Nepean River

Ecology of the Australian bass in tributaries of the Hawkesbury- Nepean River

Alan Midgley

Western Sydney University

i Statement of Authentication

I (Alan Midgley) declare that this thesis contains no material that has been accepted for the award of any other degree or diploma and that, to the best of the candidate's knowledge and belief, this thesis contains no material previously published or written by another person, except when due reference has been made in the text of this thesis.

Signature:

Date: 8 December 2015

ii Acknowledgements

Professor Shelley Burgin – provision of ongoing support throughout my candidature and supervisory changes during her at time at Western Sydney University and beyond seeking solutions to help in the completion of my PhD thesis that we have both worked hard on over the years. She was diligent and adaptable throughout the good and bad times with the mutual goal of academic excellence. She has always been an excellent mentor allowing me to evolve my skills throughout my research career. Shelley has remained dedicated above and beyond her supervisory role and with that I want to acknowledge my gratitude for her hard work.

Doctor Adrian Renshaw – ongoing assistance and supervision with progression of aspects of final thesis throughout my PhD.

PhD Student Ms Loren Hull – for assistance in collaborative fieldwork at study sites and technical support for data analysis. Always supportive throughout my candidature, without which I would not have reached this milestone.

Doctor Nathan Miles - tireless dedication in the field to assist in collection of samples for the project. Extremely helpful guidance in determining otolith microchemistry and statistical analysis of that data.

Western Sydney University – provision of Commonwealth scholarship and ‘top-up’ for assistance in ongoing research throughout my PhD.

The New South Wales Recreational Fishing Freshwater Trust and the NSW Department of Primary Industries for funding of the data collection program “NSW DPI Bass Catch Program” used for comparative purposes in this study. Additional thanks to Danielle Ghosn for personally supplying this information with a helpful attitude.

Field and laboratory assistants Mr Jabin Round, Mr Ashley Thamm, Mr Michael Aldrich and Mr Michael Franklin – tireless dedication to assist in the collection and analysis of samples for the project.

iii Mr Paul Smith – for assisting with sampling gear and taking a relaxed approach to laboratory work.

This thesis is written as a series of papers to be published in the near future. For this reason there may some repetition between chapters.

iv Table of Contents

Table of Figures ...... ix Table of Tables ...... xix Table of Plates ...... xxv List of Abbreviations ...... xxvi Abstract ...... xxviii 1. Ecological attributes and recreational fishing for Macquaria novemaculeata on Australia’s East Coast ...... 1 1.1 Introduction ...... 1 1.1.1 The importance of fish and human impacts ...... 1 1.1.2 Management requires knowledge of the fishery ...... 2 1.1.3 Percichthyidae and Macquaria novemaculeata ...... 5 1.1.4 Lifecycle and lifecycle interruption ...... 8 1.1.5 Habitat selection...... 14 1.1.6 Size and sexual differentiation ...... 17 1.1.7 Diet ...... 20 1.1.8 Recreational fishing ...... 23 1.1.9 The current project ...... 28 1.2 References ...... 30 2. Site Description and Sampling Method ...... 52 2.1 Study Sites ...... 53 2.1.1 Obstacle-Strewn Tributaries ...... 57 2.1.2 Open Tributaries ...... 64 2.2 Sampling Method ...... 69 2.3 References ...... 70 3. Attitudes and behaviour of recreational fishers of Australian bass Macquaria novemaculeata with a focus on the Hawkesbury-Nepean River ...... 73 3.1 Introduction ...... 73 3.1.1 Recreational fishing and Macquaria novemaculeata ...... 75 3.2 Methods ...... 82 3.2.1 Data Analysis ...... 83 3.3 Results ...... 83 3.3.1 Gender and age of anglers...... 85 3.3.2 Fishing group size, frequency of fishing, number of years fished ...... 85 3.3.3 Fishing sites, use, and the method of selection ...... 87 3.3.4 Percentage of effort focused on Macquaria novemaculeata, catch data (size, release rates), changes in attitude over time ...... 89

v 3.4 Discussion ...... 93 3.4.1 Gender and age of anglers...... 94 3.4.2 Fishing group size, frequency of fishing, number of years fished ...... 98 3.4.3 Fishing sites, use, and the method of selection ...... 103 3.4.4 Percentage of effort focused on Macquaria novemaculeata, catch data (size, release rates), changes in attitude over time ...... 109 3.5 Conclusions ...... 112 3.6 References ...... 113 4. Demography of Australian bass Macquaria novemaculeata in tributaries of the Hawkesbury- Nepean River ...... 152 4.1 Introduction ...... 152 4.1.1 Size, age and sexual differentiation in fish ...... 152 4.1.2 Habitat selection and density ...... 158 4.2 Methods ...... 161 4.2.1 Length and Weight ...... 161 4.2.2 Sex...... 161 4.2.3 Habitat Selection and Density ...... 161 4.2.4 Otolith Removal and Age ...... 162 4.2.5 Data Analysis ...... 163 4.3 Results ...... 166 4.3.1 Sex Ratio ...... 166 4.3.2 Length and Sex ...... 166 4.3.3 Fish Length ...... 168 4.3.4 Weight ...... 169 4.3.5 Condition...... 171 4.3.6 Age ...... 174 4.3.7 Growth ...... 175 4.3.8 Sex and Growth...... 178 4.3.9 Density ...... 180 4.3.10 Habitat Selection ...... 181 4.3.11 Length and Habitat Selection ...... 182 4.3.12 Comparison of fish length between tributaries and riverine channel .. 184 4.4. Discussion ...... 186 4.4.1 Sex ratio and associated length and growth between the sexes ...... 186 4.4.2 Fish Size Indices ...... 188 4.4.3 Age and Growth ...... 190 4.4.4 Habitat selection, habitat selection by fish of different sizes, and density 192 4.5 Conclusions ...... 196 4.6 References ...... 196 5. Dietary analysis of the Percichthyidae Australian bass Macquaria novemaculeata in tributaries of the Hawkesbury-Nepean River ..... 213 5.1 Introduction ...... 213 5.1.1 Dietary aspects of Macquaria novemaculeata...... 219

vi 5.2 Methods ...... 222 5.2.1 Dietary Analysis...... 222 5.2.2 Data Analysis ...... 223 5.3 Results ...... 225 5.3.1 Fish Length ...... 227 5.3.2 Fish Length and Stomach Content Weight ...... 229 5.3.3 Diversity of prey taken by Macquaria novemaculeata ...... 230 5.3.4 Food type diversity ...... 231 5.3.5 Abundance of prey taken by Macquaria novemaculeata ...... 233 5.3.6 Food type abundance ...... 234 5.3.7 Food type weight...... 236 5.3.8 Stomach fullness ...... 238 5.3.9 Stomach content weight ...... 240 5.3.10 Food item assemblage by weight ...... 241 5.3.11 Food item assemblage by abundance ...... 243 5.3.12 Fish size and diet ...... 245 5.4 Discussion ...... 248 5.4.1 Diversity and abundance of prey ...... 248 5.4.2 Fish Size and Diet shift ...... 260 5.4.3 Stomach Contents Weight and Fullness ...... 263 5.4.4 Food item assemblage by weight ...... 264 5.4.5 Food type diversity, abundance and weight ...... 265 5.5 Conclusions ...... 268 5.6 References ...... 270 6. Investigating migratory movements of the Percichthyidae Australian bass Macquaria novemaculeata in the Hawkesbury-Nepean River using otolith microchemistry ...... 296 6.1 Introduction ...... 296 6.1.1 Importance of fish movement ...... 296 6.1.2 Natural Fish Barriers and Flow ...... 297 6.1.3 Diadromy ...... 299 6.1.4 Methods of Fish Movement Tracking...... 300 6.1.5 Macquaria novemaculeata lifecycle and lifecycle interruption ...... 302 6.2 Methods ...... 308 6.2.1 Collection of fish for analysis ...... 308 6.2.2 Otolith Microchemistry Analysis ...... 309 6.3 Results ...... 311 6.3.1 Efficiency of results ...... 311 6.3.2 Comparison of fish age and migration between stream types ...... 313 6.4 Discussion ...... 319 6.4.1 Differences between obstacle-strewn and open tributaries ...... 321 6.5 References ...... 323 7. Discussion ...... 341 7.1 Recommendations and further research ...... 348 7.2 References ...... 350

vii 8. Appendices ...... 357 8.1 Appendix I - complete template of the recreational fisherman questionnaire 357 8.2 Appendix II - recreational fisherman questionnaire results ...... 361 8.3 Appendix III – fieldwork results ...... 382 8.4 Appendix IV – raw diet data ...... 400

viii Table of Figures

Figure 1.1 The natural Australian distribution (shaded area on insert) of Macquaria novemaculeata. (Source: Jerry and Baverstock, 1998; NSW Department of Primary Industries, undated)...... 7

Figure 2.1 Hawkesbury River below Yarramundi in New South Wales, highlighting study sites (Obstacle-strewn - Little Wheeny Creek; Popran Creek; Wheeny Creek and Open - Cattai Creek; Webbs Creek; Wrights Creek), districts, and proximity to Sydney. (Historically, this waterway is classified as the Hawkesbury River below the Grose River junction and the Nepean River above this junction; Modified from Howell and Benson 2000)...... 54

Figure 2.2 Little Wheeny Creek highlighting the reaches sampled (Source: HNCMA 2007)...... 58

Figure 2.3 Popran Creek highlighting the reach sampled (Source: GoogleMaps 2012)...... 60

Figure 2.4 Wheeny Creek highlighting the reach sampled (Source: HNCMA 2007). 62

Figure 2.5 Cattai Creek highlighting the reach sampled (Source: GoogleMaps 2012)...... 65

Figure 2.6 Webbs Creek highlighting the sampled reach (Source: GoogleMaps 2012)...... 67

Figure 2.7 Wrights Creek, highlighting the reach sampled (Source: GoogleMaps 2012)...... 68

Figure 3.1 Waterways utilised by respondents angling for Macquaria novemaculeata...... 84

Figure 3.2 Age categories of respondents that target Macquaria novemaculeata...... 85

ix Figure 3.3 Typical fishing party size for the targeting of Macquaria novemaculeata. 85

Figure 3.4 Frequency of fishing focused on the capture of Macquaria novemaculeata...... 86

Figure 3.5 The total number of years that respondents had fished for Macquaria novemaculeata...... 86

Figure 3.6 Waterway type preferred by respondents when they fished for Macquaria novemaculeata...... 87

Figure 3.7 Comparison of age of respondents who predominantly fished for Macquaria novemaculeata in creeks and rivers...... 88

Figure 3.8 Respondents’ method/s of identifying locations to fish for Macquaria novemaculeata. Bait and tackle shop = word of mouth in bait and tackle shop; Online methods = online aerial/satellite maps (e.g. Googlemaps) and Internet-based fishing forum discussion; Exploring = bushwalking/exploring, local knowledge; Club discussion = friends and fishing club discussion; Maps = topographical hard copy maps...... 88

Figure 3.9 Respondent age association with method/s of identifying locations to fish for Macquaria novemaculeata on the East Coast of Australia. Bait and tackle shop = word of mouth in bait and tackle shop; Online methods = online aerial/satellite maps (e.g. Googlemaps) and Internet-based fishing forum discussion; Exploring = bushwalking/exploring, local knowledge; Club discussion = friends and fishing club discussion; Maps = topographical hard copy maps...... 89

Figure 3.10 Percentage fishing effort used to target Macquaria novemaculeata...... 89

Figure 3.11 Most common sized Macquaria novemaculeata caught by anglers...... 90

Figure 3.12 Most frequently reported size of Macquaria novemaculeata caught from the Hawkesbury-Nepean River compared to elsewhere within the species’ range. .... 90

x Figure 3.13 Comparison of respondents’ age and their likelihood of retaining Macquaria novemaculeata for consumption or releasing their catch...... 91

Figure 3.14 Macquaria novemaculeata retained for consumption (%)...... 91

Figure 3.15 Fishing site preferred by respondents who targeted Macquaria novemaculeata for consumption (%)...... 92

Figure 3.16 Respondents’ assessment of whether other anglers released or retained for consumption the Macquaria novemaculeata they caught...... 92

Figure 3.17 Comparison of respondents’ attitude to angling for Macquaria novemaculeata over time. Sport-orientated = become more sport-orientated; Consumption = become more focused on capture for consumption...... 93

Figure 4.1 Fork length of Macquaria novemaculeata was measured from the snout to the fork of the tail (Modified from NSW Department of Primary Industries 2015). . 161

Figure 4.2 Total number of Macquaria novemaculeata males and females recorded in open and obstacle-strewn tributary types (December 2011 - April 2013) in the Hawkesbury-Nepean River...... 166

Figure 4.3 Length of Macquaria novemaculeata between male and female fish from open and obstacle-strewn tributaries (December 2011 - April 2013) in the Hawkesbury-Nepean River (± S.E.)...... 167

Figure 4.4 Length of Macquaria novemaculeata between male and female fish from open and obstacle-strewn tributaries (December 2011 - April 2013) in the Hawkesbury-Nepean River. Data remained untransformed...... 167

Figure 4.5 Mean length of Macquaria novemaculeata recorded in obstacle-strewn and open tributary types over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 168

xi Figure 4.6 Mean length of Macquaria novemaculeata recorded in obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 169

Figure 4.7 Mean weight of Macquaria novemaculeata recorded in obstacle-strewn and open tributary types over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 170

Figure 4.8 Mean weight of Macquaria novemaculeata recorded in obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 170

Figure 4.9 Mean condition of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 171

Figure 4.10 Mean condition of Macquaria novemaculeata recorded in obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 171

Figure 4.11 Mean age of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 174

Figure 4.12 Mean age of Macquaria novemaculeata recorded in obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 175

Figure 4.13 Mean growth of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 176

xii Figure 4.14 Mean growth of Macquaria novemaculeata recorded in obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 176

Figure 4.15 Growth of Macquaria novemaculeata between male and female fish from open and obstacle-strewn tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 119)...... 179

Figure 4.16 Growth of Macquaria novemaculeata between male and female fish from open and obstacle-strewn tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia. Data remained untransformed (n = 119)...... 179

Figure 4.17 Mean Macquaria novemaculeata caught per 200 casts recorded in obstacle-strewn and open tributary types over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 180

Figure 4.18 Mean Macquaria novemaculeata caught per 200 casts recorded in obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 181

Figure 4.19 Total number of Macquaria novemaculeata and their habitat selection recorded in open and obstacle-strewn tributary types over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (n = 3)...... 182

Figure 4.20 Total number of Macquaria novemaculeata and their habitat selection recorded in open and obstacle-strewn tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia...... 182

Figure 4.21 Mean length of Macquaria novemaculeata caught near structure and not near structure from open and obstacle-strewn tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 183

xiii Figure 4.22 Mean length of Macquaria novemaculeata caught near structure and not near structure from open and obstacle-strewn tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (n = 3)...... 183

Figure 4.23 Mean length of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) and mean length of Macquaria novemaculeata recorded in riverine environments over approximately one year (February 2010 – February 2011) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 185

Figure 5.1 Mean length of Macquaria novemaculeata recorded in obstacle-strewn and open tributary types over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 228

Figure 5.2 Mean length of Macquaria novemaculeata recorded in obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 228

Figure 5.3 Regression between the length of Macquaria novemaculeata and stomach content weight recorded over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia...... 229

Figure 5.4 Mean food item diversity recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 230

Figure 5.5 Mean food item diversity recorded in the stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 230

xiv Figure 5.6 Mean food type diversity recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 231

Figure 5.7 Mean food type diversity recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 232

Figure 5.8 Mean food item abundance recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 233

Figure 5.9 Mean food item abundance recorded in the stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 234

Figure 5.10 Mean food type abundance recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 235

Figure 5.11 Mean food type abundance recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 235

Figure 5.12 Mean food type weight recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 237

xv Figure 5.13 Mean food type weight recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 237

Figure 5.14 Mean stomach fullness recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 239

Figure 5.15 Mean stomach fullness recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 239

Figure 5.16 Mean weight of stomach content recorded in Macquaria novemaculeata from obstacle-strewn and open tributary types over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3)...... 240

Figure 5.17 Mean weight of stomach content recorded in Macquaria novemaculeata from obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.)...... 241

Figure 5.18 Food item assemblage by weight recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia. Data remained untransformed (n = 3)...... 242

Figure 5.19 Food item assemblage by abundance recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia. Data remained untransformed (n = 3)...... 244

xvi Figure 5.20 Food item assemblage recorded in the stomach contents of Macquaria novemaculeata between fish < 245mm and ≥ 245mm from open and obstacle-strewn tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia. Data remained untransformed (n = 3)...... 246

Figure 6.1 Transect of a female fish from Wrights Creek highlighting variation in otolith microchemistry (Sr:Ca; Ba:Ca) in the Hawkesbury-Nepean River, Australia...... 312

Figure 6.2 Transect of a female fish from Wheeny Creek highlighting variation in otolith microchemistry (Sr:Ca; Ba:Ca) in the Hawkesbury-Nepean River, Australia...... 312

Figure 6.3 Estimated number of estuary returns by six Macquaria novemaculeata from open tributaries (a-e = female; f = male) of the Hawkesbury-Nepean River, based on analysis of otolith chemistry. *Where estuarine occupancy appeared constant over a period of years, estuary returns were rated at one per year...... 314

Figure 6.4 Estimated number of estuary returns by six Macquaria novemaculeata from obstacle-strewn tributaries (g-k = female; l = male) of the Hawkesbury-Nepean River, based on analysis of otolith chemistry. *Where estuarine occupancy appeared constant over a period of years, estuary returns were rated at one per year...... 315

Figure 6.5 LA-ICP Mass Spectrometer scans of six Macquaria novemaculeata from open tributaries showing two dimensional structure of Ba:Ca (left) and Sr:Ca (right) in sagittal otoliths. Red regions in the scans represent a high elemental concentration of the chemical analysed. Females from Webbs Creek (c-e) and Wrights Creek (f), and the male from Webbs Creek, (a-f) are the same individuals as referred to in Table 6.2...... 316

Figure 6.6 LA-ICP Mass Spectrometer scans of six Macquaria novemaculeata from obstacle-strewn tributaries showing two dimensional structure of Ba:Ca (left) and Sr:Ca (right) in sagittal otoliths. Red regions in the scans represent a high elemental concentration of the chemical analysed in the female from Little Wheeny Creek (g)

xvii and females from Wheeny Creek (h-k), and the male from Popran Creek (l). ‘g’-‘l’ refer to the same individuals as in Table 6.3...... 318

xviii Table of Tables

Table 2.1 Background information for the catchments of obstacle-strewn tributaries1 ...... 57

Table 2.2 Background information for the catchments of open tributaries1 ...... 64

Table 4.2 Pairwise analysis of the length of Macquaria novemaculeata between male and female fish from open and obstacle-strewn tributaries by PERMANOVA (December 2011 - April 2013) in the Hawkesbury-Nepean River (*** = 0.001 significance, ** = 0.01 significance, * = 0.05 significance, ns = not significant). .... 168

Table 4.5 Nested Analysis of Variance of the condition of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (** = 0.01 significance, ns = not significant)...... 172

Table 4.6 A Tukey’s post hoc analysis of the condition of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years

xix (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (** = 0.01 significance, ns = not significant)...... 172

Table 4.9 A Tukey’s post hoc analysis of the growth of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (* = 0.05 significance, ns = not significant)...... 177

Table 4.10 Analysis of the growth of Macquaria novemaculeata between male and female fish from open and obstacle-strewn tributaries by PERMANOVA over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (ns = not significant)...... 180

xx Table 4.13 Pairwise analysis of the length of Macquaria novemaculeata caught near structure and not near structure from open and obstacle-strewn tributaries by PERMANOVA over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (*** = 0.001 significance, ** = 0.01 significance, ns = not significant)...... 184

Table 4.14 A one-way analysis of variance of the length of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) and mean length of Macquaria novemaculeata recorded in riverine environments over approximately one year (February 2010 – February 2011) in the Hawkesbury-Nepean River, Australia (*** = 0.001 significance)...... 185

Table 4.15 A Tukey’s post hoc analysis of the length of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) and mean length of Macquaria novemaculeata recorded in riverine environments over approximately one year (February 2010 – February 2011) in the Hawkesbury-Nepean River, Australia (*** = 0.001 significance, ns = not significant)...... 186

Table 5.1 Abundance of food items and their type recorded in the stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia...... 226

Table 5.3 Regression output between the length of Macquaria novemaculeata and stomach content weight recorded over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia...... 229

xxi Table 5.4 Analysis of Variance between the length of Macquaria novemaculeata and stomach content weight recorded over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (ns = not significant)...... 229

Table 5.5 Nested Analysis of Variance of the food item diversity recorded in the stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (** = 0.01 significance, ns = not significant)...... 231

Table 5.8 Nested Analysis of Variance of the food type abundance recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (** = 0.01 significance, ns = not significant)...... 236

xxii Table 5.10 Nested Analysis of Variance of stomach fullness recorded in Macquaria novemaculeata from obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (ns = not significant)...... 240

Table 5.13 The similarity of individual taxonomic group weight in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries by SIMPER over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia. × = aquatic invertebrate; ×× = terrestrial invertebrate; ××× = aquatic vertebrate...... 243

Table 5.15 The similarity of taxonomic group abundance recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries by SIMPER over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia. × = aquatic invertebrate; ×× = terrestrial invertebrate; ××× = aquatic vertebrate...... 245

Table 5.16 Analysis of the food item assemblage recorded in the stomach contents of Macquaria novemaculeata between fish < 245mm and ≥ 245mm from open and

xxiii obstacle-strewn tributary types and sites by Nested PERMANOVA over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (* = 0.05 significance, ns = not significant)...... 246

Table 6.1 Twelve Macquaria novemaculeata selected for otolith microchemistry from open (a-f) and obstacle-strewn (g-l) tributaries collected over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River...... 313

Table 6.2 Interpretation of migration frequency of six Macquaria novemaculeata from open tributaries (Figure 6.5) using Ba:Ca (a-d) and Ba:Ca/Sr:Ca (e-f) elemental concentrations. < Estuary = return to estuary; > Freshwater = > migration to freshwater...... 317

Table 6.3 Migration interpretations of six Macquaria novemaculeata from obstacle- strewn tributaries (Figure 6.6) using Ba:Ca (g-k) and Ba:Ca/Sr:Ca (l) elemental concentrations. < Estuary = return to estuary; > Freshwater = > migration to freshwater...... 319

xxiv Table of Plates

Plate 2.1 A characteristic example of an obstacle-strewn stretch of creek highlighting rock boulders, riffles, fringing terrestrial vegetation and shallow water...... 56

Plate 2.2 A characteristic example of an open stretch of creek highlighting a lack of discernible obstacles...... 56

Plate 2.3 One of several small waterfalls within the sampling reach of Little Wheeny Creek...... 58

Plate 2.4 Turbid section of a larger pool on Popran Creek after extensive rain...... 61

Plate 2.5 Waterfall associated, boulder-strewn section of Popran Creek during typical flow regime...... 61

Plate 2.6 A long, shallow stretch of Wheeny Creek with a sand substrate creek bed. 63

Plate 2.7 A deep section of Wheeny Creek with instream fallen tree...... 63

Plate 2.8 Characteristic view of the reach sampled on Cattai Creek...... 66

Plate 2.9 Characteristic view of area sampled on Webbs Creek...... 67

Plate 2.10 Characteristic view of area sampled on Wrights Creek...... 69

xxv List of Abbreviations

Abbreviation Description ACT Australian Capital Territory ANOSIM Analysis of Similarity ANOVA Analysis of Variance App. Appropriate CBD Central Business District C.I. Confidence Interval d.f. Degrees of Freedom DPI Department of Primary Industries e.g. For example et al. And others F F-value FL Fork length h Hours IBM International Business Machines L Litre m Metre mm Millimetres Max Maximum mg/L Milligrams per Litre Min Minute ML Megalitres M. novemaculeata Macquaria novemaculeata MS Mean Square mv Millivolts n Total NFA Native Fish Australia NSW New South Wales ntu Nephelometric Turbidity Unit No. Number

xxvi P P-value pH Potential Hydrogen PhD Doctor of Philosophy PIT Passive Integrated Transponder ppt Parts per thousand PERMANOVA Permutational Manova PRIMER Plymouth Routines in Multivariate Ecological Research Rep. Replicate Signif. Significance SPSS Statistical Package for the Social Sciences SS Sum of Squares StDevs Standard Deviations STP Sewage Treatment Plant TL Tail length ug/L Micrograms per Litre oC Degrees Celsius

xxvii Abstract

The Australian bass Macquaria novemaculeata, belonging to the family Percichthyidae, is a carnivorous fish endemic to Australia. Its distribution extends throughout Eastern-Australian streams from the Mary River (Queensland) to Lakes Entrance (Victoria). The focus of this study was to determine the ecological attributes of M. novemaculeata in open and obstacle strewn tributaries within the Hawkesbury- Nepean River Catchment; two unique habitats that M. novemaculeata commonly inhabit. Specifically, this study focused on the demography, diet, and migratory patterns of M. novemaculeata between open and obstacle-strewn tributary reaches. In addition, the attitudes and behaviours of recreational fisherman who target M. novemaculeata in their natural environment on the east coast of Australia were also investigated.

Recreational fishing pressure on M. novemaculeata in their natural environment was obtained via a survey of recreational anglers by contacting fishing clubs and affiliates. The survey included angler gender, age class, State of residence, fishing effort specifically for M. novemaculeata, including years spent targeting the species, size of angling group, areas fished and watercraft used, how fishing sites were selected, the average size of M. novemaculeata caught, and the level of catch-release employed by anglers. In order to investigate demography data, diet and migratory patterns, overall 120 M. novemaculeata were caught by hand-held rod with lure in obstacle-strewn and open tributaries and euthanised. This provided a sample to collect data on length, weight, condition, age, growth, sex ratio, density, and in-stream habitat selection. Stomach contents of euthanised fish were analysed for diet. Otoliths of these fish were removed to determine age and migratory movement using a micro-chemical procedure, involving a laser ablation-inductively coupled plasma-mass spectrometer (LA-ICPMS).

The average angler who targeted M. novemaculeata was male, between the ages of 25 and 34, had fished for this species for less than five years and typically fished with one companion. Those that target this species generally devote considerable fishing effort to their sport, identifying fishing spots commonly through online methods,

xxviii releasing at least a portion of their catch and utilising watercraft to gain greater access to fishing grounds. Smaller fish were consistently captured in the Hawkesbury- Nepean River than other water bodies examined, likely as a result of the removal of larger fish. The few anglers that did take fish for consumption were more likely to fish in readily accessible areas.

Despite the habitat differences evident between tributary types, parameters measured - fish length, weight, condition, age, growth, sex ratio, sex and growth, density and habitat selection - were not significantly different between open and obstacle-strewn tributaries. In both tributary types females were larger and more likely to be caught than males, and smaller fish were more likely to frequent habitat away from structure (e.g., coarse woody debris) than adult fish although, overall, fish of all sizes preferred habitat near structure. Such structure is, therefore, preferred habitat for this species. A comparison of fish length between tributaries and the riverine channel determined that longer fish typically occupied tributaries. This correlated to the female sex bias in the tributaries as this sex was observed to grow to a larger length than males.

