Fish surveys at Glenbrook Lagoon, Blue Mountains...Fax: (03) 9646 9242 Email: [email protected] NEW SOUTH WALES Sydney Unit 14, 17-27 Power Avenue Alexandria NSW 2015 Phone: (02)

© Biosis September 2012 – Leading ecology and heritage consultants 1

Fish surveys at Glenbrook Lagoon, Blue Mountains FINAL REPORT

Prepared for Blue Mountains City Council

23 June 2014

© Biosis 2013 – Leaders in Ecology and Heritage Consulting www.biosis.com.au i

Biosis Pty Ltd

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for the purposes for which it was commissioned and in accordance with the Terms of the

Engagement for the commission. Unauthorised use of this document in any form whatsoever is

prohibited.

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Biosis Pty Ltd has completed this assessment in accordance with the relevant federal, state and

local legislation and current industry best practice. The company accepts no liability for any

damages or loss incurred as a result of reliance placed upon the report content or for any purpose

other than that for which it was intended.

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Document information

Report to: Blue Mountains City Council

Prepared by: K. Beyer and A. Byrne

Biosis project no.: 17370

File name: 17370.BMCC.FishSurveys.FIN01.23062014.docx

Citation: Biosis (2014). Fish Surveys at Glenbrook Lagoon, Blue Mountains.

Report for Blue Mountains City Council. Authors: K. Beyer and A. Byrne.

Biosis Pty Ltd, Sydney Resource Group. Project no. 17370

Document control

Version Internal reviewer Date issued

Draft version 01 APS 25/05/14

Final version 01 APS 23/06/14

Acknowledgements

Biosis acknowledges the contribution of the following people and

organisations in undertaking this study:

Client: Christina Day, Amy St Lawrence, Geoffrey Smith (BMCC)

The following Biosis staff were involved in this project:

A. Byrne for assistance in the field

J. Shepherd for mapping

A. Steelcable for review and quality assurance

http://www.biosis.com.au/mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]

© Biosis 2012 – Leaders in Ecology and Heritage Consulting II

Contents

Summary ................................................................................................................................................................ iv

1. Introduction ................................................................................................................................................. 1

1.1 Project background ...................................................................................................................................................... 1

1.2 Aims and Objectives of the Project ........................................................................................................................... 1

1.3 Study Area ...................................................................................................................................................................... 2

2. Methods ........................................................................................................................................................ 4

2.1 Site selection and sampling design .......................................................................................................................... 4

2.2 Fish surveys.................................................................................................................................................................... 5

2.3 Freshwater Turtles ....................................................................................................................................................... 7

2.4 Frogs ................................................................................................................................................................................ 7

2.5 Water quality ................................................................................................................................................................. 7

2.6 Data Processing ............................................................................................................................................................ 7

2.7 Limitations/Qualifications ........................................................................................................................................... 7

2.8 Permits and Licences ................................................................................................................................................... 8

3. Results ........................................................................................................................................................... 9

3.1 General habitat description ....................................................................................................................................... 9

3.2 Water Quality ................................................................................................................................................................. 9

3.3 Aquatic fauna ................................................................................................................................................................ 9

3.4 Length frequencies ................................................................................................................................................... 11

3.5 Frog Habitat ................................................................................................................................................................ 13

4. Discussion and Conclusions..................................................................................................................... 14

Recommendations ............................................................................................................................................... 17

4.1 Management of native fish ..................................................................................................................................... 17

4.1.1 Native fish ........................................................................................................................................................ 17

4.1.2 Australian Bass ............................................................................................................................................... 17

4.1.3 Freshwater Catfish......................................................................................................................................... 17

4.2 Management of noxious fish species ................................................................................................................... 18

4.2.1 Eastern Gambusia ......................................................................................................................................... 18

4.2.2 Frogs ................................................................................................................................................................. 18

4.3 Freshwater turtles ..................................................................................................................................................... 18

4.3.1 Freshwater Turtles......................................................................................................................................... 18

4.4 Water Quality .............................................................................................................................................................. 19

4.5 Monitoring .................................................................................................................................................................. 19

5. Plates ........................................................................................................................................................... 20

6. References .................................................................................................................................................. 28

7. Appendix ..................................................................................................................................................... 29

© Biosis 2012 – Leaders in Ecology and Heritage Consulting III

List of Figures

Figure 1: Location of the study area, NSW ........................................................................................................... 3

Figure 2: Survey sites within Glenbrook Lagoon ................................................................................................. 6

Figure 3: Length frequencies for Flathead Gudgeon........................................................................................ 11

Figure 4: Length frequencies for Freshwater Catfish ....................................................................................... 12

Figure 5: Length frequencies for Australian Smelt ........................................................................................... 12

Figure 6: Length frequencies for Eastern Long-necked Turtle ........................................................................ 13

List of Tables

Table 1: Site locations and methods .................................................................................................................... 4

Table 2: Water quality during February and April 2014. .................................................................................... 9

Table 3: Aquatic fauna captured during February and April 2014 ................................................................. 10

List of Plates

Plate 1: GBL1 .......................................................................................................................................................... 20

Plate 2: GBL2 .......................................................................................................................................................... 20

Plate 3: GBL3 .......................................................................................................................................................... 21

Plate 4: GBL4 .......................................................................................................................................................... 21

Plate 5: GBL5 .......................................................................................................................................................... 22

Plate 6: GBL6 .......................................................................................................................................................... 22

Plate 7: GBL7 .......................................................................................................................................................... 23

Plate 8: GBL8 .......................................................................................................................................................... 23

Plate 9: Bait trap .................................................................................................................................................... 24

Plate 10: Fyke net .................................................................................................................................................. 24

Plate 12: Electrofishing ......................................................................................................................................... 25

Plate 13: Flathead Gudgeon Philypnodon grandiceps ....................................................................................... 25

Plate 14: Freshwater Catfish Tandanus tandanus .............................................................................................. 26

Plate 15: Long-finned Eel Anguilla reinhardtii..................................................................................................... 26

Plate 13: Long-Necked Turtle Chelodina longicollis ........................................................................................... 27

Plate 14: Murray River Turtle Emydura macquarii dharuk ................................................................................ 27

© Biosis 2012 – Leaders in Ecology and Heritage Consulting iv

Summary

Biosis Pty Ltd was commissioned by Blue Mountains City Council to undertake the Fish Surveys at Glenbrook

Lagoon, Blue Mountains (the Project). The study area for the Project is located within the municipality of the

Blue Mountains Local Government Area (LGA), approximately 65 kilometres (km) West of the Sydney Central

Business District (CBD).

