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Colin A. Simpfendorfer - One of the best experts on this subject based on the ideXlab platform.
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habitat use of a critically endangered elasmobranch the largetooth sawfish Pristis Pristis in an intermittently flowing riverine nursery
Endangered Species Research, 2017Co-Authors: Jeff M. Whitty, Colin A. Simpfendorfer, J Keleher, Brendan C Ebner, Adrian C Gleiss, D L MorganAbstract:Knowledge of how an animal uses its habitat is a fundamental component of effective conservation strategies. The Critically Endangered largetooth sawfish Pristis Pristis uses rivers and their estuaries as nursery habitats, where it is likely to be exposed to elevated pressures from anthropogenic-induced stresses including fishing (e.g. bycatch or direct harvest) and instream habitat modification and degradation (e.g. barriers, water extraction, and mining). With a paucity of data available on habitat use of P. Pristis, we monitored the movements of 32 juveniles (952 to 2510 mm total length; mean +/- SE = 1919 +/- 64 mm) using acoustic telemetry to explore correlations between sawfish movement and abiotic as well as biotic variables over an 8 yr period (2008 to 2015) in the freshwater reaches of the Fitzroy River, Western Australia. Monitored juveniles were least active when they occupied deeper runs and pools in proximity to large woody debris by day and were most active during night-time and twilight hours when inhabiting shallow water such as glides, pool edges, and shallow runs. These shifts in activity and habitat use were primarily mediated by foraging and refuging behaviours, which were coupled to day-night cycling of light availability. Protection of these instream habitats and the understanding of their use by P. Pristis are important for aiding in the management of intermittently flowing rivers that are used as nurseries for this species.
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ghosts of the coast global extinction risk and conservation of sawfishes
Aquatic Conservation-marine and Freshwater Ecosystems, 2016Co-Authors: Nicholas K. Dulvy, Lindsay Davidson, Peter Kyne, Colin A. Simpfendorfer, Lucy R. Harrison, John K. Carlson, Sonja FordhamAbstract:Sawfish are arguably the world's most imperilled marine fishes. All five species are classified as highly threatened with extinction: three are Critically Endangered (smalltooth sawfish Pristis pectinata, largetooth sawfish Pristis Pristis, and green sawfish Pristis zijsron); two are Endangered (narrow sawfish AnoxyPristis cuspidata, and dwarf sawfish Pristis clavata). Sawfishes are threatened primarily due to a combination of their low intrinsic rates of population increase, high catchability in fisheries, and high value. Sawfishes are among the world's largest marine fishes, and they are caught by a wide range of fishing gears owing to their tooth-studded rostra being easily entangled. Sawfish fins are some of the most valuable for shark fin soup, and their rostra have long been traded as curios. In addition, they inhabit shallow coastal waters, estuaries, and rivers of the tropics and subtropics, down to a maximum depth rarely exceeding 100 m and are associated with threatened mangrove and seagrass habitats. Historically, sawfishes were distributed in the coastal waters of 90 countries and territories. Over the past century, their geographic distribution has been greatly diminished. For example, the smalltooth sawfish is now found in <20% of its former range. Globally, sawfishes are now entirely absent from 20 countries; 43 countries have lost at least one species. Sawfishes are legally protected, to some degree, in 16 of the 90 range states. These safeguards encompass, on average, 81% of their Extant distribution; however, the quality and breadth of protection varies dramatically across countries and species. Smalltooth sawfish currently has the least amount of such coverage of only half (49%) of Extant distribution. The global conservation strategy specifies actions to protect sawfish and their habitats. Such actions are urgently warranted to avoid global extinction and to restore robust populations for the benefit of coastal ecosystem function and biodiversity. © 2014 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons, Ltd.