The study re-confirmed that M. novemaculeata is a generalist carnivore, opportunistically feeding on prey from a variety of taxonomic groups from both aquatic and terrestrial habitats. The tributary types studied offered dissimilar habitats for prey, which influenced the dietary consumption of M. novemaculeata. Diversity and abundance of prey was higher in the stomachs of fish from obstacle-strewn tributaries than open tributaries. Despite the variation in diet between habitats, however, this did not appear to affect this species ability to live and thrive in either habitat. This was evidenced by the lack of difference in the length, weight, condition and stomach fullness of fish.

Although previous studies have shown that natural barriers to movement may result in fish assemblage changes between stream reaches, this does not appear to be the situation for M. novemaculeata in tributary habitat. There was no indication that individuals were impeded in their movement to the estuary to spawn from either obstacle-strewn or open tributaries. The reason for not moving to the estuary annually may, therefore, be related to other factors associated with the ecology of this species.

xxix This study found that the impacts of recreational fishing on M. novemaculeata are more likely to occur in easy to access areas, and this may have catchment-wide implications. Since entering the fishery almost half of respondents had switched to a more sporting focus when targeting this species. However, regardless of motivation, catch-and-release angling, coupled with the high survivorship of this species after angling release is likely to play a key role in management of this species.

Maintaining tributary populations of M. novemaculeata is desirable for the species sustainability as it is apparently preferred habitat for females based on the observation that they are in greater abundance in tributaries. Tributary habitat thus would serve to maximise M. novemaculeata recruitment.

The apparent importance of the riparian zone to primary and secondary production and subsequently fish diet, highlights the complexities in managing M. novemaculeata habitat for the species long-term sustainability. Degradation of the riparian zone at the aquatic/terrestrial interface is likely to result in reduction in the availability of terrestrial prey, and also indirectly aquatic prey, through a loss of allochthonous input.

The observation that Macquaria novemaculeata from the different tributary types made equivalent numbers of estuarine visits, indicated that any fish taken by anglers is unlikely to differentially impact on populations in the two tributary habitat types studied.

xxx 1. Ecological attributes and recreational fishing for Macquaria novemaculeata on Australia’s East Coast

1.1 Introduction

1.1.1 The importance of fish and human impacts Throughout history human populations have been advantaged, directly or indirectly, by the ecological processes provided by fish populations. This is because fishes act as an essential link in the food chain, and are integral for the cycling of nutrients in most aquatic ecosystems. They supply ecosystem services, and are important as a human food source. They also support commercial and recreational fisheries, may limit diseases such as malaria (e.g. mosquito control by Gambusia spp.), supply ingredients for medicinal use, and may provide a broad appreciation of fish through recreation and aesthetics (Holmlund and Hammer 1999; Hiddink et al. 2008). The capture and consumption of wild-caught fish also provides a staple protein source for many societies. For example, Nelson (1994) reported that there were approximately 25,000 described fish species - most from marine environments. In the same period, worldwide, 101 million tonnes of fish were taken annually, a high proportion (27 million tonnes) as bycatch (FAO 1997). In the Western World, fisheries tend to target a small fraction of the species available, and this results in high fishing pressure being exerted on target species (Holmlund and Hammer 1999). Conversely, with equivalent effort, a fishery that targets a wide range of fish species is likely to have greater inherent sustainability (Dulvy et al. 2000; Hilborn et al. 2003).

Because of their ecological significance in waterways, fish are an integral component of most aquatic ecosystems, and for the long-term management of such environments their populations need to be managed sustainably (Power 1990; Power 1992; Pusey and Arthington 2003). In recent decades, much fishery management effort has been focused on the human impacts on ecosystem health of marine and freshwater ecosystems (e.g., Warner 1991; Sondergaard and Jeppesen 2007). Some of these impacts have been as a result of river regulation and flow diversion, channel alteration, dredging, sand and gravel mining, vegetation clearing, sedimentation,

1 commercial and recreational fishing, introduction of feral fauna and flora species, nutrient loading (discharge of treated wastewater, urban and agricultural runoff), and instream barriers to fish movement (Erskine 1998; Gehrke et al. 1999).

1.1.2 Management requires knowledge of the fishery Sound management of fisheries requires knowledge of the status and sustainability of the fishery. It has been established however that, worldwide, fish supply does not meet demand and, therefore, typically fisheries are not being managed for long-term sustainability. Historically, the problem has been exacerbated by open fisheries with few to no limitations on catch. For example, in 1996, the World Resources Institute reported that approximately 70% of the primary marine-derived fish had been heavily overharvested to exhaustion by 1995. Such exploitation of natural fisheries can affect predator to prey interactions. Hence, over-fishing one species can indirectly affect the ecology and livelihood of another fish species (Holmlund and Hammer 1999). For example, in the Baltic, over 20 years ago, targeting top predators in high quantities resulted in fisheries having to shift their focus to species below top predators in the food web (Hammer et al. 1993; Pauly and Christensen 1995). This over-exploitation has occurred despite wide recognition (e.g., environmental groups, fishing industry/fish retailers) that such pressure on fisheries was unsustainable, particularly in marine localities (James 1994; Sargent 1997). Subsequently there have been major shifts in fisheries management, at least in some countries, with funding directed to the buy-back of fishing licenses and a reduction in fishing processes in some seasons to allow for fish spawning, population recuperation and maintaining the economic efficiency of the commercial fleet (Holland et al. 1999; Arendse et al. 2007). Indeed, the anthropogenic approach to management of fisheries is a key element to the sustainability of a number of fishieries, both commercial and recreational (Cooke and Cowx 2006). The positive response of fishers and other stakeholders to management actions is paramount to its ultimate success, with institutional structures and beneficial incentives of high importance. Simply, this incorporates a rewards-based system whereby the needs of fisherman are balanced with those of management groups and scientists to achieve a multi-faceted positive outcome (Hilborn et al. 2005).

2 Whilst achieving positive fisheries management change is known to require a thorough understanding of the human element, it is often overlooked in the implementation of fisheries mangement approaches. These under-represtented attributes are varied, however, key issues typically encompass a lack of systems thinking and cooperative approaches. It is therefore essential to utilise a holistic approach to drive positive and long-term change in fisheries management (Arlinghaus 2006). A successful example that has incorporated this approach is the Pacific Halibut (Hippoglossus stenolepis) fishery in the Canada and US. After this species stocks plummeted in the mid-1970’s, they were monitored closely coupled with an open decision-making process between the Canada and the US. Input to these decisions was jointly informed by scientists, commercial fisherman and processors. Ultimately, this has resulted in the fishery being regarded as a biological success, with the human element forming a key component (Hilborn et al. 2005).

Within Australia, the last 200 years has seen fisheries resources move from mildly affected to a high level of exploitation. This has been caused by an increasing human population, expansion of the fishing industry, and advances in fishing technologies (Kearney et al. 1996). Management of stream fisheries generally mirrors the procedures of marine fisheries. This approach is often unsuitable in large river systems that exhibit different cycles and attributes such as devastating floods and seasonal fish migration (Cowx 2000). The past growth of commercial fishing also coincided with an intensification of recreational fishing, for example, on the densely populated eastern coastline of New South Wales (NSW) (Yapp 1986). Within industrialised countries, recreational fishers are now the dominant users of most fish stocks within freshwater and coastal zones (Arlinghaus and Cooke 2009). With an increased fishing effort, the advancement of fishing technology and a potential increase in angler skill, harvest rates can exceed sustainable levels which can have impacts on fish recruitment, trophic interactions and the entire aquatic ecosystem (Cooke and Cowx 2006). Subsequently, management groups are required to incorporate a multi-faceted approach to recreational fisheries management that encompasses the interests of anglers whilst limiting the over-exploitation of fish populations (Radomski et al. 2001; Peterson and Evans 2003; Arlinghaus 2006). Often, it is difficult to implement a program that satisfies the interests of the entire

3 angling cohort. However, what is known is that successful management programs need to incorporate an understanding of not only how fish respond to exploitation but also what drives an angler’s fishing behaviour within a social and ecological construct (Johnson and Carpenter 1994; Radomski et al. 2001; Post et al. 2008).

Inland regions of Australia have not been exposed to the equivalent fishing pressure of the coastline’s fisheries. Rather, naturally-occurring streams and the fishes that occupy them have been more heavily affected by the devastation of the instream habitat (e.g., removal of snags, flow regulation) (Dovers 1994). Australia’s aridity and rainfall variability makes its rivers susceptible to extreme loss of flow, even without anthropogenic influence (McMahon 1986; 1989; Lake 1995; Puckridge et al. 1998). Understanding the ecological effect of the increasing demand for water supply in densely-populated areas is necessary if a sustainable fishery is to be achieved (Pusey et al. 2000). Murray cod Maccullochella peelii, for example, has been shown to survive in times of low flow, but generally lack the ability to reproduce in such conditions due to an absence of elevated flow to act as a stimulant (Lloyd et al. 2003). Flow regulation in the Goulburn Catchment (New South Wales) was suspected to have restricted spawning potential for a number of species, including Macc. peelii and Macquarie perch Macquaria australasica (Koehn and O’Connor 1990). The lack of native fish in the higher reaches of the Goulburn River is likely attributed to alterations in the thermal profile and/or flow regimen that have occurred due to anthropogenic activities (Cadwallader and Rogan 1977). Likewise, a study in the Lachlan River Catchment found that during periods lacking flooding limited numbers of golden perch Macquaria ambigua spawned. These observations highlight the relationship between successful fish recruitment and appropriate riverine flows (Mackay 1973).

Managing fisheries also requires an understanding of the potential impacts of non- native fish introductions. The risk of introducing non-native species to an ecosystem is that they may have the potential to adapt to their surroundings, potentially flourishing in an environment devoid of natural limiting factors (Gozlan and Newton 2009). The impacts of introduced fish species are varied, however they may include predation (Yonekura et al. 2007), competition (Blanchet et al. 2007), hybridisation

4 (D’Amato et al. 2007), habitat modification (McDowall 2006) and disease (Gozlan et al. 2005). Determining the extent of impacts from non-native fish is difficult to isolate due to the variety of external influencing factors that affect the sustainability of fish populations, such as riverine flows and recreational fishing (Didham et al. 2005). Nevertheless, impacts from non-native fish are most likely to be concentrated in freshwater environments, where natural fish migration between freshwater drainage basins is infrequent due to geographical isolation. One of the most widely documented invasive species, C. carpio, has contributed to environmental impacts in waterways throughout the world, with Australia included (Khan et al. 2003; Koehn 2004; Pinto et al. 2005). This species benthic foraging habit, disturbs rooted plants and contributes to sedimentation issues. Subsequently, this results in elevated turbidity and associatively limits plant re-growth. This ultimately influences macrophyte density, water chemistry and plankton/invetebrate diversity among other impacts (Miller and Crowl 2006). Typically, after introduction of non-native fish that become invasive such as C. carpio, management programs are enforced. However, these programs are often fraught with a variety of environmental difficultites and are costly to implement, often resulting in limited effectiveness (Gozlan et al. 2010).

1.1.3 Percichthyidae and Macquaria novemaculeata The family of teleosts Percichthyidae characteristically range from medium-sized (500 g) to larger-bodied species (5 kg) (Harris and Rowland 1996; Buria et al. 2007). They occur in a variety of temperate and subtropical areas throughout the world including a diversity of freshwater, estuarine, and marine environments. Evolution of their life history strategies allows them to survive in a wide range of habitats (MacDonald 1978; Trnski et al. 2005; Ruzzante et al. 2006). Throughout their range, percichthyids including Australian species have been affected by ongoing anthropogenic activities, most notably commercial/recreational fishing (Reid et al. 1997; Cazorla and Sidorkewicj 2008) and limitations placed on spawning caused by environmental changes such as flow regulation (Harris 1983; Humphries et al. 1999; North and Houde 2001). According to Lintermans et al. (2004), of the eight Australian percichthyids, five species have historically been fished either commercially and/or for recreation. Based on this past practice, it is desirable to build upon the ecological knowledge of percichthyids in order to acquire an understanding

5 of the potential for anthropogenic impacts, and how these can be mitigated (Walsh et al. 2010).

Worldwide, the teleosts estuary perch Macquaria colonorum (Günther 1863) and Australian bass Macquaria novemaculeata (Steindachner 1866) are the only two recognised percichthyids that exhibit a catadromous lifecycle. Based on this characteristic, and their morphometric similarities, they were regarded as a single species until morphological analysis by Williams (1970) and MacDonald (1978).

Macquaria novemaculeata is a carnivorous, temperate species (Allen et al. 2002), endemic to Australia. The other species of the genus are estuary perch M. colonorum, golden perch M. ambigua, and Macquarie perch M. australasica. Macquaria novemaculeata grows to a maximum size of approximately 60 cm, and may attain a weight of at least 3.8 kg (Allen et al. 2002). It is a long-lived fish, with specimens aged at up to 22 years (Harris 1985a).

The natural distribution of M. novemaculeata extends throughout Eastern-Australian streams, from the Mary River (Queensland) to Lakes Entrance (Victoria; Williams 1970; Lake 1978; Harris 1983) (Figure 1.1). Throughout this natural range, populations also occur in freshwater impoundments (e.g., Queensland [QLD] - Wivenhoe Dam; [NSW] - Glenbawn Dam, Tallowa Dam), often as a result of these impoundments being stocked with fingerlings by the government fisheries’ department of the State (Battaglene and Selosse 1996; Cameron et al. 2011). Within the species range, research on this species appears to extend from its most southern point, the Snowy River (Victoria) (Brown 2009) to the most northern point of the species range, Lake Somerset (QLD) (Wilde and Sawynok 2005).

Within their environment M. novemaculeata may utilise a range of habitats, and they have the ability to survive in a wide range of salinities and water temperatures, although diet and growth may be influenced at their extremes of these water parameters (Harris 1985b, 1986, 1988; Growns and James 2005). As noted above, it has the characteristic catadromous life stage that requires it to migrate from freshwater to estuaries to spawn between May and July (Austral autumn – winter).

6 During early spring M. novemaculeata then migrate upstream into freshwater habitats including creeks, lagoons, and wetlands (van der Wal 1983; Harris and Rowland 1996).

Figure 1.1 The natural Australian distribution (shaded area on insert) of Macquaria novemaculeata. (Source: Jerry and Baverstock, 1998; NSW Department of Primary Industries, undated).

7 Despite being relatively abundant in most eastern-flowing drainages, there has been concern over the decline in numbers of M. novemaculeata since European settlement. A major cause of this decline is the development of dams and weirs that have restricted natural movement throughout waterways which, as previously indicated, is paramount to the completion of their lifecycle. Habitat degradation, as a result of changed catchment landuse (e.g., agriculture, vegetation removal, urbanisation), has also contributed to a declining population (Pollard and Growns 1993; Shaddick et al. 2011). As a consequence, for conservation purposes, a commercial fishery no longer exists for M. novemaculeata although individuals continue to be caught as incidental bycatch in commercial fisheries (e.g., school prawn Metapenaeus macleayi fishery - Gray et al. 2003).

A slow-growing fish, it also continues to be vulnerable to recreational fishing despite such angling having been identified as impacting on the species. Despite this knowledge, one reason for continued recreational fishing is that M. novemaculeata is a prized angling species, and it is a popular target for both tournament and non- tournament anglers across a range of lotic and lentic habitats throughout its range (Dowling et al. 2010).

Following is an overview of M. novemaculeata ecological attributes and recreational fishing of M. novemaculeata on Australia’s East Coast encompassing; (i) lifecycle and lifecycle interruption, (ii) habitat selection, (iii) size and sexual differentiation, (v) diet, and (vi) recreational fishing. This is followed by an outline of the current project (vii).

1.1.4 Lifecycle and lifecycle interruption Harris (1986) established that, at least in the Hawkesbury-Nepean River, M. novemaculeata spawns in waters that are approximately one-third the salinity of seawater (8-14 g/kg-1), within water temperatures ranging from 11 to 16oC. Eggs are demersal and, once hatched, juveniles move to instream macrophytes before migration to upland freshwater reaches during the following spring-summer.

8 Males reside in these upland reaches for 2-4 years, females 5-6 years, before reaching maturity (van der Wal 1983). Outside of the winter-spawning period, adult females have been observed to tend to move further upstream than males in some catchments. This results in an apparent seasonal gender-separation (Harris and Rowland 1996). At least in the Snowy River (NSW), however, M. novemaculeata may make large-scale migrations up or down stream throughout the year. Large-scale movement is, therefore, apparently not only for spawning but perhaps also for habitat, food availability, and/or to seek desirable water quality and temperature. The suggestion that there is movement to a region with enhanced water quality was highlighted by Brown (2009) who suggested that an autumn peak-flow and associated turbidity downstream of the Buchan River tributary in the Snowy River may have been the cause of fish movement away from this area. However, in this system most estuarine visiting by M. novemaculeata was correlated with periodic increases in water temperature after the winter minima. This finding is somewhat contradictory to that of Reinfelds et al. (2011) who found that fish moving downstream at base flow in the Shoalhaven River (NSW) appeared to do so in response to progressively decreasing water temperatures at the end of autumn when water temperatures could fall below 15oC. This may be due to disparities in spawning periods between the two systems. Traditionally, spawning is thought to occur between May and July (Harris and Rowland 1996), however, Brown (2009) suggested that in the Snowy River the spawning season may extend from late July to late October. Nevertheless, simply because estuarine visits in the Snowy River were correlated to increases in water temperature does not mean that movement downstream does not occur at an earlier stage when temperatures are still falling before the winter minima. Indeed, in the Snowy River, M. novemaculeata moved greater distances at colder stream temperatures.

Effectively all rivers of the Australia’s Eastern Coastline have been subjected to multiple anthropogenic impacts. For example, river regulation by damming (e.g., Hawkesbury-Nepean River, NSW) has decreased flow and reduced the potential for migratory fish, such as M. novemaculeata, to move freely throughout the river length. This is because flow regulation caused by dams weakens the natural impact of increases in flow which, in essence, mimic drought. This lack of natural cues, even

9 with environmental flows, is likely to reduce movement of M. novemaculeata and subsequent recruitment. The observation of reduced spawning in M. novemaculeata of Harris (1988), who studied ichthyoplankton surveys during drought in 1979 and 1980, supported the species reliance on flows for spawning. Such impediments to migration are problematic for M. novemaculeata. For example, naturally-occurring populations of M. novemaculeata in the Shoalhaven River have become isolated below the Tallowa Dam wall (Bishop and Bell 1978; Walsh et al. 2012b). Such barriers to fish migration have also occurred in the Hawkesbury-Nepean River (NSW). This has halved the potential for fish migration into up-stream habitats that would have naturally occurred in the past (Marsden and Gehrke 1996), although new technologies have seen improved fishways and fish passage in this waterway (Growns and James 2005). However, isolation and the impediment to movement as a result of dam construction are likely to see this fish species excluded from areas with desirable resources (e.g. habitat - Reinfelds et al. [2011], prey – Harris [1985b]). Since females of this species may move further upstream than males, they are more likely to be impacted in catchments with dams (Harris and Rowland 1996).

In a review of fish populations and associative migratory behaviours, Jonsson and Jonsson (1993) found that females tend to have a more extensive migration regime than males. The authors recognised that this was likely to arise due to females attempting to maximise body size by entering areas with the richest feeding grounds available. This would aid in maximising fitness and condition, both important for successful recruitment. In addition, these upstream habitats may have greater or even fewer resources (e.g., Brainwood 2006 – Hawkesbury-Nepean River), however, the competition for these resources is likely to be smaller than downstream areas. This would make them desirable habitat, particularly to reproductive females of this species.

Reinfelds et al. (2011) found that downstream of the Tallowa Dam (Shoalhaven River, NSW), 84% of tagged M. novemaculeata migrated downstream from freshwater reaches to estuarine habitats for spawning. Of these fish, 62% moved in conjunction with periods of flow elevation due to dam releases, and 38% moved downstream under typical baseflow conditions. However, at least some of the fish that

10 moved at baseflow did take advantage of elevated flow regimes and thus moved more efficiently in their downstream migration into estuarine spawning grounds than they would have achieved at baseflow. This is because elevated flows generally allow for more efficient passage of fish through obstacles or barriers as the higher flows can effectively flood the obstacles that may otherwise impede migration (Reinfelds et al. 2011). In contrast, Harris (1986) found that while falling autumn water temperature initiated gonadal development (onset of spermatogenesis and oocyte maturation), M. novemaculeata relied on floods to stimulate downstream migration to estuarine habitats. It therefore appears that to initiate downstream migration in regulated rivers, adequate flow is important to provide suitable passage for migration. However, to ensure that a substantial proportion of M. novemaculeata achieve downstream movement to the estuary spawning grounds, also requires conditions of natural base flow (Reinfelds et al. 2011). Taking advantage of elevated flows, including those due to flood, has also been shown to result in successful recruitment in other Australian percichthyids (e.g. Murray cod Macc. peelii) (Harris 1986; Walsh et al. 2011). Seasonally variable movement also occurs in other species. For example, use of seasonally flooded marshes by fish for reproductive purposes occurs in Southern France (Poizat and Crivelli 1997) and in curimba Prochilodus scrofa in the upper Parana River (Brazil) whose reproductive success correlates with flood events throughout summer and autumn (Gomes and Agostinho 1997).

Under typical flow conditions, M. novemaculeata readily move through pool-riffle zones during the dawn/dusk period, minimising the chance of predation (Reinfelds et al. 2010). Even below fast-spilling and flowing water released from an upstream dam, Bishop and Bell (1978) reported that M. novemaculeata had the potential to swim against the flow at speeds in excess of 2-4 m/s, although this may only have been possible for short bursts before the fish succumbed to exhaustion. This observation correlates to recent observations where it was observed that at water velocities of 1.5- 2.0 m/s over lengths of approximately 10 m, mature M. novemaculeata had difficulty proceeding upstream (Badenhop et al. 2006). For example, Reinfelds et al. (2010) observed that while negotiating shallow riffle areas at a flow rate of 130MLd-1, mature and potentially exhausted M. novemaculeata were readily predated upon by piscivorous birds. Downstream of Tallowa Dam (NSW), environmental flows may

11 have improved conditions for M. novemaculeata movement, especially in the post- spawning period during their upstream migration in late winter and early spring. This is because these environmental flows resulted in greater depths which, in turn, facilitated fish movement across extensive shallow-riffle zones. Typically, however, to negotiate natural riffle zones, M. novemaculeata require depths of 0.1 m (juveniles) and 0.2 m (adults) (Koehn and O’Connor 1990; Badenhop et al. 2006). As a consequence, environmental flows also aided in improved movement through the higher-gradient rapids, which provide a secondary pathway[s] along the margins of rapids where there is typically lower water velocity of a more suitable depth for fish to migrate than the shallows (Walsh et al. 2010; Reinfelds et al. 2010).

Because migration from freshwater reaches to the estuaries to spawn can be influenced by water flow (i.e., floods), M. novemaculeata often experience diminished recruitment during drought periods (Harris 1988). These impacts can be further exacerbated by the presence of weirs with inappropriately-constructed fishways that are based on those used internationally for salmonid migration, and are sub-optimal for M. novemaculeata. With recent advancements in weir design (e.g. suitable fishways) that have been introduced to Australia, some migratory issues that previously occurred because of these man-made obstacles have been lessened. For these to work successfully, however, depths of more than 0.3-0.4 m may be necessary for successful passage of adult M. novemaculeata (Mallen-Cooper 1992), although not all migrating individuals of this species are adults. A high proportion of these migrants are juveniles or fish that have not attained a large adult size, usually making their way upstream after being spawned in the estuaries (Harris 1984). Immature M. novemaculeata, in particular, do not possess the swimming capability crucial to passing weirs that lack a suitable fishway (Bainbridge 1958, Mallen-Cooper 1992). For example, Mallen-Cooper (1992) observed that as immature M. novemaculeata (40-94 mm) migrated upstream they grew, and with that came commensurate improvement in their swimming ability and hence they were subsequently able to swim upstream more efficiently against the increased water velocities.

In addition to the potential impacts of impeding the ability of M. novemaculeata to migrate, successful population management of migratory fish also requires specific

12 comprehension of their population density and carrying capacity across their range of habitats (Baumgartner et al. 2012). For example, during M. novemaculeata recruitment events between 1990 and 1992 (Hawkesbury-Nepean River) the potential for recruitment was not reached despite apparently suitable conditions. It was suggested (Harris and Gehrke 1993) that perhaps when the population was at carrying capacity, M. novemaculeata restrict spawning and the density of the population is, therefore, regulated (Harris and Gehrke 1993). This behaviour may correlate to year- round site fidelity observed in this species in the Shoalhaven River. Based on a selected cohort of tagged fish, Walsh et al. (2012b) found that spawning in M. novemaculeata occurred less frequently than in M. colonorum. For example, they observed that no spawning occurred in fish from some reaches, perhaps as a result of population carrying capacity. Similarly, a high density of individuals within a population during the spawning season has been associated with female egg retention in guppy Poecilia reticulata (Dahlgren 1979).

Migratory movement within catchments provides greater potential for gene flow among localities than would be experienced if M. novemaculeata was more sedimentary (Jerry and Baverstock 1998). In addition to within river migration, M. novemaculeata have been caught offshore. This indicates that they have the potential to move among catchments (Jerry 1997). Grimes and Kingsford (1996) assumed that during flood events they could move offshore within the plume of waters that were diluted with freshwater. When individual plumes at the catchment mouth meet with the plumes of adjacent river systems, there is the potential for fish to move between catchments and thus enable gene flow between normally isolated populations. Jerry (1997) reported that no M. novemaculeata eggs or larvae have ever been encountered in salinities exceeding that used in estuarine spawning; hence, their contribution to gene flow among and between catchments at this life stage is likely to be insignificant, if not non-existent. Nevertheless, the observation that M. novemaculeata populations of each catchment have only subtly different genetic attributes indicated that some gene flow occurs among catchments (Jerry and Baverstock 1998). Jerry and Baverstock (1998) also found that as the distance of separation increased between catchments, genetic differentiation among populations became greater. Since spawning and migratory events in diadromous fish species commonly occur under

13 advantageous abiotic conditions, including flooding, the scenario of flood plume- mediated exchange of genetic material between catchments is feasible (Pusey et al. 2004; Clark et al. 2005).

1.1.5 Habitat selection Outside of the spawning season, M. novemaculeata may exhibit site fidelity in the mid-upper reaches of river systems (Williams 1970; Trnski et al. 2005, Harris 1983, Harris 1986; Walsh et al. 2012b). For example, Walsh et al. (2012b) found that individuals exhibited selective use of an area, returning to a particular reach after extensive in-stream movement. This homing phenomenon would aid in regulating the distribution of individuals within a population, and reduce energy expenditure due to competition for territory (Harris 1983). Homing incentive may also occur due to favourable prey source/s and/or limited chance of predation (Dittman and Quinn 1996; Crook 2004; Walsh et al. 2012b). Indeed, provided prey were present, M. novemaculeata usually stayed within a 2-3 m radius of woody debris. These homing attributes highlight the requirement to understand habitat needs for the species, and maintain them appropriately (Kramer and Chapman 1999; Walsh et al. 2012b). Conversely, it has also been proposed (Walsh et al. 2012a, 2012b) that residency in freshwater habitats is not obligatory for M. novemaculeata, particularly in waterways such as the Shoalhaven River that exhibit a long oligohaline (higher estuary) region (0.5-5.0 ppt salinity). This disparity in the regions of waterways in which individuals may exhibit long-term fidelity is contradictory to what is considered the traditional habits for this species. This suggestion adds to the modern literature (e.g. M. novemaculeata may make large-scale migrations up or down stream in the Snowy River throughout the year – Brown 2009) that this species’ riverine habitat use does not necessarily occur in a linear or ‘textbook’ fashion.

