Fish and freshwater crayfish in streams in the Cape Naturaliste region & Wilyabrup Brook · 2011....

Fish and freshwater crayfish in streams in the Cape Naturaliste region & Wilyabrup Brook

S Beatty & D Morgan

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FFIISSHHEERRIIEESS RREESSEEAARRCCHH

Prepared for the Cape to Cape Catchments Group & GeoCatch

C Jury J Mitchell

Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish

1

Acknowledgements

Funding for the project was provided from the Cape to Cape Catchments Group through the

South West Catchments Council (National Action Plan for Salinity and Water Quality).

We would like to thank the many landholders in the region for providing site access, including

Mark Joliffe, David Burch, Paul Hick, Brookland Valley and Juniper Estate.

An electronic copy of the report is available from:

wwwscieng.murdoch.edu.au/centres/fish/curres/Freshwater.html

The report should be sited as:

Beatty, S., Morgan, D., Jury, C. & Mitchell, J. (2006). Fish and freshwater crayfish in streams in the Cape Naturaliste region & Wilyabrup Brook. Report to the Cape to Cape Catchments Group and GeoCatch.


2

Background This study was conducted in order to determine the fish and freshwater crayfish

communities of a number of streams in the Cape Naturaliste region and Wilyabrup

Brook. This information will be used by the Cape to Cape Catchment Group and

GeoCatch in the development of river action plans for the various systems. Systems

examined during this study include Wilyabrup Brook, Jingarmup Brook, Dugulup

Creek, Dandatup Brook and Meelup Brook (see Figures 1 and 2).

Freshwater fishes of south-western Australia

The south-west region of Western Australia houses 10 species of native freshwater fish,

80% of which are found nowhere else. Nine of these species are widespread or

restricted in distribution within the relatively high rainfall region from the Moore River

in the north to just east of Albany. The relatively common and widespread species

include the Western Minnow (Galaxias occidentalis), the Western Pygmy Perch (Edelia

vittata), the Nightfish (Bostockia porosa) and the Freshwater Cobbler (Tandanus bostocki).

The Mud Minnow (Galaxiella munda) and Balston’s Pygmy Perch (Nannatherina balstoni)

are threatened species restricted to the south-western corner from Margaret River to the

Albany (with disjunctive populations also occurring in the Moore River catchment).

The Black-stripe Minnow (Galaxiella nigrostriata) and the Salamanderfish (Lepidogalaxias

salamandroides) are also threatened species found in pools from Augusta to Albany with

disjunct populations of Black-stripe Minnows also occurring in pools near Bunbury and

the Swan River catchment.

The inland distribution of many of these species has contracted substantially, due

largely to habitat alterations, particularly: secondary salinisation, eutrophication,

riparian degradation and river regulation. Another major threat to these native fishes

has been impacts of introduced fishes, particularly: Rainbow Trout (Oncorhynchus

mykiss), Brown Trout (Salmo trutta), Redfin Perch (Perca fluviatilis), Eastern Mosquitofish

(Gambusia holbrooki) and Goldfish (Carassius auratus). The impacts that these species


3

have on native fishes, freshwater crayfishes and the freshwater ecosystems as a whole

are beginning to be determined and include direct predation and competition for

resources such as food and habitat (Pen and Potter 1991, Gill et al. 1999, Beatty 2000,

Morgan et al. 2002, 2004).

Estuarine fishes of south-western Australia

There are several estuarine species in south-western Australia that are also found, and

able to breed, in freshwater environments. The most common of these species (in

freshwaters) are the Swan River Goby (Pseudogobius olorum), the Western Hardyhead

(Leptatherina wallacei) and Big-headed Goby (Afurcagobius suppositus) (Morgan et al.

1998). Although several other species also occasionally enter freshwater systems in the

region, the most commonly encountered are Black Bream (Acanthopagrus butcheri),

Yellow-tail Trumpeter (Amniataba caudavittata) and Sea Mullet (Mugil cephalus).

Freshwater crayfishes of south-western Australia

Western Australia contains six naturally occurring species of freshwater crayfish from

the genus Cherax, all of which are found within the south-western corner of the State.

Translocation of the widespread Marron (Cherax cainii) has resulted in it now being

found as far north as the Hutt River (north of Geraldton) to the Esperance region. The

common Gilgie (Cherax quinquecarinatus) and the common koonac (Cherax preissii) are

found from approximately Moore River to just east of Albany (Austin and Knott 1996).

