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Water Assessment Aquatic Ecology Report Series
Status of fish communities and observations on South Esk freshwater mussel (Velesunio moretonicus) populations in the Macquarie River catchment upstream of Lake River
Wate r Assessment B r anch
Wate r and Mar i ne Resou r ces D i v i s i on
Depa r tmen t o f P r imary I n dus t r i e s , Pa r k s , Wate r and Env i r onmen t
July 2009 ISSN: 1835-9523 Report No. WA 09/02
Copyright Notice:
Material contained in the report provided is subject to Australian copyright law. Other than in accordance with the Copyright Act 1968 of the Commonwealth Parliament, no part of this report may, in any form or by any means, be reproduced, transmitted or used. This report cannot be redistributed for any commercial purpose whatsoever, or distributed to a third party for such purpose, without prior written permission being sought from the Department of Primary Industries, Parks, Water and Environment, on behalf of the Crown in Right of the State of Tasmania.
Disclaimer:
Whilst DPIPWE has made every attempt to ensure the accuracy and reliability of the information and data provided, it is the responsibility of the data user to make their own decisions about the accuracy, currency, reliability and correctness of information provided. The Department of Primary Industries, Parks, Water and Environment, its employees and agents, and the Crown in the Right of the State of Tasmania do not accept any liability for any damage caused by, or economic loss arising from, reliance on this information.
Preferred Citation:
DPIPWE (2009). Status of fish communities and observations on South Esk freshwater mussel (Velesunio moretonicus) populations in the Macquarie River catchment upstream of Lake River. Water Assessment Aquatic Ecology Report Series, Report No. WA 09/02. Water and Marine Resources Division. Department of Primary Industries, Parks, Water and Environment, Hobart, Tasmania.
Contact Details:
Department of Primary Industries, Parks, Water and Environment Water Assessment 13 St Johns Avenue, New Town Phone: 03 6233 6833 Web: www.dpiw.tas.gov.au Email: [email protected]
Cover Page Images:
Top: Goldfish (Carassius auratus). Bottom left: Macquarie River at Delmont Rd, November 2008. Bottom right: Lake Leake, February 2009.
The Department of Primary Industries, Parks, Water and Environment
The Department of Primary Industries, Parks, Water and Environment provides leadership in the sustainable management and development of Tasmania’s resources. The Mission of the Department is to advance Tasmania’s prosperity through the sustainable development of our natural resources and the conservation of our natural and cultural heritage for the future.
The Water and Marine Resources Division provides a focus for water management and water development in Tasmania through a diverse range of functions including the design of policy and regulatory frameworks to ensure sustainable use of the surface water and groundwater resources; monitoring, assessment and reporting on the condition of the State’s freshwater resources; facilitation of infrastructure development projects to ensure the efficient and sustainable supply of water; and implementation of the Water Management Act 1999, related legislation and the State Water Development Plan.
Fish and freshwater mussels in the Macquarie River catchment
ii
Summary
This assessment of fish communities and South Esk freshwater mussel (Velesunio moretonicus)
populations was undertaken in the area of a proposed water management plan (WMP) for the
Macquarie River catchment, Tasmania, which will encompass the Macquarie River and all of its
tributaries upstream of the Lake River confluence. Under the proposed WMP for the area, water
resources are to be managed in five Water Management Regions (WMRs): Upper Macquarie River,
Lower Macquarie River downstream of Elizabeth River, Blackman River, Elizabeth River and Isis
River.
During 2007-2008, sampling of fish communities and freshwater mussel populations was
undertaken across 25 sites in the catchment (23 riverine sites, and Lake Leake and Tooms Lake)
using several methods including visual observations, electrofishing and netting techniques. Where
suitable historical data were available, data collected during the recent surveys were compared to
historical data to examine temporal changes in fish communities and mussel populations in the
Macquarie catchment. This work provided a comprehensive overview of the status of fish
communities and the current distribution of V. moretonicus in this region. Additionally, information
regarding predation by great cormorants (Phalacrocorax carbo) on mussels, and fish-host
preferences of V. moretonicus larvae (glochidia) was also gathered.
Nine fish species were recorded in the catchment, including four native fishes to Tasmania (short-
finned eel (Anguilla australis), common galaxias (Galaxias maculatus), river blackfish (Gadopsis
marmoratus) and southern pymgy perch (Nannoperca australis)) and five alien species (goldfish
(Carassius auratus), rainbow trout (Oncorhynchus mykiss), redfin (Perca fluviatilis), brown trout
(Salmo trutta) and tench (Tinca tinca)); however, it is likely that G. maculatus and G. marmoratus
are not indigenous to the region. The species composition of the fish communities in all WMRs,
other than the Blackman River WMR, were similar, with the native A. australis and N. australis, and
alien P. fluviatilis, S. trutta and T. tinca being common in all four WMRs. Native (but potentially not
indigenous) G. maculatus and G. marmoratus, and alien C. auratus were uncommon and only found
in 1-2 WMRs. Based on backpack electrofishing data, alien species accounted for significant
proportions of the total catches in lowland (27%) and upland (49%) riverine sites. Perca fluviatilis,
S. trutta and T. tinca were the dominant alien species, with P. fluviatilis and T. tinca being more
prolific in lowland reaches and S. trutta in upland reaches.
Overall, the species compositions of the fish communities in the catchment during 2007-2008 were
similar to historical records for the region, although the distributions and abundances of some
species appear to have changed in recent years. Flows in rivers in the region during the study were
relatively low and had been so for some time prior to the study (the last major floods in the
catchment occurred in 2005, and, generally, flows in rivers in the catchment have been relatively
Fish and freshwater mussels in the Macquarie River catchment
iii
low since 1990). These recent low-flow conditions appear to have allowed some species which
prefer still or slow-flowing habitats (N. australis, P. fluviatilis and T. tinca) to extend their
distributions. These conditions may also have assisted the upstream dispersal of an alien pest
species (C. auratus) in the lower Macquarie River system upstream of Lake River; an area where it
has not previously been recorded. Additionally, the distribution and abundance of populations of an
alien species that was previously wide-spread and valued by recreational anglers (S. trutta) has
declined recently. This is likely to be due to low flows in the catchment causing poor recruitment and
unfavourable environmental conditions for this species.
Similarly, in recent decades, flow conditions appear to have influenced the distribution of the
endemic V. moretonicus in the Macquarie catchment upstream of Lake River by dewatering some
reaches where mussels previously occurred. This species is now restricted largely to the lower
reaches of the Macquarie River where habitats are relatively deep, and flow conditions are relatively
stable due to flow regulation. Velesunio moretonicus were found in dense aggregations in run
habitats at some sites in the lower Macquarie River; however, the viability of populations in the
catchment is unknown and requires further investigation.
Velesunio moretonicus glochidia were found on only two fish species, native A. australis and alien
T. tinca, with A. australis having a much higher prevalence of parasitism compared to T. tinca.
Furthermore, larger-sized individuals of both species appeared more likely to be parasitised. Fish
that were parasitised by glochidia were mostly collected from sites where adult V. moretonicus were
recorded, but at two sites, Isis River at Isis Road and Macquarie River at Tooms Lake Road, no live
adult mussels were observed.
This study has shown that, in recent times, broad-scale changes have occurred in fish communities
in the Macquarie catchment and that the distribution of the endemic freshwater mussel
V. moretonicus in this region may also have reduced. Both of these alterations to the ecosystems of
the Macquarie River system appear to be associated primarily with flow regime alterations;
however, in some instances, landscape degradation (e.g. removal of native riparian vegetation;
nutrient enrichment of soils, hence waterways, etc.) is likely to have caused compounding impacts.
Prolonged periods of reduced flows or unseasonal flow patterns (due to dry climatic conditions
and/or water use), similar to those which have recently occurred in the catchment, are likely to
impact on fish communities and freshwater mussel populations. Such conditions are likely to allow
alien pest fishes to further extend their distributions and continue to restrict colonisation of
V. moretonicus in areas it previously occupied. Seasonal flow variability and adequate baseflows in
all rivers in the region are critical to the long-term viability of fish and mussel populations. Proactive
management and protection of these attributes of the flow regime will promote spawning and
dispersal, and provide stable refuge habitats for these taxa.
Fish and freshwater mussels in the Macquarie River catchment
iv
Table of Contents
Summary ......................................................................................................................................... ii
Acknowledgments ........................................................................................................................ vi
Glossary and abbreviations .......................................................................................................... vi
1. Introduction ................................................................................................................................. 1
1.1 Study region ............................................................................................................................ 1
1.2 Background information .......................................................................................................... 1
1.3 Aims ........................................................................................................................................ 5
2. Methodology ............................................................................................................................... 6
2.1 Study sites .............................................................................................................................. 6
2.2 Physico-chemical parameters ................................................................................................. 6
2.3 Historical fish community data ................................................................................................. 6
2.4 Riverine fish community surveys ............................................................................................. 6
2.5 Lake fish community surveys .................................................................................................. 9
2.6 Freshwater mussel distribution observations ......................................................................... 11
2.7 Freshwater mussel predation surveys ................................................................................... 11
2.8 Freshwater mussel fish-host analyses .................................................................................. 11
2.9 Data analysis ........................................................................................................................ 12
3. Results ....................................................................................................................................... 14
3.1 Environmental variables ........................................................................................................ 14
3.2 Riverine fish communities ..................................................................................................... 15
3.3 Fish community in Lake Leake .............................................................................................. 28
3.4 Distribution of fishes in the Macquarie River catchment ........................................................ 30
3.5 Distribution of freshwater mussels in the Macquarie River catchment ................................... 42
3.6 Avian predation on freshwater mussels ................................................................................. 42
3.7 Host-parasite relationships between fishes and freshwater mussel glochidia ........................ 45
4. Discussion ................................................................................................................................ 49
4.1 Fish communities in Water Management Regions ................................................................ 49
4.2 Native fish species ................................................................................................................ 50
4.3 Alien fish species .................................................................................................................. 52
4.4 Freshwater mussel populations ............................................................................................. 55
4.5 Fish-freshwater mussel relationships .................................................................................... 58
5. Conclusion ................................................................................................................................ 61
5.1 Summary of findings ............................................................................................................. 61
5.2 Synthesis .............................................................................................................................. 62
Fish and freshwater mussels in the Macquarie River catchment
v
5.3 Support for environmental flow recommendations ................................................................. 63
6. References ................................................................................................................................ 65
7. Appendices ............................................................................................................................... 71
Fish and freshwater mussels in the Macquarie River catchment
vi
Acknowledgments
Scott Hardie managed this project and prepared this report. Stephen Pyecroft (Department of
Primary Industries, Parks, Water and Environment (DPIPWE)) designed and managed the fish-host
analyses and assisted with the interpretation of the results of that work. Field assistance was
provided by Chris Bobbi, Justine Latton, Mike Male, Greg McDonald, Danielle Warfe, Adam
Uytendaal and David Spiers (DPIPWE), and Robert Freeman and Stuart Chilcott (Inland Fisheries
Service (IFS)). Chris and Adam provided useful discussions on many aspects of the study, and
commented on a draft of the report. Stuart also provided historical fish community data for the
Macquarie catchment from IFS. Belinda Jones and Angela Williams (fish pathology), and Dane
Hayes and Catherine Marshall (histology) provided technical support with laboratory analyses (all
DPIPWE). The Water Assessment Branch would like to thank the landholders in the Macquarie
catchment for access to rivers on their properties. Seasonal fish surveys at the two uppermost
Macquarie River sites were conducted under the Tasmanian Environmental Flows Project, which
was funded by NRM South and NRM North, and the Tasmanian and Commonwealth Governments
under the National Action Plan for Salinity and Water Quality. This study was conducted with
financial support from the Tasmanian State Government via DPIPWE and IFS. This work was
undertaken in accordance with the terms of an IFS Exemption Permit (IFS Permit Number 2008/12
and PWS Permit Number TFA00022) and conditions of the DPIPWE Animal Ethics Committee
(DPIW AEC certificate No. 37/2007-08).
Glossary and abbreviations
Alien: Taxa that has been introduced into an area, thus, is not indigenous or native.
CFEV: Conservation of Freshwater Ecosystem Values Project, which is managed by DPIPWE.
CFEV database: A spatial information tool (database) that includes freshwater-dependent ecosystems values within a strategic framework for the management of Tasmania’s freshwater resources.
Cohort: A group of fish that were born during the same breeding season and, thus, are of approximately the same age (and often body length and weight).
DPIPWE: Department of Primary Industries, Parks, Water and Environment.
IFS: Inland Fisheries Service.
Indigenous: Taxa that naturally occurs in a small-scale area, thus, is native, but is not alien.
Glochidia: Larvae of freshwater mussels that are obligate ectoparasites which typically occur on the gills and fins of fish for several weeks to months.
Lentic: Pertaining to or living in standing water (i.e. habitats such as lakes or lagoons).
Fish and freshwater mussels in the Macquarie River catchment
vii
Lotic: Pertaining to or living in flowing water (i.e. habitats such as creeks and rivers).
Macrophyte: Vascular plant that is visible with the naked eye. Is this report, this terms refers to aquatic plants that grow in freshwater environments.
Native: Taxa that naturally occurs in Tasmania, thus is not alien, but may or may not be indigenous.
Pest: A taxa that is considered to be undesirable and a nuisance by the Tasmania State Government.
Physico-chemical variables: Parameters which relate to the physical and chemical properties of water (e.g. water temperature, dissolved oxygen concentration, etc.).
Recruitment: The influx of juvenile animals into the adult proportion of a population.
Substrate: The surface of the bottom of a lake or river.
Water Management Plan (WMP): A strategy under which water resources associated with freshwater ecosystems in Tasmania are managed by the Tasmanian State Government.
Water Management Region (WMR): Areas within a larger catchment where water resources are to be managed as spatial units.
Fish and freshwater mussels in the Macquarie River catchment
1
1. Introduction
1.1 Study region
This assessment of fish communities and freshwater mussel populations was undertaken in the
area of a proposed water management plan (WMP) for the Macquarie River catchment, which will
encompass the Macquarie River and all of its tributaries upstream of the Lake River confluence
(Figure 1.1). This includes almost the entire Midlands region of eastern Tasmania, from Tooms Lake
to Snow Hill in the east, to the Great Western Tiers in the west. Major tributaries of the Macquarie
River in this area include the Blackman, Elizabeth, Isis and Tooms rivers.
The Macquarie River catchment covers an area of approximately 2700 km2. Campbell Town and
Ross are the main townships in the catchment (Figure 1.1). Lake Leake and Tooms Lake
(Figure 1.1), and the Blackman Dam are the largest man-made storages in the area and have
significant impacts on flows downstream in the Elizabeth, Macquarie and Blackman rivers,
respectively. Lake Leake (maximum storage volume = 19,000 ML) was first impounded in 1885 and
Tooms Lake (maximum storage volume = 25,000 ML) was first impounded in the 1830s. Both
impoundments are used to provide water for irrigated agriculture as well as stock and domestic
purposes (including water for the townships of Ross and Campbell Town). The Blackman Dam was
completed in 2005, with a maximum storage volume of more than 7000 ML; however, a major dam
failure in October 2005 resulted in subsequent dam modifications, which have reduced its effective
storage capacity to 3000 ML.
For the purposes of the WMP, the catchment has been divided into five water management sub-
regions (WMRs): Upper Macquarie River, Macquarie River downstream of Elizabeth River,
Blackman River, Elizabeth River and Isis River (Figure 1.1). Where possible (and applicable), this
study reports findings in relation to these WMRs.