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Ghosts of the coast: global extinction risk and conservation of sawfishes
Aquatic Conservation: Marine and Freshwater Ecosystems, 2014Co-Authors: Nicholas K. Dulvy, Lindsay Davidson, Peter Kyne, Colin A. Simpfendorfer, Lucy R. Harrison, John K. Carlson, Sonja FordhamAbstract:Sawfish are arguably the world's most imperilled marine fishes. All five species are classified as highly threatened with extinction: three are Critically Endangered (smalltooth sawfish Pristis pectinata, largetooth sawfish Pristis Pristis, and green sawfish Pristis zijsron); two are Endangered (narrow sawfish AnoxyPristis cuspidata, and dwarf sawfish Pristis clavata). Sawfishes are threatened primarily due to a combination of their low intrinsic rates of population increase, high catchability in fisheries, and high value. Sawfishes are among the world's largest marine fishes, and they are caught by a wide range of fishing gears owing to their tooth-studded rostra being easily entangled. Sawfish fins are some of the most valuable for shark fin soup, and their rostra have long been traded as curios. In addition, they inhabit shallow coastal waters, estuaries, and rivers of the tropics and subtropics, down to a maximum depth rarely exceeding 100 m and are associated with threatened mangrove and seagrass habitats. Historically, sawfishes were distributed in the coastal waters of 90 countries and territories. Over the past century, their geographic distribution has been greatly diminished. For example, the smalltooth sawfish is now found in
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Utility of rostra in the identification of Australian sawfishes (Chondrichthyes: Pristidae)
Aquatic Conservation: Marine and Freshwater Ecosystems, 2013Co-Authors: Jeff M. Whitty, Colin A. Simpfendorfer, Stirling C. Peverell, Iain C. Field, Nicole M. Phillips, Dean C. Thorburn, David L. MorganAbstract:Effective management of critically endangered sawfishes can be a difficult task, in part due to interspecies misidentification. Current methods for identifying sawfishes can be impractical as they are based on morphological features that are often unobservable. Further exploration is required to develop a more reliable means of identification. This study explored the utility of sawfish rostra in determining the species, size and sex of sawfishes, as rostra are commonly the only feature of a sawfish observed by fishers or present in public and private collections. A morphometric and meristic database consisting of over 1100 narrow sawfish (AnoxyPristis cuspidata), dwarf sawfish (Pristis clavata), largetooth (or freshwater) sawfish (Pristis Pristis; formerly Pristis microdon) and green sawfish (Pristis zijsron) rostra from Australian waters, was statistically analysed. Identification of sawfishes was found to be possible through the use of the variables: inter-tooth spacing, standard rostrum width/standard rostrum length, standard rostrum length/total rostrum length, rostrum tip width/standard rostrum length, and/or rostral tooth count range, although the distinguishing variables were species-dependent. The relationship between standard rostrum length and total length was also observed to vary substantially between most species. Models for estimating total length from standard rostrum length are provided. This study has provided a tool that can be used to identify accurately the species and size of sawfishes by their rostra, and therefore can assist in clarifying historical and contemporary sawfish records, nomenclature and distributions. A better understanding of these issues should allow sawfish conservation strategies to become more focused, and thus more effective.
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Movements of juvenile endangered smalltooth sawfish, Pristis pectinata, in an estuarine river system: use of non-main-stem river habitats and lagged responses to freshwater inflow-related changes
Environmental Biology of Fishes, 2013Co-Authors: Gregg R. Poulakis, Philip W. Stevens, Amy A. Timmers, Christopher J. Stafford, Colin A. SimpfendorferAbstract:The smalltooth sawfish ( Pristis pectinata ) is one of seven critically endangered sawfishes worldwide that little is known about beyond their presence in estuaries and rivers primarily during early life history. Movements of 24 juvenile P . pectinata (
David L. Morgan - One of the best experts on this subject based on the ideXlab platform.
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Contrasting population structures of three Pristis sawfishes with different patterns of habitat use
Marine and Freshwater Research, 2017Co-Authors: Nicole M. Phillips, Stirling C. Peverell, J.a. Chaplin, David L. MorganAbstract:This research demonstrates how population structure differs in elasmobranchs with different patterns of habitat use. Population structure was assessed using data at microsatellite loci in three species of Pristis sawfishes in northern Australian waters. Statistically significant population structure was found in each of P. clavata (FST = 0.021, F′ST = 0.151, P < 0.001) and P. zijsron (FST = 0.026, F′ST = 0.130, P < 0.001), which spend their entire life in marine waters. In contrast, there was no evidence of significant population structure in P. Pristis, which uses freshwater rivers as juveniles and marine waters as adults (FST = 0.004, F′ST = 0.029, P = 0.210). When combined with the results of mtDNA analyses from a previous study, the results suggested that dispersal in P. Pristis is male-biased, whereas both male and female gene flow are restricted at large spatial scales in each of P. clavata and P. zijsron in Australian waters. The present study has provided the first evidence of sex-biased dispersal in a sawfish.