The Margaret River Hairy Marron (Cherax teniumanus) is only found in that river and

the remaining two species, the restricted Gilgie (Cherax crassimanus) and restricted

Koonac (Cherax glaber) are found in the extreme southern corner of the south-west

within the region approximately from Margaret River to Walpole (Austin and Knott

1996).

There are also five species of the ‘land crayfishes’ belonging to the genus Engaewa.

These are generally found where the water table remains under the ground surface and


4

include E. subcoerulea, E. reducta, E. similis Riek, E. walpolea and E. pseudoreducta

(Horwitz and Adams 2000). As with the fish fauna of this State, there is a high rate

(100%) of endemism of the native crayfishes.

Two introduced species of crayfish are also found in Western Australia, being the

redclaw (C. quadricarinatus) (found in the Kimberley region) and the widespread Yabbie

(C. destructor) which is found throughout the south-west region and the subject of

aquaculture in the wheatbelt region. The Yabbie has escaped into many wild systems in

the south-west (see Discussion) and has the potential to severely impact aquatic

ecosystems (Beatty et al. 2005a).

Cape Naturaliste streams and Wilyabrup Brook

The streams of Cape Naturaliste examined during this study are small, mostly

ephemeral and flow north into Geographe Bay. Wilyabrup Brook, which flows west

into the Indian Ocean, is the largest, with a catchment of ~90 km2 and a mean annual

flow the second largest in the region after Margaret River. The fish and freshwater

crayfish fauna of these streams has not previously been documented. The upstream

sections of the streams largely flow through semi-intensive agriculture (mostly

viticulture, dairy or grazing) with downstream-most sections of most streams passing

through either national park (particularly on the western side of the Cape (Leeuwin-

Naturaliste National Park)) or urban areas (e.g. Dugulup Creek and Dandatup Brook

that pass through Dunsborough). With the exception of Meelup Brook which is almost

completely within the regional park, the proportion of catchments that are cleared

ranges from approximately 50-75%. The flow regimes of some of these systems, in

particular Wilyabrup Brook, are substantially altered by a number of large dams.

Aims and utilisation of the study

The aim of this study was to determine the fish and freshwater crayfish communities of

Jingarmup Brook, Meelup Brook, Dugulup Creek, Dandatup Brook and Wilyabrup


5

Brook (see Figures 1 and 2). This information will be utilised in the development of

River Action Plans for those systems that are being prepared by the Cape to Cape

Catchments Group and GeoCatch.

Methodology A total of 10 sites were sampled during the study in September 2005: three sites on

Jingarmup Brook, two on each of Dugulup Creek and Dandatup Brook; one on Meelup

Brook; and four sites on Wilyabrup Brook. An additional two sites were sampled on

Wilyabrup Brook during November 2005 (Figures 1, 2 and 3). As flows were high in

Wilyabrup Brook during the 2005 sampling, in March 2006 two sites were re-sampled

and compared with previous sampling.

At each site, three replicates of water temperature (°C), conductivity (µS/cm), pH and

dissolved oxygen (ppm) were measured and a mean determined.

Each site was sampled over an area of up to 360 m2 depending on the degree of variable

habitat in order to ensure that all prevailing fish and freshwater crayfish fauna was

recorded. Sampling was primarily undertaken using a back-pack electrofisher (Smith-

Root Model 12-A), which temporarily stuns fish and crayfish up to a diameter of

approximately 2 m. A variety of seine nets were also deployed depending on the

habitat (suitable, for example, in the wider, shallow reaches of the systems).

All fish and freshwater crayfish were identified to species and measured to the nearest

1-mm total length (TL) (for fish) or orbital carapace length (OCL) (for freshwater

crayfish). To determine the population structures of the fish and crayfish fauna within

each system, length-frequency histograms of each species (particularly those captured

in adequate numbers to allow analysis) were produced.


6

Jingarmup 1

Jingarmup 2

Jingarmup 3

Meelup 1

Dugulup 1Dugulup 2

Dandatup 1

Dandatup 2

1 km

Figure 1 Sites sampled in streams in the Cape Naturaliste region during spring

2005 to determine their fish and freshwater crayfish communities.

Wilyabrup 3Wilyabrup 4

Wilyabrup 5

Wilyabrup 1

Wilyabrup 6

Wilyabrup 2

1 km

Figure 2 Sites sampled on Wilyabrup Brook during spring 2005 to determine the

fish and freshwater crayfish communities.


7

Figure 3 Examples of sites sampled for fish and freshwater crayfish communities in

streams flowing from Cape Naturaliste and Wilyabrup Brook.