1.2 Background information
1.2.1 Associated studies
This study complements other assessments which have recently been undertaken in the Macquarie
catchment above the Lake River confluence (DPIPWE, 2009, DPIW, 2008a, DPIW, 2008d, DPIW,
2008c, DPIW, 2009, Koehnken, 2009) to support the development of a WMP by DPIPWE for this
region. These studies, which include fauna and flora surveys, and assessments of river health,
water quality and hydrology, provide information about the condition of the freshwater ecosystems in
the Macquarie catchment. The present study assesses the status of fish communities and
populations of the endemic South Esk freshwater mussel (Velesunio moretonicus) in the study
region.
Fish and freshwater mussels in the Macquarie River catchment
2
Figure 1.1 The Macquarie River catchment above the Lake River confluence, Tasmania and the Water Management Regions for the proposed water management plan for the region. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
3
1.2.2 Recent hydrological alterations
Detailed assessments of the hydrological characteristics of the Macquarie catchment above the
Lake River are documented in separate reports (DPIW, 2008d, DPIW, 2009). Of particular
importance to the aquatic fauna of river systems in the region are recent changes to: (1) flow
regulation, (2) wet and dry periods over different temporal scales, and (3) flow seasonality and
variability (DPIW, 2009). Between 1970 and 2007, there have been substantial long-term flow
reductions in both regulated and unregulated rivers throughout the catchment (DPIW, 2009).
Additionally, since 1990, flow seasonality has decreased in all rivers in the catchment and flow
variability has increased in unregulated rivers (DPIW, 2009).
These changes are thought to largely be due to recent changes in local climatic conditions – since
1990, river systems in the Macquarie catchment have experienced several prolonged periods of
drought conditions – along with increases in consumptive water use. Because of these hydrological
alterations, along with further degradation of instream habitats due to riparian land use practices,
the composition of the fish communities and distribution of V. moretonicus in the catchment may
have changed in recent years.
1.2.3 Fish communities
Currently, little is known of the status of fish communities in rivers and waterbodies in the Macquarie
catchment. Based on previous surveys in lowland reaches (Davies and Humphries, 1996,
Humphries, 1995) and some upland areas (IFS, unpubl. data) in the early 1990s, and more recent
work in upland reaches for threatened fish species management (Threatened Species Section,
2006), it is clear that several native (e.g. southern pymgy perch (Nannoperca australis)) and alien
(e.g. brown trout (Salmo trutta)) species occur in the catchment. Furthermore, greater numbers of
species are likely to occur in lowland reaches, primarily due to the presence of more alien species.
In upland reaches, there are typically fewer species, but the fish communities in these areas are
also likely to include a mixture of native and alien species.
Historically (prior to the mid-1990s), the lowland reaches of the Macquarie River were used
frequently by recreational anglers for trout fishing. However, anecdotal evidence suggests that trout
populations in lowland reaches of the Macquarie River have declined in recent times; hence, fewer
anglers are now fishing in the river.
1.2.4 Freshwater mussel populations
At least some fish species in the Macquarie catchment are subject to a unique (for Tasmania)
parasite-host relationship: they are used as hosts by parasitic larvae (glochidia) of freshwater
mussels. The primary mussel species which is likely to be infecting fish in the catchment is
V. moretonicus. This species is a large-sized (up to c. 130 mm in shell length) freshwater mussel
which is endemic to the South Esk Basin in eastern Tasmania. Whilst this species has a restricted
Fish and freshwater mussels in the Macquarie River catchment
4
distribution in Tasmania, currently, it is not listed under State or Commonwealth threatened species
legislation; however, it is considered to be a priority fauna species in the CFEV database (CFEV,
2005) and is likely to be important to the aquatic ecosystems where it occurs.
The current status of V. moretonicus is uncertain, but it is thought to be reasonably common in
lowland river reaches in these catchments. Davies and Humphries (1996) briefly investigated the
distribution, density and habitat use of V. moretonicus in shallow (<1.5 m deep) pool, run and riffle
habitats in the Macquarie River. However, recent work (Davies and Cook, 2007) in the lower
Macquarie River-Brumbys Creek system has shown that most adult V. moretonicus occur in
relatively deep (c. 1.5-11 m in depth) benthic habitats in main river channels and broadwaters; thus,
the work of Davies and Humphries (1996) is unlikely to provide an accurate assessment of the
densities and habitat preferences of adult mussels in the Macquarie River at the time of their study.
Both of these previous studies collected few juvenile (i.e. <70 mm in length) mussels; hence, the
habitats used during this life stage are largely unknown.
Whilst the general distribution and taxonomy of V. moretonicus has been documented (McMichael
and Hiscock, 1958b, Walker, 2004, Smith, 1996), little is known of its life history or ecology. Like
most freshwater mussel species, the life history of V. moretonicus involves a larval phase (glochidia)
which parasitises (encysts) a fish-host temporarily prior to development as a free-living organism
(McMichael and Hiscock, 1958a). Glochidia are obligate ectoparasites which typically occur on the
gills and fins of fish for several weeks to months (Vaughn and Taylor, 2000, Walker, 1981, Watters
and O'Dee, 1999). Adult female mussels produce prolific numbers of glochidia which are released,
mostly in spring-summer, into the water column and remain viable for a few weeks while awaiting
attachment to a suitable host (Walker, 1981). Several factors, such as efficiency of glochidia
attachment, fish behaviour and the physical structure of riverine habitats, may affect the
predisposing of certain areas of the bodies of fish to attachment (Atkins, 1979). Glochidia typically
infect fish which are indigenous to the area where the mussels are found and several glochidial
cysts may occur on individual fish (e.g. up to c. 40 have been recorded in Australian freshwater fish
(Atkins, 1979), while >2000 have been reported in individual salmonids in Europe (Geist et al.,
2006)). The occurrence of glochidia infecting alien fishes has been documented in Australian waters
(S. trutta (Atkins, 1979), eastern gambusia (Gambusia holbrooki) and redfin perch (Perca fluviatilis)
(Walker, 1981)), but some researchers (Atkins, 1979) have suggested that the survival of glochidia
encysting alien fishes may be poor. After excystment (detachment from the fish), juvenile mussels
are thought to settle on benthic substrates where they begin to grow into their adult form.
Fish and freshwater mussels in the Macquarie River catchment
5
1.3 Aims
In order to manage water use and maintain aquatic ecosystem values in the Macquarie catchment –
an area which has been significantly modified by anthropogenic disturbances – knowledge of the
status of the fish communities and freshwater mussel populations in the catchment is required. Of
particular interest is the status of native v. alien fishes in the catchment, and the fishes which are
used by V. moretonicus as hosts at the glochidia life stage.
Thus, the aims of this study in the Macquarie River catchment upstream of Lake River were to:
• Conduct catchment-wide fish community surveys in lotic and lentic habitats in the catchment.
• Determine the composition of fish communities in the Macquarie River and its tributaries,
and in Lake Leake and Tooms Lake.
• Examine the abundance and distribution of fish species in the catchment.
• Examine the size structures of abundant fish populations in lotic and lentic habitats to assess
recent recruitment.
• Compare the results of this study with historical data from the region to assess temporal
changes in the fish communities in the area.
• Conduct catchment-wide freshwater mussel surveys in lotic habitats in the catchment.
• Examine the distribution of V. moretonicus in the catchment and compare the results to
historical data.
• Collect sub-samples of fish species from river reaches in the Macquarie catchment that are
known, or likely, to be inhabited by V. moretonicus. Using these samples, examine the fish-
host preferences of V. moretonicus glochidia. Determine if glochidia have preferences for:
(1) alien v. native fishes and (2) individual species.
Fish and freshwater mussels in the Macquarie River catchment
6
2. Methodology
2.1 Study sites
Sampling of fish communities and South Esk freshwater mussel (Velesunio moretonicus)
populations was undertaken across 25 sites in the Macquarie River catchment (Table 2.1;
Figure 2.1) between May 2007 and February 2009. These sites were distributed across the study
region (elevation range = 140-570 m a.s.l.), and included nine sites on the main stem of the
Macquarie River and several sites on main tributaries of the Macquarie River. In all of the Water
Management Regions (WMRs), there were 5-8 sampling sites, except the Blackman WMR where
there were only two sites due to low flow conditions in the region.
2.2 Physico-chemical parameters
Physico-chemical water variables (water temperature, electrical conductivity, dissolved oxygen, pH
and turbidity) were measured in situ at all fish and mussel sampling sites (Table 2.1) on each
sampling occasion using the following instruments respectively: WTW Conductivity Meter (LF 330),
YSI Oximeter (YSI 550DO), WTW pH Meter (pH 320), and HACH Turbidimeter (2100P).
2.3 Historical fish community data
To examine the historical distributions and abundances of fishes in the Macquarie catchment, data
from various sources (Davies and Humphries, 1996; Humphries 1995; IFS, unpubl. data;
P. Humphries, unpubl. data; Tasmanian Fish Database) were collated.
2.4 Riverine fish community surveys
Between May 2007 and December 2008, fish community surveys were undertaken at 23 lotic sites
in the Macquarie catchment (Table 2.1; Figure 2.1). At the two uppermost sites on the Macquarie
River (sites 1 and 2), electrofishing was undertaken seasonally between May 2007 and November
2008 (this was largely undertaken by the DPIPWE Tasmanian Environmental Flows Project; see
Acknowledgements). At most other lotic sites, electrofishing was undertaken on two occasions,
once in June 2008 and then again in November 2008; however, at sites 8, 15, 20 and 21,
electrofishing was only conducted on one occasion in December 2008. Additional to electrofishing,
at three sites with broadwater habitats (sites 3, 6 and 8), gill and fyke netting was undertaken on a
single occasion in December 2008.
Fish and freshwater mussels in the Macquarie River catchment
7
Table 2.1
St
ud
y si
tes
in t
he
Mac
quar
ie R
iver
cat
chm
ent
abo
ve t
he
Lake
Riv
er, T
asm
ania
wh
ere
fish c
om
munit
y su
rvey
s an
d f
resh
wat
er m
uss
el p
opula
tio
n
obse
rvat
ions
wer
e un
der
take
n d
uri
ng
2007
-200
9. T
he
dat
es w
hen
sit
es w
ere
sam
ple
d a
nd
met
ho
ds
that
wer
e em
plo
yed
fo
r fis
h s
urv
eys
at e
ach s
ite
duri
ng
the
stu
dy
are
also
sho
wn.
Elev
atio
n c
lass
es a
re:
low
lan
d <
220 m
an
d u
pla
nd
>22
0 m
(a.
s.l.)
. W
MR
= W
ater
Man
agem
ent
Reg
ion, an
d f
ish
ing
met
ho
ds
are:
bac
kpac
k el
ectr
ofis
hin
g =
e-f
ish,
gill
net
ting
= g
ill, f
yke
net
ting
= f
yke,
and
to
w n
etti
ng
= t
ow
. Si
te lo
cati
on
s ar
e ill
ust
rate
d in F
igure
1.1
.
Site no.
Site
WMR
Northing
Easting
Habitat
Elevation
(m a.s.l.)
Elevation class
Date
Fishing m
ethod
1
Macquarie River at Long Marsh Rd
Upper Macquarie
5338567
568989
River
444
Upland
Seasonally between
May-07 and Nov-08*
e-fish
2
Macquarie River off Honeysuckle Rd
Upper Macquarie
5331741
558085
River
254
Upland
Seasonally between
May-07 and Nov-08*
e-fish
3
Macquarie River at Tooms Lake Rd
Upper Macquarie
5331700
547800
River
207
Lowland
Jun-08, Nov-08, Dec-08
e-fish, gill, fyke
4
Macquarie River at Ashby
Upper Macquarie
5349450
538200
River
175
Lowland
Jun-08, Nov-08
e-fish
5
Macquarie River at Hogs Ford Rd
Upper Macquarie
5355262
536744
River
168
Lowland
Jun-08, Nov-08
e-fish
6
Macquarie River at Morningside
Macquarie d/s Elizabeth
5360223
532430
River
159
Lowland
Jun-08, Nov-08, Dec-08
e-fish, gill, fyke
7
Macquarie River at Barton Rd
Macquarie d/s Elizabeth
5369530
521590
River
149
Lowland
Jun-08, Nov-08
e-fish
8
Macquarie River at Barton
Macquarie d/s Elizabeth
5371019
519771
River
148
Lowland
Dec-08
e-fish, gill, fyke
9
Macquarie River at Delmont Rd
Macquarie d/s Elizabeth
5377326
515459
River
140
Lowland
Jun-08, Nov-08
e-fish
10
Kittys Rivulet at Trefusis
Upper Macquarie
5328397
547759
River
235
Upland
Jun-08, Nov-08
e-fish
11
Glen Morriston Rivulet at Moulton
Upper Macquarie
5339617
547090
River
217
Lowland
Jun-08, Nov-08
e-fish
12
Blackman River at Old Tier Rd
Blackman River
5331659
528489
River
276
Upland
Jun-08, Nov-08
e-fish
13
Blackman River at Tunbridge
Blackman River
5334410
533929
River
211
Lowland
Jun-08, Nov-08
e-fish
14
Elizabeth River at Tea Tree Hill
Elizabeth River
5355991
561177
River
542
Upland
Jun-08, Nov-08
e-fish
15
Elizabeth River at Devil's Elbow
Elizabeth River
5359004
546875
River
235
Upland
Dec-08
e-fish
16
Elizabeth River at Campbell Town
Elizabeth River
5357414
540458
River
186
Lowland
Jun-08, Nov-08
e-fish
17
Elizabeth River at Merton Vale
Elizabeth River
5358117
537129
River
174
Lowland
Jun-08, Nov-08
e-fish
18
Blanchards Creek at Valleyfield Rd
Macquarie d/s Elizabeth
5365000
529000
River
157
Lowland
Jun-08, Nov-08
e-fish
19
Isis River at Verwood Rd
Isis River
5344549
525679
River
246
Upland
Jun-08, Nov-08
e-fish
20
Isis River at Isis Rd
Isis River
5352148
525601
River
224
Upland
Dec-08
e-fish
21
Bayles Creek at Isis Rd
Isis River
5352272
523371
River
234
Upland
Dec-08
e-fish
22
Prideaux Creek at Isis Rd
Isis River
5354958
521230
River
227
Upland
Jun-08, Nov-08
e-fish
23
Isis River at Isis
Isis River
5365583
520188
River
161
Lowland
Jun-08, Nov-08
e-fish
24
Lake Leake
Elizabeth River
5348736
567921
Lake
570
Upland
Feb-09
Gill, fyke, tow
25
Tooms Lake
Upper Macquarie
5324603
565187
Lake
463
Upland
Feb-09
NA
*Seasonal fish surveys at the two uppermost Macquarie River sites were conducted under the DPIPWE Tasmanian Environmental Flows Project.
Fish and freshwater mussels in the Macquarie River catchment
8
Figure 2.1 Study sites in the Macquarie River catchment above the Lake River, Tasmania where fish community surveys and freshwater mussel population observations were undertaken between May 2007 and February 2009. Water Management Regions in the catchment are also shown. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
9
On each electrofishing occasion, fishing involved daytime sampling using a backpack electrofisher
(Smith and Root Inc, 12-B POW) in wadeable areas using 5-38 min (mean = 20 min) of fishing
effort. This fishing effort allowed 50-250 m (mean = 113 m) of river to be fished at each site. Netting
in broadwater habitats involved setting 4-5 gill nets (64 mm stretched mesh) and 3-6 fyke nets (5 or
25 mm stretched mesh) (Table 2.2). Gill nets were set in the evening for 195-345 min, whereas fyke
nets were set overnight for 985-1080 min (Table 2.2).
