Biology and Ecology Biology and Ecology

of a Sawfishof a Sawfish

TaxonomyTaxonomyPhylum: ChordataPhylum: Chordata

Class: Chondrichthyans (sharks, rays and Class: Chondrichthyans (sharks, rays and chimeras)chimeras)

Subclass: Elasmobranchii Subclass: Elasmobranchii

Superorder: Batoidea (rays)Superorder: Batoidea (rays)Order: PristiformesOrder: Pristiformes

Family: PristidaeFamily: Pristidae

BiologyBiologyLife history strategyLife history strategyK-selected life history K-selected life history

strategy strategy Long-livedLong-lived

25-30 years25-30 yearsLarge sizeLarge size

Up to 7mUp to 7mLate sexual maturityLate sexual maturity

Approx. 10 years oldApprox. 10 years oldLow fecundityLow fecundity

8-24 pups8-24 pups

Distribution and HabitatDistribution and HabitatGlobal distribution in tropical and sub-Global distribution in tropical and sub-

tropical regionstropical regionsDistribution is currently fragmented with Distribution is currently fragmented with

most populations thought to be depletedmost populations thought to be depletedOccur in marine, freshwater and coastal Occur in marine, freshwater and coastal

habitats habitats Tolerance to freshwater dependent on Tolerance to freshwater dependent on

speciesspeciesPreference for shallow, inshore coastal and Preference for shallow, inshore coastal and

freshwater habitats but can occur to at least freshwater habitats but can occur to at least 80 m depth 80 m depth

DescriptionDescriptionClosely related to

rays with modified bodies similar to sharks

Also similar to and often confused with sawsharks

Distinguished by presence of gills on the underside of head

BehaviourBehaviourSawfish are Sawfish are

nocturnalnocturnalSleep in the daySleep in the dayHunt at nightHunt at night

Sawfish are top Sawfish are top order predators order predators

Actively seek out Actively seek out prey items such as prey items such as Fish Fish CrustaceansCrustaceansSquid Squid

Use rostrum for Use rostrum for feeding byfeeding byStunning slow Stunning slow

moving schooling moving schooling fish with slashing fish with slashing motion motion

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

Locate buried prey Locate buried prey by using sensors on by using sensors on rostrumrostrum

Will also eat dead Will also eat dead prey and strike at prey and strike at lureslures

AnatomyAnatomyRostrumRostrum Most distinguishing featureMost distinguishing feature Long flat and saw-likeLong flat and saw-like Made of cartilageMade of cartilage Contains pairs of teeth on Contains pairs of teeth on

sidessides Modified scalesModified scales

Used to detect and catch Used to detect and catch prey using motion and prey using motion and electro-sensors electro-sensors Allow detection from long Allow detection from long

distance and under distance and under sedimentsediment

Rostrum can also be used Rostrum can also be used to;to; rake through sediment to rake through sediment to

find preyfind prey Stun prey with slashing Stun prey with slashing

motionmotion Protect from predatorsProtect from predators

Also used to distinguish Also used to distinguish speciesspecies Number of teethNumber of teeth Shape of rostrumShape of rostrum

AnatomyAnatomyEyesEyesOn top of head so can On top of head so can

see when partially see when partially buriedburied

Eyesight good but often Eyesight good but often not useful due to murky not useful due to murky habitathabitat

Make up for this with Make up for this with sensitive sense organs sensitive sense organs in rostrumin rostrum

SpiracleSpiracleLocated behind the eyeLocated behind the eyeUsed to take in water Used to take in water

when lying on the bottomwhen lying on the bottom

AnatomyAnatomyFinsFins The sawfish has 4 different The sawfish has 4 different

types of fins all with different types of fins all with different usesuses

PectoralPectoral Pair of pectoral fins located Pair of pectoral fins located

behind the headbehind the head Used to lift fish when Used to lift fish when

swimmingswimming Helps with steeringHelps with steering Consists of cartilage spread Consists of cartilage spread

out in fan shapeout in fan shape Does not reach edge of fin Does not reach edge of fin Makes fin pliable Makes fin pliable

increasing increasing manoeuvrability manoeuvrability

Dorsal Dorsal

Dorsal means back or upper surfaceDorsal means back or upper surface

2 dorsal fins2 dorsal fins

Used for stabilisationUsed for stabilisation

Pelvic Pelvic

Pair of pelvic fins located on side behind Pair of pelvic fins located on side behind the pectoral finsthe pectoral fins