Jingarmup 2 Meelup 1

Wilyabrup 3 Wilyabrup 6

Dugulup 2 Dandatup 1


8

Results and Discussion

Jingarmup Brook

Physicochemical variables

The mean temperature, conductivity and pH increased markedly between the

uppermost site on Jingarmup Brook and the two downstream sites whereas the

dissolved oxygen was lower at the more downstream sites (Figure 4).

C

ondu

ctiv

ity (µ

S/c

m)

500600700800900

1000110012001300

Tem

pera

ture

(oC

)

15.4

15.6

15.8

16.0

16.2

16.4

pH

7.15

7.20

7.25

7.30

7.35

7.40

7.45

Sites

Jin 1

Jin 2

Jin 3

O2

(ppm

)

8.48.68.89.09.29.49.69.8

10.0

Figure 4 Mean temperature, conductivity, pH and dissolved

oxygen (+ 1 S.E.) of the sites sampled in Jingarmup Brook during spring 2005.


9

Fish fauna

There were no native freshwater fishes captured in Jingarmup Brook during this study

(Appendix 1). However, the first record of a wild population of the introduced Rosy

Barb (Puntius conchonius) (often referred to as Barbus conchonius) in W.A. was recorded

at Jin 2 (Eagle Bay) where it was found at a density of 0.14/m2 (Appendix 1, Figure 5).

The wide size range of this species (20-58 mm TL) (Figure 6) suggests that it has formed

a self-maintaining population and was probably established after the deliberate release

of aquarium specimens (see Fish fauna general discussion).

Relatively high densities of the estuarine Swan River Goby and the Sea Mullet were

near the mouth of the stream (Appendix 1, Figures 5 and 6). The Swan River Goby is

able to complete its life-cycle in freshwater whereas the Sea Mullet spawns in deep

water off the coast (Thomson 1963) and uses estuaries and rivers as a nursery ground

(Orr 2000). Although their length-frequency distributions demonstrated that their size

ranges were similar, all Sea Mullet captured were juveniles while the population of

Swan River Goby comprised adults and juveniles (Figure 6).

Freshwater crayfish

The Gilgie was captured at all three sites in Jingarmup Brook, the greatest densities

occurring at the uppermost site (Appendix 1). This declining trend in the densities of

Gilgies moving downstream was consistent with that observed in the other streams

sampled (see Figure 7). Two distinct cohorts of Gilgies were present, with the 0+ cohort

(new recruits) dominating the population (Figure 6). As mentioned, this species has a

very wide distribution in the south-west where it occupies almost the entire range of

freshwater habitats (Austin and Knott 1996). Its success is attributed to an ability to

occupy seasonally inundated systems by burrowing into the water table, being able to

spawn multiple times over spring and summer, and being capable of tolerating low

oxygen and relatively extreme water temperatures (Austin and Knott 1996; Beatty et al.

2005b).


10

Figure 5 The fish and freshwater crayfishes captured during the present study.

Native freshwater fish Native estuarine fish

Introduced freshwater fish

Native freshwater crayfish

Introduced freshwater crayfish

Western Minnow

Rosy Barb

Western Hardyhead

Sea Mullet

Swan River Goby

Marron

Gilgie

Yabbie


11

Orbital carapace length (mm)4 8 12 16 20 24 28 32 36 40

Freq

uenc

y0

10

20

30

40

10 20 30 40 50 60

Freq

uenc

y

0

5

10

15

20

Total length (mm)

10 20 30 40 50 60

Freq

uenc

y

0

2

4

6

8

10

Total length (mm)

10 20 30 40 50 60

Freq

uenc

y

0

2

4

6

8

10

Sea Mullet

Swan River Goby

Rosie Barb

Gilgie


Native estuarine fish

Introduced freshwater fish

Figure 6 Length-frequency histograms of the most abundant species

of fish and freshwater crayfish captured in Jingarmup Brook during the study.


12

Site

Jin 1

Jin 2

Jin 3

Dug 1

Dug 2

Dan 1

Dan 2 W

il 1W

il 2W

il 4W

il 5

Den

sity

(per

m2 )

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Figure 7 Densities of the Gilgie captured at sites in Jingarmup Brook (Jin),

Dugulup Brook (Dug), Dandatup Brook (Dan) and Wilyabrup Brook (Wil) during spring 2005. N.B. General decline in densities from upstream to downstream sites.

Meelup Brook


Meelup Brook was only sampled near the mouth upstream and downstream of the dam

adjacent to the beach. This site had the highest conductivity of any site sampled in the

study (2197±36 µS/cm).


