Records of the Western Australian ivluseuIn 23: 307-308 (2007). Short communication

First record of the freshwater sawfish, Pristis microdon,from southwestern Australian waters

Justin A. Chidlow

Department of Fisheries, Western Australian Marine Research Laboratories,PO Box 20, North Beach, Western Australia 6920

Email: jchidlow@fish.wa.gov.au

Sawfishes (family Pristidae) are large (up to 7m)modified batoids with a blade-like snout edgedwith pairs of rostra I teeth. They occur worldwide insub-tropical and tropical shallow coastal sea,estuaries and freshwater systems (Last and Stevens1994; Compagno and Last 1998). There are betweenfive and seven recognised species worldwide, withfive species represented in Australian waters (Lastand Stevens 1994). Sawfish populations have beenextirpated from many parts of their original globalrange by gillnetting and trawling and are easilyentangled in nets by their toothed rostra(Simpfendorfer 2000). The little that is known aboutthe biology of sawfish suggests they have low ratesof reproduction (Tanaka 1991; Compagno and Last1998; Wilson 1999; Simpfendorfer 2000; Thorburnet al. 2004). This combined with their susceptibilityto fishing gear, make sawfish a high risk speciesand all have subsequently been listed globally ascritically endangered under the IUCN Red ListAssessment 2006 (Compagno et al. 2006).

Pristis microdon Latham, 1794Pristis microdon is a medium to large sawfish that

in Australia grows to at least 361cm TL (Tanaka1991), but is reported to reach up to 700cm TL~ inother locations (Last and Stevens 1994). They areborn at around 50011 in length after a five monthgestation period, with litter sizes ranging between 1and 12 (Wilson 1999). In the western Atlantic P.microdon matures at between 240cm and 300cm TL(Compagno and Last 1998). Tanaka (1991) reportedtwo male specimens from New Cuinea, onemeasuring 247cm that was immature and a 361cmspecimen that was mature. In Australian waters, P.microdon feeds on fish such as catfish, smallcrustaceans and molluscs (AlIen 1982; Cliff andWilson 1994; Pogonoski et al. 2002; Thorburn et al.2004).

T'ristis miuodon occurs inshore and in intertidalareas and is usually found in freshwater drainages,lakes and estuaries where it can penetrate as far as400km from the coast (Morgan et al. 2004). In theIndo-\Vest Pacific it ranges from New Cuinea, 5[:Asia, northern Australia and west to South Africa

(Last and Stevens 1994; Com pagno and Last 1998).T'ristis microdon may also occur in the Atlantic andeastern Pacific if P. perotteti Muller & Henle, 1841and P. zephyreus Jordan & Starks in Jordan, 1895are synonymised with this species (Compagno andLast 1998). In Australia, the freshwater sawfish isknown to occur in the Ord, Durack and FitzroyRivers (Western Australia), the Adelaide, Victoriaand Daly Rivers (Northern Territory), and theCilbert, Mitchell, Norman and Leichhardt Rivers(Queensland) (Last and Stevens 1994; Pogonoski etal. 2002; Thorburn et al. 2(04). Only recently has P.micfodon been reported from marine waters(Thorburn et al. 20(4).

Southwestern Australian P. microdonA female P. microdon was captured by a

commercial shark fisher operating demersal gillnetsin southwestern Australian waters on the 5th ofFebruary 2003. The capture location wasapproximately six miles east of Cape Naturaliste(33°31 'S, 11 5°0/'E) in 32m of water. The sawfish wasestimated to be 3.5m in length TL when landed andappeared to be healthy. The specimen wasprocessed and the fisher retained the remainingtrunk, fins and saw. I positively identified theprocessed sawfish as P. micfodon using anidentification key provided by Last and Stevens(1994).

The partial length (origin of the first dorsal fin tothe insertion point of the second dorsal fin) was95cm (approximate as the trunk had been cut inhalf). The rostra I saw length was 79cm with 19 pairsof teeth that extended to the basal quarter of thesaw (Figure 1). The interspace between rostra I teethat the base of the saw was 4cm, and 3cm betweenthe teeth at the tip of the saw (Figure 1). A groovewas present along the posterior margin of all rostralteeth. The origin of the first dorsal-fin was locatedanterior to the pelvic-fin origin and the height ofthe first dorsal-fin was 32cm. The second dorsal-finheight was 31cm. The ventral lobe of the caudal-finwas small, but distinct. The upper and lowerpostventral caudal-fin margins measured 44.5cmand 11.5cm respectivelv.

308 J.A. Chidlow

Figure 1 Rostral saw from a female Pristis microdon, measuring approximately 350cm in total length, captured offCape Naturaliste, Western Australia. See text for description of measurements.

This record of P. microdon from southwesternAustralia extends the range of the speciesapproximately 1600 km south of its previouslyknown southern limit, Cape Keraudren, WesternAustralia (Thorburn et al. 2004) and providesfurther confirmation that P. microdon utilizesmarine waters.

