed rostrum and demersal occurrence makes Narrow Sawfish extremely susceptible to capture in gillnets and demersal trawl nets. The species has been affected by commercial net and trawl fisheries, which operate in inshore areas of its range, reductions in habitat quality and coastal development, the impacts of which have cumulatively led to population decline. This species is listed on Appendix I of CITES, is protected in some range states as a no-take species, and is sheltered in some areas that are closed to fishing; but these actions alone will not be sufficient to ensure its survival in some regions. Ongoing fishing and development is likely to lead to future population declines. Despite a lack of quantitative data to support declines, current information indicates that Narrow Sawfish across its Indo-West Pacific range are considerably more rare than historically recorded. Declines of between 50 and 70% over three generation lengths (~18 years) are suspected and have primarily been attributed to ongoing capture in commercial net and trawl fisheries, with the Narrow Sawfish being particularly susceptible given it has poor post-release survival.
The previous assessment of this species was Critically Endangered. However, given the new information that has become available since the last assessment and the fact that the more dramatic declines have happened outside of the three generation period (~18 years), the species now meets the criteria for an Endangered listing (representing a non-genuine change in status based on new information available since the time of the last assessment).
The exact historic distribution of Narrow Sawfish is uncertain, but it is highly likely that its full range extended from the Persian (Arabian) Gulf, across southern Asia and the Indo-Australian Archipelago, and north to Japan and South Korea (Last and Stevens 2009, A.B.M. Moore pers. comm. 2012). The western extreme of the range may reach as far as Somalia, with some reports from this region (M.T. McDavitt pers. comm. 2012). The Gulf of Chihli, China, South Korea and the southern portion of Japan are reported as the northernmost extent of occurrence, although this needs clarification (Fowler 1941, Misra 1969, Chen and Chung 1971, Compagno and Cook 1995). The central coasts of western and eastern Australia are confirmed as the southernmost extent (see D’Anastasi 2010).
Native:Australia (Northern Territory, Queensland, Western Australia); Bangladesh; India; Indonesia; Iran, Islamic Republic of; Malaysia; Myanmar; Papua New Guinea; Sri Lanka
Possibly extinct:Viet Nam
|FAO Marine Fishing Areas:||
Indian Ocean – eastern; Indian Ocean – western; Pacific – northwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
Genetic and morphological data supports the division of the global range of the Narrow Sawfish into subpopulations (Faria et al. 2013). In Australia, subpopulations on the west and east coasts form distinct genetic stocks, with the Gulf of Carpentaria likely forming a third stock (D’Anastasi 2010, Green 2013). This indicates limited dispersal of at least females. It also indicates that remaining global stocks are likely to be distinct and non-interbreeding, resulting in significant population structure. Genetic diversity, based on mitochondrial DNA, throughout Australian waters is low overall (and lowest on the east coast), with the Narrow Sawfish having the lowest genetic diversity of all sawfish species that occur in Australian waters (D’Anastasi 2010). The genetic diversity throughout the rest of the range is unknown.
Although Narrow Sawfish were relatively common throughout their global distribution, they have declined to varying degrees throughout their range. Accurate estimation of levels of decline are difficult to determine due to the lack of species-specific baseline data (but see Peverell 2008, D’Anastasi 2010, Harry et al. 2011). Declines are masked by extremely poor reporting practices, misidentification (Giles et al. 2005, Stapley and Rose 2009) and the absence of adequate observer programmes. Available catch data and anecdotal evidence indicate severe global declines since the 1960s. Populations are suspected to have declined by 50-70% over the last ~20 years (three generation lengths), with 80% of the population thought to have been lost since the 1960s.
Data from the Queensland Shark Control Program in Australia, which operates ‘bather protection’ fishing gear along the Queensland east coast shows a clear decline in sawfish catch (non species-specific) over a 50-year period from the 1960s and the complete disappearance of sawfish in southern regions of the state (Stevens et al. 2005). Northern Australia, particularly the Kimberley region of northern Western Australia (R. McAuley pers. comm. 2012), the Northern Territory (Field et al. 2008), the Gulf of Carpentaria (Peverell 2005), and parts of the Queensland east coast (Harry et al. 2011), contain the most viable, ecologically functional populations that remain worldwide. Even within these areas, populations are likely to have declined significantly from historic levels. Their presence in fisheries bycatch suggests that viable stocks currently remain.