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Whole mitogenome sequencing refines population structure of the Critically Endangered sawfish Pristis Pristis
Marine Ecology Progress Series, 2015Co-Authors: Pierre Feutry, Peter Kyne, David L. Morgan, Xiao Chen, Richard D. Pillans, James R. Marthick, Peter M. GreweAbstract:The largetooth sawfish Pristis Pristis (Linnaeus, 1758) is a highly threatened euryha- line elasmobranch that in recent times has undergone a significant range contraction. It now only remains in a few areas, with northern Australia being the main stronghold. Previous work using a single mitochondrial gene approach suggested the existence of regional barriers to gene flow in northern Australia. In this study, whole mitochondrial sequences of 92 P. Pristis from 7 river drainages across northern Australia were used to refine the population structure. This approach revealed barriers to gene flow at a scale as fine as between adjacent river drainages. Except for those flowing into the Gulf of Carpentaria, all river drainages appeared to host a genetically dis- tinct population. The apparent genetic homogeneity in the Gulf is probably due to freshwater con- nectivity between river drainages, either during the last glaciation event when the Gulf was a freshwater lake or through contemporary wet season flooding. These results suggest that each river drainage across the species' range should be considered a discrete management unit unless there is evidence of freshwater connectivity. More broadly, the improved resolution of population structure obtained with whole mitogenome analysis compared to single mitochondrial gene approaches suggests that female reproductive philopatry may have been overlooked in previous studies of some elasmobranch species.
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Impacts of barriers and fishways on sawfish – Wheatstone sawfish offset 2014 annual report. Report to Western Australian Marine Science Institution
2014Co-Authors: David L. Morgan, Jeff M. Whitty, Mark G. Allen, Stephen J. Beatty, James J. KeleherAbstract:This is the first annual report of the study that is investigating the impacts of barriers to sawfish migrations in Western Australia. The Largetooth (or Freshwater) Sawfish (Pristis Pristis) is the only species of sawfish (Pristidae) to inhabit the freshwater reaches of rivers, and thus is likely to be the sawfish species that is most impacted by instream barriers. As such, P. Pristis is the primary subject of this study. This study is separated into multiple milestones or phases, with the general findings of Phase I and II, and status and preliminary findings of Phase III being discussed in this report. In depth analyses and discussions of all phases will available in the final report.
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Utility of rostra in the identification of Australian sawfishes (Chondrichthyes: Pristidae)
Aquatic Conservation: Marine and Freshwater Ecosystems, 2013Co-Authors: Jeff M. Whitty, Colin A. Simpfendorfer, Stirling C. Peverell, Iain C. Field, Nicole M. Phillips, Dean C. Thorburn, David L. MorganAbstract:Effective management of critically endangered sawfishes can be a difficult task, in part due to interspecies misidentification. Current methods for identifying sawfishes can be impractical as they are based on morphological features that are often unobservable. Further exploration is required to develop a more reliable means of identification. This study explored the utility of sawfish rostra in determining the species, size and sex of sawfishes, as rostra are commonly the only feature of a sawfish observed by fishers or present in public and private collections. A morphometric and meristic database consisting of over 1100 narrow sawfish (AnoxyPristis cuspidata), dwarf sawfish (Pristis clavata), largetooth (or freshwater) sawfish (Pristis Pristis; formerly Pristis microdon) and green sawfish (Pristis zijsron) rostra from Australian waters, was statistically analysed. Identification of sawfishes was found to be possible through the use of the variables: inter-tooth spacing, standard rostrum width/standard rostrum length, standard rostrum length/total rostrum length, rostrum tip width/standard rostrum length, and/or rostral tooth count range, although the distinguishing variables were species-dependent. The relationship between standard rostrum length and total length was also observed to vary substantially between most species. Models for estimating total length from standard rostrum length are provided. This study has provided a tool that can be used to identify accurately the species and size of sawfishes by their rostra, and therefore can assist in clarifying historical and contemporary sawfish records, nomenclature and distributions. A better understanding of these issues should allow sawfish conservation strategies to become more focused, and thus more effective.
