Status of fish communities and observations on South Esk ... of fish...This study has shown that, in recent times, broad-scale changes have occurred in fish communities in the Macquarie

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


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.


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


v

5.3 Support for environmental flow recommendations ................................................................. 63

6. References ................................................................................................................................ 65

7. Appendices ............................................................................................................................... 71


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).


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.


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.


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.


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


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.


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.


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.


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


5369530

521590

River

149

Lowland

Jun-08, Nov-08

e-fish

8

Macquarie River at Barton


5371019

519771

River

148

Lowland

Dec-08

e-fish, gill, fyke

9

Macquarie River at Delmont Rd


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


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.


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.


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.


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


9-10/12/2008 1000-1055


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



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



12/02/2009 985-995


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.


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.


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.


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).


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.


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).


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



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


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


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.


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


0

10

20

30

Upper Macquarie

Summer

Winter


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


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


0510

15

20

25

Winter : Upper Macquarie

n = 48

n = 46

n = 16

n = 32

n = 116

n = 80

n = 31

n = 25


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


100

200

300

400



010

20

30

40

50


0

1020304050Summer : Upper Macquarie


n = 31

n = 32

n = 10

n = 100

n = 8

n = 4


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


100

200

300

400


05

10152025Summer : Upper Macquarie


n = 26

n = 37

n = 46

n = 13


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


0100

200

300

400



010

20

30

40


0

10203040



n = 14

n = 16

n = 16

n = 46

n = 7

n = 8


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


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


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


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


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


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).


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.


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.


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.


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.


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.


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.


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.


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.


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.


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.


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.


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.


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


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.


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)



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


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.


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


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


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,


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.


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


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


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


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


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


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


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.


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


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.


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


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


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


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.


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).


65

6. References

Allport, M. (1869) Reasons for the introduction of the perch into Australia. Papers and Proceedings of the Royal Society of Tasmania, 1868, 56-57.

Andrews, A. P. (1982) A Tasmania landlocked population of the normally diadromous fish Galaxias maculatus (Jenyns). Papers and Proceedings of the Royal Society of Tasmania, 116, 85-90.

Atkins, L. (1979) Observations on the glochidial stage of the freshwater mussel Hyridella (Hyridella) drapeta (Iredale) (Mollusca : Pelecypoda). Australian Journal of Marine and Freshwater Research, 30, 411-416.

Bain, M. B. & Finn, J. T. (1988) Streamflow regulation and fish community structure. Ecology, 69, 382-392.

Bancroft, J. D. & Stevens, A. (1990) Theory and Practice of Histological Techniques. pp. 190. Churchill Livingston, NY.

Bauer, G. (2001) Factors Affecting Naiad Occurrence and Abundance. Ecology and Evolution of the Freshwater Mussels Unionoida (eds G. Bauer & K. Wächtler), pp. 155-162. Springer, Berlin.

Beumer, J. P. (1996) Family Anguillidae. Freshwater eels. Freshwater Fishes of South-Eastern Australia (ed R. M. McDowall), pp. 39-43. Reed Books, Sydney.

Boxall, P. B., Taylor, A. H., Howland, M. B. & Andrews, D. (2003) Assessment of the impacts of hydro-electric dams on eel stocks in Tasmania and an assessment and evaluation of mitigation strategies. FRDC Project No. 2000/186. Inland Fisheries Service, Hobart, Tasmania.

Brainwood, M., Burgin, S. & Byrne, M. (2006) Is the decline of freshwater mussel populations in a regulated coastal river in south-eastern Australia linked with human modification of habitat? Aquatic Conservation: Marine and Freshwater Ecosystems, 16, 501-516.

Brainwood, M., Burgin, S. & Byrne, M. (2008) The impact of small and large impoundments on freshwater mussel distribution in the Hawkesbury-Nepean River, southeastern Australia. River Research and Applications, 24, 1325-1342.

Bruesewitz, D. A., Tank, J. L. & Hamilton, S. K. (2009) Seasonal effects of zebra mussels on littoral nitrogen transformation rates in Gull Lake, Michigan, U.S.A. Freshwater Biology, 54, 1427-1443.

Brumley, A. R. (1996) Family Cyprinidae. Carps, minnows, etc. Freshwater Fishes of South-Eastern Australia (ed R. M. McDowall), pp. 99-106. Reed Books, Sydney.

CFEV (2005) Conservation of Freshwater Ecosystem Values Project Database. Water Resources Division, Department of Primary Industries and Water, Hobart, Tasmania.