Landings in India are also still reported (K.K. Bineesh pers. comm. 2012). Narrow Sawfish are now considered rare in many places where evidence is available, including parts of India (Roy 2010), parts of Bangladesh (Roy 2010), Myanmar (FIRMS 2007–2012), parts of Malaysia (including Borneo) (Almada-Villela 2002, Manjaji 2002), Indonesia (although remnant populations could still exist in the Java Sea) (White and Kyne 2010, P. Last pers. comm. 2012), Thailand (Vidthayanon 1997, Compagno 2002a, CITES 2007), and Singapore (CITES 2007). The last published record from the Straits of Hormuz towards the western edge of its range, is from 1997 (A.B.M. Moore pers. comm. 2012).
The status of populations in the remainder of its range, where surveys or catch monitoring are poor, is uncertain. It is however likely that these populations have declined substantially from pristine levels due to the high level of fishing in many of these areas.
|Habitat and Ecology:||
The Narrow Sawfish is a bentho-pelagic species that inhabits estuarine, inshore and offshore waters to at least 40 m depth (Last and Stevens 2009). Inshore and estuarine waters are critical habitats for juveniles and pupping females, whilst adults predominantly occur offshore (Peverell 2005).
Narrow Sawfish mature at two to three years of age, at around 200 cm total length (TL) and 230 cm TL for males and females, respectively (Peverell 2005). They are estimated to live, on average, to nine years and have a generation length of approximately six years (Peverell 2005, Tobin et al. 2010, Moreno Iturria 2012). They are presumed to have an annual birth cycle, with an average of 12 pups per litter (Peverell 2005, D’Anastasi 2010). Preliminary genetic research suggests that, in contrast to most elasmobranchs, Narrow Sawfish may not have multiple fathers per litter (D’Anastasi 2010). Intrinsic rates of population increase based on life history data from the exploited population in the Gulf of Carpentaria, Australia, has been estimated to be around 0.27 yr-1 (Moreno Iturria 2012), with a population doubling time of ~2.6 yr. These demographic parameters indicate that this species is more productive than other species of sawfish, which may explain why this species has persisted longer under moderate to heavy fishing pressure, while other sawfish species have disappeared.
The toothed rostrum of Narrow Sawfish, and their primarily coastal distribution, makes them highly susceptible to fishing pressure through entanglement of their rostrum in fishing gear and habitat degradation, which has resulted in populations becoming increasingly rare and fragmented. Demand for their high value products, along with their high incidental catch rates and high post release mortality (Peverell 2005, Tobin et al. 2010) are the drivers of the threat posed by fisheries. Fishing, especially gillnetting and trawling, is the most pervasive threat to Narrow Sawfish (Giles et al. 2005, Salini et al. 2007). Illegal, unreported and unregulated (IUU) catch may be a threat for Narrow Sawfish in many regions, such as northern Australia where it has been well documented (Lack and Sant 2008). An assessment of the sustainability of sharks and rays in Australian fisheries reported in Salini et al. (2007) found Narrow Sawfish to be at high risk of being fished unsustainably due to their high catchability in fishing gear, and their life history. More recent work on age and growth of this species has shown them to be more productive than other sawfishes and a more recent ecological risk assessment identified them as being at medium risk of being overfished (Tobin et al. 2010). The level of risk is likely to be much higher through most of the rest of its range because fishing levels in northern Australia are relatively light.
In general, juveniles, which use inshore nursery grounds, interact regularly with coastal and estuarine gillnet fisheries (Peverell 2005). Pregnant females also interact with inshore net fisheries (see D’Anastasi 2010). Late stage juveniles and mature animals tend to interact with offshore gillnet and trawl fisheries (Peverell 2005, Northern Territory Government Department of Regional Development, Primary Industry, Fisheries and Resources 2008, Stapley and Rose 2009).
