September 2009

by DL Morgan, SJ Beatty & GA Sarre

Ascending the Avon: of the Northam Pool, and the Swan‐Avon Catchment

By DL Morgan, SJ Beatty & GA Sarre Centre for & Fisheries Research Murdoch University South St Murdoch, Western

September 2009

Acknowledgements

This project was funded by the Northam Shire Council, Lotterywest andy Avon Valle Environmental Society. We greatly acknowledge the support of Karin Strehlow and the assistance of the local community. The historical data provided in this report is from the Western Australian Freshwater Fish Database of the Freshwater Fish Group at Murdoch University’s Centre for Fish & Fisheries Research.

1

Summary

The fish fauna in the vicinity of the Northam Pool Weir was sampled seasonally between winter 2008 and autumn 2009. The results indicate that the fish community was characterised by that are halotolerant including two estuarine species, the Western Hardyhead and Swan River Goby that are likely to have undergone large upstream expansions in the Swan‐Avon catchment due to secondary salinisation. However, two freshwater endemic species, the Western and Nightfish were also recorded in the vicinity of the weir. These, and other freshwater endemic species, have undergone large range reductions in this catchment as a result of salinisation. The study found evidence that the weir may be impeding the upstream movements of native fishes as found elsewhere in south‐ and that construction of a well‐designed fishway would enhance population connectivity and increase their sustainability.

It is recommended that additional sampling occurs during the major spawning periods of the freshwater species immediately below the weir to determine precisely when a future fishway would need to operate to allow maximum usage by resident native species. It is also recommended that fresh refuge habitats for freshwater fishes be identified to allow effective management measures to be implemented in those systems to halt their decline and reduce the risk of complete loss of these species from the Swan‐Avon catchment.

2

Contents

Summary………………………………………………………………………………………. 2

Contents……………………………………………………………………………………….. 3

Introduction………………………………………………………………………………….. 4

Fishes of the Swan River Catchment………………………….………………………………….. 4

Materials and Methods…………………………….………………………………….. 5

Fishes of Northam Pool……………………………………….………………………………….. 5

Environmental variables……………………………………...………………………………….. 5

‘Freshwater’ fishes of the Swan River Catchment……………………………………………….. 6

Results and Discussion……………..……………….………………………………….. 8

Fishes of Northam Pool……………………………………….………………………………….. 8

Additional aquatic taxa……………………………………….………………………………….. 13

Fishes of the Swan River Catchment………………………….………………………………….. 14

Summary and Recommendations…….……….………………………………….. 20

References……………………………………...……….………………………………….. 22

3

Introduction

Fishes of the Swan River Catchment

The Swan‐Avon catchment is the largest in all of the South West Drainage Division, which extends from the in the north to Esperance in the south‐east. The Swan‐Avon catchment, including the , drains some 120,000 km2. In contrast to the volume of published fish related studies in the Swan River Estuary (e.g. Chubb et al. 1979, 1981, Prince & Potter 1983, Chub & Potter 1984, 1986, Gill & Potter 1993, Humphries & Potter 1993, Wise et al. 1994, Gill et al. 1996, Potter & Hyndes 1999, Kanandjembo et al. 2001, Sarre et al. 2000, Sarre & Potter 2000), published studies on fishes in the freshwater environments of the Swan‐Canning Catchments are limited to: that by Watts et al. (1995) for the genetics and morphology of the Western Minnow (Galaxias occidentalis) in the Canning River, work by Smith et al. (2002a, b) for an outlining population of Black‐stripe Minnow (Galaxella nigrostriata) in a swamp in , a review of feral fishes in Western Australia by Morgan et al. (2004), the presence of an introduced parasitic crustacean Lernea cyprinoides in the Canning River by Marina et al. (2008), predation of Marron (Cherax cainii) by a self‐ maintaining population of Rainbow Trout (Oncohynchus mykiss) in Churchman Brook Reservoir by Tay et al. (2007). The majority of published studies of fishes in freshwaters of the catchments are thus almost exclusively related to the presence and/or impact of introduced species in these systems. The lack of published data is surprising when considering not only the highly endemic nature of the freshwater fishes in the South West Drainage Division, with 80% of the freshwater fishes found nowhere else, but also the fact that the catchment is now highly salinised. There are however a number of unpublished technical reports on fishes in the region. For the Canning River system this includes studies reported by Aquatic Research Laboratory (1988), Morrison (1988), Hewitt (1992), Morgan & Sarre (1995), Beatty et al. (2003, 2005), Maddern (2003), Tay (2005), Beatty & Morgan (2006) and Morgan et al. (2007). For the Swan‐Avon unpublished reports are limited to those tributaries in the lower catchment by Bamford et al. (1998), Morgan et al. (2000) and Maddern (2003). In light of the lack of published data and/or technical reports detailing the freshwater fishes of the Swan‐Avon, it is important to note that there is a large unpublished data set of fishes in the ‘freshwaters’ of the Swan‐Avon catchment, which is maintained by the Freshwater Fish Group in the Centre for Fish & Fisheries Research, Murdoch University.