13

Fish fauna

Juvenile Sea Mullet (Figure 5) were captured near the mouth of Meelup Brook

downstream of the dam. Its presence here represents the fact that small juvenile mullet

use rivers and their estuaries as nursery areas.

Freshwater crayfish fauna

Marron was the only freshwater crayfish recorded in Meelup Brook (Appendix 1,

Figure 5). This species is likely to have been introduced into the artificial dam

approximately 100 m from the mouth of Meelup Brook, with some individuals moving

downstream into rocky areas on the beach. Meelup Brook may also house Gilgies in

upstream sections that were not sampled during the current study, however none was

found in the lower part of the stream above the dam.

Dugulup Brook


The temperature and conductivity was greater and the pH and dissolved oxygen lower

at the uppermost site on Dugulup Brook compared with the downstream site in central

Dunsborough (Figure 8).

Fish fauna

There were no fish captured in Dugulup Brook during sampling (Appendix 1). The

mouth of the stream was not sampled where estuarine species (e.g. Swan River Goby

and Sea Mullet) may have been expected to have been captured.

Freshwater Crayfish

The Gilgie was recorded at both sites in Dugulup Creek (Appendix 1, Figure 7). This

species had multiple age cohorts with a relatively wide size range indicatitive of a self-

maintaining population (Figure 9). As with the other streams, the greatest density of

Gilgies was recorded at the uppermost site (Figure 7).


14

Con

duct

ivity

(µS

/cm

)

770

780

790

800

810

820

Tem

pera

ture

(oC

)

15.2

15.3

15.4

15.5

15.6

15.7

pH

6.85

6.90

6.95

7.00

7.05

7.10

7.15

Sites

Dug 1

Dug 2

O2

(ppm

)

9.0

9.2

9.4

9.6

9.8

10.0

Figure 8 Mean temperature, conductivity, pH and dissolved oxygen (+ 1

S.E.) of the sites sampled in Dugulup Brook during spring 2005.

Orbital carapace length (mm)

4 8 12 16 20 24 28 32

Freq

uenc

y

0

5

10

15

20

25Gilgie


Figure 9 Length-frequency histogram of the Gilgie captured in

Dugulup Brook during the study.


15

Dandatup Brook


In Dandatup Brook, the temperature, conductivity and pH was lower at the upstream

site compared to the downstream site whereas dissolved oxygen was relatively similar

(Figure 10).

Con

duct

ivity

(µS/

cm)

620640660680700720740760780

Tem

pera

ture

(oC

)

14.4

14.6

14.8

15.0

15.2

15.4pH

6.56.66.76.86.97.07.17.27.3

Sites

Dan 1

Dan 2

O2

(ppm

)

9.05

9.10

9.15

9.20

9.25

9.30


S.E.) of the sites sampled in Dandatup Brook during spring 2005.

Fish fauna

There were no fish captured in Dandatup Brook during sampling (Appendix 1).

Although one site sampled was located only ~300 m from the mouth of the stream, no


16

estuarine species were recorded but may have been present further toward the mouth.

Freshwater Crayfish

The Gilgie was again present in relatively high densities and was most abundant at the

upstream site (Appendix 1, Figure 7). As with the previous two streams, the length-

frequency distribution showed a dominance of 0+ individuals with older cohorts also

present indicating a sustainable population (Figure 11).


4 8 12 16 20 24 28 32 36

Freq

uenc

y

02468

10121416

Gilgie


Figure 11 Length-frequency histogram of the Gilgie captured in

Dandatup Brook during the study.

Wilyabrup Brook


Aside from Wil 1 (on the northern branch of the stream), there was a general trend for

mean temperature, conductivity, pH and dissolved oxygen to increase from

downstream to upstream (Figure 12).


17

Con

duct

ivity

(µS

/cm

)

250300350400450500550600650

Tem

pera

ture

(oC

)

1415161718192021

pH

6.26.46.66.87.07.27.47.67.88.0

SitesW

il 1

Wil 2

W

il 3W

il 4W

il 5W

il 6

O2

(ppm

)

7.07.58.08.59.09.5

10.010.511.0


S.E.) of the sites sampled in Wilyabrup Brook during spring 2005.

Fish Fauna

Wilyabrup Brook was the only stream sampled during this study where the Western

Minnow and Western Pygmy Perch were recorded (Appendix 1, Figure 5). The

Western Minnow was recorded at a high density at Wil 3 (Howard Park/Madfish

Winery) with large numbers present below an artificially created barrier (see Figure 3).