Chapman, A., Morgan, D. L., Beatty, S. J. & Gill, H. S. (2006) Variation in life history of land-locked lacustrine and riverine populations of Galaxias maculatus (Jenyns 1842) in Western Australia. Environmental Biology of Fishes, 77, 21-37.

Closs, G. P. & Lake, P. S. (1996) Drought, differential mortality and the coexistance of a native and an introduced fish species in a south east Australian intermittent stream. Environmental Biology of Fishes, 47, 17-26.

Collette, B. B., Ali, M. A., Hokanson, K. E. F., Nagiec, M., Smirnov, S. A., Thorpe, J. E., Weatherley, A. H. & Willemsen, J. (1977) Biology of the percids. Journal of the Fisheries Research Board of Canada, 34, 1890-1899.

Cook, B. D., Bunn, S. E. & Hughes, J. M. (2007) Molecular genetic and stable isotope signatures reveal complementary patterns of population connectivity in the regionally vulnerable southern pygmy perch (Nannoperca australis). Biological Conservation, 138, 60-72.


66

Davidson, N. J., Close, D. C., Battaglia, M., Churchill, K., Ottenschlaeger, M., Watson, T. & Bruce, J. (2007) Eucalypt health and agricultural land management within bushland remnants in the Midlands of Tasmania, Australia. Biological Conservation, 139, 439-446.

Davies, P. E. (1989) Relationships between habitat characteristics and population abundance for brown trout, Salmo trutta L., and blackfish, Gadopsis marmoratus Rich., in Tasmanian streams. Australian Journal of Marine and Freshwater Research, 40, 341-359.

Davies, P. E. & Cook, L. S. J. (2007) Basslink Monitoring Program Field Report: Downstream Poatina: Macrophytes, Macroinvertebrates, and Mussels. Freshwater Systems Ltd., Hobart, Tasmania.

Davies, P. E. & Humphries, P. (1996) An Environmental Flow Study of the Meander, Macquarie and South Esk Rivers, Tasmania. Hobart, Tasmania.

Davies, P. E. & McDowall, R. M. (1996) Family Salmonidae. Salmons, trouts and chars. Freshwater Fishes of South-Eastern Australia (ed R. M. McDowall), pp. 81-91. Reed Books, Sydney.

Davies, P. E., Sloane, R. D. & Andrew, J. (1988) Effects of hydrological change and the cessation of stocking on a stream population of Salmo trutta L. Australian Journal of Marine and Freshwater Research, 39, 337-354.

DPIPWE (2009) Macquarie River Broadwater Ecosystems Assessment. Water Assessment Aquatic Ecology Report Series, Report No. WA 09/03. Water and Marine Resources Division. Department of Primary Industries, Parks, Water and Environment, Hobart, Tasmania.

DPIW (2008a) Assessment of Freshwater Ecosystem Values in the Macquarie River Catchment. Water Assessment Aquatic Ecology Report Series, Report No. WA 08/51. Water Resources Division. Department of Primary Industries and Water, Hobart, Tasmania.

DPIW (2008b) Natural Values Atlas. Resource Management and Conservation, Department of Primary Industries and Water, Hobart, Tasmania.

DPIW (2008c) River Health of the Macquarie River Catchment. Water Assessment Aquatic Ecology Report Series, Report No. WA 08/53. Water Resources Division. Department of Primary Industries and Water, Hobart, Tasmania.

DPIW (2008d) Surface Water Hydrology of the Macquarie River Catchment. Water Assessment Hydrology Report Series, Report No. WA 08/46. Water Resources Division. Department of Primary Industries and Water, Hobart, Tasmania.

DPIW (2009) Environmental Flow Assessment for the Macquarie River Catchment Upstream of Lake River. Water Assessment Aquatic Ecology Report Series, Report No. WA 09/01. Water Resources Division. Department of Primary Industries and Water, Hobart, Tasmania.

Elliott, J. M. (2000) Pools as refugia for brown trout during summer droughts: trout responses to thermal and oxygen stress. Journal of Fish Biology, 56, 938-948.

French, G. (2002) Tasmanian Trout Waters, Australian Fishing Network, Melbourne.

Fulton, W. (1990) Tasmanian Freshwater Fishes, University of Tasmania - Fauna of Tasmania Committee, Hobart, Tasmania.

Gehrke, P. C. & Harris, J. H. (2001) Regional-scale effects of flow regulation on lowland riverine fish communities in New South Wales, Australia. Regulated Rivers: Research & Management, 17, 369-391.