ACKNOWLEDGEME TS

I wish to thank J. Nelson who thoughtfullyinformed the Shark Research Section, Departmentof Fisheries W A of the capture, and providedassistance in identifying and collecting data fromthe specimen. I would also like to thank P. Lastfrom CSIRO Marine Research, Hobart, R. McAuleyfrom Department of Fisheries W A, Perth and C.Simpfendorfer from the Mote Marine Laboratory,Florida for their assistance in positively identifyingthe specimen.

REFERENCES

Alien, G.R. (1982). A field guide to inland fishes ofWestern Australia. Western Australian Museum,Perth, Western Australia. 86pp.

Cliff, G. and Wilson, G. (1994). atal sharks board'sguide to sharks and other marine animals. atalSharks Board, p33.

Compagno, L.J .V. and Last, J.0. (1999). Pristiformes:Pristidae. In K.E. Carpenter and V.H. iem (eds).FAO species identification guide for fishery purposes.The living marine resources of the Western CentralPacific. Volume 3. Batoid fishes, chimaeras and bonyFishes part 1 (Elopidae to Linophrynidae). Pp. 1410­1417. FAO, Rome.

Compagno, L.J.V., Cook, S.F. and Fowler, S.L. (2006).Pristis microdon. In IUCN 2006 lUCN Red List ofThreatened Species.

Jordan, 0.5. and Starks, E.C. (1895). In The fishes ofSinaloa. 0.5. Jordan. Proceedings of the CalifforniaAcademy of Sciences (Ser. 2) 377-514.

Last, P.R. and Stevens, J.D. (1994). Sharks and rays ofAustralia. CSIRO, Melbourne, 513 pp.

Latham, J. (1794). An essay on the various species ofsawfish. Transactions of the Linnean Society ofLondon 2 (25): 273-282.

Morgan, D.L., Alien, M.G., Bedford, P. and Horstman,M. (2004). Fish fauna of the Fitzroy River in theKimberley region of Western Australia - includingBunuba,Gooniyandi, garinyin, yikina andWalmajarri Aboriginal names. Records of the WesternAustralian Museum 22:147-161.

Muller, J and Henle, F.G.J. (1841). SystematischeBeschreibung der Plagiostomen Berlin. Plagiostomeni-xxii + 1-200.

Pogonoski, J.J., Pollard, D.A. and Paxton, J.R. (2002).Conservation overview and action plan for Australianthreatened and potentially threatened marine andestuarine fishes. Environment Australia, February2002.

Simpfendorfer, CA. (2000). Predicting populationrecovery rates for endangered western Atlanticsawfishes using demographic analysis.Environmental Biology of Fishes 58: 371-377.

Tanaka, S. (1991). Age estimation of freshwater sawfishand sharks in northern Australia and Papua ewGuinea. The University Museum, University ofTokyo. ature and Culture 3: 71-82.

Thorburn, D., Morgan, D., Gill, H., Johnson, M., Wallace­Smith, H., Vigilante, T., Gorring, A., Croft, I. andFenton, J. (2004). Biology and cultural significance ofthe freshwater sawfish (Pristis microdon) in theFitzroy River, Kimberley, Western Australia. Reportto the Threatened Species etwork 2004.57 pp.

Thorson, T.B. (1982). The impact of commercialexploitation on sawfish and shark populations inLake Nicaragua. Fisheries 7(2): 2-10.

Wilson, D. (1999). Freshwater sawfish Pristis microdon.Australia ew Guinea Fishes Associations' A-Znotebook of native freshwater fish. ANGFA Bulletin41.

Mnllllscript received 23 August 2004; nccepted 3 AI/gl/st 2006

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Records of the Western Australian MuseumVolume 23 Part 3 2007

CONTENTS

Nadine A. GuthrieA new species of Gnathoxys (Coleoptera: Carabidae: Carabinae) from anurban bushland remnant in Western Australia

Terry F. HoustonObservations of the biology and immature stages of the sandgroperCyJindraustralia kochii (Saussure), with notes on some congeners(Orthoptera: Cylindrachetidae)

Scott A. Thompson and Graham G. ThompsonTemporal variation in ground-dwelling invertebrate biomass in theGoldfields of Western Australia

Paul Doughty and Marion AnstisA new species of rock-dwelling hylid frog (Anura:Hylidae)from the eastern Kimberley region of Western Australia

Marion Anstis, J. Dale Roberts and Ronald AltigDirect development in two Myobatrachid Frogs, Arenophrynerohmda Tyler and Myobatrachus gouldii Gray, from Western Australia

Brad Maryan, Ken P. Aplin and Mark AdamsTwo new species of the Delma tincta group (Squamata: Pygopodidae)from northwestern Australia

SHORT COMMUNICATION

Justin A. ChidlowFirst record of the freshwater sawfish, Pristis microdon, fromsouthwestern Australian waters

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