Blue Mountains City Council (BMCC) implemented a weed control program to address the prevalence of the

invasive aquatic weed Cabomba caroliniana in Glenbrook Lagoon, in December 2012. Immediately following

the weed control program two fish kills were recorded; possible toxic effects of the herbicide, rapid

consumption of dissolved oxygen by decaying plant matter or other causes associated with disturbance of

organic sediments. Approximately 200 Flat-headed Gudgeon mortalities were recorded near the Glenbrook

Lagoon boat ramp 1 to 2 days after weed control and ~50 Australian Bass mortalities recorded across the

lagoon 11 days after weed control. Monitoring, to evaluate the success of the program, has included

assessments of aquatic flora, macroinvertebrate and water quality assessments.

Following the fish kill, BMCC commissioned this evaluation of the native fish populations present within the

Lagoon, and sought recommendations and options for the management of native and non-native fish species

with the view to enhance aquatic species health. Surveys to assess the fish population within Glenbrook

Lagoon were undertaken over two seasons, in summer (February) and autumn (April) 2014. These included

assessments of the fish community structure, water quality and aquatic habitat condition to establish a

baseline dataset for the overall health of the fish population in Glenbrook Lagoon. A range of fish survey

techniques including fyke netting, seine netting, bait traps and electrofishing were used systematically at eight

sites to document the fish and turtle population of Glenbrook Lagoon.

Four native fish; Freshwater Catfish, Australian Smelt, Flat-headed Gudgeon and Long-finned Eel were

recorded from the Lagoon along with one introduced fish species, Eastern Gambusia, listed as noxious under

the Fisheries Management Act, 1994 (FM Act). Two indigenous turtle species were recorded; Eastern Long-

necked Turtle and the Sydney Basin Turtle. Australian Bass was not recorded during this survey. A

substantial population of Freshwater Catfish (n=52) and Flat-headed Gudgeon (n=415) persists within

Glenbrook Lagoon. Lower abundances of Australian Smelt (n=16) and Long-finned Eel (n=4) were recorded.

The most abundant fish species recorded was the noxious Eastern Gambusia (n=16,851).

The presence of large numbers of young Freshwater Catfish is a positive sign for the existing fish community.

These juveniles appear to be of the same cohort and are most likely from the spring-summer spawning

period in 2012, around the period of the weed control program. This would suggest that the weed treatment

had no long term effects on this species or at least on juvenile Freshwater Catfish. The fish fauna, with the

exception of Eastern Gambusia and Australian Smelt, is otherwise comprised of demersal (bottom dwelling)

species. Emergent rushes and snags around the margins of the lake provide extensive areas of high quality

habitat for demersal fish. In addition the substantial amounts of organic matter smothering the substrate as

a result of weed treatment may potentially impact upon water quality and aquatic fauna in the future. The

decomposition of this increased volume of organic material during warmer months may deplete dissolved

oxygen in the water. Organic matter increase may also impact the spawning success of Freshwater Catfish

due to the smothering of eggs and lack of suitable nesting sites.

Management options to enhance the aquatic habitat and attendant fauna values of this site are

recommended as part of this report. These include continued implementation of best practice stormwater

management, continued environmental monitoring and cost effective measures to enhance the

environmental values of the site and provide beneficial outcomes for native fish, turtles and frogs.

© Biosis 2012 – Leaders in Ecology and Heritage Consulting 1

1. Introduction

1.1 Project background

Biosis was engaged by BMCC to undertake fish surveys of the Glenbrook Lagoon, to assess the composition

and structure of the fish community following the implementation of a weed control program for Cabomba

caroliniana.

Blue Mountains City Council (BMCC) has undertaken a weed control program to address the prevalence of

the invasive aquatic weed Cabomba caroliniana in Glenbrook Lagoon, commencing in December 2012. As a

likely result of this weed control program, two fish kills were recorded. Monitoring, to evaluate the success of

the program, has included assessments of aquatic flora, macroinvertebrate and water quality assessments.

BMCC required an evaluation of the native fish population present within the Lagoon, and obtain

recommendations and options for the management of native and non-native fish species to enhance the

health of the resident fish and other aquatic fauna populations and their habitat.

During the weed control program and the aquatic flora and fauna survey, a number of fish species have been

observed within the Lagoon, and these include two non-native and five native species (AMBS 2012). Two of

these species were of particular interest to Blue Mountains City Council; the Flathead Gudgeon Philypnodon

grandiceps and the Australian Bass Macquaria novemaculeata. During the weed control program a large

number of Flathead Gudgeon (200 individuals) and Australian Bass (50 individuals) were killed presumed in

response to the application of the herbicide used to eradicate Cabomba and the resulting changes to water

quality. As a result of these fish kill events, BMCC was interested in obtaining a greater understanding of the

distribution and health of the Flathead Gudgeon and Australian Bass population in the Lagoon. Assessment

of the Australian Bass population within the Lagoon was deemed of further importance as BMCC was

interested in understanding the potential for the sustainable management of this species for potential re-

stocking and any associated benefits.

1.2 Aims and Objectives of the Project

As part of its Delivery Program and Operation Plan, which aims to protect, maintain and enhance the health of

the natural waterways and catchments, BMCC required a fish survey to be undertaken to assess the

composition and structure of the fish community in Glenbrook Lagoon, Blue Mountains, New South Wales

(NSW). This project was further to provide management recommendations regarding the overall health of

the fish population in the Lagoon in order to protect, maintain and enhance biodiversity and ecosystem

function.

The aim of this study was to gain a better understanding of the fish population in Glenbrook Lagoon, and

specifically to:

Conduct fish population surveys at Glenbrook Lagoon.

Complete a fish population survey report including relevant fish management recommendations.

To meet these aims, the following specific objectives were identified and form the subject of this report:

Assess the fish population structure and composition within Glenbrook Lagoon.


Investigate the population size, health, distribution and habitat use of native fish species including;

Flathead Gudgeon Philypnodon grandiceps, Australian Smelt Retropinna semoni, Long-finned Eel Anguilla

reinhardtii, and Freshwater Catfish Tandanus tandanus.

Provide recommendations regarding the potential management of non-native fish, as well as native fish

and fish habitat in Glenbrook Lagoon.

