BMRG Coastal Forum19th April 2008

Green Sawfish Recovery Plan Project

Dr Ashley BunceCentre for Environmental ManagementCentral Queensland University

SawfishSawfish• Sawfish are modified rays

which have shark like bodies

• Distinguished by a flattened head and a narrow blade-like snout armed with 24-28 pairs of lateral teeth

• Also similar to and often confused with sawsharks (distinguished by presence of gills on the underside of head)

Australian Sawfish SpeciesAustralian Sawfish Species

• There are 4 known sawfish species in Australian There are 4 known sawfish species in Australian WatersWaters– Narrow sawfish (Narrow sawfish (Anoxypristis cuspidataAnoxypristis cuspidata))– Freshwater sawfish (Freshwater sawfish (Pristis microdonPristis microdon))– Green sawfish (Green sawfish (Pristis ZijsronPristis Zijsron) ) – Dwarf sawfish (Dwarf sawfish (Pristis clavataPristis clavata) )

• These species occupy niches in marine estuarine These species occupy niches in marine estuarine and freshwater environmentsand freshwater environments

Green SawfishGreen SawfishTaxonomyTaxonomy

Order - PristiformesOrder - PristiformesFamily - PristidaeFamily - PristidaeGenus - Genus - PristisPristisSpecies - ziSpecies - zijsronjsron

Conservation StatusConservation StatusIUCN Red List - Critically endangered; IUCN Red List - Critically endangered; EPBC – vulnerableEPBC – vulnerable; QLD – ‘Back on Track’ priority species; NSW ; QLD – ‘Back on Track’ priority species; NSW – critically endangered; NT Fisheries - vulnerable– critically endangered; NT Fisheries - vulnerable

Distribution and Habitat• Very low numbers in waters of southern and central QLD• More common in nth region (including the Gulf of Carpentaria)• Live on muddy or sandy-mud soft bottom habitats • Inhabit coastal foreshores and bays mostly as juveniles• Inhabit marine waters to a depth greater than 40m as adults• Adults known to seasonally frequent inshore waters and rivers during

monsoonal months to pup

DescriptionDescription• Large slender bodyLarge slender body• Olive brown-green dorsally and pale white Olive brown-green dorsally and pale white

ventrallyventrally• Rostrum does not narrow at tipRostrum does not narrow at tip

DescriptorsDescriptors• 24-28 pair of teeth24-28 pair of teeth• Teeth are moreclosely spaced at tip and extend Teeth are moreclosely spaced at tip and extend

onto base of sawonto base of saw• No fork in caudal fin No fork in caudal fin • 1st dorsal fin begins behind pelvic fin origin1st dorsal fin begins behind pelvic fin origin• Rough skinRough skin

SizeSize• Maximum reported size 730cmMaximum reported size 730cm

DietDiet• Prawns and fishPrawns and fish

BiologyBiology

• Long-lived (25-30 years)Long-lived (25-30 years)• Gestation period (fertilisation Gestation period (fertilisation

to birth time) is approx. 5 to birth time) is approx. 5 monthsmonths

• Average of 8 pups are born at Average of 8 pups are born at around 65-90cmaround 65-90cm

• Pups born with a toothed Pups born with a toothed rostrum which is covered by a rostrum which is covered by a enclosed membrane designed enclosed membrane designed to protect mother from teethto protect mother from teeth

BehaviourBehaviour• Sawfish are nocturnalSawfish are nocturnal– Sleep in the daySleep in the day– Hunt at nightHunt at night

• Sawfish are top order Sawfish are top order predators predators

• Actively seek out prey Actively seek out prey items such as fish and items such as fish and crustaceanscrustaceans

Use rostrum for feeding Use rostrum for feeding bybyStunning slow moving Stunning slow moving

schooling fish with schooling fish with slashing motion slashing motion

Locating and dislodging Locating and dislodging prey buried in sand or prey buried in sand or mudmud