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North-western Australia as a hotspot for endangered Elasmobranchs with particular reference to sawfishes and the Northern river Shark
Journal of the Royal Society of Western Australia, 2011Co-Authors: David L. Morgan, Jeff M. Whitty, Nicole M. Phillips, Dean C. Thorburn, J.a. Chaplin, Rory McauleyAbstract:Recent targeted surveys, together with the collection of sawfish (Pristidae) rostra from the general public, have demonstrated that the Kimberley and northern Pilbara are important refuges for sawfish, with four of the world's seven species found here. These comprise all of Australia's known sawfish species, including the three species protected under the Environment Protection and Biodiversity Conservation (EPBC) Act 1999, i.e. Freshwater Sawfish (Pristis microdon), Dwarf Sawfish (Pristis clavata) and Green Sawfish (Pristis zijsron). The Northern River Shark (Glyphis garricki), which was only described in 2008, has only recently been discovered in the Kimberley and is listed as Endangered under the EPBC Act. These species are listed as Critically Endangered on the IUCN Red List and collectively represent ~45% of Australia's elasmobranchs that are listed as Vulnerable or higher under the EPBC Act. There is, however, limited information on the spatial extent of these species throughout Western Australia, particularly as most sawfish surveys have targeted only a few specific areas over a vast coastline. We therefore encouraged public participation in providing Pristis rostra, taken from the fish as curios, in order to extend the known locations of the species and relate these to life history stages based on their size. Here we report on the published records and our unpublished catches (n = 376) across three Pristis spp., and collate this with data from donated rostra, 73% (n = 283) of which were considered usable, in that catch locations were reliable and they were from Western Australian waters. We provide information on sawfish distributions in Western Australia and identify areas that are important as pupping grounds, nursery areas or harbour mature individuals. We also collate known records of G. garricki and provide information on the ecology of this and the EPBC listed sawfish species.
Vicente Faria - One of the best experts on this subject based on the ideXlab platform.
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Status and the potential for extinction of the largetooth sawfish Pristis Pristis in the Atlantic Ocean
Aquatic Conservation: Marine and Freshwater Ecosystems, 2013Co-Authors: Joana Fernandez-carvalho, John K. Carlson, Vicente Faria, Johanna L. Imhoff, George H. BurgessAbstract:Sawfishes currently are among the most threatened elasmobranchs in the world. Only two species inhabit Atlantic waters: the largetooth sawfish (Pristis Pristis) and the smalltooth sawfish (Pristis pectinata), both having suffered dramatic declines in their ranges. The goal of this study was to evaluate the status of P. Pristis in the Atlantic, and estimate local extinction risk based on historical and recent occurrence records. In order to accomplish these goals, a thorough search for historical and recent records of P. Pristis in the Atlantic was conducted, by reviewing scientific and popular literature, museum specimens, and contacting regional scientists from the species’ historical range. In total, 801 P. Pristis records (1830–2009) document its occurrence in four major regions in the Atlantic: USA (n = 41), Mexico and Central America (n = 535), South America (n = 162), and West Africa (n = 48). Locality data were not available for 15 records. Historical abundance centres were the Colorado-San Juan River system in Nicaragua and Costa Rica (and secondarily Lake Izabal of Guatemala), the Amazon estuary, and coastal Guinea-Bissau. Currently, the species faces drastic depletion throughout its entire former range and centres of abundance. It appears to have been extirpated from several areas. The probability of extinction was highest in the USA, northern South America (Colombia to Guyane), and southern West Africa (Cameroon to Namibia). Currently, the Amazon estuary appears to have the highest remaining abundance of P. Pristis in the Atlantic, followed by the Colorado–San Juan River system in Nicaragua and Costa Rica and the Bissagos Archipelago in Guinea Bissau. Therefore the protection of these populations is crucial for the preservation and recovery of the species. Copyright © 2013 John Wiley & Sons, Ltd.