In contrast to the Canning system, which arises is the , the secondary salinisation in the Avon is likely to have severely modified the faunal composition of the system in a similar pattern to that which has occurred in the , the South West Drainage Division’s second largest river system (see Morgan et al. 2003). Within the Blackwood River, the non‐halotolerant species have essentially disappeared from the salinised main channel and have become restricted to the fresh tributaries of the catchment (Morgan et al. 2003, Morgan & Beatty 2005, Beatty et al. 2006). There has been a subsequent increase in this part of the river by a halotolerant introduced species (Eastern ( holbrooki)) and two estuarine species (Swan River Goby (Pseudogobius olorum) and Western Hardyhead (Leptatherina wallacei)).

The overriding aim of this study was to examine the seasonal changes in the fish community of Northam Pool in the Avon River. However, in order to place this into context of the entire river system, a much needed overview of the fishes in the inland waters of the Swan‐Avon catchment was required, and for this we utilised the Western Australian Freshwater Fish Database (WAFFD) of the Freshwater Fish Group at Murdoch University’s Centre for Fish & Fisheries Research (CFFR).

4

Materials and methods

Fishes of Northam Pool

The fish fauna of Northam Pool was sampled during winter 2008 (July), spring 2008 (October), summer 2009 (January) and autumn 2009 (May). Fish were captured using replicate samples in fyke nets in winter 2008 and seine nets during each seasonal sample. All nets comprised of 2 or 3 mm woven mesh. Sampling areas included: immediately downstream of the Northam Weir (31.6471oS, 116.6718oE), immediately upstream of the weir (31.6476oS, 116.6725oE) and at a site approximately 1500 m upstream of the weir (31.6602oS, 116.6603oE) (see Figure 1). The inclusion of replicate samples above and below the dam was to provide an indication of whether the weir acts as a barrier to fish species migrating upstream. On capture, each fish was identified and each species counted, with a sub‐sampled measured for total length (TL) to the nearest 1 mm. Each fish, with the exception of introduced species, was then returned to the water. Comparisons were made between the diversity and the density of species captured using seines and were graphically illustrated using SigmaPlot. To determine whether there were significant differences between the fish faunal composition of the different reaches of the pools in the different seasons, these data were examined using Analysis of Similarity (ANOSIM) in the Primer package. To compare the fish fauna of the different sites around the weir, the densities of each species (from seine nets) were square root transformed and a Bray‐Curtis Similarity Matrix constructed. Classification and ordination was then utilised to illustrate the similarities between each reach of the pool. Where sufficient numbers of each species were measured, length‐frequency histograms were prepared using SigmaPlot and comparisons made between site and capture method.

Environmental variables

Water quality was measured at each site via three replicate records of temperature (oC), conductivity (µS/cm), total dissolved solids (TDS, ppm), dissolved oxygen (% and ppm), turbidity (NTU) and pH. Replicates were then used as the basis for reporting a mean and standard error (SE). Water quality parameters for Northam Pool are presented in Strehlow (2009).

5

Figure 1 Sample sites in Northam Pool during winter and spring 2008 and summer and autumn 2009. Image from Google Maps.

‘Freshwater’ fishes of the Swan River Catchment

In order to assess the overall distributions of fishes in the freshwaters of the Swan‐Avon catchment, historical distributions are based on those studies outlined in the introduction, plus the Western Australian Freshwater Fish Database (WAFFD) of the Freshwater Fish Group at Murdoch University’s Centre for Fish & Fisheries Research (see Figure 2). This includes fish surveys of 189 sites, additional to the sites sampled in Northam

6

Pool during this study. GPS data and species presence/absence information was utilised to create species distribution maps in MapInfo.

Freshwater Fish Group (CFFR, Murdoch University) Inland fish sampling locations Swan-Canning Catchments

Western Australia

MORTLOCKMORTLOCK RIVERRIVER NORTHNORTH

BROCKMANBROCKMAN RIVERRIVER

ELLENELLEN BROOKBROOK Northam Pool

MORTLOCKMORTLOCK RIVERRIVER EASTEAST

MORTLOCKMORTLOCK RIVERRIVER SWANSWAN RIVERRIVER PERTHPERTH HELENAHELENA RIVERRIVER AA HELENAHELENA RIVERRIVER VV OO NN RR IIIVV EE RR DALEDALE RIVERRIVER R CANNINGCANNING RIVERRIVER

AVONAVON RIVERRIVER SOUTHSOUTH

0 40 80 km

Figure 2 Sample sites for freshwater fish in the Swan‐Avon‐Canning catchments by the Freshwater Fish Group (CFFR, Murdoch University), and the Northam Pool sites.

