Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences

Ontogenetic depth partitioning by juvenile freshwater sawfish (Pristis microdon: Pristidae) in a riverine environment

Jeff M. Whitty A , David L. Morgan A C , Stirling C. Peverell B , Dean C. Thorburn A and Stephen J. Beatty A

A Centre for Fish and Fisheries Research, Murdoch University, Murdoch, WA 6150, Australia.

B Department of Primary Industries and Fisheries, Sustainable Fisheries, Northern Fisheries Centre, Cairns, Qld 4870, Australia.

C Corresponding author. Email:

Marine and Freshwater Research 60(4) 306-316
Submitted: 30 May 2008  Accepted: 29 December 2008   Published: 29 April 2009


The freshwater sawfish (Pristis microdon) is a critically endangered elasmobranch. Ontogenetic changes in the habitat use of juvenile P. microdon were studied using acoustic tracking in the Fitzroy River, Western Australia. Habitat partitioning was significant between 0+ (2007 year class) and larger 1+ (2006 year class) P. microdon. Smaller 0+ fish generally occupied shallower water (<0.6 m) compared with 1+ individuals, which mainly occurred in depths >0.6 m. Significant differences in hourly depth use were also revealed. The depth that 1+ P. microdon occupied was significantly influenced by lunar phase with these animals utilising a shallower and narrower depth range during the full moon compared with the new moon. This was not observed in 0+ individuals. Habitat partitioning was likely to be related to predator avoidance, foraging behaviours, and temperature and/or light regimes. The occurrence of 1+ P. microdon in deeper water may also result from a need for greater depths in which to manoeuvre. The present study demonstrates the utility of acoustic telemetry in monitoring P. microdon in a riverine environment. These results demonstrate the need to consider the habitat requirements of different P. microdon cohorts in the strategic planning of natural resources and will aid in the development of management strategies for this species.

Additional keywords: external tagging, ontogeny, telemetry.


Ackerman J. T.Kondratieff M. C.Matern S. A.Cech J. J.2000Tidal influence on spatial dynamics of leopard sharks, Triakis semifasciata, in Tomales Bay, California.Environmental Biology of Fishes583343doi:10.1023/A:1007657019696

Adam M. S.Kirkwood G. P.2001Estimating tag-shedding rates for skipjack tuna, Katsuwonus pelamis, off the Maldives.Fishery Bulletin99193196

Anthony K. R. N.Ridd P. V.Orpin A. R.Larcombe P.Lough J.2004Temporal variation of light availability in coastal benthic habitats: effects of clouds, turbidity, and tides.Limnology and Oceanography4922012211

Blaylock R. A.1990Effects of external biotelemetry transmitters on behavior of the cownose ray Rhinoptera bonasus (Mitchill 1815).Journal of Experimental Marine Biology and Ecology141213220

Breder C. M.Jr1952On the utility of the saw of the sawfish.Copeia19529091doi:10.2307/1438539

Clements S.Jepsen D.Karnowski M.2005Optimization of an acoustic telemetry array for detecting transmitter-implanted fish.North American Journal of Fisheries Management25429436doi:10.1577/M03-224.1

Compagno L. J. V., and Last P. R. (1998). Order Pristiformes Pristidae sawfishes. In ‘FAO Species Identification Guide for Fisheries Purposes. The Living Marine Resources of the Western Central Pacific, Volume 3. Batoid Fishes, Chimaeras and Bony Fishes part 1 (Elopidae to Linophrynidae)’. (Eds K. E. Carpenter and V. H. Niem.) pp. 1410–1417. (FAO: Rome.)

Compagno L. J. V., Cook S. F., and Fowler S. L. (2006). Pristis microdon. 2008 IUCN Red List of Threatened Species. Available at [accessed 27 March 2009].

Conover W. J. (1971). ‘Practical Nonparametric Statistics.’ (John Wiley and Sons: New York.)