Osmoregulation capacity in M. novemaculeata appears to be superior in saline waters in comparison to freshwater, the habitat in which they typically reside for most of the year. It was suggested that this adaptation may exist to reduce energy use by juveniles when they occupy estuarine habitats early in their lifecycle (Langdon 1987). This assertion correlates to the findings of Battaglene and Talbot (1993) who established that M. novemaculeata larvae had low survival rates (<0.5%) at salinities of 0-5%. In

14 salinities of 10-35%, survival of larvae increased markedly to 76.1 + 24.0%. These larvae are also susceptible to the impacts of oil pollution that may be encountered in estuarine environments. For example, there have been two laboratory studies undertaken on the toxicity of M. novemaculeata to crude oil and dispersed crude oil that have demonstrated this was a potential impact (Cohen and Nugegoda 2000; Gulec and Holdway 2000). In both studies the water-accommodated fraction of crude oil was toxic to larvae, and in some cases oil dispersant treatment methods only increased mortality, and thus such chemicals have the potential to further affect population sustainability. The knowledge that M. novemaculeata osmoregulates efficiently in saltwater, and exhibits site fidelity/homing (Walsh et al. 2012b), combined with recent monitoring using fish tracking (Reinfelds et al. 2011), it has been concluded that some M. novemaculeata may maintain site fidelity within oligohaline reaches in addition to the upper reaches of river systems.

One attribute of waterways which may enhance habitat opportunities for fish is the riparian zone due to its primary role in nutrient cycling. At this aquatic/terrestrial interface trees, branches and roots provide shade and cover for fish, act as a thermal buffer, stabilise the banks and channels, improve and maintain water quality, and act as a supply of woody debris to the waterway which are beneficial as macroinvertebrate and fish habitat (O’Connor 1992; Growns et al. 1998). The management of riparian zones, therefore, typically has an influence on fish habitat, although it has been observed that this does depend greatly on riparian zone width, position in a catchment, the waterway involved, and hydrological processes (Naiman and Decamps 1997). These, in turn, have implications for the sustainability of M. novemaculeata populations. For example, while the abundance of some species was not significantly different between bank types (e.g., freshwater herring Potamalosa richmondia; Australian smelt Retropinna semoni), Growns et al. (1998) found that M. novemaculeata was in higher abundance near vegetated banks than adjacent to non- vegetated banks. They also observed that individuals of this species were more likely to be distributed according to the composition and quality of the riparian vegetation, rather than water quality associated parameters. Conversely, in a study of fish assemblages in the Hawkesbury-Nepean River (Growns et al. 2003), M. novemaculeata was more commonly intercepted adjacent to grassed riparian banks

15 than otherwise vegetated banks. It was established that the higher level of macrophytes at grassed banks acted as a beneficial nursery for juvenile-young between freshwater to upper estuary zones. Although lower in number, larger individuals occupied areas adjacent to vegetated banks. The dissimilarity observed in the different reaches was probably attributable to variation in habitat (or microhabitat) preferences at different stages in the lifecycle. For example, larger M. novemaculeata appeared to benefit from the habitat structure and canopy associated with the riparian zone, whereas juveniles depended largely on macrophytes (e.g., ribbon weed Vallisneria americana, phragmites Phragmites australis) for appropriate habitat (Harris 1988; Growns et al. 2003). Differential habitat selection between fish size classes has also been exhibited internationally by Collares-Pereira et al. (1995) in a selection of Portuguese lowland streams. In these streams, the assemblages of smaller fish generally preferred shallow areas with high levels of macrophytes. Larger fish favoured deeper areas with greater levels of riparian cover. Although Growns et al. (2003) made the observation that M. novemaculeata were captured in larger numbers adjacent to grassed banks, it did not mean that banks with introduced species should be encouraged since it would result in the loss of areas with intact riparian vegetation that benefit adults (Growns et al. 2003). Further to this, in an impoundment stocked with M. novemaculeata, the condition of individuals was reduced in conjunction with the reduction in preferred habitat available for individuals. Under such conditions, high densities of M. novemaculeata are likely to inhibit growth rates, and thus lower the overall condition of resident fish (Refstie and Kittelsen 1976; Fagerlund et al. 1981). Restriction of habitat availability due to high densities of M. novemaculeata is, therefore, likely to have direct impacts on their health, which is important in impoundments with substantial stocking programs (Smith et al. 2011a). It has been recognised, however, that a reduction in food resources (Vanderploeg et al. 2009) and decreased water quality (Hayes et al. 1999) may also contribute to a loss of condition (Smith et al. 2011a). High densities of fish, nevertheless, have been associated with reduced growth rates in international rearing studies on both coho salmon Oncorhynchus kisutch (Fagerlund et al. 1981) and Atlantic salmon Salmo salar (Refstie and Kittelsen 1976).

16 1.1.6 Size and sexual differentiation As with many Australian native fish, M. novemaculeata is generally considered a slow-growing species. It is the slowest of its genus (Harris 1987), with the potential to reach a length of 100 mm in its first year (Growns and James 2005). There are apparently few studies that focus on the growth and size of M. novemaculeata. Two were undertaken in riverine environments (Harris 1987; Van Der Walt et al. 2005), and one in an impoundment (Wilde and Sawynok 2005). These studies indicated that growth in impoundments was faster than in natural riverine environments. This same phenomenon has been shown in the past on another member of the genus, M. ambigua. Mallen-Cooper and Stuart (2003) found that fish from impoundments grew at a faster rate, and to a larger size than the other three river systems of their study. This growth disparity may occur in M. novemaculeata because of more productive habitats in impoundments, due, for example, to differences in prey density, and/or latitudinal/temperature differences. However, it is more likely that the ability to divert energy input from natural extensive migrations to spawn and tailor it towards growth is the major reason for the differences (Harris 1987; Wilde and Sawynok 2005). However, even in freshwater impoundments, Wilde and Sawynok (2005) found differential growth rates between individual M. novemaculeata. Across four water bodies, for example, growth rate was slowest in the smallest/deepest impoundment (Lake Cressbrook, QLD); whereas it was highest in the largest/shallowest impoundment (Lake Somerset, QLD). These data showed that on a yearly basis, growth was between 5.0-7.8 cm (for 20.0 cm total length [TL] fish), and between 1.7- 4.9cm (30 cm TL). More recently published information on M. novemaculeata size (Van Der Walt et al. 2005) was obtained from a recreational fishers’ competition in a Department of Primary Industry study (‘Basscatch’). This research investigated size differentiation over time, and across multiple river systems. These social-competition events were first established on the upper Hawkesbury-Nepean River in 1988, and subsequently expanded to other river systems (Manning and Williams rivers, NSW) to provide long-term standardised data for comparison between catchments. All of the waterways sampled, flow through areas with varying degrees of anthropogenic impacts, and support significant recreational fisheries throughout their length, of which M. novemaculeata is a considerable component of the fishing effort. Despite these somewhat similar catchment attributes, in the three waterways M.

17 novemaculeata had a significantly different mean length, and there were significant differences among years within river systems. The Manning River produced an average mean length (330.0 mm), far in excess of the fish in the other two river systems. Fish from the Hawkesbury-Nepean River had the smallest mean length (195.0 mm), and there was also a significant difference in mean length between spring and summer. Spring competitions generally produced M. novemaculeata with the larger mean length. Between 1988 and 1998, however, the average length of Hawkesbury-Nepean-caught M. novemaculeata increased sequentially with the mode range varying from 140.0 and 160.0 mm, and between 1998-1999 the mode increased to 220.0 mm although there was a subsequent decline in average length beyond that time, at least until 2002 (Van Der Walt et al. 2005). Harris (1988) also found additional variability in the Hawkesbury-Nepean River whereby there was a lack of recruitment of M. novemaculeata, considered to be due to drought conditions experienced during the earlier years of ‘Basscatch’. As recruitment conditions apparently improved after 1998, a subsequent spike in the number of smaller fish caught became evident, likely as a result of a strong year class (Harris 1988; Van Der Walt et al. 2005).

Growth rate and size attained by M. novemaculeata has also been associated with residency in a particular habitat. Harris (1985a) observed female growth rate in gorge habitat to be approximately twice that of those that occupied tidally-influenced reaches. Unless adequate flows occur in gorge habitats to allow for migration downstream before the completion of the spawning season, fish may not be able to migrate to estuarine habitats for breeding. Under such circumstances, female M. novemaculeata may conserve energy by not attempting downstream migration and, instead, resorb ovarian yolk and increase abdominal fat (Harris and Gehrke 1993). This phenomenon has also been observed among females of fish species that skip spawning in order to improve their own condition (reviewed in Rideout et al. 2005). This presumably means that females that are somewhat restricted in selected upstream habitats and do not migrate may have the potential to attain a larger body mass than female individuals that have the capacity to migrate more readily. Differences in body weight and mass would therefore tend to be greater in upstream females during prolonged drought than in other habitats and/or climatic conditions.

Of the same genus, M. colonorum occupies similar environments and undergoes similar anthropogenic impacts as M. novemaculeata. Walsh et al. (2010) found that 96% of M. colonorum sampled from the Clyde and Hawkesbury-Nepean Rivers (NSW) were less than 12 years old, despite individuals being known to live to 41 years. This indicated that age truncation was occurring in these river systems in M. colonorum. Conversely, in the Bemm River (Victoria), 65% of individuals of this species were older than 12 years. The differences were attributed to the removal of older and larger fish from specific waterways.

Fishermen targeting the larger fish, that are typically most fecund, have the potential to reduce reproductive success in the population, especially when there is high variability in recruitment among years (Beamish et al. 2006). The Hawkesbury- Nepean River, and until 1997, the Clyde River have been subjected to commercial fishing. Commercial fishing operations are now not permitted in the Bemm River. Despite the ban on commercial fishing for M. colonorum (and M. novemaculeata), however, they are still caught as by-catch throughout estuarine environments. This has likely contributed to a decline in numbers in the species (Gray et al. 1990; 2003; 2005, West and Walford 2000). Age truncation, experienced by M. colonorum in rivers/estuaries (e.g., Hawkesbury-Nepean River) where the species was heavily fished, is likely to occur in the also long-lived M. novemaculeata with particular vulnerability during estuarine recruitment events where fishing pressure is high. Similar issues have arisen in the Northern cod Gadus morhua Commercial Fishery whereby the selective removal of larger fish affected the viability and sustainability of their populations due to the extraction of the most fecund individuals (Krohn and Kerr 1997).

Populations of M. novemaculeata are also subjected to a variety of other impacts, in addition to recreational and commercial fishing, that may also contribute to the potential for age truncation within some systems; for example, river regulation (weirs - Hawkesbury-Nepean River, Harris 1986; dams – Shoalhaven River, Reinfelds et al. 2011), riparian disturbance (Growns et al. 1998) and pollutants (wastewater effluent –

19 Growns and James 2005; oils - Cohen and Nugegoda 2000; Gulec and Holdway 2000).

Behavioural differences have been documented between the M. novemaculeata sexes. For example Harris (1986) observed that during drought years, some females did not migrate but remained in the upper freshwater reaches of the Hawkesbury-Nepean River. During the same period in the Georges River (NSW), female M. novemaculeata stayed within the tidal limit at Liverpool weir. An explanation for this lack of migration was the absence of flood event/s to stimulate spawning, and/or to allow the females to negotiate the obstacles associated with low river flows. Since females tend to be larger than males (Jerry and Cairns 1998), low flow rates are more likely to have restricted large females than smaller males (Koehn and O’Connor 1990; Badenhop et al. 2006). This size restrictive movement in-stream has been observed with other species. For example, Harvey (1991) found that the presence of shallow riffles excluded the potential for movement by large adult largemouth bass Micropterus salmoides (United States of America). However, the majority of smaller fish were not affected and were able to move freely throughout the site without restriction.

1.1.7 Diet Macquaria novemaculeata is primarily a generalist carnivore, and this can influence the composition of lotic and lentic food-webs (Allen et al. 2002; Smith et al. 2011b). As observed in other fish species (e.g., mulloway Argyrosomus japonicus; other percichthyids – Macc. peelii, M. ambigua), the segment of the home range that an individual inhabits when not undertaking migration is generally a linear stretch of the riverine environment (Crook 2004; Taylor et al. 2006; Jones and Stuart 2007). It is assumed that this trait provides individuals with the advantage of being familiar with their surrounding habitat and prey availability. Other species, for example, European sea sturgeon Acipenser sturio, have also been shown to have similar site fidelity that is directly correlated to the presence of prey, predominantly immobile benthic organisms (Lepage et al. 2005).

20 Macquaria novemaculeata generally consume a variety of small fishes and invertebrates (e.g., aquatic - freshwater shrimp Paratya australiensis; terrestrial – members of the Cicadidae family) but rarely molluscs or sizeable crustaceans (e.g., adult Cherax spp. [yabby]). However, especially in tidally-influenced reaches, a large proportion of their diet is composed of burrowing decapods. In addition to dietary variation among sites, M. novemaculeata diet has been observed to vary with season (Harris 1985b), although dietary preference appears to be more complex than simply seasonal. For example, teleost fish have been observed to be the most important prey, although invertebrates (terrestrial and aquatic) are commonly consumed, especially in summer months. The highest consumption of terrestrial invertebrates was observed to have occurred in a gorge with limited riparian vegetation, and there were differences in diet among river reaches (estuarine to freshwater – Harris 1985b). In addition, despite being considered a generalist carnivore, M. novemaculeata may exhibit phases more attributable to a specialist predator. Smith et al. (2011b) found that during the cool month of August, approximately 80% of individuals had consumed a mean of 80% Daphnia sp. Similarly, in May, more than half the fish examined had 75% Chaoboridae larvae in their gut. These data indicate that M. novemaculeata is an opportunistic generalist predator. When specific prey is in abundance, however, M. novemaculeata will switch diet. For example, Smith et al. (2011b) found that diet differed with month (e.g., fishes - May, December; insects - May, December; Chaoboridae - August; Ecnomidae - December; Chironmidae, Culicidae - March). Piscivory was highest in August for fish as small as 67 mm, although fish (e.g., flathead gudgeon Philypnodon spp.; Australian smelt Retropinna semoni) were only a common dietary component in individuals larger than 100 mm. The only prey that was restricted to a specific size category of fish were copepods and ostracods. These taxa were only consumed by individuals less than 100 mm (Smith et al. 2011b). The differences in diet are likely an adaptation to the multiplicity of M. novemaculeata habitats, coupled with the Australian environment, which is highly variable (Sternberg et al. 2008; Smith et al. 2011b). Pond-reared silver perch Bidyanus bidyanus were also observed to primarily feed on a specific prey but progressively targeted a greater diversity of prey as the available prey community moved to a more diverse state (Warburton et al. 1998). Harris (1985b) observed a similar pattern of prey selection by M. novemaculeata in riverine environments. The primary difference in diet was the

21 higher composition of Daphnia spp. in impoundment populations throughout August. This correlated to abundance in zooplankton tows which were composed of 2350 ± 276 Daphnia spp. 100 m−3 near the edge and 5730 ± 2350 Daphnia spp. 100 m−3 recorded in the impoundment’s central region (Smith et al. 2011b).

In addition to prey availability, the size of prey and the gape width of the predatory fish influence its target (i.e., the larger the gape, the larger the size of prey that can be consumed - Pearre 1986; St John 1999; Scharf et al. 2000; Smith et al. 2011b). Smith et al. (2011b) confirmed that a progressive enlargement of M. novemaculeata gape resulted in commensurately larger maximum prey size. However, the mean prey size taken has been found to usually be much smaller than the maximum size the individual’s gape would allow it to engulf. This is likely attributable to the ease with which smaller prey items (e.g., macroinvertebrates) can be consumed in comparison to larger, more mobile prey (e.g., fishes). Smaller prey may also be more abundant and available to M. novemaculeata than the larger prey items, depending upon season and/or waterway reach that the individual occupies (Harris 1985b; Smith et al. 2011b). In addition, larger prey items typically require higher energy expenditure for targeting and consumption, hence, M. novemaculeata may gain greater endpoint nutrition through consumption of smaller, less mobile organisms in greater quantities (e.g. burrowing decapods – Harris 1985b) than larger, potentially less abundant taxa. This has been shown in a study by Hansen and Wahl (1981) who found that yellow perch Perca flavescens actively targeted smaller water flea Daphnia pulex rather than larger prey that they were also capable of consuming. They attributed this to the employment of an optimal foraging strategy whereby larger D. pulex with greater potential for predation escape were avoided.

22 immediate aquatic thermal regimes. For example, successful capture of prey can depend on locomotor performance which is sensitive to variation in temperature. With a change in temperature regime, community structure can be altered due to variability in predatory pressure among prey species. Grigaltchik et al. (2012) established that mosquitofish Gambusia holbrooki had a lower tolerance for cooler waters than M. novemaculeata. Conversely, compared to M. novemaculeata, warmer temperatures did not affect locomotor performance and hence, at higher temperatures G. holbrooki were potentially more likely to evade predation than in relatively cooler waters. This demonstrates that this species has the potential for certain prey species to be more readily targeted due to the water temperature in which M. novemaculeata reside.

1.1.8 Recreational fishing The M. novemaculeata and M. colonorum recreational fisheries are managed similarly, primarily because the two species have similar traits including longevity (M. colonorum recorded up to 41 years - Walsh et al. 2010) and they have characteristic recruitment events (M. novemaculeata - Harris 1985a; M. colonorum - Walsh et al. 2010). However, M. colonorum generally do not migrate upstream beyond the tidal reaches whereas M. novemaculeata typically do so outside of spawning events (Harris and Rowland 1996), and thus would be exposed to recreational fishing in the freshwater reaches of rivers and their tributaries whereas M. colonorum would not be.

In NSW, the recreational fishery regulations on M. novemaculeata and M. colonorum have a daily take (‘bag limit’) of two fish (four is the maximum number that a person is allowed in their possession). Only one of these fish can be over 35 cm total length. In addition, in riverine environments, there is a closed season between June and August. This allows the two species protection during the period of estuarine spawning. During this period, M. novemaculeata migrate from freshwater/brackish reaches where there is relatively low fishing pressure to reaches with comparatively high fishing pressure in the estuaries. This makes them susceptible to over- exploitation during this period (Harris 1983) particularly, for example, in the Shoalhaven River where M. novemaculeata concentrate to spawn (Walsh et al. 2012b). In contrast, when individuals are not attracted to the estuary for spawning,

23 they tend to have site fidelity, often in isolated areas up-stream. During the spawning migration to the estuary, fish are generally more at risk from fisherman and changes to the estuarine environment than at other times (Heupel et al. 2006), although M. novemaculeata is released frequently after capture (Dowling et al. 2009). Fish species that occupy small defined spawning areas (e.g., white perch Morone americana - McGrath and Austin 2009) have been shown to require extended periods to re- establish following perturbation resulting in a reduction in the population.

Estuarine commercial trawling fish operations may result in high M. novemaculeata by-catch mortality (Harris 1988). Past research showed that this occurred in association with prawn trawling, particularly in the estuary of the Hawkesbury- Nepean River. For example, Gray et al. (1990) found that between March 1986 and February 1988, this species represented the highest proportion of bycatch: 1,851 M. novemaculeata were inadvertently caught. Since this time, bycatch reduction devices to reduce incidental catches have been made mandatory in the NSW Estuary Prawn Trawl Fishery, as has a closed period for winter trawling in estuaries (except for the Hawkesbury River) (NSW Fisheries 2002). Parallel to the studies of Harris (1988) and Gray et al. (1990), a study of bycatch from the estuarine prawn seining in the Richmond, Manning, Wallamba and Shoalhaven rivers of NSW, saw M. novemaculeata collected as bycatch only in the Shoalhaven River. Even in this River, they represented a small percentage of the bycatch, and were not in the top ten incidentally caught species. These results were obtained despite the sampling period encompassing September 1998 to June 1999 which excluded some months in which this species would be expected to be in elevated numbers in estuaries for spawning (Gray et al. 2003). Another study carried out on a multi-species gillnet fishery throughout 2001 yielded similar results (Gray et al. 2005). In the Richmond, Clarence and Shoalhaven rivers, M. novemaculeata were present in the bycatch but their abundance did not rate among the top five species caught incidentally except on one sampling occasion in the Richmond River where they represented 0.2% of the total catch. In the same study M. novemaculeata were not encountered in the Camden Haven River, or Wallis and Illawarra lakes, despite their known occurrence in these systems.

24 As previously noted, M. novemaculeata are a prized angling species and they have a tenacious fighting ability. There are, at least, nine fishing clubs (Hunter Native Fish, Bass Kempsey, Southern Bass Fishing Club, Big River Bass Fishing Club, Bass Fishing Sydney Club Inc., Western Sydney Bream and Bass Angling Club, Hawkesbury-Nepean Bass Angling Association, Wollondilly Bass Club, Springwood Bass) across the species range whose primary target is M. novemaculeata. At least in the Hawkesbury-Nepean River this species supports a growing recreational fishery (Growns and James 2005). As a result of their popularity as a target recreational fish, and as with M. colonorum, M. novemaculeata are captured and released in high numbers in riverine environments throughout the East Coast of Australia. Of the estimated 1.15 million M. novemaculeata caught annually, approximately 75% are released after capture (Dowling et al. 2009), however, Harris (1988) reported that in the past a large number of deaths had occurred due to exploitation by recreational fishers. With the increased participation in recreational angling for M. novemaculeata over the last two decades, recreational fishing has the potential to further impact on sustainability of populations, particularly in catchments with high recreational fishing pressure (e.g., Hawkesbury-Nepean River) (Gray et al. 1990; Harris and Rowland 1996; West and Walford 2000; Growns and James 2005; Walsh et al. 2012b).

Various biological attributes of M. novemaculeata lend it some predisposition to face the impacts of recreational fishing. As previously indicated, this species generally does not occupy the same reaches of waterways year-round, making successful angling problematic to less knowledgeable anglers (Walsh et al. 2011). A percentage of the population is also likely to occupy difficult to access waterway reaches that would require considerable effort for an angler to reach (e.g., Colo River Gorge habitat in Wollemi National Park, NSW – Harris 1985b). Furthermore, females tend to move further upstream into such environments (Harris and Rowland 1996) in non- spawning periods. In these relatively remote, upland reaches fishing pressure is typically lower compared to the more accessible estuarine reaches (Marine Parks Authority 2008). Females, particularly older more fecund fish, have the potential to provide a disproportionate number of offspring than smaller, younger individuals. Their fate (i.e., retain or release) in the recreational fishery may be relatively more important for the species’ sustainability (Harris 1986).

On a smaller habitat scale, this species association with structure (e.g. fallen logs, tree root balls) is likely to reduce the potential for recreational fishing impacts by land- based fisherman. These fishers generally require a cleared section of riverbank to act as an adequate fishing platform to allow manoeuvrability to cast their line. Since M. novemaculeata tend to be associated with areas with intact riparian vegetation present (Growns et al. 2003), the preferred habitat of the land-based fisher and M. novemaculeata differ. Fish apparently also become increasingly wary of line capture subsequent to their capture and release (Lewynsky and Bjornn 1987). The recreational targeting of this species for consumption may also be less likely to occur in waterways where the catch is consistently made up of small fish, compared to other fishing areas (e.g., mid-reaches of the Hawkesbury-Nepean River, Van Der Walt et al. 2005). This is because the time and effort required to catch sizeable fish may not appeal to an angler that is less concerned with the sporting aspect of angling as obtaining a ‘prize’ fish (Harris 1995; Walsh et al. 2010). Indeed, smaller fish may not be desirable to an angler that releases the fish because smaller fish are less likely to provide the elements of sport or ‘fight’ that larger fish provide.

The generalist feeding strategy of M. novemaculeata (Allen et al. 2002; Smith et al. 2011b) means that it can subsist on a wide variety of food items; and hence it is less likely to be impacted by the recreational fishing pressures that may be placed upon its fish prey. Also, with this species preference for foraging during crepuscular periods (Harris 1985b), it may lessen fishing effort and/or take of some fisherman who wish to maximise their catch potential and fish only during these periods. Alternatively, this can lead to negative recreational fishing impacts as they have the potential to be over-exploited by a well-informed angler who is aware of these habits (Harris 1985b; Smith et al. 2011a).

Recreational fishing in the estuaries may interrupt spawning practices (Harris 1983). Apart from M. novemaculeata congregating in relatively high numbers in the estuary compared to their more solitary upstream existence (Walsh et al. 2011; Walsh et al. 2012b), unlike some other species (e.g. Atlantic salmon Salmo salar – Jonsson et al. 1991), they will take an angler’s presentation throughout the spawning period. They

26 will also often school at barriers to movement during their migration (e.g., weirs) until adequate flow allows them to transgress beyond the obstacle. Recreational fisherman may take advantage of this phenomenon. A response to this has been the prohibition on fishing within the vicinity of some weirs (e.g., Penrith weir, Hawkesbury–Nepean River). In addition, the tendency for M. novemaculeata to occupy the water at the terrestrial/aquatic interface, and because preferred habitats are readily identifiable by fisherman, in these areas they are vulnerable, particularly to fisherman using watercraft. Furthermore, because the species can tolerate poor water quality (Growns et al. 1998) often associated with urban runoff into local waterways, recreational fisherman targeting this species are unlikely to have to travel great distances to fish. This ease of accessibility for anglers could be especially detrimental to M. novemaculeata populations during low flow periods where some individuals may be landlocked and overfishing may occur with limited likelihood of short-term recolonisation (Harris 1986). If larger fish with extensive territories are taken by recreational fishermen from these landlocked pools within waterways (e.g., obstacle- strewn tributaries), it is likely to upset natural territoriality regimes of individuals as well as reproductive success of the population overall (Beamish et al. 2006). The loss of either large or small specimens of this species is also likely to upset the natural food web. For example, smaller fish may target smaller prey items whereas the larger prey items may flourish in an area from which larger fish have been removed (Smith et al. 2011b). Macquaria novemaculeata also take a variety of natural baits and artificial lures presented by anglers, presumably because of their generalist diet. The willingness to take an angler’s presentation, particularly artificial lures, may be confounded by this species territoriality and the tendency to attack orally to deter others from their territory. This behaviour commonly results in hook penetration and resultant capture (Van Der Walt et al. 2005).

As previously reported, approximately 75% of M. novemaculeata captured by recreational anglers are released (Dowling et al. 2009). Hall et al. (2009) examined the post-release (5 days) outcome of M. novemaculeata after angling capture. They found that mortality was 0-6.3%, and death was primarily associated with smaller fish size and hook location. However, in comparable angling environments, the overall short-term post-release mortality (0-6%) was comparatively lower than in other

27 endemic species prized by anglers (M. ambigua, 0-24%; Macc. peelii, 15% - Hall et al. 2012). Use of natural baits, as opposed to artificial lures, increased mortality rate. This was because fish swallowed natural baits deeper, and this resulted in gut hooking that typically caused greater internal damage than artificial lures. Those fish that had ingested hooks that were subsequently extracted were approximately 20 times more likely to die due to the injuries than fish that were hooked through the mouth. Dowling et al. (2010) observed no immediate mortalities after release when artificial baits were used instead of natural baits fished in a stationary manner. With this technique, effectively all fish were hooked in the mouth, and less than 2% ingested the hook/s. However, without immediate mortality after the removal of ingested hooks, mortality may still occur. For example, when hooks were ingested, 38% mortality occurred within 24 hours (Hall et al. 2009). Some fish also received injuries in the capture process (e.g., fin damage, scale loss) which could result in an elevated occurrence of fungal lesions, pathogens, and bacterial infection. Mortality due to such damage is effectively unaccountable (Barthel et al. 2003; Butcher et al. 2008; Lestang et al. 2008; Hall et al. 2012). In addition, Hall et al. (2009) established that anglers who did not participate in fishing tournaments were most likely to use natural baits (e.g., worm Amynthas corticis, house cricket Acheta domesticus) and catch smaller fish overall. These anglers also more often retained their catch for consumption, and they were reported to be less knowledgeable about the best method of releasing fish (Arlinghaus et al. 2007; Dowling et al. 2010). Other effects likely to contribute to mortality include barotrauma (the physical damage to body tissues caused by differences in air pressure between the inside of the body and surrounding fluid), water temperature at capture, and recurrent captures of an individual (Hall et al. 2009).