Locate buried prey by Locate buried prey by using sensors on rostrumusing sensors on rostrum

Will also eat dead prey Will also eat dead prey and strike at luresand strike at lures

• Saw fish are threatened throughout the worldSaw fish are threatened throughout the world• All Australian species are on the IUCN Redlist of threatened All Australian species are on the IUCN Redlist of threatened

species as critically endangered species as critically endangered • Because they prefer an inshore benthic habitat for breeding, Because they prefer an inshore benthic habitat for breeding,

the juveniles are vulnerable to human interferencethe juveniles are vulnerable to human interference• They are also known to They are also known to actively seek out dead baits or strike

at lures making them vulnerable to recreational fishing

Threats to SawfishThreats to SawfishConservation StatusConservation Status

IUCN Red List - Critically endangered; IUCN Red List - Critically endangered; EPBC – vulnerableEPBC – vulnerable; QLD – ‘Back on Track’ priority species; ; QLD – ‘Back on Track’ priority species; NSW – critically endangered; NT Fisheries - vulnerableNSW – critically endangered; NT Fisheries - vulnerable

Major threats includeMajor threats include– Accidental capture/Entanglement in fishing netsAccidental capture/Entanglement in fishing nets– Illegal fishing for fins or rostrumsIllegal fishing for fins or rostrums– Habitat degradation through coastal Habitat degradation through coastal

developmentdevelopment

Threats to SawfishThreats to Sawfish

Entanglement in fishing netsEntanglement in fishing nets

• Entanglement may occur in– Trawling nets– Inshore net fishery– Recreational fishing

(line and small mesh cast and seine nets)

Sawfish are vulnerable to entanglement as the rostrum is easily entangled in nets and fishing line

The sawfish thrashes around to get free causing further tangling

When unable to swim the sawfish is unable to move water over gills and may drown

Illegal FishingIllegal Fishing • Sawfish are hunted for theirSawfish are hunted for their– RostrumsRostrums– FinsFins– FleshFlesh– Other body partsOther body parts

• These are sold for food and use These are sold for food and use in traditional Asian medicines in traditional Asian medicines

• Rostrums are sold as valuable Rostrums are sold as valuable souvenirs, trophies or curios souvenirs, trophies or curios

• Sawfish may also be collected as Sawfish may also be collected as live specimens for aquariumslive specimens for aquariums

Habitat degradation through Habitat degradation through coastal developmentcoastal development

• Building of weirs and Building of weirs and barrages can restrict barrages can restrict movement of sawfish in movement of sawfish in riversrivers

• Other problems include Other problems include increased pollution from: increased pollution from: – Use of fertilisers - Use of fertilisers -

increased nutrient runoff increased nutrient runoff – Use of pesticides - Use of pesticides -

reduced health and death reduced health and death of organisms of organisms

Loss of soft bottom Loss of soft bottom feeding and breeding feeding and breeding habitats through habitats through coastal coastal urban/industrial urban/industrial developmentdevelopment

Green Sawfish Recovery PlanGreen Sawfish Recovery PlanObjectives - • Background on species and ecology• Distribution and location• Known and potential threats• Recovery Actions

Other - Achieving multi-species outcomes that apply to estuarine stingray which occupy the same habitat

Distribution and locationDistribution and location• Once common along the east coast of Australia, and found as far

south as Jervis Bay, is now rarely found south of Cairns

• Estuaries along east coast of central QLD almost certainly provided suitable habitat in the past

• No museum records from central QLD, last records from east coast from Moreton Bay in 1970s

Spotted any Sawfish?• Unconfirmed reports of

sightings in the region as recently as 2004

• Possible breeding area located near the mouth of the Fitzroy River

For further information contact:Dr Ashley BunceCentre for Environmental ManagementCentral Queensland University

Tel: 07 4970 7285E-mail: a.bunce@cqu.edu.au

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