1.3 Study Area

The study area for the Project is located within the BMCC LGA, approximately 80 km west of the Sydney CBD

(Figure 1). The study area, Glenbrook Lagoon, is located near the township of Glenbrook 10 kilometres West

of Penrith, in the Blue Mountains. Glenbrook Lagoon is an eight hectare natural escarpment wetland in the

Hawkesbury-Nepean Catchment Management Area (CMA).

The Lagoon is a flat bottomed basin bordered by wide shallow margins holding an water volume of 225,147

m3, with a mean depth of 2.7 m and a maximum water depth of 4.1 m. The Lagoon flows into Lapstone Creek

and subsequently flows into the Nepean River.

Normic

Avenue

Old Bathurst Road

Mitchells PassGrahame S

treet

Layton Avenue

The High Road

TheHig

h Road

WilsonWay

Park Street

Fletcher

Street

St Johns Road

Haymet Street

Railway StreetWascoe Street

Coughlan RoadCow

dery St

reet

King Street

Lapsto

ne Cre

scent

Barnet

Street

Hersey

Street

Benjamin Lane

Reading Street

Levy Street

Lennox

Street

Powell

Street

Moore Street

Boyd Lane

Euroka

Road

Ross St

reet

Gr een

Str eet

Hill Str

eet

Glenbr

ookRoa

dMa

nn Stre

et

Ross S

treet

Tho

mas W ay

Kedron Street

West Str

eet

Kingmore Lane

Peel St

reet

Glenell Street

Raymo

ndStre

et

King Street

Lagoon

Drive

Claren

ce Stree

t

N ightin

galeDrive

Lemaires Lane

Pool Lane

High Street

Olivet Street

Kent St

reet

Prince Street

HuntStre

et Explorers Road

Leslie Road

Murphy Street

David S

t reet

Lagoon

Drive

Richard

s Stree

t

Tabor S

treet

Carme

l Stree

tSkarratt Street

Cathy Street

Wattleclif

fe Drive

Allen S

treet

Deane Street

Pellion

Street

Tallowood Gardens

Hersey

Street

Matthew Parade

Chisho

lm Cre

scent

Great Wes tern Hig hway

Murph

y Stree

t

Main Western R

ailway

Lapstone Creek

Glenbrook

MoreeBourke

Parkes

CanberraSydneyWollongong

Albury

Ballina

BrokenHill

Newcastle

Acknowledgement: Topo (c) NSW Land and Planning Information (2011); Overivew (c) State of NSW (c.2003)

Matter: 17370Date: 17 March 2014,Checked by: KB, Drawn by: TA, Last edited by: jshepherdLocation:P:\17300s\17370\Mapping\

LegendStudy Area

Scale 1:10,000 @ A4, GDA 1994 MGA Zone 55

0 100 200 300 400MetresBiosis Pty LtdBallarat, Brisbane, Canberra, Melbourne, Sydney, Wangaratta & Wollongong

Figure 1: Location of Study Area


2. Methods

Surveys to assess the fish population within Glenbrook Lagoon were undertaken over two seasons, in

summer (February) and autumn (April) 2014. These included assessments of the fish community structure,

water quality and aquatic habitat condition to establish a baseline dataset for the overall health of the fish

population in Glenbrook Lagoon.

Field surveys were undertaken by two aquatic ecologists over two days during both seasons in summer and

autumn 2014. During these surveys, the following tasks were undertaken according to Biosis' standard

operating procedures:

Examination of the species composition of the fish community within the study area.

Assessment of fish habitat condition, including the application of habitat assessments and the

measurement of water quality parameters. This is to provide an insight into the quality of aquatic habitat

and a snapshot profile of habitat condition during the time of survey.

Identification of habitat connectivity, including potential barriers to fish passage, availability of aquatic

refuges and/or spawning areas as relevant to the study area.

Survey was conducted in accordance with research permit regulation under the NSW National Parks and

Wildlife Act 1974 (Licence Number S10318) and the NSW Fisheries Management Act 1994 (Licence Number

P05/0016-4.1 & OUT 12/3345).

2.1 Site selection and sampling design

Throughout the study area eight sites were selected to be representative of the suite of aquatic habitats

available within Glenbrook Lagoon. At each of these sites a combination of fishing techniques were applied

and an overview of these is provided in Table 1.

Table 1. Site locations and methods

Code Easting Northing Electrofishing Seine Fyke Bait

GBL1 279127 6262237 x X

GBL2 279125 6262308 X X

GBL3 279168 6262387 X X

GBL4 279170 6262061 X X

GBL5 279360 6262271 X X

GBL6 279365 6262156 X X

GBL7 279265 6262082 X X

GBL8 279304 6262321 x X


2.2 Fish surveys

Suitable fish habitats were identified and sampled using a combination of backpack electrofishing, fyke nets,

bait traps and seine nets as detailed below. Survey sites are detailed in Figure 2. The selected capture

techniques varied in order to maximize sampling efficiency according to the respective habitat. All specimens

were identified to species, counted and measured (to nearest mm). Native fish species were returned to

point of capture and FM Act declared noxious fish species were euthanased as per permitting requirements.

Electrofishing

A Smith-Root LR-24 backpack electrofisher was used to collect fish within shallow water environments (GBL7

and GBL8). Electrofishing was undertaken at depths wadeable by the operator, usually to a depth of 1.1 m.

The sampling consisted of electrofishing the perimeter of each of the two sites where this method was

utilised with one operator and one dip netter. The power-on time was recorded during each electrofishing

reach. Output fishing parameters were selected and adjusted in accordance with the electrical conductivity of

the water, at the time of survey. Furthermore, this approach included minimising of potential for injury to

captured aquatic fauna.

Electrofishing is generally low impact and applicable to a wide size range of fish species. During the survey, all

stunned fish were captured using an insulated dip net, identified to species and then released alive following

their recovery.

Fyke netting

Fyke nets (length: ~3 m; mesh: 10 mm) with two internal throats and are set up either attached above the

waterline, to the bank or using a stake in the river bed. Fyke nets are effective at sampling a wide variety of

fish sizes and species. A single fyke net was set overnight at each of the six sites around the periphery of the

lagoon (GBL1 to GBL6). Fyke nets were set amongst suitable structural habitat (either vegetation or snags).

Fyke nets allow for the capture of larger size ranges of fish. Fyke nets were set with the "cod end" exposed

and contained a polystyrene float to avoid mortalities of other non-target aquatic fauna.