Dewar H.Mous P.Domeier M.Muljadi A.Pet J.Whitty J.2008Movements and site fidelity of the giant manta ray, Manta birostris, in the Komodo Marine Park, Indonesia.Marine Biology155121133doi:10.1007/S00227-008-0988-X

Dicken M. L.Booth A. J.Smale M. J.2006Preliminary observations of tag shedding, tag reporting, tag wounds, and tag biofouling for raggedtooth sharks (Carcharias taurus) tagged off the east coast of South Africa.Journal of Marine Science6316401648

Domeier M. L.Dewar H.Nasy-Lucas N.2003Mortality rate of striped marlin (Tetrapturus audax) caught with recreational tackle.Marine and Freshwater Research54435445

Ebert D. A.2002Ontogenetic changes in the diet of the sevengill shark (Notorynchus cepedianus).Marine and Freshwater Research53517523doi:10.1071/MF01143

Eklund A., and Schull J. (2001). A stepwise approach to investigating the movement patterns and habitat utilization of goliath grouper, Epinephelus itajara, using conventional tagging, acoustic telemetry and satellite tracking. In ‘Electronic Tagging and Tracking in Marine Fisheries’. (Eds J. R. Sibert and J. L. Nielsen.) pp. 189–216. (Kluwer Academic Publishers: Dordrecht, The Netherlands.)

Fraser N. H. C.Metcalfe N. B.1997The costs of being nocturnal: feeding efficiency in relation to light intensity in juvenile Atlantic salmon.Functional Ecology11385391doi:10.1046/J.1365-2435.1997.00098.X

Girden E. R. (1992). ‘ANOVA: Repeated Measures. SAGE University Paper Series on Quantitative Applications in the Social Sciences, 07-084.’ (SAGE Publications: Newbury Park.)

Greenwood P. E., and Nikulin M. S. (1996). ‘A Guide to Chi-Squared Testing.’ (John Wiley and Sons: New York.)

Hays G. C.Bradshaw C. J. A.James M. C.Lovell P.Sims D. W.2007Why do Argos satellite tags deployed on marine animals stop transmitting?Journal of Experimental Marine Biology and Ecology3495260doi:10.1016/J.JEMBE.2007.04.016

Henningsen A. D.1994Tonic immobility in 12 elasmobranchs: use as an aid in captive husbandry.Zoo Biology13325332doi:10.1002/ZOO.1430130406

Heupel M. R.Simpfendorfer C. A.Bennett M. B.1998Analysis of tissue responses to fin tagging in Australian carcharhinids.Journal of Fish Biology52610620doi:10.1111/J.1095-8649.1998.TB02021.X

Heupel M. R.Semmens J. M.Hobday A. J.2006Automated acoustic tracking of aquatic animals: scales, design and deployment of listening station arrays.Marine and Freshwater Research57113doi:10.1071/MF05091

Hight B. V.Lowe C. G.2007Elevated body temperatures of adult female leopard sharks, Triakis semifasciata, while aggregating in shallow nearshore embayments: evidence for behavioral thermoregulation?Journal of Experimental Marine Biology and Ecology352114128doi:10.1016/J.JEMBE.2007.07.021

Hurst R. J.Bagley N. W.McGregor G. A.Francis M. P.1999Movements of the New Zealand school shark, Galeorhinus galeus, from tag returns.New Zealand Journal of Marine and Freshwater Research332948

Last P. R., and Stevens J. D. (1994). ‘Sharks and Rays of Australia.’ (CSIRO Publishing: Collingwood, Australia.)

