-
Fish and freshwater crayfish in streams in the Cape Naturaliste region & Wilyabrup Brook
S Beatty & D Morgan
FFrreesshhwwaatteerr FFiisshh RReesseeaarrcchh && CCEENNTTRREE FFOORR FFIISSHH &&
FFIISSHHEERRIIEESS RREESSEEAARRCCHH
Prepared for the Cape to Cape Catchments Group & GeoCatch
C Jury J Mitchell
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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.
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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.
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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.
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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.
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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).
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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 freshwater crayfish
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.
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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
Physicochemical variables
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).
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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
Physicochemical variables
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).
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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
Native freshwater crayfish
Figure 9 Length-frequency histogram of the Gilgie captured in
Dugulup Brook during the study.
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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Dandatup Brook
Physicochemical variables
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
Figure 10 Mean temperature, conductivity, pH and dissolved oxygen (+ 1
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
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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).
Orbital carapace length (mm)
4 8 12 16 20 24 28 32 36
Freq
uenc
y
02468
10121416
Gilgie
Native freshwater crayfish
Figure 11 Length-frequency histogram of the Gilgie captured in
Dandatup Brook during the study.
Wilyabrup Brook
Physicochemical variables
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).
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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
Figure 12 Mean temperature, conductivity, pH and dissolved oxygen (+ 1
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.
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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Orbital carapace length (mm)
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 crayfish
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.
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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).
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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
Orbital carapace length (mm)
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 (
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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
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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
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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.
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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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Cape Naturaliste streams and Wilyabrup Brook: Fish and Freshwater Crayfish
28