Geist, J., Porkka, M. & Kuehn, R. (2006) The status of host fish populations and fish species richness in European freshwater pearl mussel (Margaritifera margaritifera) streams. Aquatic Conservation: Marine and Freshwater Ecosystems, 16, 251-266.

Gergs, R., Rinke, K. & Rothhaupt, K.-O. (2009) Zebra mussels mediate benthic-pelagic coupling by biodeposition and changing detrital stoichiometry. Freshwater Biology, 54, 1379-1391.


67

Golladay, S. W., Gagnon, P., Kearns, M., Battle, J. M. & Hicks, D. W. (2004) Response of freshwater mussel assemblages (Bivalvia: Unionidae) to a record drought in the Gulf Coastal Plain of southwestern Georgia. Journal of the North American Benthological Society, 23, 494-506.

Gómez, I. & Araujo, R. (2008) Channels and ditches as the last shelter for freshwater mussels: the case of Margaritifera auricularia and other naiads inhabiting the mid Ebro River Basin, Spain. Aquatic Conservation: Marine and Freshwater Ecosystems, 18, 658-670.

Haag, W. R. & Warren, M. L. (2008) Effects of severe drought on freshwater mussel assemblages. Transactions of the American Fisheries Society, 137, 1165-1178.

Harris, J. H. & Gehrke, P. C. (1997) Fish and Rivers in Stress: The NSW Rivers Survey. New South Wales Fisheries Office of Conservation, Sydney.

Hastie, L. C. & Toy, K. A. (2008) Changes in density, age structure and age-specific mortality in two western pearlshell (Margaritifera falcata) populations in Washington (1995-2006). Aquatic Conservation: Marine and Freshwater Ecosystems, 18, 671-678.

Hughes, J., Baker, A. M., Bartlett, C., Bunn, S., Goudkamp, K. & Somerville, J. (2004) Past and present patterns of connectivity among populations of four cryptic species of freshwater mussels Velesunio spp. (Hyriidae) in central Australia. Molecular Ecology, 13, 3197-3212.

Humphries, P. (1995) Life history, food and habitat of southern pygmy perch, Nannoperca australis, in the Macquarie River, Tasmania. Marine and Freshwater Research, 46, 1159-1169.

Humphries, P., Brown, P., Douglas, J., Pickworth, A., Strongman, R., Hall, K. & Serafini, L. (2008) Flow-related patterns in abundance and composition of the fish fauna of a degraded Australian lowland river. Freshwater Biology, 53, 789-813.

Hydro Tasmania (2001) South Esk - Great Lake Water Management Review. Scientific Report of Trevallyn Elver Passage. Hydro Tasmania, Hobart, Tasmania.

IFS (2004) Carp Management Program Report Lakes Crescent and Sorell, 1995 - June 2004. Inland Fisheries Service, Hobart, Tasmania.

Jackson, P. D. (1978) Spawning and early development of the river blackfish, Gadopsis marmoratus Richardson (Gadopsiformes: Gadopsidae), in the McKenzie River, Victoria. Australian Journal of Marine and Freshwater Research, 29, 293-298.

Jackson, P. D., Koehn, J. D., Lintermans, M. & Sanger, A. C. (1996) Family Gadopsidae. Freshwater blackfishes. Freshwater Fishes of South-Eastern Australia (ed R. M. McDowall), pp. 186-190. Reed Books, Sydney.

Jansen, W., Bauer, G. & Zahner-Meike, E. (2001) Glochidia Mortality in Freshwater Mussels. Ecology and Evolution of the Freshwater Mussels Unionoida (eds G. Bauer & K. Wächtler), pp. 185-211. Springer, Berlin.

Kat, P. W. (1984) Parasitism and the Unionacea (Bivalvia). Biological Reviews, 59, 189-207.

Koehn, J. D. (2004) Carp (Cyprinus carpio) as a powerful invader in Australian waterways. Freshwater Biology, 49, 882-894.

Koehnken, L. (2009) Review of Water Quality in the Macquarie River Upstream of Lake River. Technical Advice on Water. A report to Water Assessment Branch of the Department of Primary Industries and Water, Hobart, Tasmania.

Llewellyn, L. C. (1974) Spawning, development and distribution of the southern pygmy perch Nannoperca australis australis Gunther from inland waters in eastern Australia. Australian Journal of Marine and Freshwater Research, 25, 121-149.

Lobón-Cerviá, J. (2009) Why, when and how do fish populations decline, collapse and recover? The example of brown trout (Salmo trutta) in Rio Chaballos (northwestern Spain). Freshwater Biology, 54, 1149-1162.