The population of Western Minnow recorded here and downstream at Wil 4 (Juniper

Winery site), again below a small artificial barrier, included large numbers of juveniles

as well as lager adult fish up to 95 mm TL (Figure 13). Relatively high densities of

Western Pygmy Perch were also recorded at Juniper Winery in amongst partially

submerged riparian grasses with low densities also recorded upstream at Wil 3.


18


4 8 12 16 20 24 28 32 36 40Fr

eque

ncy

02468

101214

4 8 12 16 20 24 28 32 36 40

Freq

uenc

y

0

1

2

3

4

0 20 40 60 80 100

Freq

uenc

y

0

2

4

6

8

10

12

Total length (mm)

0 20 40 60 80 100

Freq

uenc

y

0

2

4

6

8

10

12

Marron

Western Pygmy Perch

Western Minnow

Gilgie

0 20 40 60 80

Freq

uenc

y

0

2

4

6

8

10

12Western Hardyhead

Total length (mm)

0 20 40 60 80

Freq

uenc

y

0

2

4

6

8

10

12Swan River Goby


Native freshwater fish Native estuarine fish

Figure 13 Length-frequency histograms of the most abundant species of fish and freshwater

crayfish captured in Wilyabrup Brook during spring 2005.


19

This species spawns in spring (approximately the time of sampling) which would have

resulted in only a single 0+ juvenile being recorded with age 1+ or greater fish (>~35 mm

TL) dominating catches (Figure 13).

The high density of the Western Minnow below the barrier at Wil 3 (and their absence

above) suggests that it acts as a barrier to upstream movement of this species

(Appendix 1, Figure 3). Furthermore, the very low density of Western Pygmy Perch

above the small barrier at Juniper Winery compared with the high densities below also

suggests that this may be acting as a barrier to its upstream movement (Appendix 1).

The fast-swimming, streamlined Western Minnow is more accomplished at overcoming

barriers than the Western Pygmy Perch that would explain its ability to negotiate the

relatively small barrier at Juniper Winery and attain the high densities recorded at Wil

3. However, the considerable barrier upstream at Howard Park Winery would not be

able to be negotiated by this species (see Figure 3).

The Swan River Goby was recorded at sites Wil 3, Wil 4, and Wil 6 (mouth) (Figure 3).

The high densities and wide size range incorporating multiple cohorts indicates that

this is a self-maintaining population in Wilyabrup Brook (Appendix 1, Figure 13). The

other estuarine species captured was the Western Hardyhead that was only recorded at

the mouth at a relatively high density (0.76/m2) (Appendix 1, Figure 13). There are

reports of several other estuarine species within the mouth of this system.

Freshwater crayfish

Three species of freshwater crayfish were captured in Wilyabrup Brook (Appendix 1).

The Gilgie was the most widespread and abundant species in Wilyabrup Brook being

found in four of the six sites (Appendix 1). The Gilgie was absent at the Howard

Park/Madfish Bay site where the introduced Yabbie was recorded at a density of

0.04/m2 (Appendix 1). This site also contained Marron at the same density as the Yabbie

and the presence of these two species may have resulted in the exclusion of the Gilgie

from that stretch of stream below the artificial barrier (see Figures 3 and 13).


20

Fish fauna general discussion

The only stream that contained native freshwater fishes was Wilyabrup Brook, which

contained self-maintaining populations of Western Pygmy Perch and Western Minnow.

The other systems are relatively small and generally flow from May-November. The

native freshwater fish of this region, such as the two species captured in Wilyabrup

Brook, and others not present in these streams but known to be found in this region

(such as the Nightfish and Freshwater Cobbler), require permanent water to survive at

least in the form of refuge pools with adequate water quality should the system cease to

flow in summer. Therefore, the presence of native freshwater fish only in Wilyabrup

Brook (the largest of these systems) is not unexpected. It is however, unusual that the

Nightfish was not captured within Wilyabrup Brook as it is certainly found within

nearby systems. There is also evidence, supplied by landholders, that the Mud Minnow

has previously been sighted within this system. This species is not always abundant

when found and is often associated with stream headwaters. Having a one year life-

cycle it is thus susceptible to habitat modification.

All of the streams sampled were connected to the ocean at the time of sampling and this

allowed migration of fishes between salt and fresh water in the lower reaches of

Jingarmup, Meelup and Wilyabrup Brooks. As with many streams and estuaries in

south-western Australia, the lower reaches of these systems act as important nursery

areas for species such Sea Mullet and also support populations of the Swan River Goby

and the Western Hardyhead.