1.1.9 The current project The current project focuses upon the ecology of the Australian bass Macquaria novemaculeata in tributaries of the Hawkesbury-Nepean River with a focus on open and obstacle-strewn reaches of waterways. ‘Obstacle-strewn’ tributaries were defined as irregularly connected pools, segregated by objects which were expected to impede M. novemaculeata migration under base flow conditions; and (ii) ‘Open’ tributaries

28 lacking discernible obstacles that could impede the ability of M. novemaculeata to migrate under base flow conditions.

Based on prior knowledge of the fish, it was hypothesised that M. novemaculeata would thrive better in obstacle-strewn tributaries than in those that were open. This was because, primarily, there was likely to be a higher diversity and abundance of prey where the habitat is more complex and thus there is a wider range of microhabitats for aquatic life compared to open tributaries which would have less habitat complexity and were, therefore, likely to sustain less prey diversity (Pianka 1966; Benke et al. 1985; Grenouillet et al. 2002; Chara et al. 2006).

Tailoring research efforts towards these lesser studied systems will assist in understanding how management efforts can best be utilised in the conservation of this species. Specifically, this study focuses on the differences in demography, diet, and migratory patterns of M. novemaculeata between open and obstacle-strewn tributary reaches. In addition, to investigate recreational fishing pressure on Macquaria novemaculeata in their natural environment on the East Coast of Australia, angler’s habits were also identified, with a particular focus on the Hawkesbury-Nepean River.

Chapter 1 introduces the topic.

Chapter 2 is a site description, together with the sampling method.

Chapter 3 investigates recreational fishing pressure on Macquaria novemaculeata in their natural environment obtained via a survey of recreational anglers. This survey was undertaken as there is a dearth of data on those who target this species as recreational anglers, their gender, age class, State of residence, fishing effort specifically for M. novemaculeata, including years spent targeting the species, size of angling group, areas fished and watercraft used, how fishing sites were selected, the average size of M. novemaculeata caught, and the level of catch-release employed by anglers. Acquiring this knowledge has the potential to play a key role in management of this species.

Chapter 4 compares the demographic attributes of length, weight, condition, age, growth, sex ratio, density, and in-stream habitat selection of M. novemaculeata

29 between two different tributary types (open and obstacle-strewn) in the Hawkesbury- Nepean River.

Chapter 5 investigates the diet of M. novemaculeata between two different tributary types (open and obstacle-strewn) in the Hawkesbury-Nepean River. Understanding habitat occupancy and associative diet of M. novemaculeata is important as only one other published study of this species (Harris 1985b) has extended beyond the main channel into isolated waterways. This study was undertaken as there is a dearth of data on this species dietary attributes, particularly in tributaries.

Chapter 6 investigates migratory movements of M. novemaculeata between two different tributary types (open and obstacle-strewn) in the Hawkesbury-Nepean River. The purpose of this segment of the study is to determine migratory movement of M. novemaculeata between freshwater and estuarine habitats using otolith microchemistry. Only one other study (Macdonald and Crook 2010) has focused on the otolith microchemistry of M. novemaculeata.

Chapter 7 discusses the findings of the study and provides management recommendations for M. novemaculeata.

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51 2. Site Description and Sampling Method

The Hawkesbury-Nepean River Catchment in New South Wales (Australia) encompasses an area of 21 730 km2 (HNCMT 1998) where greater than 800,000 people reside (Griffith and Peter 2014). This well populated river catchment includes approximately 145 km of estuary with tidal influence, and 110 km of its length drains through the relatively unspoiled bushland of the Greater Blue Mountains World Heritage Area. As the Hawkesbury-Nepean River moves through the landscape it collects a number of major tributaries including the Grose River, Colo River, and South Creek. The main river and its tributaries experiences a variety of environments including natural landscapes, rural lands that are devoted to agriculture, and densely urbanised areas.

The river is heavily regulated with numerous constructed dams, the most significant being Warragamba Dam which is Sydney’s main water supply (Gehrke et al. 1999). As a result of these constructed dams, 80% of potential water flow is lost to water extraction with very little returned to the waterway as treated wastewater (Growns and James 2005). Eventually the waters of the Hawkesbury-Nepean River meet the ocean at Broken Bay near Gosford approximately 30 km north from Sydney’s Central Business District (CBD) (-33.56314oS, 151.296844oN) (Howell and Benson 2000).

Although prior to European establishment in the area, the Hawkesbury-Nepean River Catchment had clear flowing water, clean sand/rock substrates and far lower nutrient levels than post-anthropogenic impacts (Recher et al. 1993), the river has always been characteristically unstable. Prior to water extraction, there were natural phases in which there was short-term river stability, but there were regularly re-occurring intense flood events which would result in large deposits of sand (Howell and Benson 2000; Brainwood et al. 2008).

The river and its tributaries are environmentally and economically important to the Sydney Region, encompassing national parks, agricultural lands, and urban districts. The management problems associated with this River and its tributaries are diverse. However, primary areas of current concern include water quality issues associated with treated wastewater and stormwater, increasing urbanisation, loss of biodiversity,

52 heightened salinity and a loss of vegetation; particularly riparian vegetation (Burgin et al. 2005). The River reaches and its tributaries most heavily influenced by anthropogenic impacts are those with the most fertile soils of the Catchment. These have been developed for agriculture and urbanisation. For example, the Cumberland Plains Woodlands of the lowland Catchment, situated on Wianamatta Shale, have been heavily cleared of native vegetation. It was estimated that only 6% intact woodlands remained by 1990 (Benson et al. 1996), and this woodland type is now protected as a ‘Critically Endangered Ecological Community’ (Hall et al. 2015). The areas dominated by Hawkesbury sandstone with characteristic sand-based soils have not been equivalently exploited and much of this natural habitat has remained intact (Warner 1998; Hall et al. 2015).

Between December 2011 and April 2013, the fieldwork phase of this study, the mean monthly maximum temperature for Richmond, NSW (central to the sites sampled in the Hawkesbury-Nepean River) ranged from 17.0oC (July 2011) to 32.1oC (January 2013), with mean monthly minimum temperature ranging from 3.0oC (August 2012) to 18.4oC (January 2013). Within this same period mean rainfall ranged from 4.8 mm (August 2012) to 159.6 mm (February 2012) (Bureau of Meteorology 2015).

2.1 Study Sites

For this study, M. novemaculeata were collected from sites located on the Hawkesbury-Nepean River (New South Wales) between Lower Portland (-33.450°S; 150.900°N) and Mooney Mooney (-33.490°S; 151.186°N). Fish were sampled from six (Figure 2.1) tributaries, three ‘obstacle-strewn’ (Wheeny Creek; Little Wheeny Creek; Popran Creek) and three were ‘open’ (Cattai Creek; Webbs Creek; Wrights Creek) (Figure 2.1). Macquaria novemaculeata were sampled at these sites over a period of approximately two years (December 2011 to April 2013).

‘Obstacle-strewn’ tributaries were defined as irregularly connected pools, segregated by objects which were expected to impede M. novemaculeata migration under base

54 flow conditions. This is characteristic of a waterway with flow broken by rocks, shallow stretches, riffles, and/or waterfalls. The interface of the aquatic and terrestrial environment was less obviously separated than in open creeks. These sampling areas were located within or bordering the fringes of national park/wilderness areas with intact vegetation (Plate 2.1).

Open tributaries lacked discernible obstacles that could impede migration of M. novemaculeata under base flow conditions. The interface between the aquatic and terrestrial environment was more obviously separated than in obstacle-strewn creeks. Sampling areas were located within/bordering agricultural/semi-rural localities. The habitat had been modified due to clearing and this had exacerbated the establishment of terrestrial weeds at the water – bank interface (Plate 2.2).

Although the catchments of open creeks had been modified, they were chosen because they were not otherwise heavily affected by on-going anthropogenic activities. The catchment of these sites did, however, exhibit greater boat/road access, farming and soil fertility in comparison to the obstacle-strewn creeks which were typically situated in a more natural environment with limited access points, and they drain relatively pristine areas.

Plate 2.1 A characteristic example of an obstacle-strewn stretch of creek highlighting rock boulders, riffles, fringing terrestrial vegetation and shallow water.

Plate 2.2 A characteristic example of an open stretch of creek highlighting a lack of discernible obstacles.

56 2.1.1 Obstacle-Strewn Tributaries

Table 2.1 Background information for the catchments of obstacle-strewn tributaries1

Catchment Little Wheeny Popran Creek Wheeny Creek Information Creek

Sub-catchment size 5084 Ha 6310 Ha 18320 Ha

Elevation at top of 465.5 m 266.1 m 535.5 m named watercourse

Elevation at bottom 11.2 m 2 m 2 m of named watercourse

Coordinates of area -33.479311 - -33.387744 - -33.461743 - sampled -33.534248 : -33.34753 : -33.473289 : 150.690745 - 151.208905 - 150.697762 - 150.671734 151.211309 150.672678

1Where appropriate, supplementary information supplied by H. Evans (Hawkesbury- Nepean Catchment Management Authority), pers. comm.

2.1.1.1 Little Wheeny Creek (Obstacle-strewn 1) Little Wheeny Creek arises in the mountains above the village of Kurrajong (Figure 2.2) and flows parallel with the village and through the margins of a golf-course. The lower reaches run through Wollemi National Park where some water extraction by neighbouring residents does occur. Below this reach the elevation of the Creek drops steeply as it flows to the confluence with Wheeny Creek where there is no tidal influence.

Throughout the sampled reach (Figure 2.1), the creek characteristically has intermittent pools with small shallow rapids. The stream also has both short sandy stretches and boulder/log-strewn stretches, with the latter dominating.

57 Figure 2.2 Little Wheeny Creek highlighting the reaches sampled (Source: HNCMA 2007).

Plate 2.3 One of several small waterfalls within the sampling reach of Little Wheeny Creek.

58 2.1.1.2 Popran Creek (Obstacle-strewn 2) Along most of its length Popran Creek runs through Popran National Park on the Central Coast (NSW) although the small townships of Mangrove Mountain and Peats Ridge do have some peri-urban development bordering the Creek (HNCMA 2007). In addition, Boral Mining operations occupy lands adjacent to the Creek in its higher reaches. There is tidal influence in the lower reaches below the sampled reach where ‘hobby farming’ occurs. The Popran Creek confluence with Mangrove Creek occurs at Glenworth Valley.

Throughout the sampled reach (Figure 2.3), the Creek has intermittent pools with small, shallow rapids. There are both short sandy stretches and boulder/log-strewn stretches.

Figure 2.3 Popran Creek highlighting the reach sampled (Source: GoogleMaps 2012).

Plate 2.4 Turbid section of a larger pool on Popran Creek after extensive rain.

Plate 2.5 Waterfall associated, boulder-strewn section of Popran Creek during typical flow regime.

2.1.1.3 Wheeny Creek (Obstacle-strewn 3) For most of its length Wheeny Creek runs through Wollemi National Park (the largest region of wilderness in NSW, covering an area of 487 648 ha [Dunk 1999]). The headwaters of the Creek rise in national park where it flows into a steep ravine known as ‘Wheeny Gap’. The creek has a natural levee at the confluence with the Colo River which results in a chain of lagoons commonly referred to as ‘Boggy Wheeny’ (Harris

61 1985). As a consequence, there is no tidal influence in the creek, even in the lower stretches.

Throughout the sampled reach (Figure 2.4) the Creek has characteristically intermittent pools with small shallow rapids. There are both short sandy stretches and boulder/log-strewn stretches.

Downstream from the sampled reach (Figure 2.4), for approximately 10 kilometres before the confluence with the Colo River, there is an extensive area of hobby farming where water extraction by neighbouring residents is generally common practice.

Figure 2.4 Wheeny Creek highlighting the reach sampled (Source: HNCMA 2007).

Plate 2.6 A long, shallow stretch of Wheeny Creek with a sand substrate creek bed.

Plate 2.7 A deep section of Wheeny Creek with instream fallen tree.

63 2.1.2 Open Tributaries Table 2.2 Background information for the catchments of open tributaries1

Catchment Cattai Creek Webbs Creek Wrights Creek Information

Sub-catchment size 28572 Ha 36176 Ha 9253 Ha

Elevation at top of 86.3 m 264.2 m 180.1 m named watercourse

Elevation at bottom of 2 m 6.1 m 2.2 m named watercourse

Coordinates of area -33.557587 -33.377298 -33.322405 sampled -33.572606 : -33.356582 : -33.309844 : 150.908755 150.955705 150.979952 150.936822 150.936908 150.992569

1Where appropriate, supplementary information supplied by H. Evans (Hawkesbury- Nepean Catchment Management Authority), pers. comm.

2.1.2.1 Cattai Creek (Open 1) Cattai Creek flows into the Hawkesbury River near the township of Cattai. In recent decades, this creek has experienced substantial urban development in its upper reaches. Water quality is generally poor, particularly in these upper reaches, around Kellyville, Castle Hill and Rouse Hill. A primary cause of the poor water quality is the increased stormwater and Sewage Treatment Plant effluent discharge into the Creek (Bailey et al. 2000). Since urbanisation began in these upper reaches the Creek’s hydrology has been substantially altered (e.g. flow regime, sedimentation). In addition to the instream changes, much of the natural riparian vegetation has also been affected by these changes as well as from past clearing. These changes are reflected in the domination by invasive weeds, such as willows Salix spp. and privet Ligustrum spp. in the riparian zone (HNCMA 2007).

Some of the lower reaches of the Creek flow through Cattai National Park. The catchment of this Creek encompasses 170 km2, and includes the tributaries: Second Ponds, Caddies, Blue Gum and O'Haras creeks. The main stream, Cattai Creek, has a

64 tidal influence below the first set of rapids, 9 km upstream of the Hawkesbury River/Cattai Creek confluence (HNCMA 2007).

Figure 2.5 Cattai Creek highlighting the reach sampled (Source: GoogleMaps 2012).

Plate 2.8 Characteristic view of the reach sampled on Cattai Creek.

2.1.2.2 Webbs Creek (Open 2) Webbs Creek flows into the Hawkesbury-Nepean River near Wisemans Ferry. For most of its length it runs through the 150,569 ha wilderness area of Yengo National Park or Parr State Conservation Area (Curtin et al. 2002). Valued as a quality recreational fishing location, there are areas of hobby farming in the lower reaches where water extraction by neighbouring residents is generally common practice. The semi-development of these rural areas has resulted in a loss of both floodplain and riparian vegetation (HNCMA 2007).

Tidal influence occurs upstream into the Creek to around the Webbs Creek Mountain Road Crossing. Upstream of this sampled reach (Figure 2.6) there are long shallow sandy stretches, above which the Creek is characterised by intermittent pools with small shallow rapids as it flows through the wilderness area of Yengo National Park.

Figure 2.6 Webbs Creek highlighting the sampled reach (Source: GoogleMaps 2012).

Plate 2.9 Characteristic view of area sampled on Webbs Creek.

67 2.1.2.3 Wrights Creek (Open 3) Wrights Creek is a tributary of the Macdonald River. The confluence of the two is at St Alban’s, 16 km from where the Macdonald River flows into the Hawkesbury River at the township of Wisemans Ferry. For most of its length Wrights Creek runs through the wilderness area of Dharug National Park.

In the lower reaches, Wrights Creek is fringed by hobby farming where water extraction by neighbouring residents is generally common practice. Much of this area of the floodplain has also had its native vegetation removed to allow for grazing.

Tidal influence in the creek occurs for approximately 4 km upstream from the mouth of the Creek. Above this point there are long sandy shallow stretches with few pools.

Figure 2.7 Wrights Creek, highlighting the reach sampled (Source: GoogleMaps 2012).

Plate 2.10 Characteristic view of area sampled on Wrights Creek.

2.2 Sampling Method

Fish sampling was conducted on 24 occasions, with four sampling events per tributary undertaken in spring, summer and autumn (2011-2013). The sequencing of sampling in the six tributaries was performed randomly. However, the same class of tributary (obstacle-strewn or open) was not sampled sequentially, and the same tributary was typically not sampled consecutively. However, the randomly planned order of sampling was altered, on occasions, due to extensive flooding in the Hawkesbury- Nepean River which precluded access to a particular tributary. The inaccessible tributary was then sampled as soon as practical after the water had receded and it was accessible.

Macquaria novemaculeata were caught with a rod (Shakespeare, 4”6’ Ugly Stik, Columbia), reel (Shimano, Stradic 1000FI, Taren Point) and line (Spectra, 5-pound Powerpro braid, Irvine) using various artificial lures (surface lures, diving lures, spinnerbaits) with barbless treble hooks (Owner, Sydney). The tackle was chosen to minimise stress on the fish (Brown 2009). To assess aspects of demography, diet, and migratory patterns, 120 (20 from each tributary sampled) M. novemaculeata were caught. In each sampling event the first five M. novemaculeata landed were retained for analysis.

69 To distinguish M. novemaculeata from M. colonorum, the shape of the head and pelvic fins were used. The concave shaped head and lack of white on the outermost pelvic fin rays of M. colonorum supported distinction between the species (Allen et al. 2002).

Once a fish was landed the treble hooks were removed while the fish’s body was supported and using a mouth grip. After the removal of hooks, fish were euthanised immediately with a swift blow to the head with an 18 inch (approx. 46 cm) aluminium fish baton (Wilson, Tingalpa) before appropriate investigation of the individual was undertaken.

2.3 References

Allen, G.R., Midgley, S.H. and Allen, M. 2002, ‘Field Guide to the Freshwater Fishes of Australia’, CSIRO Publishing, Collingwood.

Bailey, H.C., Krassoi, R., Elphick, J.R., Mulhall, A., Hunt, P., Tedmanson, L. and Lovell, A. 2000, ‘Whole effluent toxicity of sewage treatment plants in the Hawkesbury-Nepean watershed, New South Wales, Australia, to Ceriodaphnia dubia and Selenastrum capricornutum’, Environmental Toxicology and Chemistry, vol. 19, pp. 72-81.

Benson, D., Howell. J. and McDougall, L. 1996, 'Mountain Devil to Mangrove: A Guide to Natural Vegetation in the Hawkesbury-Nepean Catchment', Royal Botanical Gardens, Sydney.

Brainwood, M., Burgin, S. and Byrne, M. 2008, ‘The role of geomorphology in substratum patch selection by freshwater mussels in the Hawkesbury – Nepean River (NSW) Australia’, Aquatic Conservation: Marine and Freshwater Ecosystems, vol. 18, pp. 1285-1301.

Brown, P. 2009, ‘Australian bass movement and migration in the Snowy River recreational fishing grant program – research report’, Fisheries Victoria.

Bureau of Meteorology 2015, Climate Data Online (online). Available at http://www.bom.gov.au/climate/data/index.shtml?zoom=1&lat=- 26.9635&lon=133.4635&dp=IDC10002&p_nccObsCode=139&p_display_type=data File (Accessed 18 February 2015).

Burgin, S., Carson, J. and Maheshwari, B. 2005, ‘Local provenance in rehabilitation of degraded landscapes - a case study from the Hawkesbury – Nepean catchment’, Area, vol. 37, pp. 324-331.

Curtin, A., Lunney, D. and Matthews, A. 2002. ‘A survey of a low-density koala population in a major reserve system, near Sydney, New South Wales’, Australian Mammalogy, vol. 23, pp. 135-144.

Dunk, A. 1999, ‘Discovering the Colo Wilderness on Foot’, Envirobook, Annandale.

Gehrke, P.C., Astles, K.L. and Harris, J.H. 1999, ‘Within-catchment effects of flow alteration on fish assemblages in the Hawkesbury-Nepean river system, Australia’, Regulated Rivers: Research and Management, vol. 15, pp. 181-198.

Griffith, M. and Peter, T. 2014, ‘Hawkesbury Nepean River and South Creek Model’, Journal of the Australian Water Association, vol. 41, pp. 51-57.

Growns, I. and James, M. 2005, ‘Relationships between river flows and recreational catches of Australian bass’, Journal of Fish Biology, vol. 66, pp. 404-416.

Hall, A.A.G., Gherlenda, A.N., Hasegawa, S., Johnson, S.N., Cook, J.M. and Riegler, M. 2015, ‘Anatomy of an outbreak: the biology and population dynamics of a Cardiaspina psyllid species in an endangered woodland ecosystem’, Agricultural and Forest Entomology, vol. 17, pp. 292-301.

71 Harris, J.H. 1985, ‘Diet of the Australian Bass Macquaria novemaculeata (Perciformes: Percichthyidae) in the Sydney Basin’, Australian Journal of Marine and Freshwater Research, vol. 36, pp. 219-234.

HNCMT (Hawkesbury-Nepean Catchment Management Trust), 1998, Geomorphology of the Hawkesbury-Nepean River System HNCMT: Windsor, Australia.

HNCMA (Hawkesbury-Nepean Catchment Management Authority), 2007, Hawkesbury-Nepean River Health Strategy – Volume 2, (Online) Available from: http://www.hn.cma.nsw.gov.au/multiversions/3320/FileName/Volume2.pdf , (Accessed 8th March 2012).

Howell, J. and Benson, D. 2000, ‘Predicting potential impacts of environmental flows on weedy riparian vegetation of the Hawkesbury-Nepean River, south-eastern Australia’, Austral Ecology, vol. 25, pp. 463-475.

Recher, H.F., Hutchings, P.A. and Rosen, S. 1993, 'The biota of the Hawkesbury– Nepean catchment: reconstruction and restoration', Australian Zoologist, vol. 29, pp. 3–42.

Warner, R.F. 1998, 'Floods and floodplain management', In: Geomorphology of the Hawkesbury-Nepean River System. Hawkesbury-Nepean Catchment Management Trust: Windsor, Australia, pp. 83–96.

72 3. Attitudes and behaviour of recreational fishers of Australian bass Macquaria novemaculeata with a focus on the Hawkesbury-Nepean River

3.1 Introduction

Commercial and recreational fishing have occurred worldwide for centuries, although, commercial fishing has regularly been recognised as the primary reason for the decline in fish numbers on a global scale (Botsford et al. 1997; Smith 2002; Christensen et al. 2003; Hilborn et al. 2003; Pauly et al. 2003). Aquatic mammals and non-target fish species may also be taken in larger numbers as bycatch in commercial fisheries compared with recreational fisheries (Dayton et al. 1995; Steneck 1998). The natural processes that occur in benthic habitats may also be upset due to mechanised harvesting in commercial fisheries which does not typically occur in recreational fishing (Frid and Clark 2000; Cooke and Cowx 2006). Overall, therefore, indirect effects of commercial fishing may have greater negative consequences for the environment than the actual take of the target species (Hammer et al. 1993; Hughes 1994; Botsford et al. 1997; Estes et al. 1998). Despite this perception historically, there has been an increasing recognition that recreational fisheries also contribute to the global decline in fish stocks (Kearney et al. 1996). This has been due in part to the enhancement of angler skill; technological assistance through increasingly sophisticated fishing gear, and the more timely information available through avenues such as the internet, all of which may compound the recreational fishing impacts on fish stocks (Steffe et al. 2005), and thus, commercial and recreational fishing may affect the balance in aquatic ecosystems. For example, larger individuals of a specific species may be targeted in either fishery (recreational or commercial) leaving a fish population dominated by smaller individuals that are less likely to be as fecund as larger individuals (Conover and Munch 2002). This was highlighted in a study by Walsh et al. (2010) on the long-lived estuary perch Macquaria colonorum. They suggested that it was integral to the long-term sustainability of the recreational fisheries to conserve older individuals of the population, particularly when the species was known to be over-exploited.

73 Recreational fishing occurs across a wide range of aquatic wetlands that include rivers, creeks, lakes and the ocean, and represents an important tourist attraction internationally (FAO 1996; Ditton et al. 2002; Zwirn et al. 2005; Greiner 2010). Popularity of the activity spans effectively all sectors of society, in part, because it can be a relatively cheap form of recreation for all ages, and generally lacks any great physical exertion (Ditton et al. 2002). On the island continent of Australia, recreational fishing is one of the more popular recreational pastimes, particularly in coastal areas (Yapp 1986; Henry and Lyle 2003; Yamazaki et al. 2013). Indeed, commonly, recreational yield of some fishes (e.g. yellowfin bream Acanthopagrus australis, dusky flathead Platycephalus fuscus and tailor Pomatomus saltatrix - Richmond River - West and Gordon 1994) may be greater than the commercial yield (Henry and Lyle, 2003). This reflects the popularity of recreational fishing in Australia. For example, Henry and Lyle (2003) reported that approximately 3.36 million people in Australia participated in recreational fishing. This represents approximately 20% of the population. Participants in the sport use a variety of fishing equipment to target any number of approximately 230 species. The use of line and hooks, otherwise known as angling is by far the most popular method (used by 85% of recreational fishers) with an annual expenditure on angling in excess of AUD$1.8 billion.

As with many marine fisheries, inland fisheries of most developed countries, including Australia, have moved from commercial fishing being the primary operator to recreational fishing becoming more prevalent (Arlinghaus et al. 2002). Worldwide, approximately 50% of fish caught during recreational fishing activities are released alive; hence, it is integral to managing inland fish species that trends in recreational fishing are monitored to ensure appropriate long-term sustainability of the resource (Arlinghaus et al. 2002; Allan et al. 2005; Cooke and Cowx 2006). An example of this transition from commercial to recreational fishing can be observed in the long- term inland fishery of the long-lived Murray cod Maccullochella peelii in Australia. Between the mid-1800s and the late-1930s, Macc. peelii was heavily fished commercially and this led to an extreme reduction in the abundance of the species. This decline eventually led to commercial fishing of the species becoming economically unviable (Macleay et al. 1880; Dannevig 1903; Stead 1903; Dakin and

74 Kesteven 1938; Pollard and Scott 1966). In the 1950s, the recreational fishery for Macc. peelii became popular, but its populations had not recovered from commercial exploitation, and it was suspected that the rise in popularity of recreational fishing would further compound the past impacts on this species (Poole 1984). As a consequence, on-going targeting of Macc. peelii by recreational anglers has the potential to further impact on the species unless effective management and education programs on this recreational fishery is implemented.

While there is no longer a commercial fishery for Macc. peelii, Macquaria novemaculeata, M. colonorum and golden perch Macquaria ambigua; these species are now heavily targeted by recreational anglers (McPhee et al. 2002; Henry and Lyle 2003). Understanding angling participation and what facilitates this, aids in predicting future angler actions and how to manage this to maintain sustainable populations of the fish species targeted (Ditton 1995). Since all of these species are closely related, and have a similar pattern of exploitation, in this chapter I have chosen to survey anglers that focus on M. novemaculeata, the species of this genus that is most under pressure from expanding urbanisation in peri-urban Sydney and (potentially) increasing numbers of recreational anglers.