Matern S. A.Cech J. J.Hopkins T. E.2004Diel movements of bat rays, Myliobatis californica, in Tomales Bay, California: evidence for behavioral thrermoregulation?Environmental Biology of Fishes58173182

McElroy D. W.Wetherbee B. M.Mostello C. S.Lowe C. G.Crow G. L.Wass R. C.2006Food habits and ontogenetic changes in the diet of the sandbar shark, Carcharhinus plumbeus, in Hawaii.Environmental Biology of Fishes768192doi:10.1007/S10641-006-9010-Y

Medved R. J.Marshall J. A.1983Short-term movements of young sandbar sharks, Carcharhinus plumbeus (Pisces, Carcharhinidae).Bulletin of Marine Science338793

Morgan D.Allen M.Bedford P.Horstman M.2004Fish fauna of the Fitzroy River in the Kimberley region of Western Australia – including the Bunuba, Gooniyandi, Ngarinyin, Nyikina, and Walmajarri Aboriginal names.Records of the Western Australian Museum22147161

Nelson D. R.McKibben J. N.Strong W. R.JrLowe C. G.Sisneros J. A.Schroeder D. M.Lavenberg R. J.1997An acoustic tracking of a megamouth shark, Megachasma pelagios: a crepuscular vertical migrator.Environmental Biology of Fishes49389399

Parker R. R.1971Size selective predation among juvenile salmonid fishes in a British Columbia inlet.Journal of the Fisheries Research Board of Canada2815031510

Simpfendorfer C. A.2005Threatened fishes of the world: Pristis pectinata Latham, 1794 (Pristidae).Environmental Biology of Fishes7320

Simpfendorfer C. A. (2006). Movement and habitat use of smalltooth sawfish. Mote Marine Laboratory, Technical Report 1070. (Mote Marine Laboratory: Sarasota.)

Sims D. W.2003Tractable models for testing theories about natural strategies: foraging behaviour and habitat selection of free-ranging sharks.Journal of Fish Biology635373doi:10.1111/J.1095-8649.2003.00207.X

Sims D. W.Wearmouth V. J.Southall E. J.Hill J. M.Moore al.2006Hunt warm, rest cool: bioenergetic strategy underlying diel vertical migration of a benthic shark.Journal of Animal Ecology75176190doi:10.1111/J.1365-2656.2005.01033.X

Sogard S. M.1997Size-selective mortality in the juvenile stage of teleost fishes: a review.Bulletin of Marine Science6011291157

Stevens J. D.West G. J.McLoughlin K. J.2000Movements, recapture patterns, and factors affecting the return rate of carcharhinid and other sharks tagged off northern Australia.Marine and Freshwater Research51127141

Thorburn D. C. (2006). Biology, ecology and trophic interactions of elasmobranchs and other fishes in riverine waters of Northern Australia. Ph.D. Thesis, Murdoch University.

Thorburn D. C.Rowland A. J.2008Juvenile bull sharks Carcharhinus leucas (Valenciennes, 1839) in northern Australia rivers.The Beagle: Records of the Museums and Art Galleries of the Northern Territory247986

Thorburn D. C.Morgan D. L.Rowland A. J.Gill H. S.2007Freshwater sawfish Pristis microdon Latham, 1794 (Chondrichthyes : Pristidae) in the Kimberley region of Western Australia.Zootaxa14712741

Watsky M. A.Gruber S. H.1990Induction and duration of tonic immobility in the lemon shark Negaprion brevirostris.Fish Physiology and Biochemistry8207210

Wetherbee B. M.Gruber S. H.Rosa R. S.2007Movement patterns of juvenile lemon sharks Negaprion brevirostris within Atol das Rocas, Brazil: a nursery characterized by tidal extremes.Marine Ecology Progress Series343283293doi:10.3354/MEPS06920

Whitty J. M., Morgan D. L., Thorburn D. C., Fazeldean T., and Peverell S. C. (2008). Tracking the movements of freshwater sawfish (Pristis microdon) and northern river sharks (Glyphis sp. C) in the Fitzroy River. In ‘Habitat associations of freshwater sawfish (Pristis microdon) and northern river shark (Glyphis sp. C): including genetic analysis of P. microdon across northern Australia’. (Eds J. M. Whitty, N. M. Phillips, D. L. Morgan, J. A. Chaplin, D. C. Thorburn and S. C. Peverell.) pp. 8–46. Report to the Department of the Environment, Water, Heritage and the Arts, Australian Government, Canberra.

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