7

Results and Discussion

Fishes of Northam Pool

During this study a total of six species of fish was recorded from Northam Pool (Plate 1). These included: two freshwater species that are endemic to south‐western Australia, the Nightfish (Bostockia porosa) and Western Minnow (Galaxias occidentalis); two species of estuarine origin, the Western Hardyhead (Leptatherina wallacei) and the Swan River Goby (Pseudogobius olorum); and two introduced species, the Eastern Mosquitofish (Gambusia holbrooki) and the Goldfish (Carassius auratus).

Plate 1 Fishes of Northam Pool, clockwise from top left: Western Minnow (Galaxias occidentalis), Western Hardyhead (Leptatherina wallacei), Eastern Mosquitofish (Gambusia holbrooki), Goldfish (Carassius auratus), Swan River Goby (Pseudogobius olorum) and Nightfish (Bostockia porosa).

The results below demonstrate that most species are breeding and self maintaining within Northam Pool and that there is evidence of congregations of at least one native freshwater fish species below the Northam Pool Weir. However, the presence of the weir would undoubtedly restrict upstream movements of other species during certain migratory periods; which could be further verified by additional more intensive sampling (see Summary and Recommendations).

Western were mostly recorded below the weir in the fyke nets with the majority moving upstream. This species is known to undergo breeding during winter and early spring (Pen & Potter 1991a) and

8 undertakes upstream movements as a pre‐cursor to spawning, therefore, the capture of these individuals moving upstream below the weir would suggest that the population downstream of the weir is being impeded by this barrier. However, the species was also captured in fyke netting at the other two sites above the weir indicating that it continues to occupy upstream habitats. Although it was obvious that multiple age cohorts of this species were present, the length‐frequencies suggested that the vast majority of fish captured were older age classes (>70mm TL) with only two 0+ fish (i.e. those new recruits) being recorded in spring 2008 (Figure 5). This may suggest a very low recruitment rate to the population during the sampling period, however, more intensive sampling would be required for this to be confirmed and quantified.

Fyke netting demonstrated considerable, yet inconsistent directional movements of the Western Hardyhead at all sites with greater numbers moving in a downstream direction below the weir and an upstream direction 1500m upstream of the weir, respectively (Figure 3). Greatest numbers of this species were recorded in spring and summer at the sites 1500 m and 20 m upstream of the weir in those seasons, respectively (Figure 4). However, they were also recorded below the weir on all occasions except autumn (Figure 4). From the length‐ frequency histograms, this species was dominated by 0+ and 1+ age classes and the presence of large numbers of both juveniles and adults suggested that it is a self‐maintaining population (Figure 5). As large numbers of the species were recorded at the upstream sites and it did not clearly aggregate below the weir, it is suggested that this typically estuarine species is not severely impacted by the presence of the barrier, however, population connectivity and therefore sustainability may be enhanced if individuals downstream could freely mix with those upstream.

A similar trend was recorded for the Swan River Goby. Although lower in abundance, the species was captured on all sampling occasions both below and upstream of the weir and there were multiple age classes present. This also suggests that the species is self‐maintaining both upstream and downstream of the weir and it therefore may not be severely impacted by the barrier, however, population connectivity may be enhanced if it was to be able to easily negotiate past the barrier.

Only two Nightfish were captured during the study; both below the weir during winter 2008 (Figures 3 and 5). These were mature male fish (74 and 101 mm TL) and it is known that males of this species mature after the end of the first year of life whereas females first breed at the end of their second year (Pen & Potter 1990). The elevated salinities in this section of the river may result in very low natural recruitment to this population and probably explains the lack of Western Pygmy Perch present (see Morgan et al. 2003; Beatty et al. 2008). The salinity tolerance of the Nightfish should be determined to compare with the salinities currently occurring in the Avon River. Although only two mature individual Nightfish were captured below the weir, should natural breeding be occurring in this section of the river, it is likely that the weir would prevent these individuals moving upstream prior to spawning in late winter early spring; the known spawning period of the species (see Pen & Potter 1990).

The feral Eastern Mosquitofish was recorded at all sites sampled with greatest numbers being recorded in summer, during the known peak spawning period of larger individuals (Pen & Potter 1991b) (Figures 3, 4 and 7). It was clearly breeding with multiple age classes present and a new 0+ cohort discernable in summer. This species is extremely invasive and damaging to native fish populations as it is a live‐bearer, breeds within its first year of life, has a protracted spawning period and is extremely aggressive towards native fishes (Pen & Potter 1991b; Gill et al. 1999).