All captured fish were anaesthetised in an anesthetic solution (Aqui-s®; Isoeugenol), identified to
species, counted, and up to 50 individuals of each species were measured (total length (TL);
nearest mm). Sub-samples of up to 10 individuals (and all alien pest fish captured) from all lotic
sampling sites were euthanased (Aqui-s®) and preserved (frozen) for glochidia parasite analyses
(see section 2.8). These fish covered the size range of the catch of each species at each site. The
flow conditions (dry, not flowing or flowing) at the time of sampling and the proportions of
mesohabitats (pool, run or riffle) that were surveyed were also recorded during fish sampling at
each site.
2.5 Lake fish community surveys
The fish community of Lake Leake (Table 2.1; Figure 2.1) was surveyed on one occasion in
February 2009 using tow, gill and fyke netting (Table 2.2). Water levels were relatively low at the
time of the surveys (Appendix 1[a]). It was intended that similar work would also be conducted in
Tooms Lake, but due to very low water levels in February 2009 (Appendix 1[b]), this was not
logistically possible (a motorboat could not be launched and access to the perimeter of the lake was
difficult). Netting in Lake Leake involved collecting four tow net (conical ichthyoplankton net)
samples, and setting five gill nets (64 mm stretched mesh) and 12 fyke nets (six 5 mm and six
25 mm stretched meshed nets) (Table 2.2). Tow net samples were collected by towing the net for
10 min duration approximately 15 m behind a boat at a speed (~2 m s-1) that ensured the net
sampled the top 1 m of the water column. Gill nets were set in the evening for 165-195 min,
whereas fyke nets were set overnight for 985-995 min (Table 2.2).
All fish captured by electrofishing, gill netting and fyke netting were anaesthetised in an anesthetic
solution (Aqui-s®), identified to species, counted, and up to 50 individuals of each species were
measured (total length (TL); nearest mm). All material collected in tow net samples was euthanased
in an anesthetic solution (Aqui-s®) and preserved in 70% ethanol. Subsequently, tow net samples
were processed in the laboratory, where counts of fish species present in the samples undertaken.
Fish and freshwater mussels in the Macquarie River catchment
10
Table 2.2 Netting gear used for fish community surveys in broadwater habitats in the Macquarie River and Lake Leake during December 2008 and February 2009, respectively.
Study site Fishing gear Date Fishing effort (min)
Macquarie River at Tooms Lake Rd 4 gill nets (2 m drop, 64 mm stretched mesh)* 8/12/2008 195-260
2 fyke nets (5 m × 0.6 m wing, 600 mm D-shaped entrance and 25 mm stretched mesh)
8-9/12/2008 985-1080
1 fyke net (5 m × 0.6 m wing, 600 mm D-shaped entrance and 5 mm stretched mesh)
8-9/12/2008 990
Macquarie River at Morningside 4 gill nets (50 m × 2 m, 64 mm stretched mesh) 9/12/2008 280-345
1 gill net (100 m × 2 m, 64 mm stretched mesh) 9/12/2008 315
3 fyke nets (5 m × 0.6 m wing, 600 mm D-shaped entrance and 25 mm stretched mesh)
9-10/12/2008 1000-1055
3 fyke nets (5 m × 0.6 m wing, 600 mm D-shaped entrance and 5 mm stretched mesh)
9-10/12/2008 1000-1050
Macquarie River at Barton 4 gill nets (50 m × 2 m, 64 mm stretched mesh) 10/12/2008 225-230
1 gill net (100 m × 2 m, 64 mm stretched mesh) 10/12/2008 300
2 fyke nets (5 m × 0.6 m wing, 600 mm D-shaped entrance and 5 mm stretched mesh)
10-11/12/2008 990-1005
1 fyke net (5 m × 0.6 m wing, 600 mm D-shaped entrance and 25 mm stretched mesh)
10-11/12/2008 995
Lake Leake 1 tow net (400 mm diameter, 1.25 m tail with 500 µm mesh)†
11/02/2009 40
4 gill nets (50 m × 2 m, 64 mm stretched mesh) 11/02/2009 165-195
1 gill net (100 m × 2 m, 64 mm stretched mesh) 11/02/2009 175
6 fyke nets (5 m × 0.6 m wing, 600 mm D-shaped entrance and 25 mm stretched mesh)
12/02/2009 985-995
6 fyke nets (5 m × 0.6 m wing, 600 mm D-shaped entrance and 5 mm stretched mesh)
12/02/2009 985-995
*Gill nets at this site were set across the entire river channel which was a shorter distance than the length of the nets; thus, net lengths
are not stated. † Four tow net samples of 10 min duration were collected in the lake.
Fish and freshwater mussels in the Macquarie River catchment
11
2.6 Freshwater mussel distribution observations
The presence and/or absence of V. moretonicus was examined at all 23 lotic sites in the Macquarie
catchment where fish community surveys were undertaken (Table 1.1; Figure 1.1). At most sites,
mussel surveys were undertaken on two occasions, once in June 2008 and then again in November
2008; however, at sites 8, 15, 20 and 21, this was only conducted on one occasion in December
2008. Mussel surveys involved visual inspections of riffle, run and floodplain habitats in reaches that
were electrofished. The presence/absence of live mussels and mussel shells was recorded at each
site.
2.7 Freshwater mussel predation surveys
During the first visit to site 3 (Macquarie River at Ashby) in June 2008 for fish sampling, many
V. moretonicus shells were observed on the banks of the river in discrete piles (middens). Prior to
and during the study, great cormorants (Phalacrocorax carbo) were observed predating on mussels
in this area of the river (W. R. Bennett, landowner of the Ashby property, Ross, Tasmania, pers.
comm.). To estimate the rate at which the mussel population at this site was being predated upon,
all mussel shells on both river banks in a 100 m reach were collected on 20 August and 27
November 2008, and 16 April 2009 (Appendices 1[c] and 1[d]). The numbers of complete (joined)
and separated (split) mussel shells in each sample were counted and the length (TL; nearest mm)
of all complete and split shells was measured.
2.8 Freshwater mussel fish-host analyses
A sub-sample of preserved fish from ten lowland river sites in the Macquarie catchment, which were
known (or likely to be) inhabited by V. moretonicus, were used in fish-host analyses. These fish
were collected between 25 November and 11 December 2008 using electrofishing (n = 80) and
netting (gill and fyke netting; n = 58). Fish were thawed, identified to species and measured
(TL, mm). The left opercula were removed and all gill arches from the left side of each fish were
removed. Gill arches were fixed in 10% phosphate-buffered formal saline, embedded in wax,
sectioned at 3.5 µm and stained with haematoxylin and eosin (H & E) (Bancroft and Stevens, 1990).
Histological examination of the sections was carried out under light microscopy, and pathology and
the presence/absence of glochidia was recorded.
Fish and freshwater mussels in the Macquarie River catchment
12
2.9 Data analysis
Where suitable historical data were available, data collected during the recent surveys were
compared to these data during analyses to examine temporal changes in fish communities in the
Macquarie River catchment above the Lake River. Where applicable, all historical and recent survey
data were grouped into ‘summer’ (September-February) and ‘winter’ (March-August) periods for
analyses.
Backpack electrofishing data were used to examine the proportions of native and alien species in
the catches, and also the abundances of fishes in the WMRs; as this fishing method is the least
biased of the methods used in the survey towards catching both native and alien species that occur
in the catchment. To examine the relative abundance of fish species in WMRs, mean seasonal
catches from backpack electrofishing at sites in each WMR, where the species’ occurred, were
calculated (so as to not zero-inflate catch data, zero catch values were not included at sites where
species were not found). Length frequencies of abundant fishes (i.e. n >10 in total, with fish present
in both seasons in at least one WMR) were analysed to examine the size structure of the
populations and recent recruitment patterns in populations in WMRs.
Due to differences in the amounts of fishing effort used in historical and recent surveys at the
broadwater sites on the Macquarie River, electrofishing and netting data were pooled for each
survey period to examine the species composition of the fish communities in the three broadwater
sites during these two periods. This approach provides a good representation of what species occur
in these habitats, given the difficulty of sampling in these relatively deep habitats and the sampling
bias of different fishing methods. Similarly, catch data for all of the netting methods used in Lake
Leake were pooled to examine the composition of the fish community in the lake, and the lengths of
all fish caught were included in length frequencies.
Maps of the historical (1975-2006) and recent (2007-2009; this study) occurrence of species in the
Macquarie catchment were constructed to examine temporal changes in the spatial distribution of
the fishes in the catchment and the current distribution of species’. For clarity, only presence
records (not absence records) were included in the maps. Brook trout (Salvelinus fontinalis) was
excluded from this analysis, as this species has only recently (during 2006) been stocked into Lake
Leake by IFS. For some species, such as the Swan galaxias (Galaxias fontanus), there may be
additional records from surveys in recent years which have not been included in the State-wide fish
database.
A map of locations in the Macquarie River catchment above the Lake River where adult
V. moretonicus were found to be present (either live mussels or shells only) or absent during
historical (1990-1993; Davies and Humphries, 1996) and recent (2008) surveys was constructed to
examine temporal changes in the spatial distribution of the species and its current distribution.
Fish and freshwater mussels in the Macquarie River catchment
13
Where live mussels and dead mussel shells were observed at the same sites (which is common),
only live mussel data are presented. A map of the locations where larval mussel parasites
(glochidia) were found to be present or absent on fish that were collected in 2008 was also
constructed to examine the spatial distribution of parasitised fish.
All statistical analyses were undertaken in R version 2.7.0 (R Development Core Team, 2008). All
fish community data from historical and recent surveys have been included in the Natural Values
Atlas (DPIW, 2008b).
Fish and freshwater mussels in the Macquarie River catchment
14
3. Results
3.1 Environmental variables
3.1.1 Physico-chemical parameters
During fish and freshwater mussel sampling (between May 2007 and February 2009), physico-
chemical variables at upland and lowland sites varied, with water temperature, dissolved oxygen
concentration, pH and conductivity levels tending to be lower in upland sites (Table 3.1). Of these
parameters, conductivity levels varied the most between the regions. Conductivity levels of upland
and lowland sites differed significantly (one-way ANOVA, F1,55 = 21.06, P <0.0001), with mean
(± S.E.) values of 173.6 ± 16.2 µS cm-1 and 584.1 ± 168.2 µS cm-1, respectively. Additionally, the
maximum values recorded at upland and lowland sites were 382.0 µS cm-1 (site 12, Blackman River
at Old Tier Rd during November 2008) and 4160.0 µS cm-1 (site 13, Blackman River at Tunbridge
during June 2008), respectively. Site 13 (Blackman River at Tunbridge) and site 18 (Blanchards
Creek at Valleyfield Rd) were the most saline sites that were sampled, with values of >1500 µS cm-1
being recorded on both sampling occasions at each site. Physico-chemical variables in Lake Leake
at the time of the fish community survey in February 2009 were similar to those recorded in the
upland river sites during 2008 (Table 3.1).
Table 3.1 Mean ± 1 standard error (minimum-maximum) values for physico-chemical variables measured at upland and lowland river sites in the Macquarie catchment above the Lake River and in Lake Leake, May 2007-February 2009.
Physico-chemical variable Upland* Lowland Lake Leake†
Water temperature (°C) 11.5 ± 0.9 (4.5-22.4) 14.4 ± 0.9 (7.4-23.2) 16.8 ± 0.3
Dissolved oxygen (mg L-1) 9.7 ± 0.3 (6.1-12.4) 10.1 ± 0.3 (7.6-12.8) 8.6 ± 0.1
Dissolved oxygen (% saturation) 87.8 ± 2.1 (63.2-103.0) 99.6 ± 3.2 (74.0-132.0) 92.5 ± 0.9
pH 7.3 ± 0.1 (6.3-8.4) 7.6 ± 0.1 (6.8-8.8) 7.3 ± 0.1
Turbidity (NTU) 8.7 ± 1.6 (1.1-30.1) 6.7 ± 1.5 (1.0-34.0) 12.3 ± 0.9
Electrical conductivity (µS cm-1) 173.6 ± 16.2 (76.0-382.0) 584.1 ± 168.2 (137.3-4160.0) 94.4 ± 0.6
*Due to obvious differences to other upland sites, data for site 10 (Kittys Rivulet at Trefusis) was not included in the summary statistics for upland sites.
†Lake Leake was only sampled on a single occasion, whereas, collectively, the upland and lowland sites were sampled on several occasions; therefore, the ranges of values measured in the lake are not presented.
Fish and freshwater mussels in the Macquarie River catchment
15
3.1.1 Mesohabitats sampled and flow conditions during riverine sampling
Five of 13 lowland riverine sites that were surveyed contained broadwater habitat, whereas, in the
upland sites, only one of the ten sites contained broadwater habitat. Proportions of mesohabitats
that were fished using backpack electrofishing at upland and lowland riverine sites, were similar, but
there was greater coverage of riffles and less coverage of pools in upland sites (mean proportions
at all sites: upland: pool = 74%, run = 12%, riffle = 14%; lowland: pool = 80%, run = 12%,
riffle = 8%). At the time of sampling in upland sites, there was no flow during 42% of the 31
sampling occasions, whereas in lowland sites, there was no flow during 18% of the 28 sampling
occasions. The upland site 12 (Blackman River at Old Tier Rd) was in June 2008, but flowing during
the sampling occasion in November 2008, and the upland site 19 (Isis River at Verwood Rd) was
dry on both sampling occasions (in June and November 2008); thus, no sampling was conducted at
this site during the study.
3.2 Riverine fish communities
3.2.1 Summary of catches
A total of 1142 freshwater fish, including nine species and seven families, were collected in rivers in
the Macquarie River catchment upstream of Lake River during this study (Table 3.2). Approximately
equal numbers (c. 570) of fish were collected from lowland and upland sites, with six and eight
species being recorded in lowland and upland sites, respectively (Table 3.2). Between 10 and 629
fish, and one to eight species were captured in the five WMRs (Table 3.3); this variation was largely
due to differences in sampling effort and flow conditions in the WMRs during the study.
Southern pymgy perch (Nannoperca australis) (Appendix 1[e]) was the most abundant species
captured, accounting for 38% of the total catch (Figure 3.1). Common galaxias (Galaxias
maculatus), short-finned eel (Anguilla australis), redfin (Perca fluviatilis), brown trout (Salmo trutta)
and tench (Tinca tinca) (Appendix 1[f]) were relatively common in the catchment and collectively
accounted for 61% of the total catch (Figure 3.1). River blackfish (Gadopsis marmoratus) (Appendix
1[g]), goldfish (Carassius auratus) (Appendix 1[h]) and rainbow trout (Oncorhynchus mykiss) were
uncommon and collectively only accounted for 1% of the total catch (Figure 3.1).
Fish and freshwater mussels in the Macquarie River catchment
16
Table 3.2 Summary of catches of fish species in upland and lowland sites in rivers in the Macquarie catchment above the Lake River between May 2007 and February 2009 using all fishing methods. Note the fishing effort in upland and lowland regions was not equal (see Chapter 2).
Species Lowland Upland Total catch
Common galaxias (Galaxias maculatus) 0 70 70
River blackfish (Gadopsis marmoratus) 0 2 2
Short-finned eel (Anguilla australis) 73 73 146
Southern pymgy perch (Nannoperca australis) 301 128 429
Brown trout (Salmo trutta)* 37 120 157
Goldfish (Carassius auratus)* 8 0 8
Rainbow trout (Oncorhynchus mykiss)* 0 2 2
Redfin (Perca fluviatilis)* 95 121 216
Tench (Tinca tinca)* 55 57 112
Total species 6 8 9
Total individuals 569 573 1142
*Alien fish species.