Seine netting

The seine net used is constructed from 3 mm and 6 mm knotless nylon mesh with a small bunt in the middle

of the net to concentrate the fish. These seine nets are used, at sites GBL7 and GBL8, in shallow water,

dragging the net out from shore to encircle an area and then slowly gathering the net to the bank. Encircled

fish are kept in the shallow water to reduce stress before being transferred to holding containers for

processing. Seine netting is a non-selective technique and allows for capture of both large and small bodied

fish. The technique was limited by the presence of coarse structural habitats in the sampling areas

encumbering the action of the net (i.e. by snagging).

Bait trapping

Bait traps have a finer mesh than the fyke nets and are a useful method to target small-sized fish including

juveniles. All bait traps (length: 400 mm; width: 240 mm; depth: 240 mm; mesh size: 2 mm), baited with

yellow glow sticks, were attached to snags, vegetation or a suitable float. Seven bait traps were deployed

overnight at each of the six sites (GBL1 to GBL6) and at different depths within each site. This method is

generally used for small-bodied fish and juveniles of larger bodied species.

Glenbr

ookRoa

d

Glenbrook RoadLag

oon Dr

ive

Lagoon

Drive

Skarratt Street

Lapstone CreekGLENBROOKLAGOON

GB1

GB2

GB3

GB4

GB5

GB7

GB6

GB8

Acknowledgement: Topo (c) NSW Land and Planning Information (2011); Imagery provided by Blue Mountains City Council

Matter: 17370Date: 18 June 2014,Checked by: KB, Drawn by: TA, Last edited by: jshepherdLocation:P:\17300s\17370\Mapping\

LegendSamping SitesProject Area

Scale 1:2,000 @ A4, GDA 1994 MGA Zone 56

0 20 40 60 80MetresBiosis Pty LtdBallarat, Brisbane, Canberra, Melbourne, Sydney, Wangaratta & Wollongong

Figure 2: Location of Sampling Sites


2.3 Freshwater Turtles

Certain methods employed for fish survey (e.g. fyke nets and seine net) are suitable for the capture of turtles.

Methods for deployment are as described for fish. Turtles captured were identified to species and total

carapace length (TCL) recorded.

2.4 Frogs

During previous surveys the following frog species have been recorded within Glenbrook Lagoon: Eastern

Dwarf Tree Frog Litoria fallax, Peron's Tree Frog L. peronii and Striped Marsh Frog Limnodynastes peronii

(AMBS 2012). When undertaking fish surveys in both the summer and autumn survey personnel recorded

the habitat available within the Lagoon as well as additional frog species present within the study area.

2.5 Water quality

Water quality measurements were recorded during summer and autumn surveys using a Horiba U-52

Multiparameter Water Quality Meter. Measurements were taken ~30 cm below the surface. Parameters

measured during sampling include pH, dissolved oxygen (DO), temperature, turbidity and electrical

conductivity (EC). Alkalinity was measured using a Hach™ Field Alkalinity Kit. Water quality measurements

only provide an indication of water quality at time of sampling.

2.6 Data Processing

Data was collated, entered and cross-checked by independent staff members, as a means of quality

assurance, and subsequently formatted as required by each separate data analysis approach. The length

frequency distributions were derived for each fish species where more than 50 individuals were captured to

allow a description of the respective modal distributions and relevant cohorts. This assisted in the description

of the populations and allowed further insights into potential patterns observed in Glenbrook Lagoon.

Length modes indicate age groups and are generally most pronounced in fish with a short spawning season

and fast and uniform growth (Bagenal & Tesch 1968).

2.7 Limitations

The survey effort, combined with information available from other sources, was considered suitable to

provide an insight into the fish community structure and composition within Glenbrook Lagoon in summer

and autumn 2014. However, the following limitations apply:

The fish surveys were undertaken at a given time and season. There are a number of reasons why not all

fish species may have been detected during these surveys, such as seasonal conditions, variations in fish

movement and breeding behaviours.

The fish surveys were undertaken during summer (February) and autumn (April) 2014 as this timing was

considered suitable to assess the required parameters within the Lagoon.

Some fish species were easier to capture than others, and it is therefore possible that some species may

be underrepresented within the overall fish catch. For example, Australian Bass and Freshwater Catfish

are species that can be difficult to capture at times. The range of fish capture methodologies aimed to


maximise the capture of the range of fish species present in the Lagoon as well as a large size range of

individuals.

There are no seasonal or other external factors which are expected to have limited the results of the

survey, however, unseasonal climatic conditions, may impact on the available area for investigations and

the aquatic fauna present during sampling.

The water quality parameters measured provided a snapshot of conditions at a given point in time. Some

of these parameters typically exhibit a high degree of temporal variation and can change substantially

over small periods of time such as weeks, days and even hours, particularly in response to significant

rainfall events.

Mapping was conducted using hand-held (non differential) GPS units and aerial photo interpretation. The

accuracy of this mapping is therefore subject to the accuracy of the GPS units (generally +/- 7 metres) and

dependent on the limitations of aerial photo rectification and registration.

2.8 Permits and Licences

Aquatic fauna surveys were conducted under the following permits and licences:

NSW DPI Fisheries - Licence Numbers PO05/0016 and OUT10/4198.

NSW National Parks and Wildlife Act 1974 - Licence Number S10318.

Certificate of Approval under the NSW Animal Research Act 1985.


3. Results

3.1 General habitat description

Prior to aquatic weed control programs in 2012 the instream aquatic macrophyte community in Glenbrook

Lagoon was dominated by introduced species from the genus Cabomba and Nymphaea alba, N. mexicana and

by fringing rushes based on previous assessment (AMBS, 2012). The current macrophyte composition is

dominated by fringing native rushes, Lepironia articulata and Eleocharis sphacelata which occurred at the

majority of the sampling sites within the shallower parts of the Lagoon (up to 2m depth). Dense beds of

emergent macrophytes were interspersed with stands of Flax-leaved Paperbark Melaleuca linariifolia and

Broad-leaved Paper-Bark M. quinquenervia which was concentrated along the western extent of the lagoon.

Some clustered remnant snags (eastern and western edge) and inundated paper barks (north western edge)

provide suitable structural habitat for demersal and pelagic fish and their planktonic (juvenile) phases.

3.2 Water Quality

Water quality recorded at site GBL7 during surveys is presented in Table 2.