68

Magalhães, M. F., Beja, P., Schlosser, I. J. & Collares-Pereira, M. J. (2007) Effects of multi-year droughts on fish assemblages of seasonally drying Mediterranean streams. Freshwater Biology, 52, 1494-1510.

McDowall, R. M. (1968) Galaxias maculatus (Jenyns), the New Zealand whitebait. New Zealand Fisheries Research Bulletin, 2, 1-84.

McDowall, R. M. (1996) Freshwater Fishes of South-Eastern Australia. pp. 247. Reed Books, Sydney, New South Wales.

McDowall, R. M. & Fulton, W. (1996) Family Galaxiidae. Galaxiids. Freshwater Fishes of South-Eastern Australia (ed R. M. McDowall), pp. 52-77. Reed Books, Sydney.

McMichael, D. F. & Hiscock, I. D. (1958a) A monograph of the freshwater mussels (Mollusca: Pelecypoda) of the Australian region. Australian Journal of Marine and Freshwater Research, 9, 372-508.

McMichael, D. F. & Hiscock, I. D. (1958b) A monograph of the freshwater mussels (Mollusca: Pelecypoda) of the Australian region. Australian Journal of Marine and Freshwater Research, 9, 372-508.

Metcalfe-Smith, J. L., Di Maio, J., Staton, S. K. & Mackie, G. L. (2000) Effect of sampling effort on the efficiency of the timed search method for sampling freshwater mussel communities. Journal of the North American Benthological Society, 19, 725-732.

Nicola, G., Almodóvar, A. & Elvira, B. (2009) Influence of hydrologic attributes on brown trout recruitment in low-latitude range margins. Oecologia, 160, 515-524.

Österling, E. M., Greenberga, L. A. & Arvidssona, B. L. (2008) Relationship of biotic and abiotic factors to recruitment patterns in Margaritifera margaritifera. Biological Conservation, 141, 1365-1370.

Perry, G. L. W. & Bond, N. R. (2009) Spatially explicit modeling of habitat dynamics and fish population persistence in an intermittent lowland stream. Ecological Applications, 19, 731-746.

Playford, T. J. & Walker, K. F. (2008) Status of the endangered Glenelg River Mussel Hyridella glenelgensis (Unionoida: Hyriidae) in Australia. Aquatic Conservation: Marine and Freshwater Ecosystems, 18, 679-691.

Pollard, D. A. (1971) The biology of a landlocked form of the normally catadromous salmoniform fish Galaxias maculatus (Jenyns). 1. Life cycle and origin. Australian Journal of Marine and Freshwater Research, 22, 91-123.

Pooler, P. S. & Smith, D. R. (2005) Optimal sampling design for estimating spatial distribution and abundance of a freshwater mussel population. Journal of the North American Benthological Society, 24, 525-537.

Pusch, M., Siefert, J. & Walz, N. (2001) Filtration and Respiration Rates of Two Unionid Species and Their Impact on the Water Qulaity of a Lowland River. Ecology and Evolution of the Freshwater Mussels Unionoida (eds G. Bauer & K. Wächtler), pp. 317-326. Springer, Berlin.

R Development Core Team (2008) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria.

Sand-Jensen, K. (1998) Influence of submerged macrophytes on sediment composition and near-bed flow in lowland streams. Freshwater Biology, 39, 663-679.

Sand-Jensen, K. & Mebus, J. R. (1996) Fine-scale patterns of water velocity within macrophyte patches in streams. Oikos, 76, 169-180.

Sand-Jensen, K. & Pedersen, O. (1999) Velocity gradients and turbulence around macrophyte stands in streams. Freshwater Biology, 42, 315-328.


69

Scholes, D. (2003) Macquarie River Reflections, Stevens Publishing Pty Ltd, Launceston, Tasmania.

Sloane, R. D. (1984a) Distribution and abundance of freshwater eels (Anguilla spp.) in Tasmania. Australian Journal of Marine and Freshwater Research, 35, 463-470.

Sloane, R. D. (1984b) Preliminary observations of migrating adult freshwater eels (Anguilla australis australis Richardson) in Tasmania. Australian Journal of Marine and Freshwater Research, 35, 471-476.

Sloane, R. D. (1984c) Upstream migration by young pigmented freshwater eels (Anguilla australis australis Richardson) in Tasmania. Australian Journal of Marine and Freshwater Research, 35, 61-73.

Smith, B. J. (1996) Identification keys to the families and genera of bivalve and gastropod molluscs found in Australian inland waters, Cooperative Research Centre for Freshwater Ecology, Albury, Victoria.