Of considerable concern was the discovery of the introduced Rosy Barb within

Jingarmup Brook (in the Eagle Bay town site). This is the first recorded wild population

of this species within Western Australia, but it has previously been reported from a

suburban creek near Brisbane, Queensland (McKay 1984). The Rosy Barb is a native of

the Indian subcontinent (Afghanistan, Pakistan, India, Nepal, Bangladesh) (Allen et al.

2002, www.fishbase.org), and is a popular aquarium species. Its presence in Jingarmup


21

Brook is undoubtedly the result of a deliberate aquarium release. Within its natural

range, the species is omnivorous and is therefore likely to be important in the

structuring of food webs (Malhotra and Gupta 1990) and is likely to impact on the

prevailing aquatic community in Jingarmup Brook. Furthermore, the Rosy Barb

matures in its first year of life (Cek et al. 2003) which, together with an omnivorous diet

would aid in its rapid establishment in a new environment. An assessment of the

upstream extent of its distribution, its biology (including life-history) and ecology (diet)

of the species in this system should occur and an eradication program designed and

implemented.

Importantly, Wilyabrup Brook, or indeed none of the stream sampled during this study,

contained the undesirable introduced Eastern Mosquitofish (Gambusia holbrooki), a

species that is known to be detrimental to native fishes via competition and aggression

(Gill et al. 1999, Morgan et al. 2004).

Much of the upstream catchment of the streams in the current study was primarily

farmland and there was a resultant decline in the quality of instream habitat at those

sites. A number of sites within Wilyabrup Brook that have excluded stock from

streamlines demonstrate the benefits of improved instream habitat by allowing riparian

vegetation to re-establish. A noticeable difference in stream habitat quality was

observed at sites between the fenced and unfenced sections on Wilyabrup Brook.

Riparian protection in turn improves bank stability and allows re-generation of fish and

crayfish habitats in the form of rushes and woody debris, while also minimising

summer temperatures and turbidity.

Potential barriers to fish migration were encountered at a number of sites on Wilyabrup

Brook and also within Jingarmup Brook (see Figures 2 and 3). The major problems

associated with in-stream barriers are: the prevention of upstream spawning migrations

of native fishes (such as the Western Minnow and Western Pygmy Perch) which

reduces the overall spawning habitat available to these populations, and the potential


22

for increased mortalities (e.g. bird predation) of these species that can congregate below

these obstructions. Aside from complete removal of the obstruction, fishway

construction is proving an effective mechanism for allowing fish to negotiate these

barriers as recently shown in the Margaret River (Morgan and Beatty 2004a), the

Goodga River (Morgan and Beatty 2004b), and the Hotham River (Morgan et al. 2005).

A further assessment should be made on the potential benefit to the fishes of Wilyabrup

Brook that the construction of fishway/s may have. This should involve identifying

other obstructions that may exist on the stream and the further sampling of sites

(particularly upstream) for fishes to ensure that these barriers are in fact preventing the

establishment of native populations further upstream.

Freshwater crayfish fauna general discussion

The Gilgie was clearly the dominant species of freshwater crayfish in all systems (aside

from Meelup Brook; which was only sampled at the mouth). As mentioned, the Gilgie

has a very widespread distribution in the south-west and is found in all types of

freshwater environments including swamps, stream and rivers. Its ability to burrow to

escape drought allows it to occupy both permanent and seasonal water bodies.

Although not documented, the fact that it is a burrowing species suggests that it is

tolerant of relatively low oxygen and high temperatures. Good recruitment of the

species were found in systems where they were present with modal lengths of the new

recruits (0+ cohort) varying marginally between system, suggesting either growth or

breeding period is slightly different between the systems (see Figure 14). Further, the

0+ Gilgies were largest in the larger streams, suggesting that permanency of habitat (e.g.

Wilyabrup Brook) may lead to an earlier breeding period.

The physicochemical parameters in the streams were not extreme; however, they were

relatively small systems which do not favour Marron, a species that is most often

associated with larger, permanent waterbodies (Austin and Knott 1996). The presence

of Marron near the mouth of Meelup Brook and in Wilyabrup Brook possibly


23

represents escaped stock from nearby farm dams. At the Marron capture sites,

permanent water provided habitat (including an artificial dam at the mouth of Meelup

Brook).