Table 3.3 Summary of catches of fish species in rivers in Water Management Regions in the Macquarie catchment above the Lake River between May 2007 and February 2009 using all fishing methods. Note the fishing effort in WMRs was not equal (see Chapter 2).
Species Blackman
River
Elizabeth
River
Isis River Upper
Macquarie
Macquarie
d/s Elizabeth
Common galaxias (Galaxias maculatus) 0 0 0 70 0
River blackfish (Gadopsis marmoratus) 0 1 0 1 0
Short-finned eel (Anguilla australis) 10 26 13 56 41
Southern pymgy perch (Nannoperca australis) 0 57 47 191 134
Brown trout (Salmo trutta)* 0 51 6 85 15
Goldfish (Carassius auratus)* 0 0 0 0 8
Rainbow trout (Oncorhynchus mykiss)* 0 0 0 2 0
Redfin (Perca fluviatilis)* 0 14 2 154 46
Tench (Tinca tinca)* 0 24 4 60 24
Total species 1 6 5 8 6
Total individuals 10 173 72 619 268
*Alien fish species.
Fish and freshwater mussels in the Macquarie River catchment
17
Figure 3.1 Percent of fish species caught in rivers in the Macquarie River catchment above the Lake River between May 2007 and February 2009 using all fishing methods.
3.2.2 Proportion of alien species in catches
Of the nine species captured during the study, four are native and five are alien to Tasmania
(Table 3.1). Based on backpack electrofishing data, alien species accounted for significant
proportions of the total catches in lowland (27%) and upland (49%) sites (Figure 3.2). Perca
fluviatilis, S. trutta and T. tinca were the dominant alien species in catches in lowland and upland
sites, but there were fewer S. trutta in lowland catches compared to upland catches (Figure 3.2).
Carassius auratus were only collected in lowland sites and were uncommon (<1.5% of the total
catch in lowland sites).
Percent of total catch
N.australis
P.fluviatilis
S.trutta
A.australis
T.tinca
G.maculatus
C.auratus
G.marmoratus
O.mykiss
0 5 10 15 20 25 30 35 40
Fish and freshwater mussels in the Macquarie River catchment
18
Figure 3.2 Percent of alien fish species in backpack electrofishing catches in lowland and upland sites in the Macquarie River catchment above the Lake River, May 2007-December 2008.
3.2.3 Fish communities in Water Management Regions
Abundance
Not only did the occurrence of species differ between WMRs (Table 3.2), but the relative abundance
of species at sampling sites also varied between these regions (Figure 3.3). Based on backpack
electrofishing data, overall, the mean catches of species that were found in all WMRs, other than
the Blackman River WMR, were similar, with A. australis, P. fluviatilis, S. trutta and T. tinca in low
abundance (range in mean catch = 1-12), and N. australis in moderate abundance (range in mean
catch = 8-31). In the Blackman River WMR, during both seasons, only small numbers (range in
mean catch = 1-5) of A. australis were captured (Figure 3.3).
Mean catches of some species also varied seasonally within the regions (Figure 3.3). Anguilla
australis were more abundant during summer than in winter, whereas N. australis were more
abundant in winter than in summer. These differences are likely to be associated with changes in
habitat availability and differences in the activity patterns of species between the seasons. In winter,
flows in the rivers were generally higher than in summer, hence, water levels in the river channels at
the sampling sites were also higher. This allowed N. australis to move into shallow (<0.4 m in
Elevation class
Percent of catch
0
10
20
30
40
50
Lowland Upland
C.auratusP.fluviatilisS.truttaT.tinca
Fish and freshwater mussels in the Macquarie River catchment
19
depth), littoral areas where they could be sampled more efficiently with the electrofisher. Warmer
water temperatures in summer at sampling sites are likely to have influenced the activity patterns of
A. australis: making them generally more active and promoting foraging in shallow (<0.4 m in
depth), littoral areas where they could also be sampled efficiently with the electrofisher.
Size structure of catches and recruitment
Length frequencies of fishes that were abundant in the pooled seasonal catches in WMRs
(Figures 3.4-3.8) illustrate the size structure of the catches; hence, provide insight into the size and
age structure of the populations of the species that were captured. For some species, where
sampling times encompassed periods when juveniles were able to be caught using the fishing
methods employed in the study, these data also show evidence of recent recruitment.
Catches of G. maculatus in winter and summer in the Upper Macquarie WMR were dominated by
fish 90-130 mm TL, which would be adults of this species (Figure 3.4). There is no evidence of
recruitment in G. maculatus in this region. Catches of N. australis in winter in the Upper Macquarie,
Macquarie downstream of Elizabeth, Isis River and Elizabeth River WMRs were dominated by fish
40-70 mm TL, which would be adults of this species (Figure 3.5). However, during summer in these
WMRs, in addition to the adults, juvenile cohorts (10-20 mm TL) were also present indicating that
recruitment did occur in these regions during 2008.
Catches of the larger-sized species, P. fluviatilis, S. trutta and T. tinca, were largely dominated by
fish 100-300 mm TL (Figures 3.6-3.8). Individuals of this size range would generally be adults of this
species in these habitats, whereas individuals <90 mm TL would be juveniles. The catch data for
P. fluviatilis and T. tinca include fish of <90 mm TL in most WMRs where they occur (especially
during summer), thus, indicate recent recruitment. However, S. trutta data indicate that minimal
recruitment occurred during 2007 and 2008 in the Upper Macquarie and Elizabeth River WMRs.
This may be due, to a limited extent, to discrepancies between the timing of the sampling occasions
and the times at which new recruits would be catchable using the sampling methods that were
employed. However, if they were abundant at sampling sites during the study, greater numbers of
juvenile S. trutta are likely to have been captured, especially in the Isis River and the upper
Macquarie River. In the past, these areas provided some of the main spawning and nursery areas
for S. trutta, as is indicated by historical fry (juvenile trout) survey data from IFS (Figure 3.9), which
show fry accounting for larger proportions of electrofished catches in these areas during February
1990.
Fish and freshwater mussels in the Macquarie River catchment
20
Figure 3.3
Mea
n s
easo
nal
cat
ches
of
fish
spec
ies
(at
site
s w
her
e th
ey o
ccurr
ed)
usi
ng
bac
kpac
k el
ectr
ofis
hin
g in
Wat
er M
anag
emen
t R
egio
ns
in t
he
Mac
quar
ie
Riv
er c
atch
men
t ab
ove
th
e La
ke R
iver
bet
wee
n M
ay 2
007 a
nd
Dec
ember
2008. M
ean f
ishin
g ef
fort
at
each
sit
e o
n e
ach s
amplin
g o
ccas
ion w
as 2
0 m
in.
Fish species
Mean catch (no. of fish)
0
10
20
30
A.australis
C.auratus
G.marmoratus
G.maculatus
N.australis
P.fluviatilis
S.trutta
T.tinca
Blackman River
010
20
30
Elizabeth River
0
10
20
30
Isis River
010
20
30
Macquarie d/s Elizabeth
0
10
20
30
Upper Macquarie
Summer
Winter
Fish and freshwater mussels in the Macquarie River catchment
21
Figure 3.4
C
um
ula
tive
len
gth f
req
uen
cies
of
catc
hes
of
com
mo
n g
alax
ias
(Galaxias maculatus
) usi
ng
bac
kpac
k el
ectr
ofis
hin
g in
the
Uppe
r M
acq
uar
ie R
iver
Wat
er
Man
agem
ent
Reg
ion in
the
Mac
qu
arie
Riv
er c
atch
men
t ab
ove
the
Lak
e R
iver
bet
wee
n M
ay 2
00
7 an
d D
ecem
ber
200
8.
Total length (mm)
Frequency (%)
05
10
15
20
80
100
120
140
160
Summer : Upper Macquarie
05
10
15
20
Winter : Upper Macquaire
n = 17
n = 53
Fish and freshwater mussels in the Macquarie River catchment
22
Figure 3.5
C
um
ula
tive
len
gth f
req
uen
cies
of
catc
hes
of
south
ern
pyg
my
per
ch (Nannoperca australis
) usi
ng
fyke
net
tin
g an
d b
ackp
ack
elec
tro
fishin
g in
Wat
er
Man
agem
ent
Reg
ions
in t
he
Mac
qu
arie
Riv
er c
atch
men
t ab
ove
the
Lak
e R
iver
bet
wee
n M
ay 2
00
7 an
d D
ecem
ber
200
8.
Total length (mm)
Frequency (%)
05
10
15
20
25
020
40
60
80
Summer : Elizabeth River
020
40
60
80
Winter : Elizabeth River
Summer : Isis River
0510
15
20
25
Winter : Isis River
05
10
15
20
25
Summer : Macquaire d/s Elizabeth
Winter : Macquaire d/s Elizabeth
Summer : Upper Macquarie
0510
15
20
25
Winter : Upper Macquarie
n = 48
n = 46
n = 16
n = 32
n = 116
n = 80
n = 31
n = 25
Fish and freshwater mussels in the Macquarie River catchment
23
Figure 3.6
C
um
ula
tive
len
gth f
req
uen
cies
of
catc
hes
of
red
fin (Perca fluviatilis)
usi
ng
gill
net
tin
g, f
yke
net
ting
and
bac
kpac
k el
ectr
ofis
hin
g in
Wat
er M
anag
emen
t R
egio
ns
in t
he
Mac
quar
ie R
iver
cat
chm
ent
abo
ve t
he
Lake
Riv
er b
etw
een M
ay 2
007 a
nd D
ecem
ber
2008.
Total length (mm)
Frequency (%)
0
1020304050
100
200
300
400
Summer : Elizabeth River
100
200
300
400
Winter : Elizabeth River
Summer : Macquaire d/s Elizabeth
010
20
30
40
50
Winter : Macquaire d/s Elizabeth
0
1020304050Summer : Upper Macquarie
Winter : Upper Macquarie
n = 31
n = 32
n = 10
n = 100
n = 8
n = 4
Fish and freshwater mussels in the Macquarie River catchment
24
Figure 3.7
C
um
ula
tive
len
gth f
req
uen
cies
of
catc
hes
of
bro
wn t
rou
t (Salmo trutta
) u
sin
g bac
kpac
k el
ectr
ofis
hin
g in
Wat
er M
anag
emen
t R
egio
ns
in t
he
Mac
qu
arie
R
iver
cat
chm
ent
abo
ve t
he
Lake
Riv
er b
etw
een
May
20
07 a
nd
Dec
ember
2008.
Total length (mm)
Frequency (%)
05
10152025
100
200
300
400
Summer : Elizabeth River
100
200
300
400
Winter : Elizabeth River
05
10152025Summer : Upper Macquarie
Winter : Upper Macquarie
n = 26
n = 37
n = 46
n = 13
Fish and freshwater mussels in the Macquarie River catchment
25
Figure 3.8
C
um
ula
tive
len
gth f
req
uen
cies
of
catc
hes
of
tench
(Tinca tinca
) usi
ng
gill
net
ting,
fyk
e n
etti
ng
and
bac
kpac
k el
ectr
ofis
hin
g in
Wat
er M
anag
emen
t R
egio
ns
in t
he
Mac
quar
ie R
iver
cat
chm
ent
abo
ve t
he
Lake
Riv
er b
etw
een M
ay 2
007
and D
ecem
ber
2008.
Total length (mm)
Frequency (%)
0
10203040
0100
200
300
400
Summer : Elizabeth River
0100
200
300
400
Winter : Elizabeth River
Summer : Macquaire d/s Elizabeth
010
20
30
40
Winter : Macquaire d/s Elizabeth
0
10203040
Summer : Upper Macquarie
Winter : Upper Macquarie
n = 14
n = 16
n = 16
n = 46
n = 7
n = 8
Fish and freshwater mussels in the Macquarie River catchment
26
Figure 3.9 Total catches of brown trout (Salmo trutta) adults and fry (juveniles) using backpack electrofishing in Water Management Regions in the Macquarie River catchment above the Lake River during February 1990 (IFS, unpubl. data).
3.2.4 Fish communities in broadwater habitats
Due to differences in the amounts of fishing effort used in historical and recent surveys at the
broadwater sites on the Macquarie River, it is difficult to compare the catches of the surveys and
determine if there have been major temporal changes in the fish communities at the these sites.
However, examination of total catch data from combinations of fishing methods during these periods
(Figure 3.10) does provide information about the presence/absence of species between these
periods, and the relative abundances of fishes within each period.
Other than the occurrence of an individual alien C. auratus at the Barton site in the recent survey,
the fish communities of the three broadwater sites contained the same five species (native
A. australis and N. australis; alien P. fluviatilis, S. trutta and T. tinca) during both historical and
recent surveys (Figure 3.10). Historically, at Barton and Morningside, the relative abundances of
these five species were similar with A. australis being the least common species in the catches.
During the recent surveys, P. fluviatilis were common at all three sites, whereas the catches of
A. australis, N. australis, S. trutta and T. tinca varied, but these species appeared to be common in
at least two of the three broadwater sites (Figure 3.10).
Water Management Region
Catch (no. of fish)
0
100
200
300
400
500
Blackman River Elizabeth River Isis River Upper Macquarie
AdultFry
Fish and freshwater mussels in the Macquarie River catchment
27
Figure 3.10
T
ota
l ca
tches
of
fish
spec
ies
usi
ng
com
bin
atio
ns
of
gill
net
ting,
fyk
e net
tin
g, d
ip n
etti
ng
and
bac
kpac
k el
ectr
ofis
hin
g at
bro
adw
ater
sit
es in
the
Mac
qu
arie
Riv
er d
uri
ng
his
tori
cal (1
991-1
993)
and r
ecen
t (2
00
8) s
urv
eys.
No
his
tori
cal
dat
a w
ere
avai
lable
fo
r th
e T
oo
ms
Lake
Rd
sit
e.
Fish species
Log10(Catch (no. of fish))
0.0
0.5
1.0
1.5
2.0
A.australis
C.auratus
N.australis
P.fluvia
tilis
S.tru
tta
T.tinca
Barton : Recent
A.australis
C.auratus
N.australis
P.fluvia
tilis
S.tru
tta
T.tinca
Morningside : Recent
A.australis
C.auratus
N.australis
P.fluvia
tilis
S.tru
tta
T.tinca
Tooms Lake Rd : Recent
0.0
0.5
1.0
1.5
2.0
Barton : Historical
Morningside : Historical
Fish and freshwater mussels in the Macquarie River catchment
28
3.3 Fish community in Lake Leake
Catch data from the single-occasion fyke, gill and tow net survey in Lake Leake during February
2009 (Figures 3.11 and 3.12) provide an indication of the composition of the fish community in the
lake, the relative abundances of the species, and some coarse information about the size structure
of the populations. No fish were caught in tow net samples, which shows that at the time of the
survey, there were none (or very few) larval or juvenile fish in the water column of the lake.
However, catches in fyke and gill nets (Figure 3.11) indicate that P. fluviatilis and S. trutta are quite
abundant in the lake, and that A. australis and O. mykiss are also present in lower numbers.
Length frequencies of fishes that were captured in Lake Leake (Figure 3.12) show that only adults
(>90 mm TL) of A. australis, O. mykiss and S. trutta were captured, whereas juvenile (≤90 mm TL)
and adult P. fluviatilis were present in the catches. These results indicate that there has been
recruitment of P. fluviatilis, but minimal recruitment of A. australis, O. mykiss and S. trutta in recent
years in the lake.
