BMRG Coastal Forum

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Green Sawfish Recovery Plan Project
BMRG Coastal Forum 19th April 2008
Dr Ashley Bunce Centre for Environmental
Management Central Queensland University
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Sawfish

• 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)

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Australian Sawfish Species

• There are 4 known sawfish species in Australian
  Waters
• Narrow sawfish (Anoxypristis cuspidata)
• Freshwater sawfish (Pristis microdon)
• Green sawfish (Pristis Zijsron)
• Dwarf sawfish (Pristis clavata)
• These species occupy niches in marine estuarine
  
• and freshwater environments

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Green Sawfish

• Taxonomy

• Order - PristiformesFamily - PristidaeGenus -
  PristisSpecies - zijsron

Conservation Status IUCN Red List - Critically
endangered EPBC vulnerable QLD Back on
Track priority species NSW critically
endangered NT Fisheries - vulnerable
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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

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• Description
• Large slender body
• Olive brown-green dorsally and pale white
  ventrally
• Rostrum does not narrow at tip
• Descriptors
• 24-28 pair of teeth
• Teeth are moreclosely spaced at tip and extend
  onto base of saw
• No fork in caudal fin
• 1st dorsal fin begins behind pelvic fin origin
• Rough skin
• Size
• Maximum reported size 730cm
• Diet
• Prawns and fish

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Biology

• Long-lived (25-30 years)
• Gestation period (fertilisation to birth time) is
  approx. 5 months
• Average of 8 pups are born at around 65-90cm
• Pups born with a toothed rostrum which is covered
  by a enclosed membrane designed to protect mother
  from teeth

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Behaviour

• Sawfish are nocturnal
• Sleep in the day
• Hunt at night
• Sawfish are top order predators
• Actively seek out prey items such as fish and
  crustaceans

• Use rostrum for feeding by
• Stunning slow moving schooling fish with slashing
  motion
• Locating and dislodging prey buried in sand or
  mud
• Locate buried prey by using sensors on rostrum
• Will also eat dead prey and strike at lures

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Threats to Sawfish
Conservation Status IUCN Red List - Critically
endangered EPBC vulnerable QLD Back on
Track priority species NSW critically
endangered NT Fisheries - vulnerable

• Saw fish are threatened throughout the world
• All Australian species are on the IUCN Redlist of
  threatened species as critically endangered
• Because they prefer an inshore benthic habitat
  for breeding, the juveniles are vulnerable to
  human interference
• They are also known to actively seek out dead
  baits or strike at lures making them vulnerable
  to recreational fishing

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Threats to Sawfish

• Major threats include
• Accidental capture/Entanglement in fishing nets
• Illegal fishing for fins or rostrums
• Habitat degradation through coastal development

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Entanglement in fishing 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

• Entanglement may occur in
• Trawling nets
• Inshore net fishery
• Recreational fishing (line and small mesh cast
  and seine nets)

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Illegal Fishing

• Sawfish are hunted for their
• Rostrums
• Fins
• Flesh
• Other body parts
• These are sold for food and use in traditional
  Asian medicines
• Rostrums are sold as valuable souvenirs, trophies
  or curios
• Sawfish may also be collected as live specimens
  for aquariums

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Habitat degradation through coastal development

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

• Other problems include increased pollution from
• Use of fertilisers - increased nutrient runoff
• Use of pesticides - reduced health and death of
  organisms

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

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Green Sawfish Recovery Plan

• Objectives -
• 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
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Distribution 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

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Supported by
For further information contact Dr Ashley
Bunce Centre for Environmental Management Central
Queensland University Tel [phone] E-mail
a.bunce_at_cqu.edu.au