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 of Wild Flora and Fauna (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 listed on Convention on Migratory Species CMS Appendices I and II in 2014, 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.Despite these binding international treaty mandates, Dwarf Sawfish remain inadequately protected in a number of countries where basic regulations are lacking and/or poorly enforced. A 2018 analysis identified the western Indian Ocean and Australasia as among the priority regions for concerted, international sawfish conservation policy action (Fordham et al. 2018). Yan et al. (2021) underscored the urgent need for domestic sawfish protections, particularly by nations where sawfish presence is uncertain, low or declining, yet extinction probability is low. Countries where 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.
In Indonesia, all Pristis species are protected by national legislation Peraturan Pemerintah No 7/1999, and all sawfish are protected under the Minister Decree of Marine Affairs and Fisheries No 1/2021. However, it is unclear if these protections for sawfish are effectively enforced in Papua Province. No protections are currently in place for Papua New Guinea. There are concerns that sawfish fins, including Dwarf Sawfish, are being traded internationally, which is in contravention of Papua New Guinea’s obligations as a party to CITES.
The Dwarf Sawfish is protected by national legislation in Australia (Environmental Protection and Biodiversity Conservation EPBC Act, 1999; listed as Vulnerable in 2009) and state and territory legislation in Queensland (Fisheries Act 1994); Northern Territory (Territory Parks and Wildlife Conservation Act 2000); and Western Australia (Fish Resources Management Act 1994 and Wildlife Conservation Act 1950). Reporting of commercial fishery interactions for the Dwarf Sawfish have been mandatory since 2009, however, these data are generally inaccurate, incomplete, and prone to species misidentifications (e.g., Tillett et al. 2012). Numerous fishery spatial closures are in place within Australia that likely benefit the Dwarf Sawfish, including, notably, a restriction on gillnet fishing in King Sound (Western Australia) that overlaps with key Dwarf Sawfish habitat (Gaughan and Santoro 2021). Elsewhere, within Western Australia, the creation of a network of nine marine parks in inshore areas of the Kimberley and Canning coastline over the past decade overlap with a large proportion of Dwarf Sawfish distribution, and will likely provide considerable protection for this species from fishing. However, none of these Western Australian marine parks include areas where most of the species captures have been reported from surveys in King Sound and the Fitzroy River estuary (Morgan et al. 2021). In the Northern Territory, commercial gillnetting is not permitted in riverine environments. While in east Queensland, commercial fishing restrictions in Princess Charlotte Bay likely afford some protection if populations are persisting along this coastline. Overall, in Australia, where Dwarf Sawfish are present and relatively well protected, is considered a “lifeboat” country, but relaxation of key safeguards would immediately threaten the population.
In addition to species-specific legal protections, Dwarf 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 Dwarf Sawfish range state. Better monitoring of Dwarf 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 Dwarf Sawfish extinction.
Location Information
Historically, the Dwarf Sawfish occurred widely across the Indo–West Pacific, but it is now ‘possibly extinct’ throughout its east Indian and Southeast Asian range. There are no contemporary records of Dwarf Sawfish in Réunion Island, east India, western Indonesia, and Malaysia; Faria et al. 2013). The extant range of Dwarf Sawfish appears to now be restricted to southern New Guinea, that is, Papua Province, Indonesia, and mainland Papua New Guinea) and tropical northern Australia.In Indonesia, dried rostra from specimens caught in 2006 and 2010 have recently been observed in Papua Province, near Merauke District (Y. Wakhida unpubl. data 2022). Southern Papua Province provides an expanse of suitable macro-tidal estuarine habitat for Dwarf Sawfish, and it is likely this species occurs along this coastline. There has been limited survey effort in northern Papua and west Papua Provinces, and these regions are considered ‘presence uncertain’. Elsewhere in Indonesia, a set of Dwarf Sawfish fins were observed in the fin trade from local catch in Sulawesi in 2018 (catch location within Sulawesi unknown, B. Simeon unpubl. data 2022), and the island of Sulawesi is also here considered ‘presence uncertain’.