0

5

10

15

20

25

30

35

40

6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 98


Freq

uenc

y Dandatup - C. quinquecarinatusDugalup - C. quinquecarinatusJingarmup - C. quinquecarinatusWilyabrup - C. quinquecarinatus

Figure 14 Length-frequency distributions of the Gilgie in the four streams sampled in spring 2005. N.B. all populations were largely dominated by the smaller (


24

Figure 15 Differences between the introduced Yabbie and the native Gilgie. Note the setae

on the carpus (‘wrist’) and merus (‘arm’) of the Yabbie (top), compared to the smooth condition in all the native freshwater crayfish of Western Australia, including the Gilgie.

The Yabbie is the most widely distributed freshwater crayfish in Australia and (like the

Gilgie) is tolerant of a wide range of environmental conditions and occupies an array of

permanent and temporary habitats in its natural range in eastern Australia (Riek 1969,

b)

a)

setae

smooth

yabbie

gilgie


25

Austin 1985, Morrissy and Cassells 1992). It was introduced into Western Australia in

1932 and is cultured in wheat-belt farm dams, however, it has escaped into a number of

natural river systems in the south-west including the Hutt River, Phillips River,

Chapman River, Irwin River, Murray River, Canning River, Swan River, Harvey River

and the nearby Vasse River and Gunyulgup Brook (Morgan and Beatty 2004c, 2005,

Beatty et al. 2005a). Its potential to out-compete native species has previously been

acknowledged (Austin 1985, Beatty et al. 2005a). Their presence in Wilyabrup and

Gunyulgup Brooks in the Cape Naturaliste region highlights the risks associated with

introducing non-native animals into areas with highly endemic biota, such as the south-

west of Western Australia (Beatty et al. 2005a). Eradication of the Yabbie from

Wilyabrup Brook would be desirable, however, total eradication would be difficult and

would depend on how far it has spread throughout the system; this distribution should

be investigated and an assessment made on the potential for its eradication.

REFERENCES

Allen, G.R., Midgley, S.H. and Allen, M. (2002). Field guide to the freshwater fishes of Australia. Western Australian Museum, Perth, Western Australia.

Austin, C.M. (1985). Introduction of the yabbie, Cherax destructor (Decapoda: Parastacidae) into southwestern Australia. Western Australian Naturalist 16, 78–82.

Austin, C.M. and Knott, B. (1996). Systematics of the freshwater crayfish genus Cherax Erichson (Decapoda: Parastacidae) in south-western Australia: Electrophoretic, Morphological and Habitat Variation. Australian Journal of Zoology 44, 223–58.

Beatty, S.J. (2000). The reproductive biology and ecological role, using stable carbon isotope analysis, of marron, Cherax tenuimanus (Smith, 1912), in Lake Navarino, south-western Australia. BSc (Hons) Thesis, Murdoch University, Australia.

Beatty, S.J., Morgan, D.L. and Gill, H.S. (2005a). Role of life history strategy in the colonisation of Western Australian aquatic systems by the introduced crayfish Cherax destructor Clark, 1936. Hydrobiologia 549,219-237.

Beatty, S.J., Morgan, D.L. and Gill, H.S. (2005b). Life history and reproductive biology of the gilgie Cherax quinquecarinatus, a freshwater crayfish endemic to south-western Australia. Journal of Crustacean Biology 25(2).

Cek, S, Bromage, N., Randall, C. and Rana, K. (2003). Oogenesis, Hepatosomatic and Gonadosomatic Indexes, and Sex Ratio in Rosy Barb (Puntius conchonius). Turkish Journal of Fisheries and Aquatic Sciences. 3 (1). 33-41.

Gill, H.S., Hambleton, S.J. and Morgan, D.L. (1999). Is Gambusia holbrooki a major threat to the native


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freshwater fishes of south-western Australia? In Seret, B. and Sire, J.-Y., (eds). Proceedings 5th Indo-Pacific Fish Conference (Noumea, 3-8 November1997). pp. 79-87. Paris: Societe Francaise d’Ichtyologie and Institut de Recherche pour le Development.

Horwitz, P. (1995). A preliminary key to the species of Decapoda (Crustacea: Malocostraca) found in Australian inland waters. Identification guide number 5. Co-operative Research Centre for Freshwater Ecology: Albury, New South Wales, Australia.

Horwitz, P. and Adams, M. (2000). The systematics, biogeography and conservation status of species in the freshwater crayfish genus Engaewa Riek (Decapoda: Parastacidae) from south-western Australia. Invertebrate Taxonomy 14, 655–80.