Table 2 Water quality during summer and autumn 2014

Date Temperature (◦C)

Conductivity (µS/cm)

Turbidity (NTU)

Dissolved Oxygen (mg/L)

Dissolved Oxygen (% sat)

TDS (g/L)

pH Salinity (ppt)

Alkalinity (mg/L)

Feb 2014

25.09 197 8.7 9.46 84.7 0.129 8.1 0.1 60

Apr 2014

22.8 173 3.9 5.93 71.1 0.112 7.8 0.1 30

3.3 Aquatic fauna

During the surveys in Glenbrook lagoon in summer and autumn a total of 17,338 fish were captured

representing five native and one non-native species. During this time, a total of 27 freshwater turtles were

also captured represented by two native species: Long-Necked Turtles Chelodina longicollis and Sydney Basin

Turtle Emydura macquarii dharuk. A summary of specimens captured during the surveys are presented in

Table 3.


Table 3 Aquatic fauna captured during summer and autumn 2014

Feb-14 Apr-14 2014

Site

GBL GBL GBL GBL GBL GBL GBL GBL

To

tal

GBL GBL GBL GBL GBL GBL GBL GBL

To

tal

Ov

era

ll To

tal

1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

Gear Type *

1xF 1xF 1xF 1xF 1xF 1xF E

104s

E

254s 1xF 1xF 1xF 1xF 1xF 1xF

E

116s

E

343s

7xB 7xB 7xB 7xB 7xB 7xB Sx2 Sx2 7xB 7xB 7xB 7xB 7xB 7xB Sx2 Sx3

Fish

Anguilla reinhardtii Long-finned

Eel 0 0 0 0 0 0 0 2 2 1 0 1 0 0 0 0 0 2 4

Philypnodon grandiceps Flathead

Gudgeon 17 23 29 19 28 32 65 24 237 15 19 21 21 19 13 63 7 178 415

Gambusia holbrooki* Eastern

Gambusia 506 35 110 95 6 40 2,170 1,807 4,769 365 34 32 35 16 46 1,254 10,300 12,082 16,851

Tandanus tandanus Freshwater

Catfish 0 4 1 6 7 6 2 0 26 2 7 2 0 1 12 1 1 26 52

Retropinna semoni Australian

Smelt 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 16 16 16

Turtles

Emydura macquarii dharuk Murray River

turtle 0 1 0 0 0 0 0 0 1 2 0 0 0 0 0 0 0 2 3

Chelodina longicollis Eastern long-

necked turtle 6 2 1 2 2 0 0 0 13 4 1 0 2 4 2 0 0 13 26

* (F=Fyke Net, B=Bait Trap, S=Seine Net hauls, E=Backpack Electrofisher power on time)


3.4 Length frequencies

Length frequency analyses revealed distinct cohorts (size/year class) in some fish species although the

distinction of cohorts is difficult in species that were collected in lower abundances.

Flathead Gudgeon

A total 415 Flathead Gudgeon were captured during the surveys in 2014, of these 237 were captured during

February and 178 during April. Individuals ranged from 20 mm to 80 mm, with a mean size of 53 mm. The

length information collated from this species indicated a unimodal length frequency distribution of the

species during both sampling seasons (Figure 3).

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Figure 3: Length frequencies for Flathead Gudgeon

Freshwater Catfish

A total of 52 Freshwater Catfish were captured during the surveys in 2014, 26 during summer and 26 during

autumn. Most of these were collected using fyke nets and bait traps. Length frequency analysis reveals a

distinct cohort of smaller individuals (


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Figure 4: Length frequencies for Freshwater Catfish

Australian Smelt

No Australian Smelt were captured during summer, but 16 were collected during autumn with seine nets at

the site GBL8. While the length frequencies would be able to reveal more detail if a greater sample size had

been achieved, the analysis using the lengths of these 16 individuals indicated a weak bi-modal distribution of

this species within the Lagoon (Figure 5). Most specimens were found to be between 39 mm and 55 mm in

length. An individual at 72 mm was recorded.

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Figure 5: Length frequencies for Australian Smelt

Long-finned eel

Length frequencies were not calculated as only three specimens were captured. Only two of these were

captured during the survey in autumn and they measured 750 and 800 mm in length. The third specimen

was observed during the electrofishing surveys undertaken at site GBL-AQ8.


Eastern Long-necked turtle

A total of 25 long necked turtles were captured during surveys, primarily in fyke nets and across the 6 survey

sites. Individuals of this species ranged from 134 mm to 180 mm, and from 125 mm to 194 mm total

carapace length (TCL) in February and April respectively.

Figure 6: Length frequency distribution of Eastern Long-necked Turtle

Sydney Basin Turtle

Only three individuals of the Sydney Basin Turtle were captured and theses measured 142mm, 147mm and

155mm in length. Further analysis could not be undertaken using this limited data set.

3.5 Frog Habitat

Glenbrook Lagoon supports extensive areas of aquatic and semi-aquatic macrophytes across the Lagoon.

Dense stands of rushes provide good habitat for native frogs such as Striped Marsh Frog Limnodynastes

peronii and Eastern Dwarf Tree Frog Litoria fallax. Areas of dense woody debris and fringing terrestrial

vegetation are expected to provide more suitable habitat for the Peron’s Tree Frog L. peronii and this species

was heard calling within these areas during the surveys. Seasonally inundated margins may provide areas of

spawning habitat removed from the impacts of Eastern Gambusia predation.


4. Discussion and Conclusions

Glenbrook Lagoon provides a relatively diverse range of habitats for aquatic fauna; dense stands of

macrophytes (e.g. rushes) in shallow water, woody debris, snags and dead trees within the deeper water.

This suite of habitats is suitable for a variety of native fish, bird, frog and turtle species. Turtles, frogs,

waterbirds and fish that were recorded at Glenbrook Lagoon are relatively widespread in NSW and are

commonly found in habitats comparable to those in Glenbrook Lagoon.

The habitat is overall in good condition while the water quality indicates an impaired poor condition. The

poor water quality results may be closely linked to the recent weed control activities undertaken by BMCC.

The associated herbicide application was successful in reducing the extent, if not completely eradicating, this

species from the Lagoon and large areas of exotic Nymphaea spp.. As a result, there are some residual

floating Nymphaea spp. root masses. Overall there is a substantial build up of organic material associated

with this system, in part a direct result of herbicide application and die back. Closed lake systems such as

Glenbrook Lagoon are natural repositories for organic material from the surrounding landscape however,

substantial recent inputs of fine organic material post weed treatment are suspected to be the major

component of the current organic debris load exceeding one metre deep in certain areas. This accumulation

of organic material may have implications for water quality in the future particularly if nutrient levels increase.

This combination of factors may increase the biological oxygen demand (BOD) of the system through

increased microbial activity, particularly during warmer months.