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species delineation and global population structure of critically endangered sawfishes pristidae
Zoological Journal of the Linnean Society, 2013Co-Authors: Colin A. Simpfendorfer, Vicente Faria, Matthew T Mcdavitt, Patricia Charvet, Tonya R Wiley, Gavin J P NaylorAbstract:Sawfishes are among the most endangered of all elasmobranch species, a factor fostering considerable worldwide interest in the conservation of these animals. However, conservation efforts have been hampered by the confusing taxonomy of the group and the poor state of knowledge about the family's geographical population structure. Based on historical taxonomy, external morphology, and mitochondrial DNA sequences (NADH-2), we show here that, globally, the sawfish comprise five species in two genera: Pristis Pristis (circumtropical), Pristis clavata (east Indo-West Pacific), Pristis pectinata (Atlantic), Pristis zijsron (Indo-West Pacific), and AnoxyPristis cuspidata (Indo-West Pacific, except for East Africa and the Red Sea). This improved understanding will have implications for the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), International Union for Conservation of Nature (IUCN) Red List assessments, and endangered species laws and regulations in several countries. Furthermore, based on both or either of NADH-2 and the number of rostral teeth per side, we show that populations of P. Pristis, P. pectinata, P. zijsron, and A. cuspidata exhibit significant geographic structuring across their respective ranges, meaning that regional-level conservation will be required. Finally, the NADH-2 gene may serve as a marker for the identification of rostra and fins involved in illegal trade. © 2012 The Linnean Society of London
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the curious holotype of Pristis dubius bleeker 1852 and the unravelling of bleeker s sawfish taxonomy
2007Co-Authors: Martien J P Van Oijen, Vicente Faria, Matthew T McdavittAbstract:The recovery of a preserved sawfish caudal fin, which turned out to be the holotype of Pristis dubius Bleeker, 1852, prompted a review of Dr. P. Bleeker's publications on the family Pristidae. In his attempt to re-describe his original species P. zijsron and P. dubius, Bleeker made a number of mistakes that are addressed herein. Contrary to Bleeker's statement, P. zijsron and P. dubius are synonyms and the former name has priority over the latter. To make Bleeker's works on Pristis more accessible, English translations of relevant parts of his papers on Pristidae (in Dutch) and current locations of existing specimens from his original collection are provided. All existing specimens from Bleeker's original collection were also examined.
John K. Carlson - One of the best experts on this subject based on the ideXlab platform.
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ghosts of the coast global extinction risk and conservation of sawfishes
Aquatic Conservation-marine and Freshwater Ecosystems, 2016Co-Authors: Nicholas K. Dulvy, Lindsay Davidson, Peter Kyne, Colin A. Simpfendorfer, Lucy R. Harrison, John K. Carlson, Sonja FordhamAbstract:Sawfish are arguably the world's most imperilled marine fishes. All five species are classified as highly threatened with extinction: three are Critically Endangered (smalltooth sawfish Pristis pectinata, largetooth sawfish Pristis Pristis, and green sawfish Pristis zijsron); two are Endangered (narrow sawfish AnoxyPristis cuspidata, and dwarf sawfish Pristis clavata). Sawfishes are threatened primarily due to a combination of their low intrinsic rates of population increase, high catchability in fisheries, and high value. Sawfishes are among the world's largest marine fishes, and they are caught by a wide range of fishing gears owing to their tooth-studded rostra being easily entangled. Sawfish fins are some of the most valuable for shark fin soup, and their rostra have long been traded as curios. In addition, they inhabit shallow coastal waters, estuaries, and rivers of the tropics and subtropics, down to a maximum depth rarely exceeding 100 m and are associated with threatened mangrove and seagrass habitats. Historically, sawfishes were distributed in the coastal waters of 90 countries and territories. Over the past century, their geographic distribution has been greatly diminished. For example, the smalltooth sawfish is now found in <20% of its former range. Globally, sawfishes are now entirely absent from 20 countries; 43 countries have lost at least one species. Sawfishes are legally protected, to some degree, in 16 of the 90 range states. These safeguards encompass, on average, 81% of their Extant distribution; however, the quality and breadth of protection varies dramatically across countries and species. Smalltooth sawfish currently has the least amount of such coverage of only half (49%) of Extant distribution. The global conservation strategy specifies actions to protect sawfish and their habitats. Such actions are urgently warranted to avoid global extinction and to restore robust populations for the benefit of coastal ecosystem function and biodiversity. © 2014 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons, Ltd.