In Papua New Guinea, this species has recently been verified to occur in the Gulf of Papua and South Fly Coast (Grant et al. 2021a). Recent observations were made in the Kikori and Mia Kussa Rivers during surveys conducted in 2017–2020 (Grant et al. 2021a), and this species was also observed in batches of dried shark fin in Daru in 2014 (White et al. 2017a). There are additionally unverifiable historic records of Dwarf Sawfish from Yule Island in 1966, and from the Bensbach and Morehead Rivers, in 1973 (White et al. 2017a). It is likely that this species is persisting throughout the southern Papua New Guinea mainland. There are no known records of this species from the southeast or northern coastlines of mainland Papua New Guinea, or in any of Papua New Guinea’s Archipelago Islands (New Britain, New Ireland, or Rabal), or the Autonomous Region of Bougainville where only the Largetooth Sawfish (Pristis pristis) has anecdotally been observed (White et al. 2017a). However, survey effort has been limited in these regions and there is a lack of fisheries data available. There is a single record of a historic Dwarf Sawfish rostrum in the Solomon Islands, although it is unclear if this rostrum was obtained from local catch or traded from elsewhere (Hylton et al. 2017).
In Australia, this species is known to occur along the entire northern coastline (DoE 2015, Kyne et al. 2021), from approximately Port Hedland in the Pilbara region of Western Australia (Morgan et al. 2011, K. Lear and D.L. Morgan unpubl. data 2022) through to the Cape York Peninsula, Queensland (B. Wueringer unpubl. data 2022). The most significant global refuge for this species appears to be in the Kimberley region of Western Australia, where Dwarf Sawfish are widespread in mangrove creeks, mudflats, and tidal rivers (Thorburn et al. 2008, Morgan et al. 2011, Morgan et al. 2021). This species historically occurred in northeast Queensland, with the holotype of the species collected from Cleveland Bay, Townsville (Garmin 1906), and a confirmed sighting from Mission Bay, Cairns from 1939 (B. Wueringer unpubl. data 2022). However, contemporary records on Queensland’s east coast are sparse and unconfirmed; an individual Dwarf Sawfish was reported in the Queensland Shark Control Program in Mackay in 2004, and a likely sighting was made in the Escape River, near Cape York in 2018, although the species identification cannot be confirmed (B. Wueringer unpubl. data 2022). Owing to a lack of contemporary records and species verification issues, northeast Queensland is presently considered ‘presence uncertain’.
Geographic Range
Extant
Australia, Indonesia, Papua New Guinea
Possibly Extinct
India, Malaysia, Réunion
Population Information
The global population of Dwarf Sawfish has undergone a significant decline and range contraction. The species may have disappeared from east India, Malaysia, and Indonesian (excluding Sulawesi and Papua Province) prior to the 1960s (prior to the last three generation lengths; 63 years), although with presently available information and lack of concerted survey effort the timing is difficult to confirm. Increases in the use of gillnets in inshore and riverine fisheries became intense during the 1960s in these areas, coupled with accelerated loss of mangrove habitats (Polidoro et al. 2010) that appear to be important to the ecology of this species. Known accounts of this species from these areas are limited to a few historic museum specimens dating back to the 1800s and into the early 1900s (Faria et al. 2013), though it is possible Dwarf Sawfish has undetected persistence in some areas within the past three generation lengths (63 years).In Papua Province, Indonesia, sawfish specific local ecological knowledge (LEK) surveys conducted with fishers in Merauke indicate that while most (186/245) fishers have seen sawfishes, only 104 had reported capture since 2010, with 60 of these interviewees reporting declines in sawfishes during their lifetimes (these surveys considered all sawfish species together, Y. Wakhida unpubl. data 2022).
In Papua New Guinea (PNG), information suggests declines in sawfishes, generally within the range of the Dwarf Sawfish. Local ecological knowledge surveys found that 66% of fishers interviewed throughout southern PNG reported declines in sawfishes during their lifetimes, with most interviewees attributing declines to increased fishing activity or environmental change (e.g., from local logging or mining activity) (Grant et al. 2021b). In the Purari-Kikori Delta in the northern Gulf of Papua, sawfishes (reported as the Largetooth Sawfish (P. pristis), though no records are available to verify species identification, White et al. 2017a) were reported to be commonly caught in the 197’s (reported as '1–10 per catch'; Haines 1979). Contemporary surveys in the same area found that sawfishes are not commonly caught relative to other elasmobranchs, and only two Dwarf Sawfish were caught over approximately three months of small-scale gillnet fishery enumeration at a village in the coastal fringes of the western Purari-Kikori Delta (Grant et al. 2021a). Furthermore, 92% of fishers interviewed in the Kikori River and lower Delta, reported declines in sawfish catch during their lifetime (Grant et al. 2021b). Similarly, in the Bensbach and Morehead Rivers near the Indonesian boarder, Dwarf Sawfish were reported as ‘common’ or as ‘many caught’ in 1973 (White et al. 2017a). Contemporary small-scale fishery observations in the nearby Mia Kussa River (~100 km east, though adjoined by continuous suitable sawfish habitat) recorded one Dwarf Sawfish during one month of small-scale gillnet fishery catch observation (Grant et al. 2021a). Along this South Fly Coast region, 63% of fishers interviewed reported declines in sawfish catch during their lifetimes (Grant et al. 2021b). While Dwarf Sawfish are persisting in southern Papua New Guinea, infrequent observation of this species by small-scale fishery enumerators, and a lack of dried rostra or fins in fishing villages relative to other elasmobranch species, indicates Dwarf Sawfish are not commonly caught (White et al. 2017a, Grant et al. 2021a). It is suspected that this is due to historic and ongoing population decline, mainly from riverine and inshore gillnet fisheries pressure (White et al. 2017a, Grant et al. 2021a, Grant et al. 2021b).