In contrast to previous observations when Flathead Gudgeon were uncommon in the Lagoon when only

three individuals were captured (AMBS 2012), the species was found to be relatively common (n = 415) across

the sampling sites during both February and April 2014. Flathead Gudgeon are a freshwater fish species

widespread across lowland waters and coastal streams of South-eastern Australia (www.mdba.gov.au). They

can be found in slow-flowing areas of lowland streams or lakes and dams. They are often found in weedy or

muddy areas with abundant cover in the form of for example rocks or logs. Flathead Gudgeon are a small

species with a maximum total length of 115 mm, but mostly found at about 80 mm adult body size

(Allen1989). The species parental care behaviour includes the production of clutches of up to 900 eggs, which

is cared for by the male up until the time of hatching. The benthic Flathead Gudgeon are carnivorous

ambush predators and feed on aquatic insects, molluscs, crustaceans, and even tadpoles and small fish.

Their current distribution is relatively patchy and they have recently been found to be declining in New South

Wales. At Glenbrook Lagoon a substantial population of this species persists. The range of size classes

detected (20-80mm total length) would suggest consistent spawning and recruitment within this population.

Distribution of this species within the lagoon was relatively uniform with similar abundance recorded at each

site. This suggests no particular habitat fidelity with both dense fringing macrophytes and sparse open water

snag habitats sampled at varying depths.

Australian Smelt Retropinna semoni was not captured during 2012 (AMBS 2012), and was captured in relatively

low numbers and only on a single occasion in one of the seine netting efforts during the April 2014 survey.

The species is wide-spread across South-east Australia, and occurs in coastal drainages between the Fitzroy

River in Queensland and the Lower Murray River in South Australia (McDowall 1996). This small (TL < 80mm)

pelagic species is generally found in large shoals of thousands of individuals in slow-moving waters and feeds

on a wide range of planktonic organisms including small crustaceans and aquatic insects. At Glenbrook

Lagoon Australian Smelt were only recorded from the beach in the north east corner of the Lagoon during

April 2014.

During the previous survey in 2012, Long-finned Eel Anguilla reinhardtii was observed but could not be

confirmed at the time as no specimens could be captured (AMBS 2012). Long-finned Eel were captured in low


numbers during both, the February and April 2014 surveys. Long-finned Eel can be found in various types of

ecosystems including rivers and lakes with preferred habitats including undercut banks, woody debris and

snags (www.mdba.gov.au). They are often recorded from coastal streams commonly from lowland and

occasionally from upland sections. At Glenbrook Lagoon three individuals (two confirmed, one observed)

were recorded. The two specimens recorded were large adult fish suggesting a long period of residence pre

and post weed control.

Freshwater Catfish Tandanus tandanus is a non-migratory species and lives in a wide range of habitats

including rivers, creeks and lagoons. This species prefers sluggish or still waters. It can be found in clear to

turbid waters, and associated with a range of substrate types ranging from mud to gravel and rock.

Freshwater catfish are widely distributed throughout the Murray-Darling basin and coastal drainages from

the Shoalhaven River to southern Queensland. This species has been widely translocated. There is some

uncertainty whether coastal drainage populations south of the Karuah River are endemic (FSC, 2008). While

small to moderate remnant populations occur in the Murray-Darling Basin it is considered under threat due

to a range of impacts and is listed as an endangered population in the Murray-Darling Basin under the

Fisheries Management Act 1994. The presence of Freshwater Catfish is a new record for Glenbrook Lagoon.

This species is now presumed to have been introduced historically but was an unexpected result for this

investigation. Freshwater Catfish were recorded in moderate abundance. Proportional representation of

juveniles from the previous years breeding season was high; 51 of the 52 individuals recorded. The length

range for this juvenile cohort indicates firstly successful spawning and subsequent recruitment into the

population from the 2012 -2013 breeding season based on known growth rates for the species (Davis, 1977).

The noxious Eastern Gambusia Gambusia holbrooki was the most numerous species (n>4000) captured

during both, the February and April surveys. They were particularly dominant in catches from seine netting

and during electrofishing. Similar results were obtained during the surveys undertaken in 2012 (AMBS 2012).

As one of the most successful invasive fish species worldwide, Eastern Gambusia is extremely adaptable to a

wide range of environmental conditions. Their aggressive nature including fin-nipping and the predation on

larval stages of fish and amphibians has been found to have a significant impact on native aquatic species

(Pyke 2005). This small fish species is an adaptable generalist predator and will feed on various other food

types including terrestrial insects and aquatic invertebrates (McDowall 1996). Gambusia displays sexual

dimorphism with females being generally larger than males ranging between 35 mm and 60 mm standard

length respectively (McDowall 1996). Reproduction takes place through live-bearing up to 100 young and

giving birth on up to nine occasions in one breeding season (Pyke 2005).

Frog species recorded as part of this assessment were incidental. No targeted survey for amphibians was

undertaken. Three species were previously recorded during targeted surveys (AMBS, 2012). One of these

species, Peron's Tree Frog was confirmed in 2014. Survey methods used in 2014 were suitable for detecting

tadpoles and coincided with the breeding period for the three species previously recorded. No tadpoles were

recorded during this investigation. This is presumably due to predation pressure from Eastern Gambusia

though this is not able to be qualified in the scope of this study.

The Eastern Long-necked Turtles collected during sampling were represented by intermediate individuals

with a range in total carapace length (TCL) of 125 to 190 mm. This may be indicative of a lack older individuals

occurring within the lagoon or potential predation of larger individuals. The fyke nets used during survey can

also result in some bias, with larger individuals (> 350 mm TCL) being potentially excluded from the throat of

the net.

The presence of Sydney Basin Turtle Emydura macquarii dharuk is a new record for Glenbrook Lagoon. This

species occurs throughout the Hawkesbury-Nepean catchment. This is a sub-species of E. macquarii (Murray

River Turtle) conspicuous in having raised vertebral scales unlike the type species. While low numbers of this

species were recorded (n=3), the age class for these individuals is presumed to be greater than four years

based on known growth rates for Emydura macquarii (Spencer 2002). Suitable breeding habitat (nesting


beaches) exists for both species around the lagoon particularly in the southern and western margins of the

Lagoon.

Australian Bass Macquaria novaemaculata occurs in coastal rivers and streams along the east coast of

Australia and are mostly found near in-stream debris, fallen timber or rocky outcrops. The species grows up

to 650 mm with females being generally larger than the males. Australian Bass feed on fish, crustaceans and

other invertebrates such as insects. As they are a popular recreational angling species, they were previously

stocked into Glenbrook Lagoon. However, they were not captured during the fish surveys in February and

April 2014.