9

Below - upstream movement Below - downstream movement Above - upstream movement Upstream - upstream movement Winter 2008 Upstream - downstream movement 10000 8000 6000 4000 2000 600 400

Adjusted abundance Adjusted 200 0 y a si imp Gob dyhead r Nightifsh ambu G Har tern Minnow rn s tern th-west Shr u ste Swan Rive We as e E W So

Species

Figure 3 Fyke netting captures during winter 2008 separated on species, site and movement direction.

10

Winter 2008 Below 8 Above 6 Upstream

4

2

0

d h is now lgie hea Goby n htifsh busia df y r g Gi rd e i m Gol a iv N a H G tern Swan R Western Mi Eastern Wes South-west Shrimp

60 Spring 2008 50 40 30 20 10 0

h h p ow s n tifs m in dfi Gilgie igh M N Gol t Shri

ern Gambusia tern Hardyhead t th-wes Swan RiverWestern Goby ou Eas Wes S Summer 2009 160 Mean relative aubundance relative Mean 140 120 100 80 60 40 20 0

h h s p tifs m Goby dfi r gh Gilgie e i Gol iv N

tern Hardyhead th-west Shri Swan R Western Minnow ou Eastern Gambusia Wes S

300 Autumn 2009 250 200 150 100 50 0

h w h s p ie no ifs m g ldfi r Goby in ght o Gil M i G Shri ive N t R tern tern Gambusia th-wes Swan Wes ou estern Hardyhead Eas W S

Figure 4 Seine netting captures at each site on each sampling occasion.

11

Western Hardyhead Swan River Goby Western Minnow

Winter 2008 Seine Fyke downstream 100 40 10 Fyke upstream 35 80 30 60 25 20 5 40 15 Abundance 10 20 5 0 0 0 0 50 100 150 200 250 0 50 100 150 200 250 0 50 100 150 200 250

Spring 2008

100 40 10 35 80 30 60 25 20 5 40 15 Abundance 10 20 5 0 0 0 0 50 100 150 200 250 0 50 100 150 200 250 0 50 100 150 200 250

Summer 2009

40 40 40 35 35 35 30 30 30 25 25 25 20 20 20 15 15 15 Abundance 10 10 10 5 5 5 0 0 0 0 50 100 150 200 250 0 50 100 150 200 250 0 50 100 150 200 250

Total length (mm)

Figure 5 Length‐frequency distribution of abundant fishes captured during the study.

Analysis of similarity (ANOSIM) between seasonal seine netting samples in Northam Pool and those immediately downstream of it suggested that while there were considerable differences, indicated by a low R value (= 0.066), these differences were not significant (p = 0.133). However, when comparing the fish captured in the seine nets in each season, ANOSIM suggested that there were significant seasonal differences in the fish captured (p < 0.023). These differences, as indicated by SIMPER, were attributed to the following: higher abundances of Western Hardyheads in spring compared to winter, summer and autumn; higher abundances of Eastern Mosquitofish in summer compared to spring, winter and autumn; higher abundances of Eastern Mosquitofish and Swan River Goby in autumn compared to winter.

12

Stress: 0.13

winter

spring

summer

autumn

Stress: 0.13

above weir

below weir

Figure 6 Ordination plot (MDS) plot of the density of fish species in each individual seine separated on seasons (top) and location relative to the Northam Pool Weir (below).

Additional aquatic taxa

The invertebrate fauna of Northam Pool is outlined in Strehlow (2009), however, we have included additional invertebrates and vertebrates captured during seasonal sampling in 2008 and 2009. The South‐west Shrimp (Palaemonetes australis) was recorded during each sampling trip in high densities; particularly below the weir

13

(Figure 4). Although its migration patterns are not fully understood, its greater density below the weir on all sampling occasions (particularly summer and autumn) suggest it may be impeded by the weir’s presence.

Further, within Northam Pool the Oblong Turtle (Chelodina oblonga) was recorded during fyke netting in winter 2008 (n = 5), and in seine nets during spring 2008 (n = 2) (Figure 7).

Seine Oblong Turtle Fyke downstream Eastern Gambusia Fyke upstream

3 Winter 2008 40 Winter 2008 35 30 2 25 20 15 1

Number of fish 10 Number of turtles of Number 5 0 0 0 50 100 150 200 250 0 50 100 150 200 250

3 Spring 2008 10 Spring 2008 9 8 2 7 6 5 4 1 3 Number of fish of Number

Number of turtles 2 1 0 0 0 50 100 150 200 250 0 50 100 150 200 250

Shell Length (mm)

40 Summer 2009 35 30 25 20 15

Number of fish 10 5 0 0 50 100 150 200 250

Total Length (mm)

Figure 7 Length‐frequency distribution of Oblong Turtle and Eastern Mosquitofish captured during the study.