Used for stabilisation while swimmingUsed for stabilisation while swimming

CaudalCaudal

Also known as the tail finAlso known as the tail fin

Shape differs between speciesShape differs between species

Used to generate power and speed in Used to generate power and speed in swimmingswimming

AnatomyAnatomyPelvic Pelvic Pair of pelvic fins located on Pair of pelvic fins located on

side behind the pectoral finsside behind the pectoral finsUsed for stabilisation while Used for stabilisation while

swimmingswimming

CaudalCaudalAlso known as the tail finAlso known as the tail finShape differs between Shape differs between

speciesspeciesUsed to generate power and Used to generate power and

speed in swimmingspeed in swimming

Dorsal Dorsal Dorsal means back or Dorsal means back or

upper surfaceupper surface

2 dorsal fins2 dorsal fins

Used for stabilisationUsed for stabilisation

AnatomyAnatomyInternal AnatomySawfish don’t contain

swim bladder for buoyancy

Instead have an oil filled liver like sharks and rays

Underside of SawfishLike rays the flat

ventral or underside of sawfish containNostrils (nares)MouthGill slits

Jaw contains thousands of dome shaped teethUsed to crush small

fish and crustaceans e.g. Crabs and shrimp

Reproductive BiologyReproductive BiologyReproduce through Reproduce through

internal fertilisationinternal fertilisationMale contain claspers Male contain claspers

Modification of pelvic Modification of pelvic

finfinUsed to insert sperm Used to insert sperm

into femaleinto female

OvoviviparousOvoviviparousEggs are fertilised Eggs are fertilised

and grow within and grow within mothermother

Hatch within womb Hatch within womb and mother gives and mother gives birth to fully birth to fully developed pupsdeveloped pups

Reproductive BiologyReproductive BiologyAverage of 8 pups are born at around 65-90cmAverage of 8 pups are born at around 65-90cm

Gestation period (fertilisation to birth time) is approx. Gestation period (fertilisation to birth time) is approx. 5 months5 months

Number and size of pups increase with maturity of Number and size of pups increase with maturity of birthing motherbirthing mother

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

Growth rateGrowth rate Rapid in first year of lifeRapid in first year of life Slows considerably as maturity reachedSlows considerably as maturity reached

Saw fish are threatened throughout the worldSaw fish are threatened throughout the world

All Australian species are on the IUCN Redlist of All Australian species are on the IUCN Redlist of threatened species as critically endangered threatened species as critically endangered

Because they prefer an inshore benthic habitat for Because they prefer an inshore benthic habitat for breeding ,the juveniles are vulnerable to human breeding ,the juveniles are vulnerable to human interferenceinterference

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

Major threats includeMajor threats includeHuntingHuntingHabitat modification and Habitat modification and

pollutionpollutionEntanglement in fishing netsEntanglement in fishing nets

HuntingHunting Sawfish are hunted for theirSawfish are hunted for their

RostrumsRostrumsFinsFinsFleshFleshOther body partsOther body parts

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

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

Sawfish may also be collected Sawfish may also be collected as live specimens for as live specimens for aquariumsaquariums

Habitat modification and pollutionHabitat modification and pollutionBuilding of weirs and Building of weirs and

barrages can restrict barrages can restrict movement of sawfish movement of sawfish in riversin rivers

Other problems include Other problems include increased pollution from: increased pollution from: Land clearing - Land clearing -

increased sediment increased sediment runoff runoff

Use of fertilisers - Use of fertilisers - increased nutrient increased nutrient runoff runoff

Use of pesticides - Use of pesticides - reduced health and reduced health and death of organisms death of organisms

Urban and industrial Urban and industrial developmentdevelopment

Loss of soft Loss of soft bottom bottom feeding and feeding and breeding breeding habitats habitats also poses a also poses a threatthreat

Entanglement in fishing netsEntanglement in fishing nets

Entanglement may occur inTrawling netsShark netsRecreational

fishing line

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