3.1.1 Recreational fishing and Macquaria novemaculeata The M. novemaculeata and M. colonorum recreational fisheries are managed similarly, primarily because the two species have similar traits including longevity (M. colonorum recorded up to 41 years - Walsh et al. 2010) and they have characteristic recruitment events (M. novemaculeata - Harris 1985a; M. colonorum - Walsh et al. 2010). However, since M. colonorum generally do not migrate upstream beyond the tidal reaches whereas M. novemaculeata typically do so outside of spawning events (Harris and Rowland 1996), the impacts on M. novemaculeata are relatively more diverse than for M. colonorum and hence the focus on the former species.

In NSW, the recreational fishery regulations on M. novemaculeata and M. colonorum are managed jointly. The daily take or ‘bag limit’ allowed is two fish (four is the maximum number of fish that a person is allowed in their possession). Only one of

75 these fish can be over 35 cm total length. In addition, in riverine environments, there is a closed season between June and August. This allows the two species protection during the period of estuarine spawning. During this period, M. novemaculeata migrate from freshwater/brackish waterway reaches where there is relatively low fishing pressure to reaches with comparatively high fishing pressure in the estuaries, which makes them susceptible to over-exploitation (Harris 1983). For example, in the Shoalhaven River, M. novemaculeata concentrate in small areas to spawn (Walsh et al. 2012b). In contrast, when individuals are not attracted to the estuary for spawning, they tend to have fidelity to a specific site, often in isolated areas up-stream. During the episodic spawning events they are, therefore, generally at more risk from fisherman and changes to the estuarine environment than at other times (Heupel et al. 2006). Fish species that occupy these small defined spawning areas (e.g., white perch Morone americana - McGrath and Austin 2009) have been shown to require extended periods to re-establish following perturbation resulting in a reduction in the population.

Estuarine commercial trawling fish operations may result in high M. novemaculeata by-catch mortality (Harris 1988). Past research showed that this occurred in association with prawn trawling in the estuarine reaches of the Hawkesbury-Nepean River. For example, Gray et al. (1990) found that between March 1986 and February 1988, they represented the highest proportion of bycatch: 1,851 M. novemaculeata were inadvertently caught. Conversely, in a study of bycatch from the estuarine prawn seining in the Richmond, Manning, Wallamba and Shoalhaven rivers of NSW, M. novemaculeata were collected as bycatch only in the Shoalhaven River. Even in this river, they represented a small percentage of the bycatch, and were not in the top ten incidentally caught species. These results were obtained despite the sampling period encompassing September 1998 to June 1999 which excluded some months in which this species would be expected to be in elevated numbers in estuaries for spawning (Gray et al. 2003). Another study carried out on a multi-species gillnet fishery throughout 2001 yielded similar results (Gray et al. 2005). In the Richmond, Clarence and Shoalhaven rivers, M. novemaculeata were present in the bycatch but their abundance did not rate among the top five species caught incidentally except on one sampling occasion in the Richmond River where they represented 0.2% of the total

76 catch. In the same study M. novemaculeata were not encountered in the Camden Haven River, or Wallis and Illawarra lakes, despite their known occurrence in these systems.

As previously noted, M. novemaculeata are a prized angling species and they have a tenacious fighting ability. There are, at least, nine fishing clubs (Hunter Native Fish, Bass Kempsey, Southern Bass Fishing Club, Big River Bass Fishing Club, Bass Fishing Sydney Club Inc., Western Sydney Bream and Bass Angling Club, Hawkesbury-Nepean Bass Angling Association, Wollondilly Bass Club, Springwood Bass) across the species range whose primary target is M. novemaculeata. At least in the Hawkesbury-Nepean River this species supports a growing recreational fishery (Growns and James 2005). As a result of their popularity as a target recreational fish, and as with M. colonorum, M. novemaculeata are captured and released in high numbers in riverine environments throughout the east coast of Australia. Of the estimated 1.15 million M. novemaculeata caught annually, approximately 75% are released after capture (Dowling et al. 2009). Harris (1988) reported that in the past a large number of deaths had occurred due to exploitation by recreational fishers. With the increased participation in recreational angling for M. novemaculeata over the last two decades, recreational fishing has the potential to further impact on sustainability of populations, particularly in catchments with high fishing pressure from anglers (e.g., Hawkesbury-Nepean River) (Gray et al. 1990; Harris and Rowland 1996; West and Walford 2000; Growns and James 2005; Walsh et al. 2012b).

Various biological attributes of M. novemaculeata lend it some predisposition to face the impacts of recreational fishing. As previously indicated, this species generally does not occupy the same reaches of waterways year-round, making successful angling problematic to less knowledgeable anglers (Walsh et al. 2011). A percentage of the population is also likely to occupy difficult to access waterway reaches (and tributaries) that would require considerable effort for an angler to reach (e.g., Colo River Gorge habitat in Wollemi National Park, NSW – Harris 1985b). Furthermore, females tend to move further upstream into such environments (Harris and Rowland 1996) in non-spawning periods. In these relatively remote, upland reaches fishing pressure is typically lower compared to the more accessible estuarine reaches (Marine

77 Parks Authority 2008). Females, particularly older more fecund fish, have the potential to provide a disproportionate number of offspring than smaller, younger individuals. Their fate (i.e., retain or release) in the recreational fishery may be relatively more important for the species’ sustainability (Harris 1986).

On a smaller habitat scale, this species association with structure (e.g. fallen logs, tree root balls) is likely to reduce the potential for recreational fishing impacts by land- based fisherman. These fishers generally require a cleared section of riverbank to act as an adequate fishing platform to allow manoeuvrability to cast their line. Macquaria novemaculeata tend to be associated with areas with intact riparian vegetation present (Growns et al. 2003), where it is generally difficult for land-based anglers to target this species. Fish apparently also become increasingly wary of line capture subsequent to their capture and release (Lewynsky and Bjornn 1987). The recreational targeting of this species for consumption may also be less likely to occur in waterways where the catch is consistently made up of small fish, compared to other fishing areas (e.g., mid reaches of the Hawkesbury-Nepean River – Van Der Walt et al. 2005). This is because the time and effort required to catch sizeable fish may not appeal to an angler that is not as concerned with the sporting aspect of angling as obtaining a ‘prize’ fish (Harris 1995; Walsh et al. 2010). Indeed, smaller fish may not be desirable to an angler that releases the fish because smaller fish are less likely to provide the elements of sport or ‘fight’ that larger fish provide.

The generalist feeding strategy of M. novemaculeata (Allen et al. 2002; Smith et al. 2011b) means that it can subsist on a wide variety of food items; and hence it is less likely to be impacted by the recreational fishing pressures that may be placed upon other species which it may prey upon. Also, with this species preference for foraging during crepuscular periods (Harris 1985b), it may lessen fishing effort and/or take of some fisherman who wish to maximise their catch potential and fish only during these periods. Alternatively, this can lead to negative recreational fishing impacts as they have the potential to be over-exploited by a well-informed angler who is aware of these habits (Harris 1985b; Smith et al. 2011a).

78 Recreational fishing in the estuaries may interrupt spawning practices (Harris 1983). Apart from M. novemaculeata congregating in relatively high numbers in the estuary compared to their more solitary upstream existence (Walsh et al. 2011; Walsh et al. 2012b), unlike some other species (e.g. Atlantic salmon Salmo salar – Jonsson et al. 1991), they will take an angler’s presentation throughout the spawning period. They will also often school at barriers to movement (e.g., weirs), interrupting their migration until adequate flow allows them to transgress beyond the obstacle. Recreational fisherman may take advantage of this phenomenon. This is evidenced by the prohibition on fishing within the vicinity of some weirs (e.g., Penrith weir, Hawkesbury–Nepean River). In addition, the tendency for M. novemaculeata to occupy the water at the terrestrial/aquatic interface, and because preferred habitats are readily identifiable by fisherman, in these areas they are vulnerable, particularly to fisherman using watercraft. In addition, because the species can tolerate poor water quality (Growns et al. 1998) that is often associated with urban runoff into local waterways, recreational fishermen targeting this species are unlikely to have to travel great distances to fish. This ease of accessibility for anglers could be especially detrimental to M. novemaculeata populations during low flow periods where some individuals may be landlocked and overfishing may occur with limited likelihood of short-term recolonisation (Harris 1986). If larger fish with extensive territories are taken by recreational fisherman from these landlocked pools within waterways, it is likely to upset natural territoriality regimes as well as reproductive success in the population overall (Beamish et al. 2006). The loss of either large or small specimens of this species is also likely to upset the natural food web. For example, smaller fish may target smaller prey items whereas the larger prey items may flourish in an area from which larger fish have been removed (Smith et al. 2011b). Macquaria novemaculeata also take a variety of natural baits and artificial lures presented by anglers, presumably because of their generalist diet. The willingness to take an angler’s presentation, particularly artificial lures, may be confounded by this species territoriality and the tendency to attack orally to deter others from their territory. This behaviour commonly results in hook penetration and resultant capture (Van Der Walt et al. 2005).

79 As previously reported, approximately 75% of M. novemaculeata captured by recreational anglers are released (Dowling et al. 2009). Hall et al. (2009) examined the post-release (5 days) outcome of M. novemaculeata after angling capture. They found that mortality was 0-6.3%, and death was primarily associated with smaller fish size and hook location. However, in comparable angling environments, the overall short-term post-release mortality (0-6%) was comparatively lower than in other endemic species prized by anglers (M. ambigua, 0-24%; Macc. peelii, 15% Hall et al. 2012). Use of natural baits, as opposed to artificial lures, increased mortality rate. This was because fish swallowed natural baits deeper, and this resulted in gut hooking that typically caused greater internal damage than artificial lures. Those fish that had ingested hooks that were subsequently extracted were approximately 20 times more likely to die due to the injuries than fish that were hooked through the mouth. Dowling et al. (2010) observed no immediate mortalities after release when artificial baits were used instead of natural baits fished in a stationary manner. With this technique, effectively all fish were hooked in the mouth, and less than 2% ingested the hook/s. However, without immediate mortality after the removal of ingested hooks, mortality may still occur. For example, when hooks were ingested, 38% mortality occurred within 24 hours (Hall et al. 2009). Some fish also received injuries in the capture process (e.g., fin damage, scale loss) which could result in an elevated occurrence of fungal lesions, pathogens, and bacterial infection. Mortality due to such damage is effectively unaccountable (Barthel et al. 2003; Butcher et al. 2008; Lestang et al. 2008; Hall et al. 2012). In addition, Hall et al. (2009) established that anglers who did not participate in fishing tournaments were determined most likely to use natural baits (e.g., worms, house cricket) and catch smaller fish overall. These anglers also more often retained their catch for consumption, and they were reported to be less knowledgeable about the best method of releasing fish (Arlinghaus et al. 2007; Dowling et al. 2010). Other effects likely to contribute to mortality include barotrauma - the physical damage to body tissues caused by differences in air pressure between the inside of the body and surrounding fluid (in impoundments), water temperature at capture, and recurrent captures of an individual (Hall et al. 2009).

Reduced survivorship can also occur because of the use of inappropriately engineered live wells that are constructed to hold live fish during tournaments (Dowling et al.

80 2010). Within these wells, fish are commonly subjected to greatly reduced dissolved oxygen levels, primarily due to a lack of aeration and overstocking of the well. Low oxygen levels result in heightened stress, fitness issues, or an increased potential of mortality that may not be readily recognised (Kwak and Henry 1995; Gilliland 2002; Suski et al. 2006; Suski et al. 2007). This facet of tournament angling, therefore, potentially causes even greater harm to fish than their actual capture on the line. An additional contribution to reduced survivorship after release may be attributable to the use of low-breaking strength line (Balon 2000). Such line typically requires the fish to tire before landing it to reduce chance of line breakage. A released fish, suffering from exhaustion, is likely to be more susceptible to predation, by piscivorous birds or predatory fish (Reinfelds et al. 2010).

In managing riverine populations of M. novemaculeata it is also essential to consider the impact of recreational fishing on the genetic diversity of the species, with direct angler removal of fish giving rise to restocking of hatchery-bred fish to supplement wild populations. Currently, this species is regularly stocked (20.0-80.0 mm fork- length [FL] fish) into upland reaches of selected river systems in which they naturally occur (Cameron et al. 2012). For example, in NSW rivers and impoundments, 5.1 million hatchery-produced M. novemaculeata fingerlings were released between 1980 and 2010 (Doolan 2009). Shaddick et al. (2011) suggested that there was a need to determine the genetics of M. novemaculeata broodstock for release. This is because they may hybridize with M. colonorum. In stocked impoundments (e.g., Lostock Dam - NSW) hybrids have been detected, assumed to be due to the accidental use of hybrid broodstock. Whilst in dams, such fish are generally unable to migrate to spawn. During flood periods they may, however, be able to do so, potentially increasing the incidence of hybrids in NSW river systems. Despite this concern, extensive sampling throughout south-eastern Australia, Shaddick et al. (2011) only found riverine hybrids within the Snowy River and Gippsland regions (Victoria).

Jerry (1997) had a related reason when he cautioned the need to be cognisant of the genetic integrity of M. novemaculeata when supplementing wild populations with hatchery-bred populations. He noted that there was some genetic heterogeneity across the species’ range. To ameliorate potential effects on population fitness (i.e.,

81 alteration to unique genetic diversity with local adaptations to the environment) he suggested that broodstock should be sourced from local populations.

In this chapter I survey the attitudes and behaviour of recreational anglers of M. novemaculeata on the East Coast of Australia. Recreational anglers, were asked their gender, age class, State of residence, fishing effort specifically for M. novemaculeata, including years spent targeting the species, size of angling group, areas fished and watercraft used, how fishing sites were selected, the average size of M. novemaculeata caught, and the level of catch-release employed by anglers. Acquiring this knowledge has the potential to play a key role in management of this species, now and into the future.

3.2 Methods

To investigate recreational fishing pressure on Macquaria novemaculeata in their natural environment on the East Coast of Australia, a questionnaire was distributed online and in person to fishing clubs and members/affiliates. Clubs sampled were the Bass Sydney Fishing Club Inc., Western Sydney Bream and Bass Angling Club, Hawkesbury-Nepean Bass Angling Association, Hunter Native Fish, Bass Kempsey, Southern Bass Fishing Club, Big River Bass Fishing Club, and Wollondilly Bass Club. Anglers from the Hawkesbury-Nepean River were specifically targeted as this is the largest river system in the Sydney-Metropolitan Area (Roberts et al. 1999), draining urbanising areas to the west of Sydney (Planning and Infrastructure undated). The questionnaire was conducted between August 2012 and April 2013, which encompasses the most popular fishing period of the year for this species.

Information sought was angler’s demographics (gender, age class, State of residence), and fishing effort that targeted M. novemaculeata, including years spent targeting the species, size of angling group, areas fished and watercraft used, how fishing sites were selected, the average size of M. novemaculeata caught and the level of catch- release employed by anglers (see Appendix 1 for copy of questionnaire).

82 3.2.1 Data Analysis Analysis of each of the survey questions was undertaken with a Chi Square Goodness of Fit Analysis. For low numbers, some categories at the extremes were collapsed for statistical validity.

3.3 Results

A total of 150 questionnaires were returned. Of these, 88.7% of respondents were New South Wales (NSW) residents, < 5.0% came from any of the other states (Queensland, Victoria, Australian Capital Territory), and 6.7% did not supply this information. The majority of the anglers (65.1%, n = 140) most frequently fished for M. novemaculeata in the Hawkesbury-Nepean River (Sydney Region). All other river systems identified were each fished for the species by fewer than 5.0% of the total number of respondents who responded to the survey (Figure 3.1).

Figure 3.1 Waterways utilised by respondents angling for Macquaria novemaculeata.

84 3.3.1 Gender and age of anglers 1 There was a highly significant difference (χ 1 = 127.680. p = 0.0) in the proportion of male and female anglers. Most were male (96.6%, n = 147). There was also a 1 significant difference (χ 4 = 11.467. p = 0.02, n = 150) in the age of anglers. Respondents were most likely to be between the ages of 25 and 44 years with few fishing beyond 45 years (Figure 3.2).

Figure 3.2 Age categories of respondents that target Macquaria novemaculeata.

3.3.2 Fishing group size, frequency of fishing, number of years fished 1 There was a highly significant difference (χ 3 = 56.235. p = 0.0, n = 149) in the size of fishing parties. Most fished with a single companion, although a substantial number also fished alone. Few fished in parties of five or more (Figure 3.3).

Figure 3.3 Typical fishing party size for the targeting of Macquaria novemaculeata.

85 1 There was a significant difference (χ 3 = 11.547. p = 0.01, n = 150) in fishing frequency for M. novemaculeata. Broadly, equal numbers fished at least weekly, fortnightly, or monthly whereas few fished less frequently (Figure 3.4).

Figure 3.4 Frequency of fishing focused on the capture of Macquaria novemaculeata.

1 There was a highly significant difference (χ 4 = 46.2. p = 0.0, n = 150) in the total number of years respondents had fished for M. novemaculeata. Most anglers had fished for the species for ≤ 4 years while fewer had fished for this species for between 15-19 years (Figure 3.5).

Figure 3.5 The total number of years that respondents had fished for Macquaria novemaculeata.

86 3.3.3 Fishing sites, use, and the method of selection 1 There was a highly significant difference (χ 2 = 25.554. p = 0.0) in the waterway types typically fished for M. novemaculeata. Approximately half (52.0%, n = 148) fished exclusively in rivers. More fished for M. novemaculeata in both rivers and creeks than exclusively in creeks (Figure 3.6).

Figure 3.6 Waterway type preferred by respondents when they fished for Macquaria novemaculeata.

1 There was no significant difference (χ 1 = 2.189. p = 0.14, n = 148) in preferred fishing sites (easy access or secluded). There was, however, a highly significant 1 difference (χ 1, = 40.026. p = 0.0) in how respondents accessed fishing sites. Respondents most frequently used watercraft (75.7%, n = 152) and few walked to their fishing site.

1 There was no significant difference (χ 4 = 8.823. p = 0.07, n = 148) in waterway type (i.e., creek or river) utilised for targeting M. novemaculeata due to age groups (Figure 3.7).

Figure 3.7 Comparison of age of respondents who predominantly fished for Macquaria novemaculeata in creeks and rivers.

1 There was a highly significant difference (χ 4 = 75.613. p = 0.0, n = 140) in respondents’ method/s of identifying locations to fish for M. novemaculeata. Individuals most frequently relied on online resources or word of mouth (i.e., bait and tackle shop, club discussion). Few preferred topographical hard copy maps (Figure 3.8).

Figure 3.8 Respondents’ method/s of identifying locations to fish for Macquaria novemaculeata. Bait and tackle shop = word of mouth in bait and tackle shop; Online methods = online aerial/satellite maps (e.g. Googlemaps) and Internet- based fishing forum discussion; Exploring = bushwalking/exploring, local knowledge; Club discussion = friends and fishing club discussion; Maps = topographical hard copy maps.

1 There was no significant difference (χ 16 = 17.811, p = 0.34) due to age in the method/s of identifying locations to fish for M. novemaculeata (Figure 3.9).

3.3.4 Percentage of effort focused on Macquaria novemaculeata, catch data (size, release rates), changes in attitude over time 1 There was a significant difference (χ 5 = 11.680, p = 0.04, n = 150) in fishing effort specifically associated with M. novemaculeata. Respondents most frequently dedicated 51.0-70.0% of their fishing effort to M. novemaculeata while few spent > 90.0% of their fishing effort targeting the species (Figure 3.10).

Figure 3.10 Percentage fishing effort used to target Macquaria novemaculeata.

89 1 There was a highly significant difference (χ 4 = 46.667. p = 0.0) in the most common sized M. novemaculeata caught. Most frequently the size range of fish caught was 22.0-27.0 cm. Few individuals caught exceeded 34.0 cm (Figure 3.11).

Figure 3.11 Most common sized Macquaria novemaculeata caught by anglers.

1 There was a highly significant difference (χ 3 = 27.876, p = 0.0, n = 130) in the size of M. novemaculeata caught in the Hawkesbury–Nepean River compared to elsewhere in the species’ natural range. In the Hawkesbury–Nepean River the catch was biased towards smaller sized fish, whereas the trend was the opposite in other rivers systems where most were at the upper end size range for the species. Anglers reported commonly catching fish that were ≤ 21.0 cm in the Hawkesbury–Nepean River whereas this size was not caught commonly elsewhere (Figure 3.12).

Figure 3.12 Most frequently reported size of Macquaria novemaculeata caught from the Hawkesbury-Nepean River compared to elsewhere within the species’ range.

1 There was no significant difference (χ 4 = 2.71. p = 0.61) due to age of angler in the number of the M. novemaculeata caught and retained for consumption (Figure 3.13).

Figure 3.13 Comparison of respondents’ age and their likelihood of retaining Macquaria novemaculeata for consumption or releasing their catch.

1 There was a highly significant difference (χ 3 = 299.33, p = 0.0, n = 150) in the number of anglers who practiced catch and release of M. novemaculeata compared to those that retained their catch for consumption. Most respondents released all of their M. novemaculeata catch. Few kept more than 20.0%, and all of these individuals retained > 50.0% of the M. novemaculeata they caught (Figure 3.14).

Figure 3.14 Macquaria novemaculeata retained for consumption (%).

1 There was a significant difference (χ 1 = 6.387. p = 0.01, n = 148) in fishing site preference among anglers who retained M. novemaculeata for consumption. Secluded areas were more frequently preferred by those who released all of their catch than

91 those who did not. Those that retained at least part of their catch, preferred to fish in areas with ease of access (Figure 3.15).

Figure 3.15 Fishing site preferred by respondents who targeted Macquaria novemaculeata for consumption (%).

1 There was a highly significant difference (χ 2 = 201.88., p = 0.0, n = 150) in the perceptions of anglers of other fishers targeting M. novemaculeata. Most assumed that the majority of anglers released the M. novemaculeata they caught and relatively few considered that others fished for consumption (Figure 3.16).

Figure 3.16 Respondents’ assessment of whether other anglers released or retained for consumption the Macquaria novemaculeata they caught.

Respondents were asked if their attitude had changed since they commenced fishing 1 for M. novemaculeata. There was a highly significant difference (χ 2 = 66.779. p = 0.0, n = 149) in the responses. Most recorded that there had been no change in their

92 attitude, and few reported that they had switched to consuming their catch/consuming a higher proportion of the catch (Figure 3.17).

3.4 Discussion

Rivers used by anglers to fish for Macquaria novemaculeata spanned areas from as far south as the Bega River (Victoria) and north to the Maroochy River (Queensland; Figure 3.1). This parallels this species natural range (Williams 1970; Lake 1978; Harris 1983; Allen et al. 2002). However, the majority of anglers were from New South Wales, and typically these anglers fished for M. novemaculeata in the Hawkesbury-Nepean River Catchment (Figure 3.1).

Henry and Lyle (2003) also reported that the distribution of recreational fishermen across Eastern Australia was highest near the densely-populated Sydney Basin (i.e., including the Hawkesbury-Nepean River). This is also the situation for the M. novemaculeata fishery (Harris 1983; Henry and Lyle 2003; Growns and James 2005). The majority of fishing clubs that target M. novemaculeata were also located in the Sydney Basin. Further indications that fishing pressure is greatest in the Hawkesbury- Nepean Basin is that previous researchers (Van Der Walt et al. 2005; Walsh et al. 2010) have reported that the size of fish caught in the Hawkesbury-Nepean River Basin was smaller than elsewhere in the species range. This is typically indicative of over-fishing.

3.4.1 Gender and age of anglers Only 3.4% of respondents to the survey were female. Throughout the developed world (Ditton and Sutton 2004), hunting, including recreational fishing, have been observed to be preferred by males (Toth and Brown 1997; Ditton and Sutton 2004), and historically, recreational activities (e.g., hunting, camping), that have been deemed to be ‘masculine’ have attracted low female participation (Kelly 1980). Such trends continue. In the current study, almost all recreational fishing for M. novemaculeata was undertaken by males, although, in Queensland (Australia), Sutton (2007) found that females accounted for 19.0% of anglers. However, there was even less bias towards males in the Australian National Recreational and Indigenous Fishing Survey. Of the 3.4 million responses Henry and Lyle (2003) received, approximately 33% (1.1. million) were female. These data indicate that while there is a strong bias towards males in Australian recreational fishing, the extent of the bias does vary in extent.

The same trend has been observed in the United States of America (U.S.) for sport hunting as was observed in the current study for recreational anglers. For example, in the 1980s, female participation in sport hunting in the U.S. was low (1.5-2.7%) compared to males (16.4-19.5%; Heberlein and Thomson 1996), and the number of female hunters has remained low since that time. For example, Mattila and Burgin (2014) reported that females made up only a modestly higher proportion of hunters for white-tailed deer Odocoileus virginianus in Finland (6.0%) than recorded for sport hunting in the U.S. and in the current angling study. Overall, studies of recreational fishing in the U.S. (US Department of Interior 2002; Schuett and Pierskalla 2007), have also revealed the same gender bias among recreational fishers as was found for M. novemaculeata. For example, in the U.S. (West Virginia), 81.4% of fee-paying anglers were male (Schuett and Pierskalla 2007), and black bass Micropterus spp. tournament and non-tournament anglers of Texas (U.S.) were also strongly biased towards males. The male bias; however, has been greatest amongst tournament anglers (Wilde et al. 1998).

94 One potential reason for the bias towards males in the current study is that some segments of the population are less likely to participate in surveys than others. For example, Norris and Burgin (2009) surveyed a community within the area of study (Hawkesbury-Nepean River) about their knowledge and attitudes to stormwater management. They did not find a gender bias although others have observed that there is frequently a female bias in response to surveys. Since the bias in respondents was strongly male, it is assumed that if there was a bias it would be towards females and thus, if anything, the female response rate obtained would be inflated.

Bias towards males may also occur because women who fish with male partners may not belong to the local fishing club. Since anglers for this study were often targeted via club membership, if only one member of an angling family was a club member, the bias could have been towards males. For example, it has been shown that women are more likely to partake in park/forest-based recreation when ’going with a partner’ than without one (Henderson and Bialeschki 1993; Manning et al. 2001). Female participation in sport fishing may also follow this trend and thus females may consider that they are the ‘junior’ partner and allow the male partner to complete the survey. This is supported by the comments of previous studies, for example, that women do not feel ‘entitled’ to pursue their own needs (Colley 1984; Woodward et al. 1989; Boyle and McKay 1995). The observation that most individuals that participated in the M. novemaculeata fishery were between 25 and 44, the peak period for women to have dependent children where time constraints are high, is also likely to be a reason why women were under-represented in this survey (Shaw 1994).

Despite these potential biases, the observation of a male bias among anglers in the current study reflects previous observations that, historically, women have been typically less involved in recreational activities than males (Manning 1999). Nevertheless, participation by women in outdoor recreation, whilst still low, has increased over time (McFarlane et al. 2003). As social expectations of gender roles change, it is expected that participation rates in angling will change concurrently (Schroeder et al. 2006). This is because time, finances, and facilities have been observed to be major constraints against female participation (Shaw 1994).