Fishes of the Swan River Catchment

Collation of historical data in the WAFFD revealed that the Swan‐Avon‐Canning catchments house 60% of the South‐west Drainage Division’s native freshwater fauna (i.e. six of 10 species) (Morgan and Beatty unpublished

14 data). There is a further single record of another species in the Western Australian Museum’s records, taking the total to 70% or seven species (see Morgan et al. 1998). Figure 8 shows that the Western Minnow is relatively widespread throughout the catchment; however it appears to occur more frequently within tributary sites that are known to be fresher than the main channel of the Swan‐Avon. This suggests that it may be avoiding the higher salinity of the main channel and/or is preferring those fresh tributaries in which to spawn (see Pen & Potter 1991a; Beatty et al. 2006). However, as demonstrated by the current study, they continue to persist in the main channel.

Freshwater Fish Group (CFFR, Murdoch University) Inland fish sampling locations Swan-Canning Catchments

Galaxias occidentalis Western Australia

MORTLOCKMORTLOCK RIVERRIVER NORTHNORTH

BROCKMANBROCKMAN RIVERRIVER

ELLENELLEN BROOKBROOK

MORTLOCKMORTLOCK RIVERRIVER EASTEAST

MORTLOCKMORTLOCK RIVERRIVER SWANSWAN RIVERRIVER PERTHPERTH HELENAHELENA RIVERRIVER AA HELENAHELENA RIVERRIVER VV OO NN RR IIIVV VVEE EERR DALEDALE RIVERRIVER RR CANNINGCANNING RIVERRIVER

AVONAVON RIVERRIVER SOUTHSOUTH

0 40 80 km

Figure 8 Distribution of Western Minnow in the Swan‐Canning catchment.

15

The known distributions of the Nightfish and Western Pygmy Perch in the Swan‐Avon catchment are shown in Figures 9 and 10. In the current sampling around the Northam Pool Weir we recorded two individual Nightfish and no Western Pygmy Perch. The Nightfish is now largely absent from the main channel and the Western Pygmy Perch is known from only one site east of the Darling Scarp, in the . This is likely to be attributed to, at least in part, the salinity tolerances of these species being exceeded with adult the Western Pygmy Perch recently shown to have an acute tolerance of 14 ppt (Beatty et al. 2008) and a range reduction due to salinisation is believed to have occurred in the Blackwood River for the species (Morgan et al. 2003). As mentioned, the tolerance of the Nightfish is as yet unknown and requires determination and comparison with those experienced throughout the catchment. Furthermore, the sub‐adult and chronic (gradual) salinity tolerances of these species require determination. The salinity of Northam Pool exceeded the tolerance of at least the Western Pygmy Perch in all seasons except winter (see Strehlow 2009).

Freshwater Fish Group (CFFR, Murdoch University) Inland fish sampling locations Swan-Canning Catchments

Bostockia porosa Western Australia

MORTLOCKMORTLOCK RIVERRIVER NORTHNORTH

BROCKMANBROCKMAN RIVERRIVER

ELLENELLEN BROOKBROOK

MORTLOCKMORTLOCK RIVERRIVER EASTEAST

MORTLOCKMORTLOCK RIVERRIVER SWANSWAN RIVERRIVER PERTHPERTH HELENAHELENA RIVERRIVER AA HELENAHELENA RIVERRIVER VOVVOV OO NN RR IIIVVEV VVEE EERR DALEDALE RIVERRIVER RR CANNINGCANNING RIVERRIVER

AVONAVON RIVERRIVER SOUTHSOUTH

040 80 km

Figure 9 Distribution of the Nightfish in the Swan‐Canning catchment.

16

Freshwater Fish Group (CFFR, Murdoch University) Inland fish sampling locations Swan-Canning Catchments

Edelia vittata Western Australia

MORTLOCKMORTLOCK RIVERRIVER NORTHNORTH

BROCKMANBROCKMAN RIVERRIVER

ELLENELLEN BROOKBROOK

MORTLOCKMORTLOCK RIVERRIVER EASTEAST

MORTLOCKMORTLOCK RIVERRIVER SWANSWAN RIVERRIVER PERTHPERTH HELENAHELENA RIVERRIVER AA HELENAHELENA RIVERRIVER VV OO NN RR IIIVV VVEE EERR DALEDALE RIVERRIVER RR CANNINGCANNING RIVERRIVER

AVONAVON RIVERRIVER SOUTHSOUTH

0 40 80 km

Figure 10 Distribution of the Western Pygmy Perch in the Swan‐Canning catchment.