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Occurrence and habitat use of the critically endangered smalltooth sawfish Pristis pectinata in the Bahamas
Journal of fish biology, 2015Co-Authors: Tristan L. Guttridge, John K. Carlson, Simon J. B. Gulak, Bryan R. Franks, Samuel H. Gruber, Katie S. Gledhill, Mark E. Bond, G. Johnson, R. D. GrubbsAbstract:This study documents and discusses recent (2002-2015) sightings and captures of smalltooth sawfish Pristis pectinata in the Bahamas. Movement patterns and habitat preferences of five P. pectinata are examined: two tracked with acoustic telemetry in Bimini and three tagged with pop-up archival transmitting tags in Andros. Historically, P. pectinata may have been distributed throughout the Bahamas; however, since 2002 only 61 encounters were recorded including: Andros (30), Bimini (19) and a handful across other Islands (12). In Bimini, all P. pectinata were >225 cm (stretched total length, LST) suggesting that it is not used as a nursery area. Pristis pectinata in Andros ranged from c. 80 to 450 cm (LST) indicating that this island might be an important nursery and breeding habitat. Pristis pectinata tracked in both islands remained at depths
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occurrence and habitat use of the critically endangered smalltooth sawfish Pristis pectinata in the bahamas
Journal of Fish Biology, 2015Co-Authors: Tristan L. Guttridge, John K. Carlson, Simon J. B. Gulak, Bryan R. Franks, Samuel H. Gruber, Katie S. Gledhill, Mark E. Bond, G. Johnson, R. D. GrubbsAbstract:This study documents and discusses recent (2002-2015) sightings and captures of smalltooth sawfish Pristis pectinata in the Bahamas. Movement patterns and habitat preferences of five P. pectinata are examined: two tracked with acoustic telemetry in Bimini and three tagged with pop-up archival transmitting tags in Andros. Historically, P. pectinata may have been distributed throughout the Bahamas; however, since 2002 only 61 encounters were recorded including: Andros (30), Bimini (19) and a handful across other Islands (12). In Bimini, all P. pectinata were >225 cm (stretched total length, LST) suggesting that it is not used as a nursery area. Pristis pectinata in Andros ranged from c. 80 to 450 cm (LST) indicating that this island might be an important nursery and breeding habitat. Pristis pectinata tracked in both islands remained at depths <3 m, often adjacent to mangrove habitats, displaying residency from 42 days (Bimini) to 180 days (Andros). These preliminary findings confirm the Bahamas as an important habitat for P. pectinata and emphasize the urgent need for national protection and management of this population.
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Ghosts of the coast: global extinction risk and conservation of sawfishes
Aquatic Conservation: Marine and Freshwater Ecosystems, 2014Co-Authors: Nicholas K. Dulvy, Lindsay Davidson, Peter Kyne, Colin A. Simpfendorfer, Lucy R. Harrison, John K. Carlson, Sonja FordhamAbstract:Sawfish are arguably the world's most imperilled marine fishes. All five species are classified as highly threatened with extinction: three are Critically Endangered (smalltooth sawfish Pristis pectinata, largetooth sawfish Pristis Pristis, and green sawfish Pristis zijsron); two are Endangered (narrow sawfish AnoxyPristis cuspidata, and dwarf sawfish Pristis clavata). Sawfishes are threatened primarily due to a combination of their low intrinsic rates of population increase, high catchability in fisheries, and high value. Sawfishes are among the world's largest marine fishes, and they are caught by a wide range of fishing gears owing to their tooth-studded rostra being easily entangled. Sawfish fins are some of the most valuable for shark fin soup, and their rostra have long been traded as curios. In addition, they inhabit shallow coastal waters, estuaries, and rivers of the tropics and subtropics, down to a maximum depth rarely exceeding 100 m and are associated with threatened mangrove and seagrass habitats. Historically, sawfishes were distributed in the coastal waters of 90 countries and territories. Over the past century, their geographic distribution has been greatly diminished. For example, the smalltooth sawfish is now found in
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Status and the potential for extinction of the largetooth sawfish Pristis Pristis in the Atlantic Ocean