Figure 3.11 Total catches of fish species using fyke netting and gill netting in Lake Leake during February 2009. No fish were collected in tow net samples.
Fish species
Catch (no. of fish)
0
5
10
15
20
25
A.australis O.mykiss P.fluviatilis S.trutta
Fish and freshwater mussels in the Macquarie River catchment
29
Figure 3.12
C
um
ula
tive
len
gth f
requen
cies
of
fish s
pec
ies
cap
ture
d u
sing
fyke
net
tin
g an
d g
ill n
etti
ng
in L
ake
Leak
e d
uri
ng
Feb
ruar
y 2009.
Total length (mm)
Frequency (%)
0
10
20
30
40
50
0100
200
300
400
500
Anguilla australis
010
20
30
40
50
Oncorhynchus mykiss
0
10
20
30
40
50
Perca fluviatilis
010
20
30
40
50
Salmo trutta
n = 12
n = 23
n = 2
n = 4
Fish and freshwater mussels in the Macquarie River catchment
30
3.4 Distribution of fishes in the Macquarie River catchment
Locations where fish species were found during historical (1975-2006) and recent (2007-2009; this
study) surveys in the Macquarie River catchment above the Lake River are presented in Figures
3.13-3.22. Short-finned eels (Anguilla australis) (Figure 3.13) and southern pymgy perch
(Nannoperca australis) (Figure 3.18) are by far the most widely distributed native fishes in the
Macquarie catchment. The extent of the distributions of both of these species appears to have
remained reasonably stable in recent decades. During recent surveys, A. australis was found in
lowland and upland areas (Figure 3.13), whereas N. australis was generally found in lowland
reaches in the catchment (Figure 3.18). Anguilla australis was found in all five WMRs during both
historical and recent surveys, whilst N. australis was found in four WMRs during both historical and
recent surveys; this species is likely to also occur in the lower reaches on the Blackman River WMR
when there are sufficient flows in the Blackman River.
The most widely distributed alien species’ in the Macquarie catchment are redfin (Perca fluviatilis)
(Figure 3.20), brown trout (Salmo trutta) (Figure 3.21) and tench (Tinca tinca) (Figure 3.22). The
extent of the distributions of P. fluviatilis and T. tinca appears to have remained reasonably stable in
recent decades, although T. tinca appears to have extended its distribution into the upper
Macquarie River and the mid-reaches of the Elizabeth River (Figure 3.22). During recent surveys,
P. fluviatilis was found in lowland and upland areas (Figure 3.20), whereas T. tinca was mostly
found in lowland reaches in the catchment (Figure 3.22). Both species were found in four of the five
WMRs during recent surveys; however, they are also likely to occur in the lower reaches of the
Blackman River WMR during stable flow conditions in the Blackman River (as they have previously
been recorded in this area (S. A. Hardie, DPIPWE, Tasmania, unpubl. data)).
Historically, S. trutta was one of the most widely distributed species in the catchment, being found in
lowland and upland areas and in all five WMRs; however, the findings of the 2007-2009 surveys
suggest that the extent of its distribution has contracted in recent years (Figure 3.21). Salmo trutta
was still found in lowland and upland areas and in four WMRs during the recent surveys, but its
range appears to be mostly restricted to the Macquarie, Elizabeth and Isis rivers, with few fish being
found in small-sized tributaries of the main rivers in the catchment (Figure 3.21).
The native river blackfish (Gadopsis marmoratus) (Figure 3.15), Swan galaxias (Galaxias fontanus)
(Figure 3.16) and common galaxias (Galaxias maculatus) (Figure 3.17) all have highly restricted
distributions in the Macquarie catchment. Historically, G. marmoratus appears to have inhabited the
upper Macquarie River and most of the Elizabeth River; there are also records of small numbers
being collected in the Macquarie River at Hoggs Ford Rd, a few kilometres upstream of the
Elizabeth River confluence (Figure 3.15). However, during recent surveys, G. marmoratus was only
found in the upper Macquarie River and a mid-reach of the Elizabeth River, and at both sites only
Fish and freshwater mussels in the Macquarie River catchment
31
one individual was captured. Therefore, the distribution of G. marmoratus in the catchment appears
to have contracted recently.
Galaxias fontanus is the only threatened (i.e. listed under State and Commonwealth threatened
species legalisation) fish species known to occur in the Macquarie catchment upstream of Lake
River. The historical (since 1975) distribution of this species was primarily confined to headwaters in
the Upper Macquarie, Isis River and Blackman River WMRs; however, there is one isolated
population in an unnamed tributary of the Macquarie River in Macquarie Tier (Figure 3.16). Galaxias
fontanus was not captured during the recent surveys (Figure 3.16) because areas where this
species is known to occur were not sampled.
Historically, G. maculatus has occurred in the upper reaches of the Upper Macquarie River WMR,
including Tooms Lake, and there is also a dubious record of this species being collected in the
Elizabeth River at Campbell Town (Figure 3.17). During recent surveys, this species was only
collected in the upper Macquarie River at two sites near Honeysuckle Rd (Figure 3.17). It is also
likely to still occur in Tooms Lake, which was unable to be surveyed during this study due to low
water levels.
The alien goldfish (Carassius auratus) (Figure 3.14) and rainbow trout (Oncorhynchus mykiss)
(Figure 3.19) both have highly restricted distributions in the Macquarie catchment. There were no
historical records of C. auratus occurring in the catchment (Figure 3.14). During the recent surveys,
this species was found at three sites in the Macquarie downstream of Elizabeth WMR (Figure 3.14);
therefore, this pest species appears to have recently invaded drainages in the lower end of the
catchment.
Historically, O. mykiss has occurred in Lake Leake and Tooms Lake (where its populations have
been largely maintained by stocking by IFS), and there is also a record of the species being
captured in the upper Macquarie River (Figure 3.19). However, during the recent surveys, this
species was only found in Lake Leake (Figure 3.19).
Fish and freshwater mussels in the Macquarie River catchment
32
Figure 3.13 Sites in the Macquarie River catchment above the Lake River, Tasmania where short-finned eels (Anguilla australis) were recorded during historical (1975-2006) and recent (2007-2009; this study) surveys. Water Management Regions in the catchment are also shown. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
33
Figure 3.14 Sites in the Macquarie River catchment above the Lake River, Tasmania where goldfish (Carassius auratus) were recorded during recent (2007-2009; this study) surveys. Water Management Regions in the catchment are also shown. There were no historical records of this species in the region. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
34
Figure 3.15 Sites in the Macquarie River catchment above the Lake River, Tasmania where river blackfish (Gadopsis marmoratus) were recorded during historical (1975-2006) and recent (2007-2009; this study) surveys. Water Management Regions in the catchment are also shown. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
35
Figure 3.16 Sites in the Macquarie River catchment above the Lake River, Tasmania where Swan galaxias (Galaxias fontanus) were recorded during historical (1975-2006) surveys. Water Management Regions in the catchment are also shown. This species was not captured in the region during recent surveys. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
36
Figure 3.17 Sites in the Macquarie River catchment above the Lake River, Tasmania where common galaxias (Galaxias maculatus) were recorded during historical (1975-2006) and recent (2007-2009; this study) surveys. Water Management Regions in the catchment are also shown. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
37
Figure 3.18 Sites in the Macquarie River catchment above the Lake River, Tasmania where southern pygmy perch (Nannoperca australis) were recorded during historical (1975-2006) and recent (2007-2009; this study) surveys. Water Management Regions in the catchment are also shown. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
38
Figure 3.19 Sites in the Macquarie River catchment above the Lake River, Tasmania where rainbow trout (Oncorhynchus mykiss) were recorded during historical (1975-2006) and recent (2007-2009; this study) surveys. Water Management Regions in the catchment are also shown. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
39
Figure 3.20 Sites in the Macquarie River catchment above the Lake River, Tasmania where redfin (Perca fluviatilis) were recorded during historical (1975-2006) and recent (2007-2009; this study) surveys. Water Management Regions in the catchment are also shown. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
40
Figure 3.21 Sites in the Macquarie River catchment above the Lake River, Tasmania where brown trout (Salmo trutta) recorded during historical (1975-2006) and recent (2007-2009; this study) surveys. Water Management Regions in the catchment are also shown. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
41
Figure 3.22 Sites in the Macquarie River catchment above the Lake River, Tasmania where tench (Tinca tinca) were recorded during historical (1975-2006) and recent (2007-2009; this study) surveys. Water Management Regions in the catchment are also shown. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
42
3.5 Distribution of freshwater mussels in the Macquarie River catchment
Historical data from work by Davies and Humphries (1996) shows that, during the early 1990s,
South Esk freshwater mussels (Velesunio moretonicus) (Appendix 1[i]) occurred in the Macquarie
River from the confluence of the Lake River upstream to the township of Ross (Figure 3.23;
Appendix 2). During surveys in 2007-2009, even though sampling effort for mussels was relatively
limited, live V. moretonicus were found to have a similar distribution range in the Macquarie River,
and live mussels were also recorded in the Blackman River at the township of Tunbridge
(Figure 3.23; Appendix 2). Additionally, similar to the historical findings, dead mussel shells were
recorded upstream of Ross in the Macquarie River at Tooms Lake Rd. Furthermore, during the
recent surveys, mussel shells were also found in the lower reaches of Kittys Rivulet at Trefusis
(Appendix 1[j]) and the Elizabeth River at Merton Vale (Figure 3.23; Appendix 2). Therefore,
currently, the distribution of V. moretonicus in the Macquarie River catchment upstream of Lake
River appears to be primarily confined to the lower reaches of the Macquarie River downstream of
Tooms Lake Rd or possibly Ross, with some mussels also being present in the lower reaches of the
Blackman River.
3.6 Avian predation on freshwater mussels
A total of 1157 V. moretonicus shells were collected from the Macquarie River at Ashby
(Appendices 1[c] and 1[d]) over the three sampling occasions during the study. Of these, 367 were
whole (joined) and 790 were split (separated) mussel shells; therefore, assuming two split shells
represent a single mussel, a total of 762 mussels were collected at this site. The numbers collected
on each sampling accession varied markedly, with 148, 605 and 10 V. moretonicus being collected
on 20 August and 27 November 2008, and 16 April 2009, respectively. Interestingly, the rates at
which the shells accumulated on the banks at the site, hence predation rate by waterbirds, varied
considerably during the last two samplings. Between August and November 2008, the predation
rate was 6.11 mussels day-1, whereas between November 2008 and April 2009, the predation rate
was 0.07 mussels day-1.
The total lengths (TL) of the shells that were collected ranged from 36.6 to 119.2 mm, but most
shells were between approximately 75 and 115 mm TL (mean ± SE = 89.4 ± 0.4; Figure 3.24). The
samples collected in August and November 2008, contained several shells that were <75 mm TL
(Figure 3.24), which may suggest that recruitment of juveniles had recently occurred in the area.
Fish and freshwater mussels in the Macquarie River catchment
43
Figure 3.23 Sites in the Macquarie River catchment above the Lake River, Tasmania where South Esk freshwater mussels (Velesunio moretonicus) were found to be present (either live mussels or shells only) or absent during historical (1990-1993) and recent (2008) surveys. Where live mussel and dead mussel shells were observed at the same sites (which is common), only live mussel data are presented. Where there are multiple records at single sites on the Macquarie River, data points have been jittered for clarity. Water Management Regions in the catchment are also shown. Historical data are from Davies and Humphries (1996). Location data are presented in Appendix 2. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
44
Figure 3.24
C
um
ula
tive
len
gth f
requen
cies
of
South
Esk
fre
shw
ater
mu
ssel
s (Velesunio moretonicus
) sh
ells
co
llect
ed o
n t
he
ban
ks o
f th
e M
acquar
ie R
iver
at
the
Ash
by
pro
per
ty d
uri
ng
2008-2
009. T
he
lengt
hs
of
who
le a
nd
sp
lit m
uss
el s
hel
ls a
re p
lott
ed.
Shell length (mm)
Frequency (%)
05
101520August 2008
0510
15
20
November 2008
05
101520
40
6080
100
120
April 2009
n = 182
n = 964
n = 11
Fish and freshwater mussels in the Macquarie River catchment
45
3.7 Host-parasite relationships between fishes and freshwater mussel glochidia
A total of 138 fish, representing two native and four alien species, were examined for
V. moretonicus glochidia parasites (Tables 3.4 and 3.5). The material examined was mostly of
relatively poor quality, due to inadequate preservation; however, the methods used enable the
presence or absence of glochidia cysts to be assessed with some confidence.
Overall, 17 fish had encysted glochidia (Figure 3.25), two fish were possibly parasitised
(indeterminate), glochidia were absent on 117 fish, and two fish had an inconclusive result.
Glochidia were found on two species: native A. australis and alien T. tinca (Table 3.5), but one of
the indeterminate specimens was a P. fluviatilis (the other was an A. australis). Anguilla australis
had a much higher prevalence of parasitism (14 fish; 33%), compared to T. tinca (three fish; 13%)
(Table 3.5). Glochidia were found attached to gill filaments (see Figure 3.25) or within gill cartilage.
The numbers of glochidia on parasitised individuals were quite low (usually 1-2; <5 on all fish).
Length data of examined (mean length: A. australis = 479 mm TL; T. tinca = 238 mm TL) and
parasitised (mean length: A. australis = 559 mm TL; T. tinca = 327 mm TL) fish indicate that larger-
sized individuals of both A. australis and T. tinca appeared more likely to be parasitised (Table 3.5).
Generally, parasitised fish were collected from sites where adult V. moretonicus were recorded
during the study (Figures 3.23 and 3.26). However, parasitised fish were recorded at two sites
where live adult mussels were not found: Isis River at Isis Road where no adult mussels were
observed and Macquarie River at Tooms Lake Road where only mussel shells were found
(section 3.5; Figure 3.23). Some fish, especially A. australis, also presented with myxosporian cysts
within their secondary gill filaments. These are common, naturally occurring protozoan parasites in
freshwater fish.
Fish and freshwater mussels in the Macquarie River catchment
46
Table 3.4 Sites where fish samples were collected in the Macquarie River catchment above the Lake River for glochidia analyses and the numbers of each species analysed. Sampling was conducted during November-December 2008 using electrofishing, and fyke and gill netting.
Fish species
Site A. australis N. australis C. auratus† P. fluviatilis
† S. trutta
† T. tinca
†
Blackman River at Tunbridge* 6 0 0 0 0 0
Elizabeth River at Merton Vale 2 6 0 0 0 3
Isis River at Isis Rd* 4 2 0 0 0 2
Macquarie River at Ashby* 4 0 0 1 0 0
Macquarie River at Barton 1 1 1 4 3 1
Macquarie River at Barton Rd 5 1 1 0 0 0
Macquarie River at Delmont Rd* 10 0 0 2 0 1
Macquarie River at Hogsford Rd* 1 0 0 1 0 1
Macquarie River at Morningside* 7 3 0 26 11 11
Macquarie River at Tooms Lake Rd* 3 3 0 5 1 4
Total 43 16 2 39 15 23
*Sites where South Esk freshwater mussels (Velesunio moretonicus) glochidia were found to be present on fish. Locations are shown in Figure 3.26.
†Alien fish species.
Table 3.5 Summary of fish samples that were examined for glochidia and the prevalence of parasitisation on gills. Total length (TL) data are mean (minimum-maximum) values. Fish samples from ten lowland river sites in the Macquarie catchment above the Lake River are pooled.