In Australia, there have been significant, but mostly unquantified, population declines for all sawfish species, particularly in the early to mid-1900s, and considerably reduced ranges on the east coast, due to gillnet and trawl fisheries pressure coupled with habitat modification (Kyne et al. 2013, Wueringer et al. 2017). Most of the published records of the species are from the King Sound and Fitzroy River estuary in the Kimberley region of Western Australia (Thorburn et al. 2008, Morgan et al. 2011, Morgan et al. 2021), or from the Gulf of Carpentaria in Queensland (Peverell 2005). Scientific observer surveys of nearshore gillnet fisheries provide some indication of the relative abundance of Dwarf Sawfish over the last 20 years; however, inconsistencies in reporting of fishing effort make direct regional comparisons and overall population trend difficult to interpret. The following information collectively indicates higher interaction rates with inshore gillnets in Western Australia and Northern Territory, and lower interactions of Dwarf Sawfish in Queensland where historical fishing pressure has been highest. Within Western Australia, 31 Dwarf Sawfish were observed in 160 fishing days in inshore gillnet fisheries operating on the Canning and Kimberley coastline between 2003– 2004 (McAuley et al. 2005) and eight individuals observed over 18 fishing days in the central Kimberley coastline in 2017 (A.V. Harry unpubl. data 2022). An independent study between 2002–2016 in Western Australia’s Fitzroy River estuary and King Sound has reported the highest number of Dwarf Sawfish incidental catches (Morgan et al. 2021). There were 118 Dwarf Sawfish reported equally from the macrotidal King Sound (931 h of 20-m gillnet sets) and the Fitzroy River estuary (931 h of 20-m gillnet sets), with high catch-per-unit-effort (Morgan et al. 2021). Some 44 of these individuals were reported in Thorburn et al. (2008). In the Northern Territory, 20 Dwarf Sawfish were observed during 52 fishing days in the inshore gillnet fishery between 2002–2008 (Field et al. 2013). In the Gulf of Carpentaria, two Dwarf Sawfish were observed during 105 fishing days in the inshore gillnet fishery between 1998–2000 (Rose and McLoughlin 2001), while 24 Dwarf Sawfish were observed in 1,120 fishing days between 2000–2002 in this same inshore gillnet fishery (Peverell 2005). On the east coast of Queensland between Cape York and Bundaberg, no Dwarf Sawfish were observed during 166 intertidal and river fishing days between 2006–2009 (Harry et al. 2011). Data (1962–2016) from the east Queensland Shark Control Program (QSCP) is generally not species-specific, though it indicates declines in catch rates of all sawfish species, potentially including Dwarf Sawfish (Wueringer 2017).
Australian populations of the Dwarf Sawfish have low to moderate levels of genetic diversity, with very low genetic diversity and evidence of a population bottleneck in the Gulf of Carpentaria (Phillips et al. 2011, Phillips et al. 2017b). Populations in Western Australia, the northern coast of the Northern Territory, and the Gulf of Carpentaria are genetically distinct stocks (Phillips et al. 2011, Phillips et al. 2017a). From independent sampling effort, there are areas known to be supporting relatively dense populations of Dwarf Sawfish in Western Australia (Morgan et al. 2021) and the Northern Territory (Kyne et al. 2013). In Western Australia, spatial exclusions of commercial fishing in the southern region of the species' range were implemented in 2005, and commercial fisheries effort within the Gillnet and Barramundi Managed Fisheries and Kimberley Prawn Managed Fisheries (Gaughan and Santoro 2021) is low in comparison to fisheries likely to interact with this species in Northern Territory and Queensland. Western Australia probably supports the most significant refuge area for the Dwarf Sawfish globally (Morgan et al. 2021). In the Northern Territory, reductions in commercial inshore gillnet fishing effort, are possibly leading to the population beginning to stabilize and recover in some areas.