As opposed to the reduction in the distribution of the obligate freshwater species, i.e. Nightfish and Western Pygmy Perch, in the Swan‐Avon catchment due to salinisation, the results from the current sampling regime in the Avon River and the sites sampled in Figure 11 below, indicate that the estuarine Western Hardyhead has now colonised large inland areas of the catchment. This distribution includes much of the salinised main channel of the Swan‐Avon River and the and would have been facilitated by the secondary salinisation of the main channel as has previously been demonstrated in the salinised Blackwood River (Morgan et al. 2003). Similar to the Western Hardyhead, the estuarine Swan River Goby has also colonised large inland areas of the catchment (Figure 12).

17

Freshwater Fish Group (CFFR, Murdoch University) Inland fish sampling locations Swan-Canning Catchments

Leptatherina wallacei Western Australia

MORTLOCKMORTLOCK RIVERRIVER NORTHNORTH

BROCKMANBROCKMAN RIVERRIVER

ELLENELLEN BROOKBROOK

MORTLOCKMORTLOCK RIVERRIVER EASTEAST

MORTLOCKMORTLOCK RIVERRIVER SWANSWAN RIVERRIVER PERTHPERTH HELENAHELENA RIVERRIVER AA HELENAHELENA RIVERRIVER VV OO NN RR IIIVV VVEE EERR DALEDALE RIVERRIVER RR CANNINGCANNING RIVERRIVER

AVONAVON RIVERRIVER SOUTHSOUTH

0 40 80 km

Figure 11 Distribution of the Western Hardyhead in the Swan‐Canning catchment.

18

Freshwater Fish Group (CFFR, Murdoch University) Inland fish sampling locations Swan-Canning Catchments

Pseudogobius olorum Western Australia

MORTLOCKMORTLOCK RIVERRIVER NORTHNORTH

BROCKMANBROCKMAN RIVERRIVER

ELLENELLEN BROOKBROOK

MORTLOCKMORTLOCK RIVERRIVER EASTEAST

MORTLOCKMORTLOCK RIVERRIVER SWANSWAN RIVERRIVER PERTHPERTH HELENAHELENA RIVERRIVER AA HELENAHELENA RIVERRIVER VV OO NN RR IIIVV VVEE EERR DALEDALE RIVERRIVER RR CANNINGCANNING RIVERRIVER

AVONAVON RIVERRIVER SOUTHSOUTH

040 80 km

Figure 12 Distribution of the Swan River Goby in the Swan‐Canning catchment.

Since its introduction in the 1930’s, the Eastern Mosquitofish has spread throughout much of the Swan‐ Canning catchments including the majority of the main channel and its tributaries (Figure 13) along with the majority of the catchments of south‐western Australia (Morgan et al. 2004). It is also known to be very tolerant of salinity with the authors having previously recorded them in 58 ppt (Morgan et al. 2004); well in excess of seawater which has a salinity of ~35 ppt.

19

Freshwater Fish Group (CFFR, Murdoch University) Inland fish sampling locations Swan-Canning Catchments

Gambusia holbrooki Western Australia

MORTLOCKMORTLOCK RIVERRIVER NORTHNORTH

BROCKMANBROCKMAN RIVERRIVER

ELLENELLEN BROOKBROOK

MORTLOCKMORTLOCK RIVERRIVER EASTEAST

MORTLOCKMORTLOCK RIVERRIVER SWANSWAN RIVERRIVER PERTHPERTH HELENAHELENA RIVERRIVER AA HELENAHELENA RIVERRIVER VV OO NN RR IIIVV EE RR DALEDALE RIVERRIVER R CANNINGCANNING RIVERRIVER

AVONAVON RIVERRIVER SOUTHSOUTH

0 40 80 km

Figure 13 Distribution of the feral Eastern Mosquitofish in the Swan‐Canning catchment.

Summary and Recommendations

• In the vicinity of Northam Pool, the study recorded: two freshwater species endemic to south‐western Australia, the Nightfish and the Western Minnow; two species of estuarine origin, the Western Hardyhead and the Swan River Goby; and two introduced species, the Eastern Mosquitofish and the Goldfish. • The study found evidence that the estuarine species were self‐maintaining with considerable recruitment occurring whereas the freshwater species appeared to have only limited recruitment at those sites. • The seasonal sampling upstream and downstream of the Northam Pool Weir suggested that it may be acting as a barrier to fish movements as has been found previously for other barriers in rivers of south‐western Australia.

20

• This impact may be greatest on the two the freshwater species that undertake upstream migrations in order to access tributaries for use as spawning habitats. • Examination of the distributions of several freshwater, estuarine and an introduced species suggests that salinisation within the catchment has resulted in large contraction of freshwater species and concomitant inland expansion of the ranges of those typically estuarine species. • Despite these range reductions due to salinisation, construction of a fishway at the Northam Pool Weir to allow population connectivity of native freshwater species, and use also by native estuarine species, would benefit these populations and may enhance their sustainability. Such a fishway exists for the nearby Lion’s Weir in Boddington and has been shown to successfully allow passage of the Western Minnow in the (pictured below). • It is recommended that additional monthly sampling occurs during the major spawning period of the freshwater species (i.e. July to November) immediately below the weir to determine precisely when a future fishway would need to operate to ensure maximum usage by resident native species.