Aquatic Conservation: Marine and Freshwater Ecosystems, 2013Co-Authors: Joana Fernandez-carvalho, John K. Carlson, Vicente Faria, Johanna L. Imhoff, George H. BurgessAbstract:Sawfishes currently are among the most threatened elasmobranchs in the world. Only two species inhabit Atlantic waters: the largetooth sawfish (Pristis Pristis) and the smalltooth sawfish (Pristis pectinata), both having suffered dramatic declines in their ranges. The goal of this study was to evaluate the status of P. Pristis in the Atlantic, and estimate local extinction risk based on historical and recent occurrence records. In order to accomplish these goals, a thorough search for historical and recent records of P. Pristis in the Atlantic was conducted, by reviewing scientific and popular literature, museum specimens, and contacting regional scientists from the species’ historical range. In total, 801 P. Pristis records (1830–2009) document its occurrence in four major regions in the Atlantic: USA (n = 41), Mexico and Central America (n = 535), South America (n = 162), and West Africa (n = 48). Locality data were not available for 15 records. Historical abundance centres were the Colorado-San Juan River system in Nicaragua and Costa Rica (and secondarily Lake Izabal of Guatemala), the Amazon estuary, and coastal Guinea-Bissau. Currently, the species faces drastic depletion throughout its entire former range and centres of abundance. It appears to have been extirpated from several areas. The probability of extinction was highest in the USA, northern South America (Colombia to Guyane), and southern West Africa (Cameroon to Namibia). Currently, the Amazon estuary appears to have the highest remaining abundance of P. Pristis in the Atlantic, followed by the Colorado–San Juan River system in Nicaragua and Costa Rica and the Bissagos Archipelago in Guinea Bissau. Therefore the protection of these populations is crucial for the preservation and recovery of the species. Copyright © 2013 John Wiley & Sons, Ltd.
Stirling C. Peverell - One of the best experts on this subject based on the ideXlab platform.
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Contrasting population structures of three Pristis sawfishes with different patterns of habitat use
Marine and Freshwater Research, 2017Co-Authors: Nicole M. Phillips, Stirling C. Peverell, J.a. Chaplin, David L. MorganAbstract:This research demonstrates how population structure differs in elasmobranchs with different patterns of habitat use. Population structure was assessed using data at microsatellite loci in three species of Pristis sawfishes in northern Australian waters. Statistically significant population structure was found in each of P. clavata (FST = 0.021, F′ST = 0.151, P < 0.001) and P. zijsron (FST = 0.026, F′ST = 0.130, P < 0.001), which spend their entire life in marine waters. In contrast, there was no evidence of significant population structure in P. Pristis, which uses freshwater rivers as juveniles and marine waters as adults (FST = 0.004, F′ST = 0.029, P = 0.210). When combined with the results of mtDNA analyses from a previous study, the results suggested that dispersal in P. Pristis is male-biased, whereas both male and female gene flow are restricted at large spatial scales in each of P. clavata and P. zijsron in Australian waters. The present study has provided the first evidence of sex-biased dispersal in a sawfish.
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Utility of rostra in the identification of Australian sawfishes (Chondrichthyes: Pristidae)
Aquatic Conservation: Marine and Freshwater Ecosystems, 2013Co-Authors: Jeff M. Whitty, Colin A. Simpfendorfer, Stirling C. Peverell, Iain C. Field, Nicole M. Phillips, Dean C. Thorburn, David L. MorganAbstract:Effective management of critically endangered sawfishes can be a difficult task, in part due to interspecies misidentification. Current methods for identifying sawfishes can be impractical as they are based on morphological features that are often unobservable. Further exploration is required to develop a more reliable means of identification. This study explored the utility of sawfish rostra in determining the species, size and sex of sawfishes, as rostra are commonly the only feature of a sawfish observed by fishers or present in public and private collections. A morphometric and meristic database consisting of over 1100 narrow sawfish (AnoxyPristis cuspidata), dwarf sawfish (Pristis clavata), largetooth (or freshwater) sawfish (Pristis Pristis; formerly Pristis microdon) and green sawfish (Pristis zijsron) rostra from Australian waters, was statistically analysed. Identification of sawfishes was found to be possible through the use of the variables: inter-tooth spacing, standard rostrum width/standard rostrum length, standard rostrum length/total rostrum length, rostrum tip width/standard rostrum length, and/or rostral tooth count range, although the distinguishing variables were species-dependent. The relationship between standard rostrum length and total length was also observed to vary substantially between most species. Models for estimating total length from standard rostrum length are provided. This study has provided a tool that can be used to identify accurately the species and size of sawfishes by their rostra, and therefore can assist in clarifying historical and contemporary sawfish records, nomenclature and distributions. A better understanding of these issues should allow sawfish conservation strategies to become more focused, and thus more effective.