No European Carp Cyprinus carpio were recorded during the current assessment, although the species has

previously been recorded within the Lagoon in low numbers (pers comm. C. Day, 2014). The still water

habitat within the lagoon is suitable for the species, although fluctuating water levels are favoured by the

species for successful recruitment (Koehn 2004). The species is considered noxious under the FM Act. Koi

Carp and European Carp are the same species with Koi Carp individuals representing an ornamental strain

developed in Japan. The species is considered a significant pest in Australian waterways and is expected to be

exceptionally difficult, if not impossible, to eradicate from the lagoon.

The lack of more detailed pre-treatment survey with respect to the fish fauna of Glenbrook Lagoon makes an

assessment of the changes to this fauna in response to the weed control difficult. Australian Bass were not

recorded during this survey. While the survey effort was considered sufficient to document the fish fauna of

Glenbrook Lagoon, it is not exhaustive, and Australian Bass may still be present in low abundance. The

presence of large numbers of young catfish is encouraging. These juveniles appear to be of the same cohort

and are most likely from the spring / summer spawning period in 2012 around the period of the weed

treatment. This would suggest that the weed treatment had no long term effects on this species or at least

on juvenile catfish. The fish fauna, with the exception of Eastern Gambusia and Australian Smelt, is

comprised of demersal (bottom dwelling) species. Emergent rushes and snags around the margins of the

lake provide extensive areas of high quality habitat for demersal fish. The substantial amounts of organic

matter covering the substrate as a result of weed treatment may potentially limit the spawning ability of some

species (i.e. Freshwater Catfish). There may be some population suppression as a result of these changes to

the lagoon substrate or direct impacts from the weed treatment. This is difficult to determine in the scope of

this study. While no larval (young of year) catfish were recorded, the mesh size of fyke nets, the more

successful capture technique for catfish in this study, was too large to retain larval catfish. The lack of floating

and submerged aquatic vegetation post weed treatment has resulted in much reduced refuge habitat for

more open water (pelagic) fish (Australian Smelt).


Recommendations

4.1 Management of native fish

4.1.1 Native fish

Blue Mountains City Council is actively engaged in providing measures to improve water quality in Glenbrook

Lagoon through the construction of storm water wetland treatment systems, upgrades to storm water

infrastructure to reduce untreated inputs to the Lagoon and intervention water quality monitoring. These

measures are important as they are best practice methods to improve the health of Glenbrook Lagoon and

its aquatic fauna. The augmentation of the aquatic vegetation lost as a result of the weed treatment is

recommended through supplementary plantings / introductions of indigenous submerged aquatic vegetation

where feasible. The introduction, where possible, of coarse woody debris to the Lagoon from native

vegetation sources (snags etc.) is to be encouraged as this will create habitat not only for fish but for birds,

frogs and turtles.

4.1.2 Australian Bass

The proposal to re-introduce Australian Bass to the lagoon for potential ecological benefits associated with

the re-introduction of an apex predator. The habitat currently present in the lagoon is substantially modified.

The removal of large areas of aquatic vegetation has resulted in a much reduced extent of aquatic habitats.

Stocked fingerlings of more open water dwelling species such as Australian Bass would be vulnerable to

predation from piscivorous birds without suitable refuge habitat. Australian Bass require migration to the

lower estuarine reaches of rivers to spawn. This would mean that the population within the lagoon would

never be self sustaining and would need continual replenishment over time. The time and monetary

requirements of re-introducing this species would be better utilised exploring other management options or

monitoring. More importantly this species would likely impact upon the Freshwater Catfish population at

certain developmental stages. The local community may also target the species within the lagoon and result

in human health issues associated with the capture and consumption of Australian Bass. This should be

evaluated with respect to continued elevated levels of faecal coliforms recorded from the Lagoon.

4.1.3 Freshwater Catfish

The population of Freshwater Catfish does appear to be self sustaining, with significant recruitment recorded

from the 2012-2013 breeding season. The presence of this species in Glenbrook Lagoon is to be valued. The

critical factor in maintaining suitable environmental conditions for breeding is relatively static water levels

during the spawning period (spring and summer). Freshwater Catfish lay eggs in a constructed nest at a

particular depth (usually less than one metre) (Clunie and Keohn 2001). Water temperatures above 24ºC are

needed to initiate spawning. This charismatic species has all but disappeared from its native riverine

environment in the Murray Darling Basin, where it currently persists in restricted impoundments (reservoirs)

and a small number of refuge sites that are isolated, susceptible to localised impacts and systemic decline

from low genetic diversity within populations. The decline of this species has been attributed to reduced

water quality, modified flow regimes in managed systems and the incursion of European Carp (Clunie and

Keohn 2001). Introduced carp occupy the same trophic niche as Freshwater Catfish and actively out-compete

them through direct competition for food resources as well as suspected disturbance of nests, ingestion of

eggs and impacts to water quality. European Carp are commonly introduced to waterbodies in urban

environments. Community education and engagement is the best approach to minimise the potential of

these introductions that would likely result in the extirpation of Freshwater Catfish at the Lagoon.


4.2 Management of noxious fish species

4.2.1 Eastern Gambusia

Few options exist for the management of Eastern Gambusia in this system. Given Glenbrook Lagoon's

volume and the complex habitats and diversity of native species present, traditional alternatives such as

dewatering and drying of the waterbody are unfeasible. Recent control trials where Gambusia were actively

removed from small waterbodies to below a critical density have achieved remarkable results in reducing the

size of these populations for extended periods (Tonkin et al 2014). This required repeated netting and

removal of Gambusia in isolated waterbodies less than 1000 m2. This may have some limited application in

Glenbrook Lagoon but may be more appropriate for habitat management for frogs (detailed below).

4.2.2 European Carp

While European Carp have been previously recorded within the lagoon in low numbers, they still pose a

significant threat to the ecological values currently present . Control of this species is known to be time

consuming and costly (Koehn 2004) and it is recommended that monitoring be undertaken regularly to

evaluate the abundance of the species within the Lagoon. A larger number of fyke nets should be deployed

in conjunction with boat mounted electrofishing, and would result in a higher degree of confidence in the

detection of the species.