21

References

Aquatic Research Laboratories (1988). Lower Canning River stream fauna study results and recommendations. Report 11 June 1988, University of Western Australia. Bamford, M., Morgan, D. & Gill, H. (1998). The freshwater fish fauna of Bennett Brook. Murdoch University Fush Group Report to the Bennett Brook Catchment Group. Beatty, S.J., McAleer, F.J., Morgan, D.L., Koenders, A. & Horwitz, P.H.J. (2006). Influence of surface and groundwater on the fish and crayfish fauna of the Blackwood River. Centre for Fish & Fisheries Research (Murdoch University), Centre for Ecosystem Management (Edith Cowan University) report to Department of Water and South West Catchments Council. Beatty, S., Morgan, D. & Gill, H. (2003). Fish resource survey of Churchman Brook Reservoir. Report to the Water Corporation of Western Australia. Beatty, S.J., Morgan, D.L. & Gill, H.S. (2005a). Life history and reproductive biology of the gilgie Cherax quinquecarinatus, a freshwater crayfish endemic to south‐western Australia Journal of Crustacean Biology 25(2): 251‐262. Beatty, S., Morgan, D. & Tay, M. (2006). Management of aquatic fauna during the refurbishment of Churchman Brook Reservoir. Murdoch University, Centre for Fish & Fisheries Research report to the Water Corporation of Western Australia. Beatty, S., Rashnavidi, M., Morgan, D. & Lymbery, A. (2008). Salinity tolerances of native freshwater fishes of the Blackwood River. Centre for Fish & Fisheries Research, Murdoch University report to South West Catchments Council. Beatty, S., Wild, S. & Morgan, D. (2005b). Impact of culvert construction on the aquatic macroinvertebrate and fish fauna of the Wungong River: preliminary report. Report to the Main Roads Department. Chubb, C.F., Hutchins, J.B., Lenanton, R.C.J. & Potter, I.C. 1979. An annotated checklist of the fishes of the Swan‐Avon River system, Western Australia. Records of the Western Australian Museum 8, 1‐55. Chubb, C.F. & Potter, I.C. (1984). The reproductive biology and estuarine movements of the gizzard shad, Nematalosa vlaminghi (Munro). Journal of Fish Biology 25: 527‐543. Chubb, C.F. & Potter, I.C. (1986). Age, growth and condition of the Herring, Nematalosa vlaminghi (Munro) (Dorosomatinae), in the Swan Estuary, south‐western Australia. Australian Journal of Marine and Freshwater Research 37: 105‐112. Chubb, C.F., Potter, I.C., Grant, C.J., Lenanton, R.C.J. & Wallace, J. (1981). Age structure, growth rates and movements of sea mullet, Mugil cephalus L., and yellow‐eye mullet, Aldrichetta forsteri (Valenciennes), in the Swan‐Avon River system, Western Australia. Australian Journal of Marine and Freshwater Research 32: 605‐628.

22

Gill, H.S., Hambleton, S.J. & Morgan, D.L. (1999). Is Gambusia holbrooki a major threat to the native freshwater fishes of south‐western Australia? In Seret, B. & Sire, J.‐Y., (eds). Proceedings 5th Indo‐ Pacific Fish Conference (Noumea, 3‐8 November 1997). pp. 79‐87. Paris: Societe Francaise d’Ichtyologie & Institut de Recherche pour le Development. Gill, H.S. & Potter, I.C. (1993). Spatial segregation amongst goby species within an Australian estuary, with a comparison of the diets and salinity tolerance of the two most abundant species. Marine Biology 117: 515‐526. Gill, H.S., Wise, B.S., Potter, I.C. & Chaplin, J.A. (1996). Biannual spawning periods and resultant divergent patterns of growth in the estuarine goby Pseudogobius olorum: temperature‐induced? Marine Biology 125: 453‐466. Hewitt, M.A. (1992). The biology of the south‐western Australian catfish Tandanus bostocki Whitley (Plotosidae). Honours Thesis, Murdoch University, Perth, Western Australia. Humphries, P. & Potter, I.C. (1993). Relationship between the habitat and diet of three species of atherinids and three species of gobies in a temperate Australian estuary. Marine Biology 116: 193‐204. Kanandjembo, A.N., Potter, I.C. & Platell, M.E. (2001). Abrupt shifts in the fish community of the hydrologically variable upper estuary of the Swan River. Hydrological Processes 15: 2503‐2517. Maddern, M. (2003). The distribution, biology and ecological impacts of three introduced freshwater teleosts in Western Australia. Honours Thesis, Murdoch University, Perth, Western Australia. Marina, H., Beatty, S.J., Morgan, D.L., Doupé, R.G. & Lymbery, A.L. (2008). An introduced parasite, Lernaea cyprinacea, found on native freshwater fish in the south west of Western Australia. Journal of the Royal Society of Western Australia 91: 149‐153. Morgan, D.L. & Beatty, S.J. (2005). Baseline study on the fish and freshwater crayfish fauna in the Blackwood River and its tributaries receiving discharge from the Yarragadee Aquifer. Centre for Fish & Fisheries (Murdoch University) Report to the Department of Environment, Government of Western Australia. Morgan, D.L., Beatty, S.J. & McAleer, F.J. (2007). Canning River – freshwater fishes and barriers to migrations. Centre for Fish & Fisheries Research (Murdoch University), report to Department of Water and South East Regional Centre for Urban Landcare. Morgan, D.L., Chapman, A., Beatty, S.J. & Gill, H.S. (2006). Distribution of the spotted minnow (Galaxias maculatus (Jenyns, 1842)) (Teleostei: Galaxiidae) in Western Australia including range extensions and sympatric species. Records of the Western Australian Museum 23: 7‐11. Morgan, D., Gill, H. & Cole, N. (2000). The fish fauna of the catchment. Report to the Water & Rivers Commission of Western Australia.