While many studies (e.g., Schuett and Pierskalla 2007; Sutton 2007) have reported that only a small percentage of anglers are females, some studies (e.g., Henderson, 1990; Schroeder et al. 2006) have reported that when women do fish, their harvest rates are often higher than males. Previous researchers (Shaw, 1994; Schroeder et al. 2006) have reported that women may feel that they can justify time spent angling when the catch is used for consumption rather than for sport. The observation that few women fished for the species compared to men may; therefore, be because of the high level of catch and release (i.e., sport fishing) and less focus on capture for consumption. The disparity between male and female participation rates in the current study compared to the higher levels nationally (Henry and Lyle 2003) may, therefore, have a relationship with the high-release rates recorded in the M. novemaculeata fishery. Women may feel they cannot justify the time to fish in this community of anglers where release rates are high but when angling is undertaken to supplement the household budget women may be more likely to participate in angling. It has also been suggested that women feel less ‘entitled’ to leisure, placing others needs before their own (Colley 1984; Woodward et al. 1989; Boyle and McKay 1995). This has been observed to occur frequently among women who do not undertake paid work with financial support from elsewhere (Henderson 1990; Manning 1999) and thus provides further support to the suggestion that women prefer to fish for consumption rather than for sport.

Although most anglers that targeted M. novemaculeata were between 25 and 44, fishers spanned the age-range surveyed (18 to ≥ 55), with fewer individuals over 45 fishing than younger people (Figure 3.2). Ditton and Sutton (2004) also observed that recreational fishers spanned a wide age range. Despite some complication with the differences in recording of age categories, in Australia, more generally, it has also been observed (Henry and Lyle 2003) that recreational fishers were typically between 30 and 44 years of age, a broadly similar trend to that observed in the current study. This also appears to be the situation more broadly among those who undertake outdoor recreation. For example, in another outdoor water-related recreation pursuit of the area (canyoning, in Sydney Basin wilderness), Hardiman and Burgin (2010) found that canyoners tended to be in their late 30s. This indicates that, at least in the

96 Sydney Basin, water sports tend to be more popular among adults under 45 years of age than those over this age.

As observed in the current study, Australian angler participation rates appear to decline with age, with a decline in numbers beyond 44 years of age (Henry and Lyle 2003). In contrast, a U.S. national fishing survey held in 2001 (U.S. Department of the Interior 2002), revealed that almost half of the anglers were ≥ 45 years. Similarly, an evaluation of Kentucky’s urban fishing program found that most anglers at Stein Lake (U.S.) were ≥ 40 years of age (Emme and Bunyak 2008). Based on these data, the profile of U.S. recreational fishers is different to that of Australian recreational anglers. Despite these observations, the American Fishing Tackle Manufacturers Association (1990) established that participants that have ceased angling were most likely to be in the older age groups. More recently, Schuett and Pierskalla (2007) found that only 16.3% of fee-paying anglers in West Virginia (U.S.) were aged ≥ 55 years. There was an equivalent low percentage of older anglers (16.7%) in the current study.

An outdoor recreation study in Texas also found that older people were more likely to be constrained in their angling pursuits than younger people, with constraints becoming increasingly important for respondents over 65 years of age (Shores et al. 2007). Kelly (1980) stated that participation by younger participants in physically demanding activities was far higher than among older persons, and even such activities as walking, golf, sightseeing, and driving decreased with age, at least marginally. The physical rigours of targeting M. novemaculeata in upland riverine stretches could be considered greater for older anglers when compared to estuarine- oceanic recreational fishing where there are, for example, more likely to be sealed boat ramps, and greater potential for powered watercraft use than in the upper reaches of rivers. Indirect evidence that this may be occurring, is that it has been observed that hydrologically isolated lakes that lacked boat ramps and public facilities were rejected by anglers in favour of more accessible lakes (Reed-Anderson et al. 2000). Since age tends to restrict involvement in physical activities, such as angling, in favour of more passive pursuits (Lawton 1985; Wearing 1999), a factor in the loss of older anglers

97 from the M. novemaculeata fishery is likely to be associated with physical constraints (Floyd et al. 2006).

A more seemingly esoteric reason for the loss of older anglers from the M. novemaculeata fishery surveyed is the apparent increase in the use of artificial lures (Van Der Walt et al. 2005; Dowling et al. 2010). These may have less appeal to older anglers who have traditionally used bait. Also, although the legal right to take M. novemaculeata for consumption remains, older anglers may not feel inclined to take fish for consumption in a fishing community that embraces catch and release angling (Dowling et al. 2010). Changing conventions may, therefore, deter older anglers who have in past years retained their catch for consumption and/or used bait rather than lures.

3.4.2 Fishing group size, frequency of fishing, number of years fished In this study it was observed that most anglers fished alone or with a single companion. As people age they may become less confident (Kelly 1980; Shores et al. 2007), and thus may be more hesitant to fish in isolated areas where once they would have embraced the solitude of the area. Loss of confidence or a companion angler would also have a tendency to remove the motivation to fish, and because few fished in groups of five or more, there would be few options to join other groups. The most likely outcome would be to cease fishing, and thus the numbers of older anglers would be reduced over time (Fedler and Ditton 2001; Floyd et al. 2006).

The large percentage of anglers who fished with a single companion or alone also indicates that there may be some aspect of solitude and/or aesthetics associated with fishing for many people. In national forest areas of Pennsylvania (U.S.) solo climbers claimed that they were motivated most strongly by catharsis/escape than anything else (Graefe et al. 2000). Likewise, Swatton and Potter (1998) established that canoeists undertaking solo trips were motivated by solitude which offered the individual tranquillity and a lack of disturbance from others in a natural setting. Another reason why people fish alone or in pairs is because they lack companions willing to fish with them. Fedler and Ditton (2001) probed these interpersonal constraints on fishing. Over half of their respondents identified ‘the people I know don’t have time to fish’ as

98 a key constraining factor. Lapsed Queensland anglers were also likely to not fish due to a lack of fishing partners (Sutton et al. 2009). In addition, whilst Australians participate in recreational fishing in substantial numbers (McPhee et al. 2002), those who successfully fish for M. novemaculeata are relatively few. The annual catch of M. novemaculeata has been approximately 1.15 million fish. By contrast, saltwater species, for example, bream Acanthopagrus spp. and flathead Platycephalus spp., ranged in catch from 13 to 13.5 million each. Some freshwater fish including redfin perch Perca fluviatilis (2.26 million fish) and golden perch Macquaria ambigua (1.86 million fish) are also caught in higher numbers than M. novemaculeata. These data indicate that finding others with the same specific angling interests may be problematic (Henry and Lyle 2003). However, respondents to the current survey were largely drawn from fishing clubs and affiliates that specifically targeted M. novemaculeata. Thus the respondents were drawn from a sub-set of the community who had access to potential fishing companions through their club affiliations. This would maximise the potential to identify appropriate fishing companions.

Since the majority of respondents preferred to fish with at least one companion, this indicates that for many, there is a social aspect to fishing. However, since the survey tended to target anglers associated with fishing clubs it would be expected that it was the more socially-inclined anglers that were respondents. This is supported by the observation that only 4.3% of Australian recreational fishers had a fishing club association/membership prior to 2000 (Henry and Lyle 2003).

Apart from being an opportunity for a social outing, the preferred number of a party of two may also be based on convenience. Many smaller waterways are likely to be more effectively fished by two people, rather than a larger group. It is also simpler to organise a fishing event with a single companion than a larger group (Fedler and Ditton 2001). If the angling companion is a life partner, typically the ease of organising a trip would be simplified (Henderson and Bialeschki 1993; Manning et al. 2001). However, approximately 25.0% of respondents fished in groups of three or more. Although these larger groups could represent family affiliations, they are also likely to be associated with club fishing events which have a more social aspect and generally require greater levels of pre-organisation for a fishing trip than if someone

99 was fishing solo or with only one other individual. Indeed, most wilderness recreation is carried out in groups (Bowker et al. 2006). Canyoning in the Sydney Basin, for example, is carried out in small groups of friends and family and is rarely conducted alone (Hardiman and Burgin 2010). Elsewhere, in Texas (U.S.), angling was rarely conducted alone, and the average mean party size was 3.3 persons (Ditton and Fedler 1983).

More than half of the respondents in the current study fished, on average, at least weekly or fortnightly (Figure 3.4). The regularity of fishing for M. novemaculeata, indicates that many anglers focus all of their fishing effort on M. novemaculeata. This frequency of fishing is in contrast with Australian recreational fishers more generally. On average it has been reported that most recreational anglers fish only once every two months with few fishing trips made annually (Henry and Lyle 2003); however, Sutton (2007) reported that ‘dedicated’ Queensland fishers fished, on average between 1.6 - 3.0 times monthly. Elsewhere, Fisher et al. (2002) reported that individuals made between 1.1 and 1.9 fishing trips monthly to Eastern Oklahoma (U.S.) streams. However, a survey of fishing frequency by residents of Montana (U.S.) established that the average number of fishing trips was equivalent to 0.8 monthly (U.S. DOI 1993). Conversely, the recreational fishery off Majorca Island (Western Mediterranean) exceeded the frequency of fishing occurring in the M. novemaculeata fishery with an average of 5.5 fishing trips per month (Morales-Nin et al. 2005), however being a popular tourist destination presumably influenced this result. The current study was focused on targeting one species specifically and hence may compound the bias associated with comparing the outcomes to these multi- species fisheries. It is, therefore, assumed that the frequency of fishing by those that target M. novemaculeata is relatively high in comparison to the studies of multi- species fisheries referred to above. This is particularly evident when comparing the frequency of recreational fishing more generally in Australia. Fishing in estuarine waters (35.0%) and coastal waters (41.0%) exceeded that of freshwater rivers (11.0%; Henry and Lyle 2003) where M. novemaculeata resides for most of the year (Walsh et al. 2012b).

100 Despite the regularity with which anglers fished for M. novemaculeata in the current study, involvement in outdoor recreation is, in general, declining worldwide. This trend has been specifically recorded for aquatic-based recreation, including angling and boating (Pergams and Zaradic 2008). For example, in Queensland, participation in recreational fishing waned between 1996 and 2004, falling from 28.1% to 20.6%. The decline has also occurred in the U.S. For example, between 1992 and 2006, U.S. fishing participation rate weakened from 19.0% to 13.0%. Similarly, Canada’s fishing participation rate between 1995 and 2005 declined from 10.8% to 7.6% (DFO 2007). These declines are important for fishery management as a loss of interest will likely mean aquatic resources are valued less strongly by the community (Sutton et al. 2009), and any inherent business relating to angling is likely to also suffer (Fedler and Ditton 2001).

The reduced level in fishing participation rate could potentially be offset in New South Wales, at least, where the population is predicted to increase from 4.7 million (Australian Bureau of Statistics 2013) to approximately 6.0 million by 2036 (Planning and Infrastructure undated). A large portion of this growth is proposed for the Sydney Region. Close proximity to potential fishing areas is likely to increase the frequency of fishing events (Arlinghaus et al. 2007). In addition, if the angler is on foot or even fishing from paddle craft with artificial lures it typically requires little effort to organise a fishing trip. This is because issues such as bait/fuel acquisition and towing a powered boat on a trailer are typically unnecessary under such circumstances. It is also a relatively cheap form of fishing compared to, for example, offshore fishing (Graefe and Ditton 1986). Recreational angling in riverine systems for M. novemaculeata is, therefore, likely to appeal to members of any socioeconomic level of society. This is reflected in the study of Fedler and Ditton (1986) who reported that anglers vary greatly in their financial and social standing. For example, lower income can preclude participation in expensive recreational activities whereas angling for M. novemaculeata in a river near the angler’s residence without the need for boats and other expensive equipment (e.g., trailers) is assumed to be affordable. Sutton (2007) supported this concept. He noted that Queensland fishers were likely to be constrained by the costs of fishing; although it was also suggested that high-income earners may be inhibited due to time constraints. In the past, the availability of fishing areas close

101 to a person’s place of residence has been regarded as an important consideration when engaging in fishing activity (Kelley 1980). This claim aligns with the opportunity theory whereby outdoor recreation will be participated in if costs are limited and the venue is close to home (Lindsay and Ogle 1972; Manfredo et al. 1984; Schramm et al. 2003).

In the current study, approaching half of the respondents had fished for M. novemaculeata for less than five years (Figure 3.5). Elsewhere, for example, among anglers in Texas (U.S.), the average length of time that anglers had fished for black bass Micropterus spp. (Wilde et al. 1998) was between 19.9 and 21.5 years. By comparison to the length of time these U.S. anglers had fished, most anglers in the current study were relatively recently introduced to fishing for M. novemaculeata. A large proportion of those in the current study are, therefore, relatively new to the activity despite the fishing clubs from which many respondents were drawn having been in existence for more than 30 years (e.g., Bass Sydney Fishing Club est. 1981 - President of Bass Sydney Club Inc. Thamm, A. 2013, pers. comm., 20th September). This finding may reflect the observation that most of the respondents fished in the Hawkesbury-Nepean River and it flows through much of the urbanising western fringe of Sydney where urbanisation has been (and continues to be) rapidly expanding in lands adjacent to the River (Planning and Infrastructure undated). The resulting higher concentration of residents in this area may, therefore, have increased the potential for many new initiates to become involved in fishing. There is also the potential for angler dropout, likely due to constraints as the angler ages (Shores et al. 2007) or due to a waning interest (Jackson 1988), for example, if favourite fishing sites are engulfed by expanding suburbia. However, almost 20.0% of M. novemaculeata anglers had angled for this species for two decades or more. This demonstrates that although the largest proportion of anglers had relatively more recently entered the sport, the fishery has been active for in excess of two decades. However, a large number of respondents had been fishing for a much shorter time, indicating that despite the longevity of the sport, the interest in fishing for M. novemaculeata has been apparently increasing over time. It could, therefore, be assumed that the probability of fishing impacts is increasing. This does assume that over time the impacts among anglers have been equivalent. However, catch and

102 release angling has increased in recent decades, particularly for M. novemaculeata (Dowling et al. 2010). The impact per angler has, therefore, presumably diminished.

3.4.3 Fishing sites, use, and the method of selection The majority of anglers fished in the main river, although a substantial number of these spread their fishing effort between rivers and creeks (Figure 3.6). Morey et al. (2002) reported that most fishing effort occurred in larger streams, and thus presumably mainly rivers. Henry and Lyle (2003) found that Australian anglers put 11.0% of their fishing effort into angling in freshwater rivers, including creeks. They observed that fishing in coastal waters accounted for 41.0%, estuarine waters for 35.0%, freshwater lakes and dams for 8.0%, and only offshore waters attracted fewer (4.0%) anglers. The results of the current study could be explained, in part, by ease of access since rivers tend to have more boat ramps and direct road access than creeks where access tends to be more limited, for example, due to steep terrain (Reed- Anderson et al. 2000; Fisher et al. 2002). Rivers are also typically more navigable than creeks (Reed-Anderson et al. 2000). In addition, Hunt (2005) suggested that some anglers may have limited knowledge of fishing sites available for many species. This is despite the increased use of the Internet to share information on angling, including that relating to M. novemaculeata (Martin et al. 2012).

Anglers of all ages preferred to fish for M. novemaculeata in rivers, while younger anglers (18-24), and those 45 and over were most likely to fish in the rivers (Figure 3.7). Anglers seek different benefits from recreational fishing, with motivations ranging from trophy angling, companionship, food, relaxation, and nature (Moeller and Engelken 1972; Fedler and Ditton 1986; Finn and Loomis 2001; Hunt et al. 2002). Those under 24 years of age may focus primarily on rivers because of ease of access to rivers compared to creeks, or their knowledge of the fishery may not extend to the creek systems (Hunt 2005). With age and/or experience (≥ 45) anglers would typically have acquired more knowledge of the fishery, however, even at this older age there was observed to be a preference for fishing in rivers and not creeks. This may be due to the belief that creeks do not yield as many fish, and/or the older anglers may be time-limited and thus prefer powerboats which limit physical exertion, and are typically more suited to rivers (Shores et al. 2007). In addition, the physical rigours

103 and exertion involved with accessing some creeks, and subsequently fishing a creek on foot or perhaps through paddling non-powered watercraft, may not appeal as readily to the more mature-aged fisherman as it does to younger anglers (Kelly 1980).

In the current study, respondents were equally likely to seek areas with ease of access and those that were more secluded. Often the motivation to reach more secluded areas has been said to be to access ‘better fishing grounds’ (Fedler and Ditton 1994), with larger fish and/or preference for seclusion and aesthetics. For example, the capture of fish is often less important to anglers than natural area aesthetics (e.g. water quality, natural beauty, privacy; Fedler and Ditton 1994; Toth and Brown 1997; Burger 2002). Specialised anglers, in particular, place greater importance on non-consumptive attributes of fishing such as the enjoyment of being outdoors (Ditton et al. 1992; Salz et al. 2001). Holland and Ditton (1992) found that freshwater anglers from the Mississippi routinely identified ‘experiencing nature’ as an important non-catch motive for angling. This same group of anglers also stated that a clean fishing environment and, at least, the possibility of catching fish were important considerations in choosing where to fish (Schramm et al. 2003). In the Sydney Basin, canyoning access typically requires walking several kilometres to reach desired sites. Reaching these sites often involves using basic walking tracks, or even a compass bearing, through wilderness areas without tracks (Jamieson 2001; Hardiman and Burgin 2010). Their preference for accessing these more secluded, generally difficult to access areas was to recreate in canyons that were less busy and more aligned with true wilderness (Hardiman and Burgin 2010). It is likely that those who sought secluded areas in the current study had similar motivations.

The use of a recreation area is affected by spatial characteristics related to cities and transportation (Reed-Anderson et al. 2000). Access to fishing sites has been identified as a limiting factor for anglers in lake environments (Reed-Anderson et al. 2000). Similarly, a survey of freshwater anglers from Mississippi (U.S.) found that the respondents preferred the ease of fishing locally, despite having a preferred fishing location further away (Schramm et al. 2003). Indeed, Manfredo et al. (1984) established that the overriding reason for fishing urban areas was due to the close proximity to place of residence. It has been reported, however, that as new anglers

104 from urban regions improve their fishing specialisation they will progressively fish more rural areas (Ditton et al. 2002; Arlinghaus et al. 2008). In Berlin (Germany), a survey of anglers found that approximately two-thirds fished outside of the city limits (Arlinghaus et al. 2008). It was hypothesised that this was because anglers were seeking an ‘escape’ from the urban lifestyle in less busy, remote areas (Manfredo et al. 1984). The findings of the current study could be interpreted as broadly similar to these observations. The potential for recreational fishing impacts on M. novemaculeata is apparent in perhaps less recognised secluded areas where respondents commonly reported that they prefer to fish. Since less than 20.0% fished primarily in creeks, it is less likely that angler impacts would be observed in creeks due to the low frequency of fishing for this species in such areas. However, ease of access accounted for a substantial portion of an angler's preference when considering destinations to fish for M. novemaculeata.

There is some evidence that passive outdoor recreation such as canoeing, hiking, and cross-country skiing is more aligned with a positive attitude towards the environment than activities such as trail biking, motor boating, and fishing (Jackson 1987). Anglers who fished in secluded areas, reported that they rarely, if ever, kept fish (Figure 3.15). These anglers presumably find more merit in the escape and outdoor aspect of the activity than the activity per se (Fedler and Ditton 1986). Henry and Lyle (2003) supported this view. They found that Australian anglers placed more importance on the ability to ‘relax and unwind’ and ‘to be outdoors’ than to catch fish for consumption. This indicates that M. novemaculeata anglers that seek readily accessible areas are more likely to have an impact on the fishery due to recreational fishing because they are more likely to retain fish for consumption than those who fish in more secluded areas that are generally more difficult to access. However, because M. novemaculeata migrate from the upper reaches of rivers to the estuary to spawn (Walsh et al. 2012b), migrating individuals move along the main river channel and are likely to pass through at least some areas that anglers can readily access, although during non-reproductive periods the adult fish may remain in creeks and isolated river reaches (i.e., secluded areas). Since anglers who fish in areas of easy access are more likely to retain at least a portion of their catch, the fish caught in the main river are more likely to be retained for consumption than they would be when

105 they are caught while resident in creeks and isolated river reaches. Resources required to fish (i.e., time and cost of fishing) may also be a motivation for anglers. This pattern was observed in freshwater anglers from the Mississippi River Region where those who kept fish ranked cost of the sport as extremely important (Schramm et al. 2003). Those fishing with the aim of supplementing the family budget are likely to have a greater focus on the catch than on other attributes of fishing (e.g., solitude, natural area aesthetics) and thus seek to minimise the resources required to obtain fish for consumption.

It was observed that approximately 75.0% of anglers that target M. novemaculeata use watercraft (kayak/canoe/boat) to access fishing grounds. In 1999-2000 more than half a million Australians used boats for recreational fishing and 43.0% of fishing events were associated with boats (Henry and Lyle 2003). The current study had equivalent levels of recreational fishing from watercraft as was reported by Morales-Nin et al. (2005) on Majorca Island (Western Mediterranean). It is more than 50 years since recreational boating began gaining popularity (Sessoms 1963). These watercraft provide anglers with access to areas not readily accessible by foot, particularly in the upper reaches of the rivers (e.g., Nepean Gorge, Hawkesbury-Nepean River). In addition, where there is an absence of obstacles (e.g. shallow riffles), powered watercraft allow for faster, more efficient access to fishing grounds and provide greater ease to fish, for example during crepuscular periods. As a consequence, such boats allow anglers greater flexibility on the waterways to fish (Fisher et al. 2002). The use of such boats would, therefore, allow more efficient use of many of the lower freshwater reaches of the coastal rivers of Eastern Australia within M. novemaculeata habitat but would typically not allow efficient access to creeks and the upper reaches of these rivers. The greater propensity to fish in the river rather than creeks may, therefore, simply be due to ease of access.

Unlike motorboats, kayaks and canoes typically lack a motor and are more versatile for use in a range of waterways where, typically, motorised vessels have difficulty negotiating. They can be launched without the need for a boat ramp in areas such as bridge crossings (Fisher et al. 2002). This versatility means that many waterways that appear unnavigable for watercraft may actually experience some unrecognised

106 recreational fishing impacts (Fisher et al. 2002). Similar conclusions have been made in lake environments whereby hydrologically isolated lakes that lack boat ramps and public facilities were often rejected by anglers in favour of more accessible lakes (Reed-Anderson et al. 2000). It has also been hypothesised that the less accessible lakes would likely see more kayaks and canoes used as fishing platforms due to their versatility. Since, in the current study, most anglers preferred secluded areas, it is likely that the use of such vessels would allow greater access to such localities. However, those who fish in such areas are more likely to release their fish and thus, it is likely that they will not individually have the same impact as if they retained their fish for consumption. Unlike the current survey where approximately 25.0% of fishing was conducted from the shore, more generally in Australia, over half (57.0%) of all recreational fishing is conducted from shore (Henry and Lyle 2003). In Eastern Oklahoma (U.S.), the majority of anglers also fished without the use of vessels (Fisher et al. 2002). However, Fisher (1997) suggested that shore-based anglers may be less specialised than those that fished from water craft. It has been suggested (Kelly 1980) that such anglers were not willing, or could not afford, watercraft for their sporting activities. Alternatively, some may prefer to fish narrow, obstacle-strewn waterways that are unnavigable by most watercraft (Hunt 2005).

In the current study, the approach to identifying fishing locations was equivalent among fishers irrespective of age (Figure 3.9). The most frequent method (38.2%) was to use online resources (Figure 3.8). Traditionally, this avenue was not the typical approach to identify fishing sites (Wilde and Pope 2013). Fishing information was more typically exchanged through person-to-person contact. However, there has been a shift to information sharing online. This method may provide up to date fishing information through search engines, fishing forums, and a variety of other social media sites. Indeed, with the availability of mobile phone internet it has become commonly used, even for exchange of information amongst anglers during fishing events (Martin et al. 2012). Specialised anglers, in particular, were most likely to gather information from a variety of online sources to advance their own fishing knowledge (Fisheries Centre 1998) even to the point of determining Global Positioning System (GPS) fishing locations (McPhee et al. 2002). For example, when salmon anglers were asked to identify methods that they employed to gather

107 information on responsible fishing, the majority identified ‘internet websites’ and only approximately 20.0% identified word-of-mouth from family and friends as a source of information (Nguyen et al. 2012). Similarly, Gray and Jordan (2010) found that U.S. marine anglers frequently sourced fishery management information from online resources. Respondents in the current study reported that they used online maps. A benefit of using such maps include potentially finding fishable stretches of water and establishing access points to the site (Reed-Anderson et al. 2000). However, the relative importance that participants placed on the use of online resources in the current study may be, as Harris and Rowland (1996) suggested, because M. novemaculeata occupy ‘difficult to access’ upland riverine stretches and tributaries. The use of online maps would thus typically help such anglers to streamline their access points into such areas.

In addition to using online information sources, anglers targeting M. novemaculeata also obtained information by word of mouth in bait and tackle shops. This traditional avenue of identifying fishing locations (Wilde and Pope 2013) is likely to be important in the M. novemaculeata fishery. It was the second most frequently used method (30.2%) to gain such information. Martin et al. (2012) found that such social sharing of information on fishing spots remained an important form of information sharing. Gray and Jordan (2010) also found that sourcing information from bait and tackle shops occurred even more frequently than in the current study. Contrary to these studies, Nguyen et al. (2012) reported that bait and tackle shop discussion was not a major source of information among salmon anglers. Thus, there is a disparity between this fishery and the current study, indicating that the source for gathering fishing information varies between different fisheries and/or among cultures.

In contrast to bait and tackle shop discussion, fishing clubs were relied on less as a source of information than discussion within the shop or online sources. Nguyen et al. (2012) found that few people used information from club discussion as a source of information. Conversely, Gray and Jordan (2010) found that sourcing such information for fishery management occurred informally among one-third of anglers. One explanation for this variability among fishing codes is that many anglers are protective of their fishing locations, particularly when it is divulging information on

108 sites in isolated creek systems where a female fish bias has been considered common (Harris and Rowland 1996; President of Bass Sydney Club Inc. Thamm, A. 2013, pers. Comm., 20th September). Another potential reason for the limited use of fishing clubs as a source of information could be that this medium may not present the most current fishing information as many meetings could be held monthly or even less frequently. In contrast, bait and tackle shop discussion is likely to provide timely fishing information from anglers whose information is current.

Few anglers reported that they explored to find new fishing sites to fish for M. novemaculeata or used topographical hard copy maps. These methods may not appeal as readily to M. novemaculeata anglers as fishing spots are not specifically identified through these sources. Also, the purchase of such maps may not appeal to someone with financial restrictions (Kelly 1980). Hard copy maps may also be difficult to acquire, particularly if stores specialising in these items are not in the angler’s locality. Anglers that consider that they can obtain useful information through a 'free' source, such as the internet or through word of mouth in a bait and tackle shop would likely choose this free information over seeking it out and paying for it (Martin et al. 2012).

3.4.4 Percentage of effort focused on Macquaria novemaculeata, catch data (size, release rates), changes in attitude over time Most anglers specifically targeted M. novemaculeata for more than 50.0% of their fishing effort, although relatively few anglers spent more than 90.0% of their angling time focused only on M. novemaculeata (Figure 3.10). This is despite other fish species (e.g. P. fuscus – Butcher et al. 2008a; A. australis – Butcher et al. 2008b) being present in nearby localities.