Species Number Length
(TL, mm)
Parasitised
(%)
Length of parasitised fish
(TL, mm)
Short-finned eel (Anguilla australis) 43 479 (180-770) 33 559 (290-770)
Southern pymgy perch (Nannoperca australis) 16 47 (30-70) 0 -
Goldfish (Carassius auratus)* 2 138 (105-170) 0 -
Redfin (Perca fluviatilis)* 39 172 (40-400) 0 -
Brown trout (Salmo trutta)* 15 332 (210-400) 0 -
Tench (Tinca tinca)* 23 238 (30-450) 13 327 (290-380)
*Alien fish species.
Fish and freshwater mussels in the Macquarie River catchment
47
Figure 3.25 (a) Section of gill arch from short-finned eel (Anguilla australis) showing gill cartilage and filaments, and an encysted South Esk freshwater mussel (Velesunio moretonicus) glochidia. Material is stained with hematoxylin and eosin; (b) Image of the same material that is presented in (a), but at higher magnification.
(a)
(b)
Gill cartilage Glochidia
Gill filament
Gill cartilage
Glochidia
Gill filament
Fish and freshwater mussels in the Macquarie River catchment
48
Figure 3.26 Sites in the Macquarie River catchment above the Lake River, Tasmania where South Esk freshwater mussels (Velesunio moretonicus) glochidia were found to be present or absent on fish collected during November-December 2008. Water Management Regions in the catchment are also shown. Site names are presented in Table 3.4. Base data by the LIST, © State of Tasmania.
Fish and freshwater mussels in the Macquarie River catchment
49
4. Discussion
4.1 Fish communities in Water Management Regions
This study has provided a comprehensive assessment of the status of the fish communities in
freshwater habitats in the Macquarie River catchment above the Lake River, and is the first study to
do so broadly across this region. Generally, flows in rivers in the region during the study were
relatively low and had been so for some time prior to the study (the last major floods in the
catchment occurred in 2005). These low-flow conditions are likely to have significantly influenced
catches at some sites, especially those in the Blackman River WMR where only small numbers of
short-finned eel (Anguilla australis) were caught. However, the two seasonal sampling occasions
that were undertaken at most riverine sites allowed all ephemeral sites, except the upper Isis River
at Verwood Rd, to be sampled at least once. This, coupled with the use of netting techniques in
deep-water habitats in the Macquarie River (Appendix 1[k]), has allowed the study to provide a
reasonably robust assessment of the composition of the fish communities in the WMRs during
2007-2008.
The species composition of the fish communities in all WMRs, other than the Blackman River WMR,
were similar, with the native A. australis and southern pymgy perch (Nannoperca australis), and
alien redfin (Perca fluviatilis), brown trout (Salmo trutta) and tench (Tinca tinca) being common in all
four WMRs. Native (but potentially not indigenous; section 4.3) common galaxias (Galaxias
maculatus) and river blackfish (Gadopsis marmoratus), and alien goldfish (Carassius auratus) and
rainbow trout (Oncorhynchus mykiss) were uncommon and only found in 1-2 WMRs. Furthermore,
length data indicated that N. australis, P. fluviatilis and T. tinca have been breeding and recruiting in
recent years, and that minimal recruitment of S. trutta has occurred recently. Recent low-flow
conditions in rivers in the catchment are likely to have allowed species such as N. australis,
P. fluviatilis and T. tinca (which prefer still or slow-flowing habitats (McDowall, 1996)) to extend their
distributions in recent years into tributaries of the Macquarie River and the upper reaches of this
river. Thus, to some extent, due to the dry climatic conditions in the catchment, habitat conditions
have been homogenised within lowland and mid-elevation reaches, and this is likely to have allowed
the fish communities in these areas to also be homogenised.
The fish communities in the three broadwaters that were surveyed had similar compositions to those
of their surrounding WMRs. In comparison to surveys conducted by Davies and Humphries (1996)
during the early 1990s, the species composition of the fish communities at the Barton and
Morningside sites on the Macquarie River were also found to be similar; however, the abundance of
S. trutta at both sites and N. australis at Barton, appeared to have decreased. Low flows in recent
years, which would have provided unfavourable conditions for S. trutta spawning and recruitment
(Davies et al., 1988), are likely to have reduced the abundance of this species at these sites. The
Fish and freshwater mussels in the Macquarie River catchment
50
apparent decline in the abundance of N. australis may be a result of differences in sampling effort
between the historical and recent surveys, with substantially more effort being used in the historical
surveys. Similar to the broadwater habitats, the fish community in Lake Leake contained similar
species to those found in the surrounding Elizabeth River WMR; with the exception of O. mykiss,
which is stocked into Lake Leake by IFS.
4.2 Native fish species
Of the nine fish species captured during this study, four (A. australis, G. maculatus, G. marmoratus
and N. australis) are native to Tasmania. According to the CFEV database (CFEV, 2005, DPIW,
2008a), three of these species (A. australis, G. marmoratus and N. australis) are included in the
native fish assemblage that is thought to have occurred across the South Esk Basin prior to
European settlement. This database also includes one other species, G. fontanus, in this
assemblage (the lack of this species in catches during the recent surveys and its distribution in the
catchment is discussed later). Based on backpack electrofishing data, native fishes numerically
comprised 73% of the total catch in lowland sites and 51% of the catch in upland sites. These
relatively high proportions of native species in the catches were strongly associated with the
prevalence of the small-sized species N. australis in lowland and upland areas. This species was
found in four of the five WMRs and was by far the most abundant species collected during the
recent surveys accounting for 38% of the total catch using all fishing methods. Recent years of low
flows in the catchment do not appear to have significantly impacted on the distribution or abundance
of N. australis. This is not surprising given that it has a strong preference for shallow, slow-flowing,
macrophyte-dominated habitats (Humphries, 1995, Woodward and Malone, 2002). Such habitats
are unlikely to have been significantly affected by low flows; indeed, they may have become more
prevalent in some areas, especially in lowland and mid-elevation reaches (e.g. Blanchards Creek;
Appendix 1[l]).
However, the importance of refuge habitats and suitable conditions that allow movement of species
between populations that are isolated during periods of low flow has been demonstrated by genetic
research on N. australis populations in Victoria, Australia (Cook et al., 2007). Nannoperca australis
are short-lived with populations being dominated by young-of-the-year fish, and most fish only living
for ≤2 years (Humphries, 1995, Llewellyn, 1974). In the Macquarie River, this species spawns
during spring – early summer (Humphries, 1995), and, as has recently been shown in the Murray
River, Australia (Tonkin et al., 2008), recruitment and dispersal can be significantly increased by
floodplain inundation. Therefore, the natural seasonal patterns of flow regimes of rivers in the
Macquarie catchment (DPIW, 2009) – especially high flows and flood events during winter-spring –
are likely to be important to the long-term viability of this species in the area. Such hydrological
conditions will provide refuge habitat for adults and habitat (flooded littoral vegetation) for spawning,
Fish and freshwater mussels in the Macquarie River catchment
51
assist recruitment and dispersal of juveniles, and allow movement of adults between populations
that are isolated during periods of low flow.
Anguilla australis was the most widely distributed species during the 2007-2008 surveys. This
species was found at 83% of the sites that were sampled during the study and historical data also
indicate that it has had an extensive distribution in the catchment in the past. This species is a
strong migrator and habitat generalist (Beumer, 1996); for these reasons, A. australis has an
extensive distribution across Tasmania (Sloane, 1984a). However, the barrier to fish passage
created by Trevallyn Dam on the lower South Esk River has basically eliminated natural migrations
of A. australis from the ocean into rivers in the South Esk Basin (Boxall et al., 2003, Sloane, 1984c).
The persistence of populations of this species in the catchment, which are likely to be in lower
abundance than prior to the construction of Trevallyn Dam, is now largely maintained by the capture
and stocking of elvers (juveniles eels) which congregate below Trevallyn Dam into waters upstream
of the impoundment (Hydro Tasmania, 2001). This stocking program has helped maintain natural
eel populations and commercial eel fisheries in Lake Leake and Tooms Lake, and a number of
other smaller lentic waters in the catchment. These fisheries support two commercial licenses in the
catchment, one in the area upstream of the Elizabeth River confluence, which includes the
Elizabeth River, Upper Macquarie and Blackman River WMRs, the other encompasses the Isis
River and Macquarie River downstream of Elizabeth River WMRs (and includes other downstream
reaches of the Macquarie River and the South Esk River, etc.) (S. J. Chilcott, IFS, Tasmania, pers.
comm.).
During the 2007-2008 surveys, a total of 70 G. maculatus were captured at a single location, the
upper Macquarie River at Honeysuckle Rd. Historically, this species has been recorded at a site
further upstream in the Macquarie River and in Tooms Lake; there is also a dubious record of this
species being collected in the Elizabeth River at Campbell Town. It is likely that G. maculatus still
occurs in Tooms Lake, which was unable to be surveyed during this study due to low water levels.
Whilst this species is native to Tasmania, it is not thought to be indigenous to the upper Macquarie
River (i.e. not found there prior to European settlement). This is because this species typically: (1)
occurs in low-elevation habitats, primarily in coastal rivers and to a lesser extent in lagoons or lakes
(McDowall and Fulton, 1996), (2) has a diadromous (migratory) life history, which involves a marine
larval phase and migration by juveniles back into low-elevation reaches of coastal rivers (Chapman
et al., 2006, McDowall, 1968), (3) the relatively steep gradient and boulder-dominated habitat of the
mid-elevation reaches of the Macquarie River (between Trefusis and the Tooms River confluence)
would have prevented natural migrations from the coast to the upper reaches of the Macquarie
River, and (4) the construction of Trevallyn Dam would now prevent migrations of this species into
rivers in the South Esk Basin.
Fish and freshwater mussels in the Macquarie River catchment
52
Galaxias maculatus is known to form landlocked populations in some coastal lagoons and low-
elevation lakes in southern Australia, where its life history is completed without a marine phase
(Andrews, 1982, Chapman et al., 2006, Pollard, 1971). Because of this flexibility in its life history
strategy, the most likely scenario which has led to the existence of G. maculatus in the upper
Macquarie River is that: (1) it was accidentally translocated into Tooms Lake, possibly with elver
stockings, (2) it has since established a self-sustaining population in the lake, (3) G. maculatus
(especially pelagic juveniles) are periodically washed out of Tooms Lake and into the Tooms and
Macquarie rivers with water that is released from the lake, and (4) fish that originate from Tooms
Lake move into the upper reaches of the Macquarie River. Alternatively, G. maculatus could also be
breeding in the upper Macquarie River, but it is highly likely that the populations in this area have
originated from Tooms Lake.
Similar to G. maculatus, G. marmoratus was found to have a highly restricted distribution in the
Macquarie catchment during the 2007-2008 surveys and it is also thought to not be indigenous to
rivers in this area. The natural distribution of G. marmoratus in Tasmania is generally thought to
have been restricted to drainages along the north coast, excluding the South Esk Basin (Jackson et
al., 1996). Therefore, its occurrence in the Macquarie River catchment may be due to translocations
during early European settlement or more recent times. Only two G. marmoratus were captured in
the recent surveys: one in the Elizabeth River at Devils Elbow (Appendix 1[g] and 1[m]) and one in
the upper Macquarie River at Honeysuckle Rd. These individuals were captured at sites where this
species had previously been recorded (between 1975 and 2006) and indicate that there are at least
two isolated populations in the catchment: one in the upper Macquarie River and one in the mid-
reaches of the Elizabeth River. As G. marmoratus has previously been recorded at sites
downstream of the locations where it was collected in this study, it appears that the distributions of
these two populations have reduced in recent years. This is likely to be associated with land
clearance in the region, and declining health and coverage of stream-side remnant native
vegetation (Davidson et al., 2007), thus, reductions in the amount of instream woody debris, which
this species prefers for refuge and requires for breeding (Davies, 1989, Jackson, 1978)
(Appendix 1[m]). This is especially the case in the lower Elizabeth River, where G. marmoratus has
been recorded historically and habitats appear to have degraded recently.
4.3 Alien fish species
Five alien fish species to Tasmania (C. auratus, O. mykiss, P. fluviatilis, S. trutta and T. tinca) were
recorded during the 2007-2008 surveys. Based on backpack electrofishing data, alien fishes
accounted for significant proportions of the total catches in lowland (27%) and upland (49%) sites.
Perca fluviatilis, S. trutta and T. tinca were the dominant alien species, with P. fluviatilis and T. tinca
Fish and freshwater mussels in the Macquarie River catchment
53
being more prolific in lowland reaches and S. trutta in upland reaches. Conversely, C. auratus and
O. mykiss were uncommon in the catchment, and found to have restricted distributions.
Despite repeated stockings over many decades in the early to mid-1900s (French, 2002), in the late
1900s, O. mykiss had a restricted distribution in the catchment and the results of this study show
that this is still the case. Oncorhynchus mykiss appears to be primarily restricted to Lake Leake and
probably Tooms Lake, where it is frequently stocked by IFS, but some migrants from the lakes may
occur in the headwaters of the Elizabeth and Macquarie rivers. Conversely, S. trutta was first
introduced in the Macquarie catchment in the 1870s (French, 2002) and, in recent decades, it had a
broad distribution across the catchment and was in greater abundance in lowland reaches than was
recorded during this study. Up until the early 1990s, this species formed the basis of a significant
recreational trout fishery in the lowland reaches of the Macquarie River (French, 2002); however,
due to declining numbers of S. trutta in the river in recent years, the fishery appears to have
declined (Scholes, 2003) (S. J. Chilcott, IFS, Tasmania, pers. comm.).
Long-term hydrological patterns can have a profound influence on the abundance of S. trutta
populations (Lobón-Cerviá, 2009). This is particularly the case in southern Australia, where the
broad-scale distribution of the species and abundance of localised populations are often limited by
hydrological and climatic conditions (Davies and McDowall, 1996, Harris and Gehrke, 1997). Whilst
S. trutta are able to survive during drought conditions in refuge pools which have sub-optimal
environmental conditions (i.e. water temperatures and dissolved oxygen concentrations), they
typically require water temperatures less than c. 25°C and dissolved oxygen concentrations of
greater than c. 2.5-5 mg L-1 (depending on water temperatures) (Elliott, 2000). Therefore, poor
water quality conditions that are associated with droughts can have direct effects on the health of
S. trutta, hence, abundance of their populations. Due to reduced flows in recent times, such
conditions are likely to have impacted on S. trutta populations in tributaries of the Macquarie River
in lowland areas, largely confining their distribution to the main stem of the Macquarie River, where
there are ample refuge pools (i.e. broadwaters), and the Elizabeth River which receives regulated
flows from Lake Leake.
However, more fundamentally, recruitment strength of riverine S. trutta populations is often highly
correlated with flow conditions during spawning and the early life stages (Davies et al., 1988,
Lobón-Cerviá, 2009, Nicola et al., 2009). Therefore, recruitment-discharge relationships may be
more influential to S. trutta populations over a wide range of climatic and flow conditions than direct
impacts of extreme water quality, which are likely to occur in short-term episodes in localised
habitats. This is likely to have been the most influential process on the S. trutta populations in rivers
in the Macquarie catchment in recent years, with low and unseasonal flow patterns being common
in the Macquarie River and its major tributaries since 1990 (DPIW, 2008d, DPIW, 2009). These
conditions are likely to have reduced recruitment of S. trutta in the catchment, especially from
Fish and freshwater mussels in the Macquarie River catchment
54
tributaries of the Macquarie River, such as the Isis River which previously provided reliable sources
of recruitment to the main river system (IFS, Tasmania, unpubl. data).