Overall, while extinctions have possibly occurred prior to the past three generation lengths (63 years) in east India, Malaysia, and western Indonesia, currently it is not possible to confirm either the timing of this or that there are no undetected, remnant populations. As such, a population reduction of >80% is suspected in this ‘possibly extinct’ range over the past three generation lengths. The level of population reduction in its currently extant range in Papua Province (Indonesia) and Papua New Guinea appears to be severe, and likely >80% over the past three generation lengths. Within Australia, in Western Australia, and possibly also in areas of the Northern Territory, populations recently appear to be improving, providing a stronghold and refuge for this species. However, in both these areas over the longer period of the past three generation lengths, population reductions of 30–49% in Western Australian and 50–79% in the Northern Territory are inferred. The population reduction in Queensland is suspected to be >80% over the past three generation lengths, including a reduction in extent of occurrence along the east coast (although it is difficult to determine if the east coast population declines occurred prior to the past three generation lengths). To estimate a global population trend, the estimated three generation population trends for each area (including possibly extinct, presence uncertain, and extant areas) were weighted according to the relative size of each area. Accordingly, a population reduction of >80% over the past three generation lengths (63 years) is suspected due to levels of exploitation, habitat degradation, and a reduction in extent of occurrence.
Threats
The Dwarf Sawfish is subject to inshore and estuarine fishing pressure throughout 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). Habitat degradation though coastal and riverine development and land repurposing for agriculture has likely reduced the quality of available habitat throughout much of this species' range. Shallow inshore environments and lower estuarine reaches of rivers environments have historically been intensively fished and developed in areas of moderate to high human population density (Compagno and Cook 1995, Grant et al. 2019), and a combination of these threats have likely led to the disappearance of this species in east India and parts of Southeast Asia.In Papua Province, Indonesia, fisheries operate along the southern coast of Papua and in the Arafura and Banda Seas, and these fisheries have potential to interact with the Dwarf Sawfish (e.g., the congener Largetooth Sawfish was recorded in catch during 2002; D'Alberto et al. 2022). Three Dwarf Sawfish rostra were recently observed from catches of small-scale fishers in Merauke, although there is no catch data available for this fishery. In Papua Province, swim bladder (also known as ‘fish maw’ trade) is targeted by local fishers using gillnets, while sharks and rays, including Wedgefishes (Rhinidae) and Guitarfishes (Rhinobatidae), are also targeted for their fins with larger mesh size gillnets (> 8 inches, locally called ‘Liong Bun’ gillnet) (Y. Wakhida unpubl. data 2022). The Dwarf Sawfish is likely caught incidentally in both of these fisheries.
In Papua New Guinea (PNG), most fishing occurs in the estuarine zone of rivers or in coastal areas receiving river outflow (Busilacchi et al. 2014, Eisemberg et al. 2015). Fishers in southern PNG primarily target estuarine fish species with gillnets for the swim bladder, while shark fin is also traded as a supplementary product (Busilacchi et al. 2014, Busilacchi et al. 2021, Grant et al. 2021a, Grant et al. 2021b). The swim bladder fishery in southern PNG currently lacks any management, and this fishery is rapidly expanding owing to the exceptionally high local value of swim bladder, and is driven by demand in East Asia (Sadovy de Mitcheson et al. 2019, Busilacchi et al. 2021, Grant et al. 2021a). Similar to Papua Province, the Dwarf Sawfish is considered to be highly susceptible to this fishery. In PNG, the Dwarf Sawfish is also likely susceptible to the Gulf of Papua Prawn Trawl Fishery (White et al. 2019), and historically it was likely captured during intermittent periods of drift gillnet fisheries operating in the Gulf of Papua (White et al. 2017a). Human development in both Papua Province (Indonesia), and Papua New Guinea is low, and consequently habitat degradation is relatively minimal and is unlikely to have a significant impact on this species.
In Australia, the Dwarf Sawfish is mainly caught in gillnet fisheries with limited interactions observed in trawl and line fisheries (Rose and McLoughlin 2001, Fry et al. 2018). The species likely benefits from spatial closures to commercial fishing in parts of Western Australia and the Northern Territory. In Queensland, commercial fishing is permitted within riverine environments, and this likely increases the susceptibility of this species to fisheries pressure across its life history stages. In Queensland, this species is likely to have suffered greater impacts owing to habitat degradation, particularly along its historical east coast range. Habitat degradation is a less severe threat in the Northern Territory, while it is an almost non-existent threat in this species' Western Australian range.