23

Morgan, D.L., Gill, H.S., Maddern, M.G. & 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. & Sarre, G. A. (1995). The freshwater fish fauna of the Bickley Brook Reservoir. Report to the Water Authority of Western Australia. Morgan, D.L., Thorburn. D.C. & Gill, H.S. (2003). Salinization of south‐western Western Australian rivers and the implications for the inland fish fauna – the Blackwood River, a case study. Pacific Conservation Biology 9: 161‐171. Morrison, P.F. (1988). Reproductive biology of two species of plotosid catfish, Tandanus bostocki and Cnidoglanis macrocephalus, from south‐western Australia. PhD Thesis, University of Western Australia. Pen, L.J. & Potter, I.C. (1990). Biology of the nightfish, Bostockia porosa Castelnau, in south‐western Australia. Australian Journal of Marine and Freshwater Research 41: 627‐645.

Pen, L.J. & Potter, I.C. (1991a). Biology of the western minnow, Galaxias occidentalis Ogilby (Teleostei: Galaxiidae), in a south‐western Australian river. 1. Reproductive biology. Hydrobiologia 211: 77‐88.

Pen, L. J. & Potter, I. C. (1991b). Reproduction, growth and diet of Gambusia holbrooki (Girard) in a temperate Australian river. Aquatic Conservation: Marine and Freshwater Ecosystems 1: 159‐172.

Prince, J.D. & Potter, I.C. (1983). Life‐cycle duration, growth and spawning times of five species of Atherinidae (Teleostei) found in a Western Australian estuary. Australian Journal of Marine and Freshwater Research 34: 287‐301. Sarre, G.A., Platell, M.E. & Potter, I.C. (2000). Do the dietary compositions of Acanthopagrus butcheri in four estuaries and a coastal lake vary with body size and season and within and amongst these water bodies? Journal of Fish Biology 56: 103‐122.

Sarre, G.A. & Potter, I.C. (1999). Comparisons between the reproductive biology of black bream Acanthopagrus butcheri (Teleostei: Sparidae) in four estuaries with widely differing characteristics. International Journal of Salt Lake Research 8: 179‐210.

Sarre, G.A. & Potter, I.C. (2000). Variation in age compositions and growth rates of Acanthopagrus butcheri (Sparidae) among estuaries: some possible contributing factors. Fishery Bulletin 98: 785‐799. Tay, Y.M. (2005). The diet of wild and cultured rainbow trout, Oncorhynchus mykiss in Western Australia. Honours Thesis, Murdoch University, Perth, Western Australia. Tay, M.Y., Lymbery, A.J., Beatty, S.J. & Morgan, D.L. (2007). Predation by Rainbow Trout (Oncorhynchus mykiss) on a Western Australian icon: Marron (Cherax cainii). New Zealand Journal of Marine and Freshwater Research 41: 197–204.

24

Wise, B.S., Potter, I.C. & Wallace, J.H. (1994). Growth, movements and diet of the terapontid Amniataba caudavittata in an Australian estuary. Journal of Fish Biology 45: 917‐931. Watts, R.J., Story, A.W., Hebbert, D.R. & Edward, D.H.D. (1995). Genetic and morphological differences between populations of the western minnow, Galaxias occidentalis, from two river systems in south‐ western Australia. Marine and Freshwater Research 46: 769‐777.

25