Threatened Species Section (2006) Recovery Plan: Tasmanian Galaxiidae 2006-2010. Department of Primary Industries and Water, Hobart, Tasmania.

Tonkin, Z., King, A. J. & Mahoney, J. (2008) Effects of flooding on recruitment and dispersal of the Southern Pygmy Perch (Nannoperca australis) at a Murray River floodplain wetland. Ecological Management & Restoration, 9, 196-201.

Tyrrell, M. & Hornbach, D. J. (1998) Selective predation by muskrats on freshwater mussels in 2 Minnesota rivers. Journal of the North American Benthological Society, 17, 301-310.

van Tets, G. F. (1994) Do cormorants eat freshwater mussels? If not what does? Emu, 94, 127-128.

Vaughn, C. C. & Hakenkamp, C. C. (2001) The functional role of burrowing bivalves in freshwater ecosystems. Freshwater Biology, 46, 1431-1446.

Vaughn, C. C., Nichols, S. J. & Spooner, D. E. (2008) Community and foodweb ecology of freshwater mussels. Journal of the North American Benthological Society, 27, 409-423.

Vaughn, C. C. & Taylor, C. M. (1999) Impoundments and the decline of freshwater mussels: a case study of an extinction gradient. Conservation Biology, 13, 912-920.

Vaughn, C. C. & Taylor, C. M. (2000) Macroecology of a host-parasite relationship. Ecography, 23, 11-20.

Vestjens, W. J. M. (1973) Feeding of white ibis on freshwater mussels. Emu, 72, 71-72.

Wächtler, K., Dreher-Mansur, M. C. & Richter, T. (2001) Larval Types and Early Postlarval Biology in Naiads (Unionoida). Ecology and Evolution of the Freshwater Mussels Unionoida (eds G. Bauer & K. Wächtler), pp. 93-125. Springer, Berlin.

Walker, K. F. (1981) Ecology of Freshwater Mussels in the River Murray. Australian Water Resources Council Technical Paper No. 63. Australian Government Publishing Service, Canberra, ACT.

Walker, K. F. (2004) A guide to provisional identification of the freshwater mussels (Unionoida) of Australasia, Cooperative Research Centre for Freshwater Ecology, Albury, Victoria.

Walker, K. F., Byrne, M., Hickey, C. W. & Roper, D. S. (2001) Freshwater Mussels (Hydriidae) of Australasia. Ecology and Evolution of the Freshwater Mussels Unionoida (eds G. Bauer & K. Wächtler), pp. 5-31. Springer, Berlin.

Watters, G. T. (1996) Small dams as barriers to freshwater mussels (Bivalvia, Unionoida) and their hosts. Biological Conservation, 75, 79-85.

Watters, G. T. & O'Dee, S. H. (1999) Glochidia of the freshwater mussel Lampsilis overwintering on fish hosts. Journal of Molluscan Studies, 65, 453-459.


70

Weatherley, A. H. (1959) Some features of the biology of the tench Tinca tinca (Linnaeus) in Tasmania. Journal of Animal Ecology, 28, 73-87.

Weatherley, A. H. (1963) Zoogeography of Perca fluviatilis (Linnaeus) and Perca flavescens (Mitchell) with special reference to the effects of high temperature. Proceedings of the Zoological Society of London, 141, 557-576.

Weatherley, A. H. (1977) Perca fluviatilis in Australia: zoogeographic expression of a life cycle in relation to an environment. Journal of the Fisheries Research Board of Canada, 34, 1464-1466.

Winter, T. C., Harvey, J. W., Franke, O. L. & Alley, W. M. (1998) Ground Water and Surface Water: A Single Resource. Circular 1139. U.S. Geological Survey, Denver, Colorado, U.S.A.

Woodward, G. M. A. & Malone, B. S. (2002) Patterns of abundance and habitat use by Nannoperca obscura (Yarra pymgy perch) and Nannoperca australis (southern pygmy perch). Proceedings of the Royal Society of Victoria, 114, 61-72.

Zahner-Meike, E. & Hanson, J. M. (2001) Effect of Muskrat Predation on Naiads. Ecology and Evolution of the Freshwater Mussels Unionoida (eds G. Bauer & K. Wächtler), pp. 163-184. Springer, Berlin.


71

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.


72

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.


73

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.


74

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.


75

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.


76

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.


77

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.


78

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

Status of fish communities and observations on South Esk ... of fish...This study has shown that, in recent times, broad-scale changes have occurred in fish communities in the Macquarie

Documents