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Sensory systems in sawfishes. 1. The Ampullae of Lorenzini
Brain behavior and evolution, 2011Co-Authors: Barbara E. Wueringer, Lyle Squire, Stirling C. Peverell, Jamie Seymour, Stephen M. Kajiura, Shaun P. CollinAbstract:The distribution and density of the ampullary electroreceptors in the skin of elasmobranchs are influenced by the phylogeny and ecology of a species. Sensory maps were created for 4 species of pristid sawfish. Their ampullary pores were separated into pore fields based on their innervation and cluster formation. Ventrally, ampullary pores are located in 6 areas (5 in Pristis microdon), covering the rostrum and head to the gills. Dorsally, pores are located in 4 areas (3 in P. microdon), which cover the rostrum, head and may extend slightly onto the pectoral fins. In all species, the highest number of pores is found on the dorsal and ventral sides of the rostrum. The high densities of pores along the rostrum combined with the low densities around the mouth could indicate that sawfish use their rostrum to stun their prey before ingesting it, but this hypothesis remains to be tested. The directions of ampullary canals on the ventral side of the rostrum are species specific. P. microdon possesses the highest number of ampullary pores, which indicates that amongst the study species this species is an electroreception specialist. As such, juvenile P. microdon inhabit low-visibility freshwater habitats.
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Sensory systems in sawfishes. 2. The lateral line
Brain behavior and evolution, 2011Co-Authors: Barbara E. Wueringer, Lyle Squire, Stirling C. Peverell, Jamie Seymour, Shaun P. CollinAbstract:The lateral line system allows elasmobranchs to detect hydrodynamic movements in their close surroundings. We examined the distribution of pit organs and lateral line canals in 4 species of sawfish (AnoxyPristis cuspidata, Pristis microdon, P. clavata and P. zijsron). Pit organs could only be located in A. cuspidata, which possesses elongated pits that are lined by dermal denticles. In all 4 pristid species, the lateral line canals are well developed and were separated into regions of pored and non-pored canals. In all species the tubules that extend from pored canals form extensive networks. In A. cuspidata, P. microdon and P. clavata, the lateral line canals on both the dorsal and ventral surfaces of the rostrum possess extensively branched and pored tubules. Based on this morphological observation, we hypothesized that these 3 species do not use their rostrum to search in the substrate for prey as previously assumed. Other batoids that possess lateral line canals adapted to perceive stimuli produced by infaunal prey possess non-pored lateral line canals, which also prevent the intrusion of substrate particles. However, this hypothesis remains to be tested behaviourally in pristids. Lateral line canals located between the mouth and the nostrils are non-pored in all 4 species of sawfish. Thus this region is hypothesized to perceive stimuli caused by direct contact with prey before ingestion. Lateral line canals that contain neuromasts are longest in P. microdon, but canals containing neuromasts along the rostrum are longest in A. cuspidata.
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Population genetic structure and genetic diversity of three critically endangered Pristis sawfishes in Australian waters
Marine Biology, 2011Co-Authors: Nicole M. Phillips, David L. Morgan, J.a. Chaplin, Stirling C. PeverellAbstract:Northern Australia is considered to be one of the last strongholds for three critically endangered sawfishes, Pristis zijsron, Pristis clavata, and Pristis microdon, making these populations of global significance. Population structure and levels of genetic diversity were assessed for each species across northern Australia using a portion of the mitochondrial control region. Statistically significant genetic structure was detected in all three species, although it was higher in P. microdon (FST = 0.811; N = 149) than in either P. clavata (FST = 0.419; N = 73) or P. zijsron (FST = 0.202; N = 49), possibly due to a much higher and/or localized level of female philopatry in P. microdon. The overall levels of haplotype diversity in P. zijsron (h = 0.555), P. clavata (h = 0.489), and P. microdon (h = 0.650) were moderate, although it appears to be reduced in the assemblages of P. zijsron and P. clavata in the Gulf of Carpentaria (h = 0.342 and h = 0.083, respectively). Since female migration (replenishment) between regions is unlikely, conservation plans should strive to maintain current levels of diversity and abundances in the regional assemblages of each species.