4.2.3 Frogs

The absence of tadpoles in Glenbrook Lagoon is conspicuous as extensive areas of suitable refuge and

breeding habitat are present. Three species of frog having previously been recorded in breeding chorus

(AMBS, 2012). The presence of large numbers of Gambusia is likely to have impacted upon breeding success

of frogs as Gambusia may prey upon tadpoles and eggs. Simple habitat improvements such as small

excavations within reed beds above the high water mark may encourage breeding of frogs. These pools

would require manual filling prior to the breeding season. This could be overcome by being situated to take

advantage of stormwater overflow from stormwater wetlands. Alternatively they could be excavated in the

littoral zone (just below the high water mark) in areas of dense vegetation. These created pools would be

filled by natural fluctuations in the water level of the Lagoon, where Gambusia may have to be controlled.

Gambusia can be reduced by repeated seine netting within these pools (Tonkin et al 2014) during the

observed breeding season, of the recorded species, during spring-summer.

4.3 Freshwater turtles

4.3.1 Freshwater Turtles

Two species of freshwater turtles, Eastern Long-necked Turtle and the Sydney Basin Turtle, are found in

Glenbrook Lagoon. Efforts to improve breeding success of these species are considered important for their

long term survival. As recommended for fish habitat augmentation, the inclusion of snags away from the

bank would provide basking habitat for these turtle species. The heavily vegetated western edge of the

lagoon has extensive areas of habitat suitable for nesting. The feasibility of firstly identifying the best areas

for nesting, incorporating signage identifying 'no go zones' and potentially fencing these areas to exclude

dogs and people during the breeding season (September – February) can be investigated. While reasonably

large numbers of plus four year old turtles were recorded during survey, no younger cohorts were recorded.

Both species population dynamics are typified by low juvenile survivorship.


4.4 Water Quality

Efforts to improve water quality are being undertaken by BMCC. This includes the recent addition of a

stormwater treatment wetland at the southern end of the Lagoon. The 'beach' area on the northern edge of

Lagoon continues to be a source of litter and sediment. Run-off and foot traffic adjacent to the fenced beach

area contribute to increased disturbance of the riparian zone and sedimentation. The deposition of large

amounts of organic material as a result of weed treatment may impact upon water quality during warmer

months where accelerated decomposition of this material may result in reduced dissolved oxygen. This

should be monitored more regularly during warmer months. Should declining levels of DO be recorded over

time then some alternatives may be employed. Sub-surface aeration systems are reasonably cost effective

measures that would ameliorate the reduced DO for short periods. In the longer term, biological agents

(bacteria and beneficial enzymes) can be periodically added to the Lagoon to accelerate the decomposition

process of the accumulated organic matter. A number of commercial operations provide these services in

Australia. This would typically involve the continued use of sub-surface aeration to improve decomposition

rates and replenish dissolved oxygen resulting from these processes.

4.5 Monitoring

Continued monitoring of Glenbrook Lagoon is recommended to document the responses of the aquatic flora

and fauna to changes in the Lagoon system as a result of Cabomba weed treatment. Annual survey

conducting flora, amphibian, bird, fish and turtle monitoring will allow for interpretation of trends in the floral

and faunal groups. This will inform management objectives for the coming year and seek to evaluate the

effectiveness of management recommendations made to date. This monitoring information would be

interpreted in the context of broader environmental management initiatives undertaken by BMCC and collate

and analyse data from annual monitoring, water quality and macroinvertebrate monitoring and

environmental management programs.


5. Plates

Plate 1: GBL1 sampled using seven bait traps and one fyke net



Plate 7: GBL7 sampled using seine netting and electrofishing

Plate 8: GBL8 sampled using seine netting and electrofishing


Plate 9: Bait trap

Plate 10: Fyke net


Plate 11: Electrofishing

Plate 12: Flathead Gudgeon Philypnodon grandiceps


Plate 13: Freshwater Catfish Tandanus tandanus

Plate 14: Long-finned Eel Anguilla reinhardtii


Plate 15: Eastern Long-Necked Turtle Chelodina longicollis

Plate 16: Sydney Basin Turtle Emydura macquarii dharuk


6. References

Allen, G.R. (1989). Freshwater fish of Australia. T.F.H. Publications, Inc., Neptune City, New Jersey.

AMBS (2012) Aquatic Flora and Fauna Survey of Glenbrook Lagoon. Australian Museum Business Services. AMBS

Reference: 1201080. 44 pp.

Barker, D., Allan, G.L., Rowland, S.J., Kennedy, J.D. & Pickles, J.M. (2004) A Guide to Acceptable Procedures and

Practices for Aquaculture and Fisheries Research. 71 pp.

Biosis (2013) Code of Practice for Aquatic Fauna Surveys, 21 pp.

Cann, J. (1998). Australian Freshwater Turtles. Beaumont Publishing, Singapore.

Clunie, P. and Koehn, J.D. 2001. Freshwater Catfish: A Recovery Plan. Final Report for Natural Resource

Management Strategy Project 7 R7002 to the Murray Darling Basin Commission. Department of Natural

Resources and Environment, Heidelberg, Victoria.

Davis, T.L.O. (1977). Age determination and growth of the Freshwater Catfish Tandanus tandanus Mitchell, in the

Gwydir River, Australia. Journal of Marine and Freshwater Research. 1977 28: 119-137.

Fisheries Scientific Committee 2008. Final determination. The Tandanus tandanus – Eel-tailed Catfish in the

Murray/Darling Basin as an endangered population. Department of Primary Industries. Nelson Bay, NSW.

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

pp 882-894.

McDowall, R.M. (1996). Freshwater Fish of South-Eastern Australia. Reed Books, Chatswood, NSW.

NHMRC (1997) Australian code of practice for the care and use of animals for scientific purposes. National

Health and Medical Research Council, 84 pp.

Pyke, G. H. (2005). A review of the biology of Gambusia affinis and G. holbrooki. Reviews in Fish Biology and

Fisheries. 15: 339-365.

Spencer, R.J. (2002). Growth patterns of two widely distributed freshwater turtles and a comparison of common

methods used to estimate age. Australian Journal of Zoology 2002 50: 477 – 490.

Tonkin, Z. Ramsey, D.S.L. Macdonald, J. Crook, D. King, A.J. and Kaus, A. (2014). Does localized control of invasive

eastern gambusia (Poeciliidae: Gambusia holbrooki) increase population growth of generalist wetland fish? Austral

Ecology. 39. 355-366.


7. Appendix

Documents

Fish surveys at Glenbrook Lagoon, Blue Mountains...Fax: (03) 9646 9242 Email: [email protected] NEW SOUTH WALES Sydney Unit 14, 17-27 Power Avenue Alexandria NSW 2015 Phone: (02)