Malhotra, Y.R., and Gupta, A. (1990). Seasonal fluctuations in food and feeding of Puntius conchonius inhabiting Lake Mansar, Jammu. Journal of Freshwater Biology 2(2), 147-151.

McKay, R.J. (1984). Introductions of exotic fishes in Australia. p. 177-199. In Courtenay, W.R. Jr. and J.R. Stauffer, Jr. (eds). Distribution, Biology and Management of Exotic fishes. The John Hopkins University Press, Baltimore, Maryland, USA.

Morgan, D.L. and Beatty, S.J. (2004a). Margaret River Fishway. Report to the Margaret River Regional Environment Centre.

Morgan, D.L. and Beatty, S.J. (2004b). Fish utilisation of the Goodga River Fishway - conserving the Western Australian trout minnow (Galaxias truttaceus). Report to the Department of Fisheries Western Australia.

Morgan, D. and Beatty, S. (2004c). Fish fauna of the Vasse River and the colonisation by feral goldfish (Carrassius auratus). Report to Fishcare WA and Geocatch.

Morgan, D. and Beatty, S. (2005). Fish and crayfish fauna of Ellen Brook, Cowaramup Brook and Gunyulgup Brook in the Cape to Cape Region of Western Australia. Report to Ribbons of Blue/Waterwatch WA.

Morgan, D.L., Beatty, S.J. and McAleer, F.J. (2005). The Lion’s Weir Fishway – Hotham River, Western Australia. Report to the Peel-Harvey Catchment Council.

Morgan, D.L., Gill, H.S., Maddern, M.G. and Beatty, S.J. (2004). Distribution and impacts of introduced freshwater fishes in Western Australia. New Zealand Journal of Marine and Freshwater Research 38, 511-523.

Morgan, D.L., Gill, H.S. & Potter, I.C. (1998). Distribution, identification and biology of freshwater fishes in south-western Australia. Records of the Western Australian Museum Supplement No. 56: 97 pp.

Morgan, D.L., Hambleton, S.J., Gill, H.S. and Beatty, S.J. (2002). Distribution, biology and likely impacts of the introduced redfin perch (Perca fluviatilis) (Percidae) in Western Australia. Marine and Freshwater Research 53, 1211–221.

Morrissy, N.M. and Cassells, G. (1992). Spread of the introduced yabbie Cherax albidus Clark 1936 in Western Australia. Fisheries Research Bulletin Western Australia, 92.

Orr, P. (2000). The biology of four commercial fish species in a seasonally closed estuary. PhD Thesis, Murdoch University, Perth, Western Australia.

Pen, L.J., and Potter, I.C. (1991). Reproduction, growth and diet of Gambusia holbrooki (Girard) in a temperate Australian river. Aquatic Conservation: Marine and Freshwater Ecosystems 1, 159–72.

Riek, E.F. (1969). The Australian freshwater crayfish (Crustacea: Decapoda: Parastacidae), with the description of new species. Australian Journal of Zoology 17, 855–918.

Appendix 1 The densities (per m2) of the species of fish and freshwater crayfish captured in the streams sampled during this study.

Site Native freshwater

fish

Introduced freshwater

fish

Native estuarine

fish

Native decapods

Introduced decapods

Western Minnow

Western Pygmy Perch

Rosy Barb Swan River Goby

Western Hardyhead

Sea Mullet Big-headed Goby

Gilgie Marron Freshwater Shrimp

Yabbie

Jingarmup Bk Cape Naturalist Rd Jin 1

2.6

Jingarmup Bk Water Lily Cres. Jin 2

0.14

0.41

Jingarmup Bk Fern Rd Jin 3

0.39

0.14

0.07

Meelup Bk Mouth Jin 4

0.01

0.02

Dugulup Ck Caves Rd Dug 1 2.32

Dugulup Ck central Dunsborough

Dug 2 0.80

Dandatup Bk Gibson Dr. Dan 1 0.67

Dandatup Bk Gifford Rd Dan 2 0.20

Willyabrup Bk Puzey Rd Wil 1 0.07

Wilyabrup Bk Wil 2 1.56 Wilyabrup Bk

Howard Park/Madfish Wil 3

3.16 0.01 0.55 0.04 0.04

Wilyabrup Bk Juniper Winery

Wil 4 1.17 2.66 0.28 0.12

Willyabrup Bk Brookland Valley

Winery Wil 5 0.11 0.02

Wilyabrup Bk mouth Wil 6

0.04 0.76

0.04

3.10


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Fish and freshwater crayfish in streams in the Cape Naturaliste region & Wilyabrup Brook · 2011....

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