Most M. novemaculeata caught were between 16 and 33 cm in length (Figure 3.11). Larger individuals, that Harris (1986) reported were typically fecund females, were seldom caught. When the Hawkesbury-Nepean, the river system most heavily fished, was compared with all other river systems, substantially greater numbers of fish ≤ 21 cm were reported to be caught than from other river systems within the species’ range. The majority of fish caught in other river catchments were more than 28 cm in

109 length (Figure 3.12). Van Der Walt et al. (2005) previously observed that M. novemaculeata caught in the Hawkesbury-Nepean River were smaller in size than the two other rivers they sampled (Manning and Williams rivers). In addition, Walsh et al. (2010) observed that 96.0% of the catch of a closely related species, M. colonorum, which occupies comparable environments to M. novemaculeata and undergoes similar anthropogenic impacts, sampled from the Clyde and Hawkesbury- Nepean rivers were less than 12 years old, despite it being recorded that individuals may live to at least 41 years. This indicated that age truncation was occurring in these river systems for M. colonorum. However, in the Bemm River (Victoria) where fishing pressure was not substantial, 65.0% of this closely related species to M. novemaculeata were older than 12 years. The differences were attributed to the removal of older and larger fish from specific waterways by anglers and commercial fisherman. Size differentiation between different regions has been observed in a range of marine and freshwater fish (e.g. Ricker 1981; Beard and Kampa 1999; Zwanenburg 2000; Harvey et al. 2006). Typically, it occurs as a result of size-selective harvesting whereby the larger individuals are targeted by both recreational and commercial fishermen (Fenberg and Roy 2008). In Australia, the lack of larger Murray cod Mac. peelii in the Murray and Goulburn rivers was attributed to fishing mortality among larger individuals (Brown 2008; Allen et al. 2009). In Minnesota (U.S.), anglers were suspected of impacting upon bluegill Lepomis macrochirus population size structure (Coble 1988; Parsons and Reed 1998). Thus, it is likely that anglers in the M. novemaculeata fishery of the Hawkesbury-Nepean River have impacted upon the size structure of this population in a similar fashion to these other species fisheries.

Most respondents reported that they did not retain any M. novemaculeata for consumption and this did not vary with age of angler (Figure 3.13; Figure 3.14). When asked for an opinion on the behaviour of other anglers, almost 90.0% estimated that others did not retain M. novemaculeata for consumption (Figure 3.16). It is assumed, therefore, release of caught M. novemaculeata occurs over the whole range of this fishery. These findings supported observations by Dowling et al. (2009). They found that approximately 75.0% of anglers’ catches of this species were released while Higgs (2001) estimated that Queensland anglers released 87.0% of the M. novemaculeata they caught. It has also been estimated (Henry and Lyle 2003) that

110 approximately 77.0% of Macc. peelii caught were released. The primary motivation for release of the catch was assumed to be a shifting view of this species from a table species to a sportfish with a high conservation status. Evidence that the switch has been driven, at least in part, by higher awareness of the perceived conservation status of M. novemaculeata is evident from the comparatively lower catch and release of fish practiced in other Australian freshwater finfish fisheries (e.g., European carp Cyprinus carpio, 11.4%; redfin perch Perca fluviatilis, 42.8%; golden perch Macquaria ambigua, 44.0%; barramundi Lates calcarifer, 71.7%; Salmonidae trout/salmon, 51.3%; Henry and Lyle 2003). It is also supported by the observation of Henry and Lyle (2003) who estimated that M. novemaculeata harvest was uncommon (75.6%) despite it being legal to retain M. novemaculeata. Based on the substantial numbers of captured fish said to be released, the relatively small take for human consumption (Higgs 2001; Dowling et al. 2009), and the high survivorship of released M. novemaculeata (Dowling et al. 2009), it would be assumed that even in the Hawkesbury–Nepean River, where recreational fishing pressure is high it would not be expected that the M. novemaculeata fishery would be under the pressure it appears to be under. Previous removal of larger fish from this river system which presumably did not occur in other catchments due to the substantially lower fishing pressure could have contributed to the observed deficit of large fish. This could be predicted due to the slow growth rate of M. novemaculeata (Harris 1987). After a crash in the population and particularly in the breeding population, a lag phase of some decades is likely to occur before the population recuperates. This phenomenon has been observed in other fisheries (Conover and Munch 2002), and may be a reason for the current size structure of the population in the Hawkesbury-Nepean River; however, current over-fishing cannot be ruled out.

Approximately half of the respondents reported that their attitudes to angling had not changed since they commenced fishing for M. novemaculeata (Figure 3.17). An equivalent percentage of anglers said that their fishing had switched to a more sporting focus than a catch for consumption approach since they commenced the sport. Anglers who fish for sport have been shown to exhibit higher levels of catch- and-release than those that fish to supplement their diet (Edison et al. 2006; Schramm and Gerard 2004). It is likely that, for example, interaction with other anglers and

111 research of online resources (e.g. ausbass.com.au; sweetwaterfishing.com.au – online discussion forums) have had some influence on this decision. This is supported by the finding that only 2.0% of respondents have switched from capture-release to a stronger focus on capture for consumption since they commenced fishing for this species. The overall shift in attitude to a more sporting focus may therefore, at least in part, be due to consistently catching small fish, and/or the belief that releasing at least part of the catch supports the fishery’s sustainability. A greater understanding of the potential for fishing impacts as an explanation has been previously noted to occur as a result of the direct observations of anglers than occurred when information on the fishery was obtained from elsewhere (Ditton et al. 1992; Sutton and Ditton 2001).

Anglers who fish for consumption may even feel alienated in an angling community that has a preference for release of their catch. They may, therefore, conform without actually preferring it as a choice. For example, anglers were more likely to harvest muskellunge Esox masquinongy in regions that lacked fishing clubs. These fishing clubs likely endorse employment of catch-and-release angling for this species (Gasbarino 1986; Oehmke et al. 1986). In this situation, peer pressure encouraged the adoption of a capture and release strategy. This is somewhat inconsistent with the observations of the current study whereby fishing clubs were rarely used as a means to identify fishing sites, however, even infrequent exposure to peer pressure is likely to impart some influence on decision making (Ditton and Stoll 2003; Eades et al. 2008). With the reports of the high catch and release rates identified in this study, it is reasonable to suppose that the majority of those entering this fishery without a progressive change in attitude do not keep this species for consumption.

3.5 Conclusions

The average angler who targets M. novemaculeata is a male, between the ages of 25 and 34, has been fishing for this species less than five years and typically fishes with one companion. Those that target this species generally devote considerable fishing effort towards it, identifying fishing sites commonly through online methods, releasing at least a portion of their catch, and utilising watercraft to give greater access to fishing grounds.

112

Few respondents had fished for more than five years and if this trend continues then there will be an ongoing turnover of new anglers in this fishery. These new anglers are likely to continue to use online methods to determine fishing sites. This has the potential to result in impacts in new areas. Smaller fish were reported to be captured in the Hawkesbury-Nepean River compared to elsewhere within the M. novemaculeata range, likely as a result of the removal of larger fish due to past angling. The few anglers that did take fish for consumption were more likely to fish in easy access areas, indicating that impacts are more likely to occur in these localities; however, these impacts can have whole-of-catchment implications. Knowing the angler’s choice of fishing sites allows management of their impacts to maintain resource quality.

After entering the M. novemaculeata fishery nearly half of respondents had switched to a more sporting focus when targeting this species; likely as a result of environmental observation and peer pressure. Regardless of motivation, catch-and- release angling, coupled with the high survivorship of this species after angling release is likely to play a key role in management of this species, now and into the future. However, the long-term viability of this fishery would benefit from more in- depth studies of the species age, size, sex, reproductive migrations, and tributary use in the Hawkesbury-Nepean Catchment.

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151 4. Demography of Australian bass Macquaria novemaculeata in tributaries of the Hawkesbury- Nepean River

4.1 Introduction

4.1.1 Size, age and sexual differentiation in fish An understanding of the importance of size and sexual differentiation of fish within a population may reveal patterns that link to growth, survival, and recruitment attributes (Walsh et al. 2010). With most animals, including fish, such attributes may alter the effectiveness by which protein consumed in the diet is used for continued growth and bodily maintenance. Of importance is the origin of protein, specifically the typical profile of amino acids, as well as percentage utilisation of the dietary protein. Other factors that may impact on the effectiveness of the protein includes the weight of the fish, fish age, quantity of protein intake in the diet and environmental attributes such as water temperature (Hepher 1988; De Silva and Anderson 1995; Halver and Hardy 2002; Wilson 2002). Indeed, water temperature variation due to the removal of riparian vegetation may affect the natural metabolism of fish, and manipulate growth and reproduction which may critically affect population structure and fish assemblages (Jobling 1995). This phenomenon was observed by Greenberg and Brothers (1991) in juvenile fish growth rates of snubnose darter Etheostoma sirnoterum. Growth was three times greater from sites at high elevation than those from lower elevation sites. This was attributed to a temperature regime which saw differences of 3-4oC during spring and summer between the two elevations.

Within and among fish populations, competition for prey may also inhibit the growth of juvenile fish. Individual fish that compete most successfully have the greatest access to preferred prey and subsequently they have a faster growth rate compared to those that compete less successfully (Yamagishi 1962; Fenderson et al. 1968; Li and Brocksen 1977; Morse 1980; Fausch 1984). Differences in competitive advantage may be further accentuated during periods of reduced prey availability (Magnusson 1962; Symons 1968; Symons 1971). For example, reduced potential food prey has been shown to directly cause growth stunting in brook trout Salvelinus fontinalis

152 (Reimers 1979). Some studies (Craig 1982; Craig and Fletcher 1984) have, however, shown that a lack of prey in a fish’s environment can be correlated to an increase in life expectancy. This has been more recently demonstrated in an Australian study on the eastern freshwater cod Maccullochella ikei. Older individuals were shorter in total length in comparison to many of the fish that were younger (Butler and Rowland 2008). In the same study, undertaken on the Mann and Nymboida rivers of Northern New South Wales, it was also observed that the geomorphology of the rivers were unlikely to sustain large fish in great numbers. This conclusion was drawn from the observation that, in areas where few larger fish were present, there was a relative dearth of larger deeper pools in the reach, and presumably the habitat was inappropriate for larger Macc. ikei. It was also assumed that Macc. ikei movement was inhibited in obstacle-strewn environments. Larger individuals of this species, and many other fishes, usually only occur in areas with the potential for individuals to inhabit a large home range with an associated plentiful supply of prey to facilitate growth (Werner et al. 1983; Clapp et al. 1990; Gowan et al. 1994; Schlosser 1995).

Habitat type can also result in variation in fish size. Rowland (1985) observed this in his study of Murray cod Maccullochella peelii. He observed that fish were of greater weight for length in lake environments than in riverine environments. Despite being resident in the same system (i.e., Murray-Darling Basin), in different habitats, Macc. peelii varied in size attributes among habitats. Such variation in growth rate could have been, at least in part, due to earlier spawning of Macc. peelii in the Northern regions of the Murray-Darling Basin. This may have limited growth in the first year which could have compounded slower growth rates over the fish’s lifecycle (Lake 1967). Some studies have also shown size differences in growth within localised habitats. A study of brown trout Salmo trutta established that the quantity of overhanging riparian vegetation in well vegetated riparian zones directly correlated with the larger size of fish (Wesche et al. 1987).

Whilst variation in fish weight can be attributed to prey availability, changes in water temperature and other habitat characteristics throughout the year may influence gonadal development prior to spawning, and consequently may also affect weight attained by the offspring. Butler and Rowland (2008) examined the disparities in

153 weight of Macc. ikei between winter and summer. They also identified that the timing of gonadal development was a principal contributor to variation in weight among seasons. This is assumed to be because prior to spawning in spring, Macc. ikei may progressively increase in weight. As the spawning period concludes, the fish tend to be in the poorest condition of the reproductive cycle. This has also been shown to occur, post-spawning for other freshwater fishes (Davis 1977; Rimmer 1985; Busacker et al. 1990; Meretsky et al. 2000).

In addition, to seasonal variation, there may be impacts due to home range. Fish, such as mulloway Argyrosomus japonicus, and percichthyids including Macc. peelii and golden perch Macquaria ambigua, have been observed to inhabit a linear home range when not undertaking migration (Crook 2004; Taylor et al. 2006; Jones and Stuart 2007). This trait has been assumed to enable fish to develop the advantage of becoming familiar with their surrounding habitat, including prey availability, and therefore, ameliorate energy loss in their daily activities. This, in turn, will result in a greater growth rate, and an increased chance of survival under such circumstances (McGrath and Austin 2009). For example, home range fidelity has been shown to directly correlate to amount of prey consumed by European sea sturgeon Acipenser sturio (Lepage et al. 2005).

As with many Australian native fish, M. novemaculeata is considered a slow-growing species. Harris (1987) reported that it was the slowest growing species of its genus (Harris 1987), with the potential to reach a length of 100 mm in its first year (Growns and James 2005). There has, however, been limited research that focused on M. novemaculeata growth and size attained: two studies have been undertaken in riverine environments (Harris 1987; Van Der Walt et al. 2005), and one in impoundment environments (Wilde and Sawynok 2005). These studies indicated that growth in impoundments was faster than in riverine environments, and this may be expected to be reflected in obstacle-strewn tributaries where movement was inhibited during, for example, low flow. This same phenomenon was shown for another member of the genus, Macquaria ambigua. Mallen-Cooper and Stuart (2003) found that M. ambigua from impoundments grew at a faster rate, and attained a larger size, than the three riverine systems of their study. This difference in growth may occur in M.

154 novemaculeata because of differences in prey density among habitats. However, it is more likely that the ability to divert energy input from, for example, migration to spawn, and instead tailor it towards growth may be a reason for the differences previously observed (Harris 1987; Wilde and Sawynok 2005). Even within freshwater impoundments, however, Wilde and Sawynok (2005) found differences in growth rate among individual M. novemaculeata. Across four water bodies, growth rate was slowest in the smallest and deepest impoundment (Lake Cressbrook, Queensland [QLD]); whereas it was highest in the largest and shallowest impoundment (Lake Somerset, QLD). These data showed that annually, growth was between 5.0 - 7.8 cm (for 20.0 cm total length [TL]), and between 1.7 - 4.9 cm (30 cm TL). More recently published information on M. novemaculeata length (Van Der Walt et al. 2005) was obtained from the data of a recreational fishers’ competition (‘Basscatch’). All of the waterways sampled (Hawkesbury-Nepean, Manning, Williams), flow through areas with varying degrees of anthropogenic impacts, and support significant recreational fisheries throughout their systems, of which M. novemaculeata is a considerable component of the fishing effort. Despite similar catchment attributes, M. novemaculeata had a significantly smaller mean length than the other two waterways sampled, and there were significant differences among years within river systems. The Manning River produced an average mean length of 330.0 mm. This far exceeded the length of fish in the other two river systems. Fish from the Hawkesbury-Nepean River had the smallest mean length (195.0 mm), and there was also a difference in mean length between spring and summer. Spring competitions generally produced M. novemaculeata with a larger mean length. However, between 1988 and 1998, the average length of M. novemaculeata caught in the Hawkesbury-Nepean River increased sequentially with the mode range varying from 140.0 to 160.0 mm, and between 1998-1999 the mode increased to 220.0 mm although there was a subsequent decline in average length beyond that time, at least until 2002 (Van Der Walt et al. 2005). Harris (1988) also found variability in the size of M. novemaculeata from the Hawkesbury-Nepean River. He observed a lack of recruitment which he concluded was due to drought conditions experienced during the earlier years of ‘Basscatch’. As recruitment conditions apparently improved after 1998, there was a subsequent spike in the number of smaller M. novemaculeata caught, which was assumed to be the result of a strong year class (Harris 1988; Van Der Walt et al. 2005).

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Growth rate and size attained by M. novemaculeata has also been associated with residency in different in-stream habitats within a river system. For example, Harris (1985a) observed female growth rate in gorge habitats to be approximately twice that of those that occupied tidally-influenced reaches. Unless adequate flows occur in gorge habitats to allow for migration downstream before the completion of the spawning season, fish may not be able to migrate to estuarine habitats to breed. Under such circumstances (or indeed in obstacle-strewn tributaries), female M. novemaculeata may conserve energy by not attempting downstream migration and, instead, resorb ovarian yolk and increase abdominal fat (Harris and Gehrke 1993). This phenomenon has also been observed among female fish of different species that do not undertake annual spawning. Those fish that did not spawn had better condition than those that did spawn (Rideout et al. 2005). This presumably means that females, and to a lesser extent males, that are impeded in their movement downstream and/or do not migrate would conserve the energy expended in migration and spawning and thus have the potential to attain a larger body mass compared to those fish whose migration is not restricted. Differences in body weight and mass would, therefore, tend to be greater in upstream individuals (e.g., obstacle-strewn tributaries), particularly females, during prolonged drought than in other habitats and/or climatic conditions.

Of the same genus, estuary perch Macquaria colonorum occupies similar environments and undergoes similar anthropogenic impacts as M. novemaculeata. Walsh et al. (2010) found that 96.0% of M. colonorum sampled from the Clyde and Hawkesbury-Nepean Rivers (NSW) were less than 12 years old, despite individuals being known to live to 41 years. This indicated that age truncation was occurring in M. colonorum in these river systems. Conversely, in the Bemm River (Victoria, [VIC]), 65.0% of individuals of this species were older than 12 years. The differences were attributed to the removal of older and larger fish from specific waterways due to fishing. Fishermen targeting larger individuals that are typically the most fecund, have the potential to reduce reproductive success in the population more effectively than smaller individuals, especially when there is high variability in recruitment among years (Beamish et al. 2006).

156

The Hawkesbury-Nepean River, and until 1997, the Clyde River have been subjected to commercial fishing although these operations have never been permitted in the Bemm River. However, despite the ban on commercial fishing for M. colonorum (and M. novemaculeata), they are still caught as by-catch throughout estuarine environments where commercial fishing occurs. This has likely contributed to stock loss (Gray et al. 1990; 2003; 2005, West and Walford 2000). Age truncation, experienced by M. colonorum in rivers/estuaries (e.g., Hawkesbury-Nepean River) where it is heavily fished, is likely to occur in the also long-lived M. novemaculeata. Macquaria novemaculeata would be particularly vulnerable during estuarine migratory visits in the presence of heavy fishing pressure. Similar issues have arisen in the Atlantic cod Gadus morhua commercial fishery whereby the selective removal of larger fish affected the viability and sustainability of their populations due to the extraction of the most fecund fish (Krohn and Kerr 1997).

Sexual maturity of M. novemaculeata is attained at a smaller size for males compared to females (Harris 1986). This trait has also been confirmed in M. colonorum (Walsh et al. 2011). However, growth of M. novemaculeata is much greater in females of this species (Harris 1987). For example, Jerry and Cairns (1998) observed that female fish from seven different drainages were, on average, 2.6 cm longer than males. This phenomenon has also been observed in two other closely related species, M. ambigua (Anderson et al. 1992) and M. colonorum (Walsh et al. 2010). This may be due to differences in preferred habitat. For example, outside of the spawning season, female M. novemaculeata typically move into higher reaches of river systems than males (Harris and Rowland 1996). It is likely that such differences in preferred habitat between the sexes are likely to influence their growth (Harris 1987).

Other behavioural differences have also been documented between M. novemaculeata sexes. For example, Harris (1986) observed that during drought years some females did not migrate to the estuary but remained in the upper, freshwater reaches of the Hawkesbury-Nepean River. During the same period, in the Georges River (NSW), female M. novemaculeata stayed within the tidal limit at Liverpool Weir. An explanation for this lack of migration was the absence of flood event/s to stimulate

157 spawning, and/or to allow the fish to negotiate the obstacles associated with low river flows. However, since females tend to be larger than males (Jerry and Cairns 1998), low flow rates are more likely to restrict downstream movement of large females than smaller individuals of either sex (Koehn and O’Connor 1990; Badenhop et al. 2006) from upstream gorge areas and, presumably, obstacle-strewn tributaries. This size restriction on instream movement has been observed in other species. For example, Harvey (1991) found that the presence of shallow riffles excluded movement of adult largemouth bass Micropterus salmoides (U.S.). In contrast, most smaller fish were able to move freely throughout the site without impediment.

4.1.2 Habitat selection and density Such observations reinforce the need for management of fishes to consider the fundamental attributes of fish ecology. This is because to deliver sound fish management includes understanding the patterns of distribution of animals and what causes anomalies (Pittman and McAlpine 2003; Gillanders 2005). The structure of fish communities can be affected by location in their environment (e.g., stream, main river channel), habitat availability, water characteristics, prey availability, competition and susceptibility to predation (Growns et al. 1998). Previous studies (e.g. freshwater ecosystems, Pusey et al. 1993; 1995a), have revealed how fishes may use habitat in significantly different ways, due to preference for particular depths, flow regimes (e.g., water flow rates), and/or stream bed attributes. Such variation in habitat preference is integral for the co-existence of fish within an aquatic ecosystem (Gorman and Karr 1978; Pusey and Kennard 1996). However, influences on community structure in fish assemblages are often multi-factorial, and may include anthropogenic disturbance, together with an array of ecological processes (Grossman et al. 1982; Pusey et al. 2000).

Such ecological processes may relate to the lifecycles of fish. Outside of the spawning season, M. novemaculeata may exhibit site fidelity in the mid-upper reaches of river systems (Williams 1970; Harris 1983; Harris 1986; Trnski et al. 2005; Walsh et al. 2012b). For example, Walsh et al. (2012b) found that individuals exhibited selective use of an area, returning to a particular reach after extensive in-stream movement. This homing phenomenon would aid in regulating the distribution of individuals

158 within a population, and reduce energy expenditure due to competition for territory (Harris 1983). Homing incentive may also occur due to favourable prey source/s and/or limited chance of predation (Dittman and Quinn 1996; Crook 2004; Walsh et al. 2012b). Indeed, when prey was present, M. novemaculeata were observed to usually stay within a 2-3 m radius of woody debris. These homing attributes highlight the requirement to understand habitat needs for a species, and maintain them appropriately (Kramer and Chapman 1999; Walsh et al. 2012b). Conversely, it has also been proposed (Walsh et al. 2012a, 2012b) that residency in freshwater habitats is not obligatory for M. novemaculeata, particularly in waterways such as the Shoalhaven River (NSW) that exhibit a long oligohaline (higher estuary) region (0.5- 5.0 ppt salinity). This disparity in the regions of waterways in which individuals may exhibit long-term fidelity is contradictory to what is considered the traditional habits for this species. However, Brown (2009) found that M. novemaculeata may make large-scale migrations up or down stream in the Snowy River throughout the year. This indicates that the species’ riverine habitat use, at least in the Snowy River, does not fit a linear or ‘textbook’ movement pattern.

In contrast to freshwater herring Potamalosa richmondia and Australian smelt Retropinna semoni, Growns et al. (1998) found that M. novemaculeata were in higher abundance near vegetated banks than adjacent to non-vegetated banks. These authors also observed that M. novemaculeata were more likely to be distributed according to the composition and quality of the riparian vegetation, rather than water quality associated parameters. Conversely, in a study of fish assemblages in the Hawkesbury- Nepean River (Growns et al. 2003), M. novemaculeata was more common adjacent to grassed riparian banks than otherwise vegetated banks. It was established that the extent of macrophytes at grassed banks acted as a beneficial nursery for juvenile- young from freshwater to upper estuary zones. Although lower in number, larger individuals occupied areas adjacent to vegetated banks. The differences observed in the different reaches were probably attributable to variation in habitat (or microhabitat) preferences at different stages in the lifecycle. Larger M. novemaculeata appeared to benefit from the habitat structure and canopy associated with the riparian zone, whereas juveniles depended largely on macrophytes (e.g., Vallisneria americana, phragmites Phragmites australis) for appropriate habitat (Harris 1988;

159 Growns et al. 2003). Differential habitat selection between size classes was also observed by Collares-Pereira et al. (1995) in Portuguese lowland streams. In these streams, the assemblages of smaller fish generally preferred shallow areas with extensive coverage of macrophytes. Larger fish favoured deeper areas with more riparian cover, while Growns et al. (2003) made the observation that M. novemaculeata were captured in larger numbers adjacent to grassed banks. In an impoundment stocked with M. novemaculeata, the condition of individuals was poorer where preferred habitat available for individuals was limited than in areas with more extensive preferred habitat. High densities of M. novemaculeata are, therefore, likely to inhibit growth rates, lowering the overall condition of fish (Refstie and Kittelsen 1976; Fagerlund et al. 1981). Restriction of habitat availability due to high densities of M. novemaculeata is, therefore, likely to have direct impacts on their ecology (Smith et al. 2011). It has been recognised, however, that a reduction in prey (Vanderploeg et al. 2009), and decreased water quality (Hayes et al. 1999) may also contribute to loss of condition (Smith et al. 2011). Nevertheless, high densities of fish have been associated with reduced growth rates in both coho salmon Oncorhynchus kisutch (Fagerlund et al. 1981) and Atlantic salmon Salmo salar (Refstie and Kittelsen 1976). During M. novemaculeata recruitment events in the Hawkesbury River between 1990 and 1992, however, it was observed that although conditions appeared appropriate for reproduction, recruitment to the population did not occur. It was suggested (Harris and Gehrke 1993) that perhaps when the population of M. novemaculeata approaches carrying capacity, reproduction does not occur. This would provide a mechanism for population density regulation.

In this chapter I compare the demographic attributes of length, weight, condition, age, growth, sex ratio, density and in-stream habitat selection of M. novemaculeata between two different tributary types in the Hawkesbury-Nepean River Catchment; (i) ‘Obstacle-strewn’ tributaries were defined as irregularly connected pools, segregated by objects which were expected to impede M. novemaculeata migration under base flow conditions; and (ii) ‘Open’ tributaries lacking discernible obstacles that could impede the ability of M. novemaculeata to migrate under base flow conditions. The null hypothesis tested was that there is no significant difference in length, weight,

160 condition, age, growth, sex ratio, density, and in-stream habitat selection of M. novemaculeata between obstacle-strewn and open tributaries.

4.2 Methods

Site Description is described in Chapter 2, Section 2.1. Techniques used to capture fish are described under Sampling Method (Chapter 2, Section 2.2).

4.2.1 Length and Weight Fish were weighed (g) using an electronic balance (resolution – 0.1; AND ek-3000i, Bradford) and fork-length (mm; Figure 4.1) was calculated using a fish ruler (NSW Department of Primary Industries, 1 mm intervals).

Figure 4.1 Fork length of Macquaria novemaculeata was measured from the snout to the fork of the tail (Modified from NSW Department of Primary Industries 2015).

4.2.2 Sex Fish were dissected in situ using a cut from the anal fin to the gill slits with an extra- wide blade boning knife (Victorinox™, Schwyz). The sex of fish was established by viewing the gonads. Fish were classified as females if the gonads appeared yellow in colour (light to vibrant) and associated with external blood vessels indicating ovaries. Fish were classified as males if the gonads appeared white or cream in colour and lacked associated external blood vessels indicating testes (Harris 1986).

4.2.3 Habitat Selection and Density A comparison was made of M. novemaculeata in-stream habitat selection. To determine habitat selection, lures were cast near structure and away from structures into open water. Lures were cast by one fisherman, either from shore or kayak

161 (Australis, Sydney). When the fish attacked the lure it can be estimated where the fish took the lure, due to the feel in the lure retrieval process. Lures were cast 100 times into open water (approximately > 2 m from any visible structure) in conjunction with 100 casts close to structure (approximately < 2 m from visible structure) to ensure equivalent effort for each area. Casts were alternatively thrown into open water and towards structure. A tally was kept with the aid of a simple hand counter. The first five fish that were caught with the lure were euthanised. Further captures were released at point of capture until a total of 200 casts had been achieved. By using equivalent effort to catch fish, this procedure was used as a surrogate to measure the comparative fish density in the different feeding habitats.

4.2.4 Otolith Removal and Age Otoliths were removed from the head of each of the five fish retained. This was carried out in vitro using the boning knife. This procedure for removing the otoliths was a modification of Harris’ (1985a) method. This involved extraction of the gills and viscera by parting of the vertebral column from the skull. The bulbous posteroventral component of the basioccipital bone was then removed surgically using scissors. Physical handling was then used to remove excess flesh still attached to the removed segment, and to lever open the cavity housing the otoliths. Once removed, the otoliths were rinsed with Milli-Q water and stored dry in separate jars.