Perca fluviatilis and T. tinca were dominant species in lowland reaches in the catchment and had
similar distributions; although P. fluviatilis was more wide-spread and also found in the upper
reaches of the regulated Elizabeth and Macquarie rivers. Perca fluviatilis was introduced in
Tasmania (and possibly the South Esk Basin) in 1861 from Europe (Weatherley, 1963), and,
similarly, T. tinca was introduced in the 1870s, and had established populations in the South Esk
Basin by 1882 (Weatherley, 1959). Whilst not as highly regarded as salmonids (trout), both species
were introduced for angling by European settlers, as these quotes from Allport (1869) regarding the
reasons for the introduction of P. fluviatilis illustrate: “No sensible man would compare salmon or
trout with perch, but while there are in Tasmania hundreds of miles of rivers, and acres of lagoons
and backwaters devoid of good indigenous fish, which will not produce salmon and trout, and will
produce perch, surely the latter fish ought not to be altogether excluded”. “As a mere question of
sport, the introduction of perch will be regarded as a boon by a large number of people…”.
Both P. fluviatilis and T. tinca are not particularly strong swimmers or migrators (T. tinca are
regarded as reasonably sedentary) and prefer still or slow flowing, macrophyte-dominated habitats
(Weatherley, 1959, Weatherley, 1963, Weatherley, 1977), such as those found in the lower
Macquarie River system. Populations of neither species are likely to be significantly affected by
water quality conditions (i.e. water temperatures and dissolved oxygen concentrations) in Tasmania
(Weatherley, 1959, Weatherley, 1963), but, because of their limited swimming abilities, steep-
gradient reaches of streams would limit their distribution range in the Macquarie catchment. Both
P. fluviatilis and T. tinca are largely reliant on aquatic macrophytes for spawning, as they deposit
their eggs on vegetation (Collette et al., 1977, Weatherley, 1959).
In comparison to historical distribution data, both species have recently invaded the mid-reaches of
the Elizabeth River, and T. tinca has also spread into the middle to upper reaches of the Macquarie
River. Recent low flow conditions, including a lack of significant flood events, appear to have
provided suitable conditions for P. fluviatilis and T. tinca to expand their distributions. Prevailing low
flows would have provided appropriate hydraulic conditions for the species to move into habitats
they have not previously occupied. Furthermore, such flow conditions, coupled with nutrient
enrichment in some areas of the catchment (particularly in the Upper Macquarie WMR (Koehnken,
2009)), would also have allowed instream vegetation to become more dominant in some areas
(Appendix 1[l]), which would have increased the availability of refuge and spawning habitats for
these species. Both species now have very similar distributions to the native N. australis, which also
prefers low-flow conditions and macrophyte habitats. As small-bodied fish form a significant
proportion of the diet of adult P. fluviatilis, this overlap in the distributions of the two species is of
concern. Tinca tinca is not a piscivorous (fish eating) species (Brumley, 1996); therefore, is unlikely
Fish and freshwater mussels in the Macquarie River catchment
55
to directly impact on N. australis populations in the catchment; however, T. tinca may indirectly
affect native fishes by altering aquatic ecosystems in the catchment.
Carassius auratus belongs to the family Cyprinidae; this family includes T. tinca, and European carp
(Cyprinus carpio) which have also been introduced to Tasmania (IFS, 2004). This pest species was
found at three locations in the Macquarie downstream of Elizabeth River WMR: two in the lower
Macquarie River and one in Blanchards Creek. Carassius auratus had not previously been recorded
in the Macquarie catchment above the Lake River. Furthermore, according to Fulton (1990), up until
1990, this species was mostly confined to liberated stocks in farm dams with only occasional
records in rivers in Tasmania. More recently, Brumley (1996) does not even mention its existence in
Tasmania. However, currently, the Tasmanian Fish Database shows that this species has a
restricted distribution in the State, with 22 records from farm dams around Tasmania, four records
from rivers in the South Esk Basin, and three other records from rivers in the Huon, Tamar and
Rubicon catchments.
The four previous records of C. auratus from the South Esk Basin were from: Trevallyn Dam (1994),
South Esk River below Macquarie River confluence at Longford (1979), South Esk River upstream
of Longford (1994), and Macquarie River at Longford (1994). Therefore, this species appears to
have recently invaded the lower reaches of Macquarie River system above the Lake River from
populations further downstream. Because this species has similar habitat preferences to those of
P. fluviatilis and T. tinca (i.e. likes still water or low flows, and macrophytes for refuge and
spawning), it is likely to further invade the lowland reaches of the Macquarie River system if low flow
conditions prevail in rivers in the area. Eventually, C. auratus may have a similar distribution to
T. tinca in the Macquarie River catchment. Similar to T. tinca, this species is not piscivorous
(Brumley, 1996); therefore, is unlikely to directly impact on N. australis populations in the catchment;
however, C. auratus may also indirectly affect native fishes by altering aquatic ecosystems in the
catchment. Elsewhere in Australia, the closely related pest C. carpio has been found to negatively
impact on aquatic ecosystems (Koehn, 2004).
4.4 Freshwater mussel populations
Because of their complex life cycles (i.e. reliance on fish hosts for a larval stage) and their sessile
behaviour, many factors can influence the occurrence and abundance of freshwater mussels
(Bauer, 2001). Mussel species are declining in other catchments in Australia (Brainwood et al.,
2006, Playford and Walker, 2008) and drought conditions have been found to impact on mussel
populations in North America (Golladay et al., 2004, Haag and Warren, 2008), especially in areas
where there is a lack of instream habitat to provide refugia (e.g. depressions under logs) or
baseflows have decreased because of increased water abstraction. Mussels play several important
roles in aquatic ecosystem processes (Bruesewitz et al., 2009, Gergs et al., 2009, Vaughn and
Fish and freshwater mussels in the Macquarie River catchment
56
Hakenkamp, 2001, Vaughn et al., 2008, Pusch et al., 2001). Key functional roles that mussels
provide include nutrient cycling, via their filter and deposit feeding, and bioturbation of sediments
(i.e. disturbance of sediments via their movements) which increases sediment water and oxygen
content, and releases nutrients from the sediment to the water column (Vaughn and Hakenkamp,
2001). Therefore, declines in mussel populations are likely to have serious consequences for the
ecosystems they inhabit; particularly in river systems, such as those in the Macquarie catchment,
which are nutrient enriched, have episodes of poor water quality and the potential for algal blooms.
The South Esk freshwater mussel (Velesunio moretonicus) is known to occur in the Macquarie and
South Esk rivers, and the lower reaches of their large-sized tributaries in Tasmania. The results of
this study indicate that the current distribution of adult V. moretonicus in the Macquarie River
catchment upstream of Lake River is primarily confined to lowland reaches of the Macquarie River
downstream of Tooms Lake Rd (or possibly the township of Ross), with some mussels also being
present in the lower reaches of the Blackman River. Similar to Davies and Humphries (1996), dead
mussel shells were also recorded upstream of Ross in the Macquarie River at Tooms Lake Rd
during 2007-2008. Additionally, mussel shells were also found in the lower reaches of Kittys Rivulet
at Trefusis and the Elizabeth River at Merton Vale. The occurrence of shells at these locations
suggests that V. moretonicus has inhabited these areas in the past, possibly during periods of
higher and more stable baseflows. Therefore, in recent decades, the distribution of V. moretonicus
in the Macquarie catchment upstream of Lake River appears to have constricted largely to the main
channel of the Macquarie River.
Densities and size distributions of mussel populations across the catchment were not assessed
during the recent study, due to the substantial effort that is required to undertake rigorous sampling
of this kind (Metcalfe-Smith et al., 2000, Pooler and Smith, 2005). However, observations and
sampling in the Macquarie River at Ashby provide some information in these areas. At this site, in
the river, live V. moretonicus were found in dense aggregations (>20 mussels m-2 in some mussel
beds) in run habitats. On the river banks at this site, the shells of >700 mussels were collected
semi-quantitatively in a 100 m reach between August 2008 and April 2009. The occurrence of these
shells on the river banks was thought to have been the result of avian predation in the reach
(discussed later). Overall, the size distribution of the predated mussel shells was dominated by
large-sized adult mussels (i.e. 75-115 mm TL). This pattern is similar to the findings of actual
V. moretonicus population survey data that were collected in the early 1990s from eight sites in the
Macquarie River upstream of Lake River (Davies and Humphries, 1996), and data collected more
recently in the Brumbys Creek system (Davies and Cook, 2007). Thus, the data from the predated
shells are likely to be representative of the size structure of the mussel population at the Ashby site.
This dominance of large-sized adults in the size distribution is typical of populations of mussels of
the Hyriidae family (Walker et al., 2001), to which this species belongs. The substantial longevity of
Fish and freshwater mussels in the Macquarie River catchment
57
many mussel species of similar size to V. moretonicus (i.e. c. 30 years (Walker et al., 2001)), means
that there is often a lag between when recruitment becomes impeded by habitat alterations and
reductions in the abundance of adults in populations (Hastie and Toy, 2008). Populations of
V. moretonicus in the Brumbys Creek system have been found to have sporadic recruitment (Davies
and Cook, 2007), and the mechanisms which influence recruitment in these populations are
unclear. The mussel shell samples collected in the Macquarie River at Ashby in August and
November 2008 contained several shells that were <75 mm TL, which suggests that some
recruitment of juveniles had recently occurred in the area; however, further work should be done to
examine the age structure, recruitment processes and viability of mussel populations in the
Macquarie catchment to improve scientific knowledge of the status of the species.
Freshwater mussels are known to be predated on by several taxa including crayfish, fish, rodents,
turtles and waterbirds (Vestjens, 1973, Walker et al., 2001, Winter et al., 1998, Zahner-Meike and
Hanson, 2001, Tyrrell and Hornbach, 1998, van Tets, 1994). In Australia, anecdotal evidence
suggests that cormorants predate of freshwater mussels (van Tets, 1994), but the mechanisms they
use to open the mussels are not known. In this study, the evidence of predation by great cormorants
(Phalacrocorax carbo) is anecdotal, with the landowner of the Ashby property observing birds with
mussels on the banks of the Macquarie River and in nearby paddocks in the vicinity of the study
reach. The mechanisms the cormorants used to open the mussels are not known, but the separated
shells were generally found intact (i.e. not broken or with holes present), which suggests that they
did not break the shells open.
Assuming cormorants were responsible for the middens of shells on the banks of the river at the
Ashby site (Appendix 1[d]), thus, were predating on the mussels, this study provides preliminary
data regarding predation rates and seasonal patterns of predation. Interestingly, the rates at which
the shells accumulated on the banks at the site, hence predation rates by cormorants, varied
considerably. Between August and November 2008, the predation rate was 6.11 mussels day-1,
whereas between November 2008 and April 2009, the predation rate was 0.07 mussels day-1. This
difference suggests predation varied seasonally, being more intense during late winter – spring than
in summer – autumn. This indicates that predation by cormorants is not constant throughout the
year, and that perhaps the birds only predate on mussels at times when other food sources are
scarce (assuming food sources are more abundant during summer-autumn).
Because V. moretonicus populations in the Macquarie catchment occur in an agricultural landscape
and in rivers that have regulated flow regimes, several processes may impact on their long-term
viability. Firstly, physical habitat attributes are likely to be important. Davies and Humphries (1996)
found mussels to be in greater numbers in riffle and run habitats in vegetated reaches in the
Macquarie River above the Lake River, and Davies and Cook (2007) found high densities to be at
the edge of macrophyte beds in the Brumbys Creek system. Therefore, instream vegetation
Fish and freshwater mussels in the Macquarie River catchment
58
appears to be important, possibly due to the hydraulic shelter (Sand-Jensen and Mebus, 1996,
Sand-Jensen and Pedersen, 1999) and stable sediments it provides, and the food resources it
concentrates by promoting the settling of particles that are carried in the water column onto the
benthos (Sand-Jensen, 1998). Because V. moretonicus often occur in relatively shallow (<0.4 m
deep) areas in riffle and run habitats, the magnitude of baseflows and the water levels they provide
are also likely to be critical to aggregations of mussels in these habitats. It has been suggested that
artificial channels and ditches may provide suitable habitat for freshwater mussels (Gómez and
Araujo, 2008); however, during limited searches in this study, no mussels were found in such
habitats.
Secondly, physico-chemical properties of habitats are also likely to influence mussel populations.
According to reported tolerances of other Velesunio species (Walker et al., 2001), V. moretonicus is
likely to be reasonably tolerant of low dissolved oxygen concentrations and high water
temperatures, but high salinities (approximately 4,700 µS cm-1) are a potential threat and may limit
the distribution of their populations in Macquarie catchment, which already contains some
waterways with elevated salinities. For example, during this study, an electrical conductivity of
4,160 µS cm-1 was recorded in the Blackman River at Tunbridge, a site where live mussels were
also sampled.
4.5 Fish-freshwater mussel relationships
Some aspects of the habitats used by adult V. moretonicus have been documented (Davies and
Humphries, 1996, Davies and Cook, 2007), but little is known about the early life stages of this
species which are likely to be critical to dispersal (Vaughn and Taylor, 2000, Hughes et al., 2004)
and the viability of their populations. This study has undertaken preliminary work in this area by
investigating which species of fish are used as hosts by V. moretonicus glochidia. Whilst the fish
preservation methods used were not ideal (i.e. fixing whole fish, or selected body parts, in formalin
would have provided better quality material for analyses), this work has provided evidence of
encystment on two fish species, thus, provides insight into the mechanisms involved in host-
attachment and dispersal of glochidia.
Fish communities in reaches of the lower Macquarie River system that contain adult mussels are
comprised of two native (A. australis and N. australis), and four alien (C. auratus, P. fluviatilis,
S. trutta and Tinca tinca) species; therefore, theoretically, glochidia of V. moretonicus are presented
with several possible host-fishes. Even though specimens of all six of these species were
examined, glochidia were found on only two species, native A. australis and alien T. tinca, with
A. australis having a much higher prevalence of parasitism compared to T. tinca. Furthermore,
larger-sized individuals of both species appeared more likely to be parasitised.
Fish and freshwater mussels in the Macquarie River catchment
59
Glochidia typically infect fish which are indigenous to the area where the mussels are found (Kat,
1984, Geist et al., 2006); therefore, it is no surprise that V. moretonicus glochidia use A. australis as
hosts. However, the occurrence of glochidia on T. tinca is interesting. In Australia, other mussel
species have also been found to parasitise alien fishes (e.g. S. trutta (Atkins, 1979), eastern
gambusia (Gambusia holbrooki) and P. fluviatilis (Walker, 1981)), but survival of glochidia encysting
on alien fishes may be poor, as they may not successfully metamorphose, thus, complete the host-
based life stage (Jansen et al., 2001). Furthermore, an abundance of unsuitable host-fish – to which
glochidia are likely to attach, but not successfully develop – may impact on the likelihood of
encystment on suitable host-fish (Geist et al., 2006). The glochidia of hydriid mussels are typically
released from adults in straw-coloured, worm-like conglutinates that may attract fish, and they
attach to the fins, gills and body surface of their hosts (Walker et al., 2001). The infection strategies
used by V. moretonicus are not known, but both fishes that were found to be parasitised during this
study are primarily benthic (bottom-dwelling) species (McDowall, 1996). Therefore, infection may
involve direct contact with adult mussels and/or attraction to released glochidia during foraging in
benthic areas. Additionally, the occurrence of glochidia on large-sized individuals of both fishes
maybe due to differences in behaviour between juveniles and adults of these species, which
predispose larger fish to contact with glochidia, and the greater surface area of the gills of larger
individuals.