In Australian waters, Narrow Sawfish are the most commonly caught sawfish in the Northern Territory (Field et al. 2008), Gulf of Carpentaria (Peverell 2005), Queensland east coast (Harry et al. 2011) and Western Australia (Giles et al. 2005, McAuley et al. 2005). Commercial fishery catches of Narrow Sawfish in Australian waters remain significant, including in the inshore gillnet fishery on the east coast of Queensland, with Narrow Sawfish making up ~1.1% of the total elasmobranch catch (Harry et al. 2011). In addition to the demersal net and trawl fisheries in which all sawfishes are caught, Narrow Sawfish are also caught in pelagic gillnets (i.e. those that do not reach the sea floor), indicating a more diverse set of threats from fishing gear. Narrow Sawfish rostra and fins have also been confiscated from illegal foreign fishing vessels in Australian waters (Salini et al. 2007b, Holmes et al. 2009).
The presence of distinct genetic stocks suggests that if localised depletions do occur, populations may not necessarily be replenished by adjacent stocks within ecologically relevant timeframes (D’Anastasi 2010). The low mitochondrial genetic diversity observed in Australia may also be a risk factor since populations with lower genetic diversity may be at greater risk of losing genetic diversity to a point where losses cannot be recovered and this can lead to inbreeding depression and/or reduced resilience (Frankham 2003, D’Anastasi 2010, Phillips et al. 2011).
Coastal development associated with the rapidly expanding mining industry (including mineral, coal, gas and oil mining and associated processing plants and port facilities) is a growing threat to Narrow Sawfish. Increased urbanisation of coastlines is a growing threat too. These activities result in the modification and/or destruction of critical habitat and lead to degraded water quality through pollution (see Mudd and Patterson 2010 for an example). Given the species reliance on estuarine and inshore coastal areas, where most development and pollution is occurring, these threats are of growing concern, although relative to fishing, they are unlikely to substantially affect global status.
At the global level, Narrow Sawfish are listed on the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendix I, which forbids international trade in the majority of cases. There is a ban on trade in pristid products on eBay, but this is currently ineffective because it is not enforced and material is only removed if it is reported by outside parties. In Australia, legislative protection for Narrow Sawfish as a ‘no-take’ species is in place in Western Australia and Queensland. There are no protections in place in commercial fisheries in the Northern Territory or Commonwealth waters. The take of sawfish is banned in India, but the level of compliance is low, with Narrow Sawfish still being recorded in landings (K.K. Bineesh pers. comm. 2012).
In Australia, codes of practice and training in safe handling of sawfish, as well as measures to avoid catching them, have been promoted in all states and territories. While Narrow Sawfish are the most productive sawfish, they also have the lowest levels of survival following capture and handling (Salini et al. 2007). Careful handling and live release of Narrow Sawfish may play a role in reducing fishery effects, however unlike other sawfish, high post release mortality in this species may ameliorate the positive benefits of good handling practices.
Closures (spatial and temporal) are likely to provide Narrow Sawfish with some level of protection (see D’Anastasi 2010, Tobin et al. 2010). For example, inshore net fisheries in Western Australia, the Northern Territory and Queensland have seasonal spatial closures of varying durations between October and January to protect spawning barramundi stocks. These closures afford some protection to a portion of the Narrow Sawfish population, including a portion of the pupping female population (for example, pupping females have been observed inshore in Queensland during October). Some permanent spatial closures implemented within the Great Barrier Reef Marine Park Representative Areas Program rezoning in 2004 and in Princess Charlotte Bay in 2006 may have benefited Narrow Sawfish. The Northern Territory Government implemented a temporary spatial closure in 2008 in response to the killing of a considerable number of young Narrow Sawfish that was deemed unsustainable.
Fishing gear modifications offer some options for reducing the bycatch of sawfish. Turtle exclusion devices (TEDs) are mandatory in all Australian prawn trawl fisheries and a study by Brewer et al. (2006) showed that the use of TEDs in a prawn trawl fishery reduced catch of Narrow Sawfish, although the realised conservation benefit may be limited (see Griffiths et al. 2006). Brewer et al. (2006) also found that 20% of sawfish were entangled in the top of nets before they reach the TED and it was suggested that lining the front section of the net with canvas, fine metal mesh or tough flexible plastic had potential to reduce sawfish bycatch further, but this remains untested.
|Citation:||D'Anastasi, B., Simpfendorfer, C. & van Herwerden, L. 2013. Anoxypristis cuspidata. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 10 March 2014.|
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