Velesunio moretonicus glochidia were found to be most prevalent on large-sized A. australis.
Anguilla australis is the larger-sized and stronger migrator of the two indigenous fishes that occur in
the lowland reaches of the Macquarie River system (the other being N. australis). Several mussel
species in Australia spawn and release glochidia during spring – summer (Walker et al., 2001). This
is also a time when the activity of A. australis increases in Tasmanian rivers, with elvers undertaking
upstream migrations (Sloane, 1984c), adults generally becoming more active (as indicated by
increased catches at this time during this study) and sexually mature fish migrating downstream
(Sloane, 1984b). Therefore, use of this species as a host would allow V. moretonicus to widely
disperse during the glochidial encystment phase, which can last for several days to 10 months, but
is commonly c. 20 days in many mussel species (Wächtler et al., 2001). The spatial distribution of
sites where parasitised fish where collected during this study provides evidence that supports this
theory. Generally, parasitised fish were collected from sites where adult V. moretonicus were
recorded, but at two sites, Isis River at Isis Road and Macquarie River at Tooms Lake Road, no live
adult mussels were observed. This suggests that glochidia attached to the A. australis in
downstream reaches before the eels moved upstream to where they were captured.
Because of their ability to provide substantial barriers to fish passage, instream dams are a
significant threat to freshwater mussels (Brainwood et al., 2008, Vaughn and Taylor, 1999, Watters,
1996). As previously discussed, the persistence of A. australis in the catchment now relies on
Fish and freshwater mussels in the Macquarie River catchment
60
translocations of elvers upstream of the Trevallyn Dam (Hydro Tasmania, 2001). As V. moretonicus
glochidia appear to rely on A. australis as hosts, the elver stocking program which is conducted by
Hydro Tasmania in the South Esk Basin is critical to the viability of mussel populations in the region.
Whilst A. australis was found to be the most wide-spread species in the catchment during the 2007-
2008 surveys and appeared to be reasonably abundant, the abundance of its populations is likely to
be significantly less than occurred historically in the catchment before the construction of Trevallyn
Dam. The construction of further instream dams in the lower reaches of rivers in the South Esk
Basin would have further detrimental impacts on V. moretonicus populations.
Currently, the habitats used by post-settlement juvenile V. moretonicus are unknown. This life stage
has little control over where they settle, as this process is largely dependent on flow conditions and
available substrata. As mussels are typically highly fecund and populations the two fish species that
were found to be hosts in the Macquarie system are reasonable abundant, suitable habitats for
detached juvenile mussels may have greater influence on recruitment strength (Österling et al.,
2008). The habitat requirements of this early life stage of V. moretonicus should be investigated, as
knowledge in this area would assist management of the riverine ecosystems which support its
populations. It should also be noted, that this was a brief investigation and more detailed work is
required to fully examine host-use of V. moretonicus glochidia.
Because V. moretonicus relies on host-fishes to complete their life cycle, the health of mussel
populations in the Macquarie catchment is dependent on fish populations. Whilst there is limited
information about the general habitat requirements of mussels, the needs of the fish communities in
the catchment are reasonably well known (as discussed in this report). Therefore, until further
information about the requirements of the mussels is gathered, attention should be directed towards
maintaining the integrity of fish communities in lower reaches on the Macquarie River system.
Fish and freshwater mussels in the Macquarie River catchment
61
5. Conclusion
5.1 Summary of findings
In summary, the main findings of this study are as follows:
• The species composition of the fish communities in all WMRs, other than the Blackman
River WMR, were similar, with the native short-finned eel (Anguilla australis) and southern
pymgy perch (Nannoperca australis), and alien redfin (Perca fluviatilis), brown trout (Salmo
trutta) and tench (Tinca tinca) being common in all four WMRs. Native (but potentially not
indigenous; section 4.3) common galaxias (Galaxias maculatus) and river blackfish
(Gadopsis marmoratus), and alien goldfish (Carassius auratus) and rainbow trout
(Oncorhynchus mykiss) were uncommon and only found in 1-2 WMRs.
• Based on backpack electrofishing data, alien species accounted for significant proportions of
the total catches in lowland (27%) and upland (49%) riverine sites. Perca fluviatilis, S. trutta
and T. tinca were the dominant alien species, with P. fluviatilis and T. tinca being more
prolific in lowland reaches and S. trutta in upland reaches.
• During both historical and recent surveys, fish communities at three broadwater sites on the
lower Macquarie River contained the same five species (native A. australis and N. australis,
and alien P. fluviatilis, S. trutta and T. tinca).
• The fish community in Lake Leake contained similar species to those found in the
surrounding Elizabeth River WMR, with the exception of O. mykiss, which was only found in
the lake. Perca fluviatilis and S. trutta were quite abundant in the lake, and A. australis and
O. mykiss were present in low numbers.
• Length data indicated that N. australis, P. fluviatilis and T. tinca have been breeding and
recruiting in recent years in rivers in the catchment, and that minimal recruitment of S. trutta
has occurred recently.
• Recent low-flow conditions in rivers in the catchment are likely to have allowed N. australis,
P. fluviatilis and T. tinca (which prefer still or slow-flowing, macrophyte-dominated habitats)
to extend their distributions into tributaries of the Macquarie River and the upper reaches of
this river.
• The distribution and abundance of alien S. trutta populations in the catchment have declined
recently. This is likely to be due to low flows in the catchment causing poor recruitment and
unfavourable environmental conditions for this species.
• The distribution of the South Esk freshwater mussel (Velesunio moretonicus) in the
Macquarie River catchment upstream of Lake River appears to be primarily confined to
Fish and freshwater mussels in the Macquarie River catchment
62
lowland reaches in the Macquarie River downstream of Tooms Lake Rd (or possibly Ross),
with some mussels also being present in the lower reaches of the Blackman River. The
extent of the distribution of mussels in the system may have contracted in recent decades.
• Velesunio moretonicus were found in dense aggregations in run habitats at some sites in the
lower Macquarie River; however, the viability of populations in the catchment is unknown
and requires further investigation.
• Anecdotal evidence of predation by great cormorants (Phalacrocorax carbo) on
V. moretonicus was gathered at one site on the lower Macquarie River. Predation rates were
found to vary seasonally, being high in late winter-spring and low in summer-autumn.
• Velesunio moretonicus glochidia were found on only two fish species, native A. australis and
alien T. tinca, with A. australis having a much higher prevalence of parasitism compared to
T. tinca. Furthermore, larger-sized individuals of both species appeared more likely to be
parasitised.
• Generally, fish that were parasitised by glochidia were collected from sites where adult
V. moretonicus were recorded, but at two sites, Isis River at Isis Road and Macquarie River
at Tooms Lake Road, no live adult mussels were observed.
5.2 Synthesis
Overall, the species compositions of the fish communities in the catchment during 2007-2008 were
similar to historical records for the region, although the distributions and abundances of some
species appear to have changed in recent years. Flows in rivers in the region during the study were
relatively low and had been so for some time prior to the study (the last major floods in the
catchment occurred in 2005, and, generally, flows in rivers in the catchment have been relatively
low since 1990). These recent low-flow conditions appear to have allowed some species, which
prefer still or slow-flowing habitats (N. australis, P. fluviatilis and T. tinca), to extend their
distributions. These conditions may also have assisted the upstream dispersal of an alien pest
species (C. auratus) into the Macquarie River system upstream of Lake River; an area where it has
not previously been recorded.
Additionally, the distribution and abundance of populations of an alien species that was previously
wide-spread and valued by recreational anglers (S. trutta) has declined recently. This is likely to be
due to low-flows in the catchment causing poor recruitment and unfavourable environmental
conditions for this species. Similarly, in recent decades, flow conditions appear to have influenced
the distribution of the endemic V. moretonicus in the Macquarie catchment upstream of Lake River.
This species is now restricted largely to the lower reaches of the Macquarie River where habitats
are relatively deep, and flow conditions are relatively stable due to flow regulation. Anguilla australis
Fish and freshwater mussels in the Macquarie River catchment
63
was found to be the primary host of V. moretonicus glochidia. This fish-mussel relationship
highlights the importance of providing passage for elvers upstream of Trevallyn Dam in the lower
South Esk Basin to the aquatic ecosystems in the Macquarie catchment.
Flow alterations, via regulation (Bain and Finn, 1988, Gehrke and Harris, 2001, Humphries et al.,
2008) or drought conditions (Closs and Lake, 1996, Magalhães et al., 2007, Perry and Bond, 2009),
have been found to influence riverine fish communities in many regions, and freshwater mussels are
known to be susceptible to impacts from reduced flows (Golladay et al., 2004, Haag and Warren,
2008). This study has shown that, in recent times, broad-scale changes have occurred in fish
communities in the Macquarie catchment and that the distribution of the endemic freshwater mussel
V. moretonicus in this region may also have reduced. Both of these alterations to the ecosystems of
the Macquarie River system appear to be associated primarily with flow regime alterations;
however, in some instances, landscape degradation (e.g. removal of native riparian vegetation;
nutrient enrichment of soils, hence waterways, etc.) is likely to have caused compounding impacts.
Prolonged periods of reduced flows or unseasonal flow patterns (due to dry climatic conditions
and/or water use), similar to those which have recently occurred in the catchment, are likely to
further impact on fish communities and freshwater mussel populations in the catchment. Seasonal
flow variability and adequate baseflows are critical to the long-term viability of aquatic fauna in the
region.
5.3 Support for environmental flow recommendations
The findings of this study provide support for the environmental flow assessment that was prepared
by DPIPWE for rivers in the Macquarie River upstream of the Lake River (DPIW, 2009). More
specifically, this study has validated aspects of the ecosystem conceptual models in that
assessment which relate to fish and freshwater mussels, and justified several of its objectives. The
principle focus of the environment flows assessment has been the preservation of high flows. This
focus will have several benefits for fish and mussels, with the main ones being:
• Seasonal (winter-spring) high flow events will inundate littoral macrophyte beds which are
used as habitat by A. australis and N. australis for refuge and feeding; N. australis also
spawns in these areas and juveniles use them as nursery habitat.
• Seasonal (winter-spring) high flow events will provide stimuli and suitable conditions for
native species (N. australis and A. australis) to undertake small- and large-scale movements
within the Macquarie system.
• Maintenance of high flow events at any time of year will help restrict the distribution and
abundance of alien pest fishes (C. auratus, P. fluviatilis and T. tinca) in the Macquarie
system.
Fish and freshwater mussels in the Macquarie River catchment
64
• The dispersal and, hence, distribution of V. moretonicus will be enhanced by high flows
which promote A. australis migrations (as this fish species appears to be the primary host for
its parasitic glochidia larvae).
Fish and freshwater mussels in the Macquarie River catchment
65
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7. Appendices
Appendix 1. Pictorial of field work activities, sampled taxa, and selected study sites during work in the Macquarie River catchment upstream of Lake River, 2007-2009.
Appendix 1[a]. View of Lake Leake from the dam wall, February 2009.
Appendix 1[b]. View of Tooms Lake from the boat ramp, February 2009.
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Appendix 1[c]. Macquarie River at the Ashby property, November 2008. South Esk freshwater mussel (Velesunio moretonicus) shells were collected on both banks of this reach on three occasions during the study.
Appendix 1[d]. Chris Bobbi (DPIPWE – Water Assessment Branch) collecting South Esk freshwater mussel (Velesunio moretonicus) shells on a bank of the Macquarie River at the Ashby property, August 2008.
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Appendix 1[e]. Southern pymgy perch (Nannoperca australis) captured in Kittys Rivulet at the Trefusis property, June 2008.
Appendix 1[f]. Tench (Tinca tinca) captured in Blanchards Creek at Valleyfield Rd, June 2008.
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Appendix 1[g]. River blackfish (Gadopsis marmoratus) captured in the Elizabeth River at Devils Elbow, December 2008.
Appendix 1[h]. Goldfish (Carassius auratus) captured in Blanchards Creek at Valleyfield Rd, November 2008.
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Appendix 1[i]. South Esk freshwater mussel (Velesunio moretonicus) collected in the Macquarie River at the Ashby property, June 2008.
Appendix 1[j]. Kittys Rivulet at the Trefusis property, June 2008. A shell of a South Esk freshwater mussel (Velesunio moretonicus) was collected in the dry river bed at this site during June 2008.
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Appendix 1[k]. ‘The Broadwater’ in the Macquarie River at the Barton property, August 2008.
Appendix 1[l]. Blanchards Creek at Valleyfield Rd, November 2008. Prolific submerged and emergent macrophytes at this site are likely to have resulted from reduced flows and increased nutrients concentrations in the creek. Many tench (Tinca tinca) and some goldfish (Carassius auratus) (both of which are alien pest fish) were captured at this site during 2008.
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Appendix 1[m]. Elizabeth River at Devils Elbow, December 2008. A river blackfish (Gadopsis marmoratus) was captured at this site. Note the abundant native riparian vegetation and presence of instream woody debris, which are important habitat attributes for G. marmoratus.
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Appendix 2. Sites in the Macquarie River catchment above the Lake River, Tasmania where South Esk freshwater mussels (Velesunio moretonicus) were found to be present (either live mussels or shells only) or absent during historical (1990-1993) and recent (2008) surveys. Where live mussel and dead mussel shells were observed at the same sites (which is common), only live mussel data are presented. Historical data are from Davies and Humphries (1996). Period Site Northing Easting Observation
Recent Macquarie River at Barton 5371019 519771 Alive
Recent Blackman River at Tunbridge 5334410 533929 Alive
Recent Macquarie River at Merton Vale Ford 5357200 535700 Alive
Recent Macquarie River at Hogs Ford Rd 5355262 536744 Alive
Recent Macquarie River at Ashby 5349450 538200 Alive
Recent Macquarie River at Morningside 5360223 532430 Shell
Recent Elizabeth River at Merton Vale 5358117 537129 Shell
Recent Kittys Rivulet at Trefusis 5328397 547759 Shell
Recent Macquarie River at Tooms Lake Rd 5331700 547800 Shell
Recent Macquarie River at Delmont Rd 5377326 515459 None
Recent Isis River at Isis 5365583 520188 None
Recent Prideaux Creek at Isis Rd 5354958 521230 None
Recent Macquarie River at Barton Rd 5369530 521590 None
Recent Bayles Creek at Isis Rd 5352272 523371 None
Recent Isis River at Isis Rd 5352148 525601 None
Recent Isis River at Verwood Rd 5344549 525679 None
Recent Blackman River at Old Tier Rd 5331659 528489 None
Recent Blanchards Creek at Valleyfield Rd 5365000 529000 None
Recent Elizabeth River at Campbell Town 5357414 540458 None
Recent Elizabeth River at Devil's Elbow 5359004 546875 None
Recent Glen Morriston Rivulet at Moulton 5339617 547090 None
Recent Macquarie River off Honeysuckle Rd 5331741 558085 None
Recent Elizabeth River at Tea Tree Hill 5355991 561177 None
Recent Macquarie River at Long Marsh Rd 5338567 568989 None
Historical Macquarie River at Delmont Rd 5377326 515459 Alive
Historical Macquarie River at Barton 5371019 519771 Alive
Historical Macquarie River at Morningside 5360223 532430 Alive
Historical Macquarie River at Merton Vale Ford 5357200 535700 Alive
Historical Macquarie River at Hogs Ford Rd 5355262 536744 Alive
Historical Macquarie River at Ross 5346450 540450 Alive
Historical Macquarie River at Tooms Lake Rd 5331700 547800 Shell
Historical Macquarie River at Trefusis 5330500 548900 Shell