Otoliths were measured (mm) with digital callipers (resolution = 0.01; Whitworth, California) in both a longitudinal and transverse dimension where possible. The saggital otoliths were embedded within epoxy resin (Epofix, Struers, Denmark) and were cut centrally utilising an isomet low speed diamond band saw (Buehler, Illinois), ran at low speed, with lubrication provided by water (Elsdon and Gillanders 2002; Crook et al. 2006). The cutting was aimed centrally through the core of the otolith which is denoted by a cloudy white spot. The thickness of the sections was measured with callipers (mm) (resolution = 0.001; Mitutoyo, Japan) to approximately 0.4 mm. These segments were subsequently rinsed with Milli-Q water and allowed to dry on glass slides. After preparation, a sectioned otolith was placed on a glass microscope slide and affixed with additional epoxy resin and/or heated crystal bond around the edge of the hardened resin. Otoliths were then lightly polished with an aluminium

162 oxide (Al2O3) paste (20 M; 3 M; 0.3 M in a sequential manner) on a series of 6” microcloths (Buehler, Illinois) to remove any residual resin on the otolith surface and to create a smooth surface for analysis. At the completion of this process, sectioned otoliths were approximately 0.3 mm thick. To complete the preparation, the otoliths were rinsed with Milli-Q water and sonicated for five minutes. The prepared slides were subsequently dried in a laminar flow cabinet before storage in glass specimen containers prior to analysis of age (Miles 2007).

Successful aging occurred for 87 individual fish (Obstacle-Strewn 1 - 13; Obstacle- Strewn 2 - 16; Obstacle-Strewn 3 - 11; Open 1 - 18; Open 2 - 16; Open 3 - 13). The aging method employed by Harris (1985a) was used. An incremental annulus was classified as a growth-check when it formed a discrete ring around the dorsal half of the sectioned otolith. As often occurred, individual annuli would divide into separate lines at their dorsal flexure with reestablishment of a single line medially. Minimum age was subsequently obtained from the total number of annuli. Aging of fish was validated by Nathan Miles (Western Sydney University) and Jerom Stocks and Chris Walsh (New South Wales Department of Primary Industries).

4.2.5 Data Analysis

4.2.5.1 Length and Weight To investigate fish length and weight between tributary type and among sites, a nested analysis of variance (ANOVA) using IBM SPSS Version 20 was undertaken.

4.2.5.2 Condition To investigate fish condition, a condition factor (CF) was calculated using the formula employed by Ingram (2009):

To investigate fish condition between tributary type and among sites, a nested analysis of variance (ANOVA) was undertaken. If appropriate, a Tukey’s post-hoc test was used to identify specific differences in fish condition among tributaries.

163 4.2.5.3 Age To investigate fish age between tributary type and among sites a nested analysis of variance (ANOVA) was undertaken.

4.2.5.4 Growth To determine mean fish growth, length divided by age was calculated for all fish that were successfully aged. To investigate mean fish growth between tributary types and among sites, a nested analysis of variance (ANOVA) was undertaken. If appropriate, a Tukey’s post-hoc test was used to identify specific differences in fish growth among tributaries.

4.2.5.5 Sex Ratio To investigate sex ratio of fish between tributary types and among sites, a Chi Square Goodness of Fit analysis was conducted.

4.2.5.6 Length and Sex To investigate if fish length differed due to sex in different tributary types a 2d non- metric MDS ordination was created to visually represent these data. These data remained untransformed. Stress levels of all MDS plots were interpreted as follows: <0.05 = an excellent representation of the data, <0.1 = a good representation of the data, <0.2 = a useful plot although the results should be considered with caution, and >0.3 = not an ideal representation of the data (Clarke and Warrick 2001). PRIMERV6 with PERMANOVA was used to analyse the length of fish associated with sex between tributary type. A PERMANOVA test was undertaken for tributary type. If appropriate, pairwise PERMANOVA tests were used to identify where differences occurred.

4.2.5.7 Sex and Growth To investigate fish growth due to sex in different tributary types a 2d non-metric MDS ordination was created to visually represent these data. These data remained untransformed. Stress levels of all MDS plots were interpreted as outlined in Section 4.2.5.6. PRIMERV6 with PERMANOVA was used to analyse growth of fish associated with sex between tributary type. If appropriate, a pairwise PERMANOVA test was undertaken to identify where differences occurred.

164 4.2.5.8 Density To investigate fish density between tributary type and among sites a nested analysis of variance (ANOVA) was undertaken.

4.2.5.9 Habitat Selection To investigate in-stream fish habitat selection between tributary type and among sites, a Chi-Square Goodness of Fit Analysis was conducted.

4.2.5.10 Length and Habitat Selection To compare fish length between in-stream habitats in the different tributary types a 2d non-metric MDS ordination was created to visually represent these data. These data remained untransformed. Stress levels of all MDS plots were interpreted as outlined in Section 4.2.5.6. PRIMERV6 with PERMANOVA was used to compare the length of fish in different in-stream habitats, and between tributary type. A PERMANOVA test was undertaken for tributary type and, where appropriate, pairwise PERMANOVA tests identified where differences occurred.

4.2.5.11 Comparison of fish length between tributaries and riverine channel To compare the length of fish between riverine and tributary types, the length of fish caught in the tributaries by lure, were compared to M. novemaculeata data provided by Danielle Ghosn (DPI). The data provided by Danielle Ghosn was collected from fish caught in the main channel of the Hawkesbury-Nepean River between February 2010 - February 2011 by anglers in ‘Basscatch’ events. These anglers target fish close to structures (< 2 m) (D. Ghosn, pers. comm.). In an attempt to standardise the two datasets, analysis was restricted to fish caught near structure in the tributaries. In addition, only M. novemaculeata from the Basscatch data that had been caught in the Hawkesbury section of the Hawkesbury-Nepean River, between the North Richmond Road Bridge and Wisemans Ferry (i.e., excluding the Nepean reaches of the Hawkesbury-Nepean River, upstream of the Grose River confluence) because this was within the area where the tributaries of this study were sampled.

With these caveats, a one-way analysis of variance (ANOVA) was used to compare length of fish between the tributaries and the main channel of the river. Where appropriate, a Tukey’s post-hoc test was used to identify specific differences in fish length among habitats.

165

4.3 Results

4.3.1 Sex Ratio 2 There was no significant difference (χ 1=0.005. p=0.94, n=119) in the sex ratio of fish between open and obstacle-strewn tributary types (Figure 4.2). There were more females than males in both tributary types.

Figure 4.2 Total number of Macquaria novemaculeata males and females recorded in open and obstacle-strewn tributary types (December 2011 - April 2013) in the Hawkesbury-Nepean River.

4.3.2 Length and Sex There was a highly significant difference in the length of male and female fish between tributary type (Figure 4.3; Figure 4.4; Table 4.1). Pairwise PERMANOVA tests confirmed that males from open and obstacle-strewn tributaries were significantly smaller in size than females (Figure 4.3; Table 4.2). Females and males did not significantly differ in size between tributary types (Table 4.2).

166

Figure 4.3 Length of Macquaria novemaculeata between male and female fish from open and obstacle-strewn tributaries (December 2011 - April 2013) in the Hawkesbury-Nepean River (± S.E.).

Table 4.1 Analysis of the length of Macquaria novemaculeata between male and female fish from open and obstacle-strewn tributaries by PERMANOVA (December 2011 - April 2013) in the Hawkesbury-Nepean River (*** = 0.001 significance). Source d.f. Sum of Mean Pseudo- P Perms Squares Square F Tributary/Fish length 3 14558 4852.6 3.1745 0.001*** 998 Residual 44 67258 1528.6 Total 47 81816

167 Table 4.2 Pairwise analysis of the length of Macquaria novemaculeata between male and female fish from open and obstacle-strewn tributaries by PERMANOVA (December 2011 - April 2013) in the Hawkesbury-Nepean River (*** = 0.001 significance, ** = 0.01 significance, * = 0.05 significance, ns = not significant). Groups T P Unique perms (perm) Open Male, Open Female 2.3729 0.001*** 997 Open Male, Obstacle-strewn Male 0.66493 0.764ns 991 Open Male, Obstacle-strewn Female 2.0389 0.005** 998 Open Female, Obstacle-strewn Male 2.2242 0.002** 998 Open Female, Obstacle-strewn Female 1.0098 0.424ns 998 Obstacle-strewn Male, Obstacle-strewn 1.7164 0.013* 998 Female

4.3.3 Fish Length Overall, M. novemaculeata varied in length (114 – 390 mm, mean = 244.98 mm, s.e. = 4.38); however, there was no significant difference in the length of fish between open and obstacle-strewn tributary types (Figure 4.5; Table 4.3) or among tributaries (Figure 4.6; Table 4.3).

168

Figure 4.6 Mean length of Macquaria novemaculeata recorded in obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.).

Table 4.3 Nested Analysis of Variance of the length of Macquaria novemaculeata recorded in obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia (ns = not significant). Sum of Squares d.f. Mean Square F Sign. Tributary type 73.633 1 73.633 0.009 0.930ns Error 33880.067 4 8470.017 Tributary site (nested in 33880.067 4 8470.017 2.328 0.060ns tributary type) Error 414720.300 114 3637.897

4.3.4 Weight Overall, M. novemaculeata varied in weight between 31.9 - 996.4 g (mean = 299.43 g, s.e. = 16.93); however, there was no significant difference in the weight of fish between open and obstacle-strewn tributary types (Figure 4.7; Table 4.4) or among tributaries (Figure 4.8; Table 4.4).

169

Table 4.4 Nested Analysis of Variance of the weight of Macquaria novemaculeata recorded in obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia (ns = not significant). Sum of Squares d.f. Mean Square F Sign. Tributary type 706.160 1 706.160 0.01 0.925ns Error 281533.955 4 70383.489 Tributary site (nested in 281533.955 4 70383.489 2.106 0.085ns tributary type) Error 3809630.541 114 33417.812

170

4.3.5 Condition Overall, M. novemaculeata varied in condition between 1.12 – 2.28 (mean = 1.67, s.e. = 0.02); however, there was no significant difference in the condition of fish between open and obstacle-strewn tributary types (Figure 4.9; Table 4.5). There was, however, a highly significant difference in the condition of fish in different tributaries (Figure 4.10; Table 4.5). Differences were observed between open 2 and obstacle-strewn 3 as well as obstacle-strewn 2 and obstacle-strewn 3 (Table 4.6).

Figure 4.9 Mean condition of Macquaria novemaculeata recorded in obstacle- strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3).

Figure 4.10 Mean condition of Macquaria novemaculeata recorded in obstacle- strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.).

171 Table 4.5 Nested Analysis of Variance of the condition of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia (** = 0.01 significance, ns = not significant). Sum of Squares d.f. Mean Square F Sign. Tributary type 0.096 1 0.096 0.719 0.444ns Error 0.533 4 0.133 Tributary site (nested in 0.533 4 0.133 4.205 0.003** tributary type) Error 3.610 114 0.032

Table 4.6 A Tukey’s post hoc analysis of the condition of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia (** = 0.01 significance, ns = not significant). Tributary Tributary Site Mean Std. Sig. Lower Upper Site diff. error bound bound

Open 1 Open 2 0.052 0.056 0.937ns -0.110 0.2157

Open 3 -0.03 0.056 0.984ns -0.201 0.1252 -0.06 0.056 0.884ns -0.224 0.1017 Obstacle- strewn 1 0.059 0.056 0.900ns -0.104 0.2222 Obstacle- strewn 2 -0.15 0.056 0.081ns -0.315 0.0107 Obstacle- strewn 3

Open 2 Open 1 -0.05 0.056 0.937ns -0.215 0.1106

Open 3 -0.09 0.056 0.595ns -0.253 0.0727 -0.11 0.056 0.335ns -0.277 0.0492 Obstacle- strewn 1 0.006 0.056 1.000ns -0.156 0.1696 Obstacle- strewn 2 -0.20 0.056 0.005** -0.368 -0.0419 Obstacle- strewn 3

172 Tributary Tributary Site Mean Std. Sig. Lower Upper Site diff. error bound bound Open 3 Open 1 0.037 0.056 0.984ns -0.125 0.2011

Open 2 0.090 0.056 0.595ns -0.072 0.2536

Obstacle- -0.02 0.056 0.998ns -0.186 0.1396 strewn 1

Obstacle- 0.097 0.056 0.520ns -0.066 0.2601 strewn 2

Obstacle- -0.11 0.056 0.329ns -0.277 0.0486 strewn 3

Obstacle- Open 1 0.061 0.056 0.884ns -0.101 0.2245 strewn 1

Open 2 0.114 0.056 0.335ns -0.049 0.2771

Open 3 0.023 0.056 0.998ns -0.139 0.1866

Obstacle- 0.120 0.056 0.274ns -0.042 0.2836 strewn 2

Obstacle- -0.09 0.056 0.589ns -0.254 0.0721 strewn 3

Obstacle- Open 1 -0.05 0.056 0.900ns -0.222 0.1041 strewn 2

Open 2 -0.00 0.056 1.000ns -0.169 0.1566

Open 3 -0.09 0.056 0.520ns -0.260 0.0662

Obstacle- -0.12 0.056 0.274ns -0.283 0.0427 strewn 1

Obstacle- -0.21 0.056 0.004** -0.374 -0.0484 strewn 3

Obstacle- Open 1 0.152 0.056 0.081ns -0.010 0.3156 strewn 3

Open 2 0.205 0.056 0.005** 0.0419 0.3681

Open 3 0.114 0.056 0.329ns -0.048 0.2777

173 Tributary Tributary Site Mean Std. Sig. Lower Upper Site diff. error bound bound Obstacle- 0.091 0.056 0.589ns -0.072 0.2542 strewn 1

Obstacle- 0.211 0.056 0.004** 0.0484 0.3746 strewn 2

4.3.6 Age Fish varied in age between a minimum of three and a maximum of 28 years (mean = 8.91 years, S.E. = 0.53); however, there was no significant difference in the minimum age of fish between open and obstacle-strewn tributary types (Figure 4.11; Table 4.7) or among tributaries (Figure 4.12; Table 4.7).

174

Table 4.7 Nested Analysis of Variance of the age of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (ns = not significant). Sum of Squares d.f. Mean Square F Sign. Tributary type 1.957 1 1.957 0.053 0.829ns Error 150.904 4.091 36.891 Tributary site (nested in 148.468 4 37.117 1.550 0.196ns tributary type) Error 1939.486 81 23.944

4.3.7 Growth Mean growth rate ranged from 11.67 – 62.00 mm per year (mean = 34.24 mm, S.E. = 1.34); however, there was no significant difference in the growth of fish between open and obstacle-strewn tributary types (Figure 4.13; Table 4.8). There was, however, a significant difference in the growth of fish among tributaries (Figure 4.14; Table 4.8). Differences were observed between open 1 and obstacle-strewn 3 (Table 4.9).

175

Figure 4.13 Mean growth of Macquaria novemaculeata recorded in obstacle- strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3).

Figure 4.14 Mean growth of Macquaria novemaculeata recorded in obstacle- strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.).

Table 4.8 Nested Analysis of Variance of the growth of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (* = 0.05 significance, ns = not significant). Sum of Squares d.f. Mean Square F Sign. Tributary type 114.514 1 114.514 0.261 0.636ns Error 1771.841 4.045 437.997 Tributary site (nested in 1772.538 4 443.135 3.087 0.020* tributary type) Error 11625.563 81 143.525

176 Table 4.9 A Tukey’s post hoc analysis of the growth of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (* = 0.05 significance, ns = not significant). Tributary Tributary Mean Std. Sig. Lower Upper Site Site diff. error bound bound

Open 1 Open 2 -9.44 4.116 0.208ns -21.45 2.5721

Open 3 -11.3 4.360 0.110ns -24.05 1.3998 -5.37 4.360 0.819ns -18.10 7.3513 Obstacle- strewn 1 -7.57 4.116 0.446ns -19.59 4.4365 Obstacle- strewn 2 -14.7 4.584 0.022* -28.17 -1.4111 Obstacle- strewn 3

Open 2 Open 1 9.44 4.116 0.208ns -2.572 21.459

Open 3 -1.88 4.473 0.998ns -14.94 11.17 4.066 4.473 0.943ns -8.99 17.124 Obstacle- strewn 1 1.864 4.235 0.998ns -10.49 14.228 Obstacle- strewn 2 -5.35 4.692 0.863ns -19.04 8.3461 Obstacle- strewn 3 Open 3 Open 1 11.32 4.360 0.110ns -1.39 24.05

Open 2 1.885 4.473 0.998ns -11.17 14.943

Obstacle- 5.951 4.699 0.802ns -7.765 19.668 strewn 1

Obstacle- 3.749 4.473 0.959ns -9.30 16.807 strewn 2

Obstacle- -3.46 4.907 0.981ns -17.79 10.860 strewn 3

Obstacle- Open 1 5.377 4.360 0.819ns -7.35 18.105 strewn 1

177 Tributary Tributary Mean Std. Sig. Lower Upper Site Site diff. error bound bound Open 2 -4.06 4.473 0.943ns -17.12 8.9916

Open 3 -5.95 4.699 0.802ns -19.66 7.7652

Obstacle- -2.20 4.473 0.996ns -15.25 10.85 strewn 2

Obstacle- -9.45 4.907 0.398ns -23.74 4.909 strewn 3

Obstacle- Open 1 7.579 4.116 0.446ns -4.43 19.595 strewn 2

Open 2 -1.86 4.235 0.998ns -14.22 10.499

Open 3 -3.74 4.473 0.959ns -16.80 9.3084

Obstacle- 2.202 4.473 0.996ns -10.85 15.259 strewn 1

Obstacle- -7.21 4.692 0.641ns -20.91 6.4817 strewn 3

Obstacle- Open 1 14.79 4.584 0.022* 1.4111 28.178 strewn 3

Open 2 5.351 4.692 0.863ns -8.34 19.048

Open 3 3.465 4.907 0.981ns -10.86 17.792

Obstacle- 9.417 4.907 0.398ns -4.909 23.744 strewn 1

Obstacle- 7.215 4.692 0.641ns -6.481 20.912 strewn 2

4.3.8 Sex and Growth There was no significant difference in the mean growth of male and female fish in open and obstacle-strewn tributaries (Figure 4.15; Figure 4.16; Table 4.10).

178

179 Table 4.10 Analysis of the growth of Macquaria novemaculeata between male and female fish from open and obstacle-strewn tributaries by PERMANOVA over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia (ns = not significant). Source d.f. Sum of Mean Pseudo-F P Perms Squares Square Tributary/Fish growth 3 5753.9 1918 1.28 0.212ns 998 Residual 44 65931 1498.4 Total 47 71685

4.3.9 Density There was no significant difference in the density of fish between open and obstacle- strewn tributary types (Figure 4.17; Table 4.11) or among tributaries (Figure 4.18; Table 4.11).

180

Table 4.11 Nested Analysis of Variance of Macquaria novemaculeata caught per 200 casts recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (ns = not significant). Sum of Squares d.f. Mean Square F Sign. Tributary type 16.667 1 16.667 1.476 0.291ns Error 45.167 4 11.292 Tributary site (nested in 45.167 4 11.292 0.863 0.505ns tributary type) Error 235.500 18 13.083

4.3.10 Habitat Selection 1 There was no significant difference (χ 1 = 1.685. p = 0.59, n = 120) in fish habitat selection between open and obstacle-strewn tributary types (Figure 4.19) or among 1 tributaries (χ 5, = 9.014. p = 0.12, n = 120, Figure 4.20). More fish were caught near structure at both tributary types. Approximately 86% of all fish were caught within 2 m from structure.

181

4.3.11 Length and Habitat Selection There was a highly significant difference in the length of fish caught near structure and away from structure in open and obstacle-strewn tributaries (Figure 4.21; Figure 4.22; Table 4.12). Pairwise PERMANOVA tests confirmed that fish caught near structure from open and obstacle-strewn tributaries were significantly different in length from fish that were not caught near structure. Those near structure were longer than those caught away from it (Table 4.13).

182

Figure 4.22 Mean length of Macquaria novemaculeata caught near structure and not near structure from open and obstacle-strewn tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia (n = 3).

Table 4.12 Analysis of the length of Macquaria novemaculeata caught near structure and not near structure from open and obstacle-strewn tributaries by PERMANOVA over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (*** = 0.001 significance). Source d.f. Sum of Mean Pseudo- P Perms Squares Square F Tributary/Fish length 3 14861 4953.8 3.3505 0.001*** 999 Residual 44 65055 1478.5 Total 47 79917

183 Table 4.13 Pairwise analysis of the length of Macquaria novemaculeata caught near structure and not near structure from open and obstacle-strewn tributaries by PERMANOVA over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (*** = 0.001 significance, ** = 0.01 significance, ns = not significant). Groups T P Unique (perm) perms Open Structure, Open Not near structure 1.9396 0.006** 990 Open Structure, Obstacle-strewn Structure 0.86422 0.594ns 997 Open Structure, Obstacle-strewn Not near 2.3434 0.001*** 997 structure Open Not near structure, Obstacle-strewn 2.0364 0.004** 995 Structure Open Not near structure, 0.45567 0.919ns 819 Obstacle-strewn Not near structure Obstacle-strewn Structure, 2.3793 0.001*** 990 Obstacle-strewn Not near structure

4.3.12 Comparison of fish length between tributaries and riverine channel There was a very highly significant difference in fish length among habitats (Figure 4.23; Table 4.14). The length of fish from open and obstacle-strewn tributaries was very highly significantly different from the length of riverine fish. The average length of fish from riverine habitats was substantially smaller than those from either tributary type (Figure 4.23; Table 4.15).

184

Figure 4.23 Mean length of Macquaria novemaculeata recorded in obstacle- strewn and open tributaries over approximately two years (December 2011 - April 2013) and mean length of Macquaria novemaculeata recorded in riverine environments over approximately one year (February 2010 – February 2011) in the Hawkesbury-Nepean River, Australia (± S.E., n = 3).

185 Table 4.15 A Tukey’s post hoc analysis of the length of Macquaria novemaculeata recorded in obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) and mean length of Macquaria novemaculeata recorded in riverine environments over approximately one year (February 2010 – February 2011) in the Hawkesbury-Nepean River, Australia (*** = 0.001 significance, ns = not significant). Habitat Habitat Mean Std. Sig. Lower Upper diff. error bound bound

Obstacle- 6.10 9.233 0.787ns -15.65 27.84 Open strewn Riverine 80.75 8.370 0.000*** 61.04 100.47 Obstacle- -6.10 9.233 0.787ns -27.84 15.65 Open strewn Riverine 74.65 7.535 0.000*** 56.91 92.40 Riverine Open -80.75 8.370 0.000*** -100.47 -61.04 Obstacle- -74.65 7.535 0.000*** -92.40 -56.91

strewn

4.4. Discussion

4.4.1 Sex ratio and associated length and growth between the sexes The sex ratio of M. novemaculeata was equivalent between tributary types (Figure 4.2), with more females in both habitats. Although it has been reported that female M. novemaculeata will typically move further upstream than males outside of the spawning season (Harris and Rowland 1996), the upland obstacle-strewn tributaries of the current study had a similar female bias as the lowland open tributaries. Indeed, in the Sydney Basin, Harris (1985a) found contrasting results wherein 60% of fish from freshwater tidal habitats were males and 87% of fish caught in gorge and lagoon habitats were female. The areas sampled in the open tributaries of the current study were at the furthest extent of freshwater tidal habitat, before being classified as wholly freshwater habitat upstream. Fish caught at this interface may, therefore, not be consistent with Harris’s (1985a) freshwater tidal habitat fish, which likely spanned a greater portion of this habitat into more saline habitats where males may predominate. In the Murray-Darling Basin, female M. ambigua are also suspected of traveling farther distances upstream than males, some over 1000 km (Reynolds 1983; Mallen- Cooper and Stuart 2003). In three NSW rivers, the sex ratio of longfin eel Anguilla dieffenbachia was skewed strongly with a female bias (≤ 97 %) in freshwater (non-

186 tidal) reaches, with this bias becoming weaker in the tidal reaches (Walsh et al. 2004). This female bias was present in the current study, although it did not vary between the habitats studied. It appears, therefore, that there is some plasticity between the M. novemaculeata sexes associated with preferred habitat types.

Female M. novemaculeata were larger than males in both open and obstacle-strewn tributary types (Figure 4.3). Females of this species have been shown to be typically larger than males in the Sydney Basin (Harris 1987). This has also been observed elsewhere (Jerry and Cairns 1998), where female fish from seven different drainages were on average 2.6 cm longer than males. This differential growth between the sexes therefore appears to be consistent in this species throughout its range. This phenomenon has also been observed in other Australian percichthyids including M. ambigua (Anderson et al. 1992) and M. colonorum (Walsh et al. 2010). This sexual dimorphism has also been reported in the Australian freshwater species Macc. peelii (Gooley et al. 1995), and may occur in other species within the genus including Macquarie perch M. australasica (Appleford et al. 1998). Catadromous female A. reinhardtii have also been reported to have a greater mean size than males in three NSW rivers (Walsh et al. 2004). Elsewhere, for example in Spain, Herrera and Fernandez-Delgado (1992) observed that female and male Andalusian barbel Barbus bocagei sclateri attained different lengths. In contrast to these studies, S. trutta in Norway, exhibited no sexual dimorphism (Jonsson 1985). Overall, in many Australian and some fish species from other continents, females are larger than males, potentially as an ecological adaptation for successful recruitment (Harris 1986).

Harris (1987) found that male and female M. novemaculeata from tidal habitats were smaller than at upstream locations. This did not occur in the current study. In all habitats the sexes were of equivalent length (Table 4.2).

Average annual growth of male and female M. novemaculeata was equivalent in different habitats (Figure 4.15). Harris (1985a) observed female growth rate in gorge habitats was approximately twice the average of individuals that occupied tidally- influenced reaches. Jerry and Cairns (1998) also showed that female fish from seven different drainages were on average 2.6 cm longer than males indicating that they

187 attained a greater size than males. This pattern has also been observed in M. ambigua (Anderson et al. 1992) and M. colonorum (Walsh et al. 2010). The faster growth rates of females shown in these previous studies of M. novemaculeata and other percichthyids contrast with the current study. Faster male fish growth rates have been observed in populations of banded morwong Cheilodactylus spectabilis in North- eastern New Zealand (McCormick 1998). Contrary to the study on M. ambigua by Walsh et al. (2010), Mallen-Cooper and Stuart (2003) found that there was no difference in the growth rates of M. ambigua in the Murray River. Elsewhere, for example in England, growth rate did not differ between male and female dace Leuciscus leuciscus. The growth rate of males and females in the current study also typically contrasts with that of other Australian percichthyids. In both tributary types (open and obstacle-strewn) studied it appeared that fish grew at equivalent rates, regardless of sex.

4.4.2 Fish Size Indices Macquaria novemaculeata were of equivalent length (Figure 4.1) and weight (Figure 4.7) between tributary types and among tributaries. Similarly, Harris (1987) found that the length of M. novemaculeata in lagoon, gorge, and tidal freshwater habitats was equivalent. From 1977 to 1982, the average length of M. novemaculeata in the Hawkesbury-Nepean Catchment varied between an average of 230 and 255 mm (Harris 1988). In the current study the average fish length was approximately 250 mm from both tributary types. The findings of similar mean M. novemaculeata length in the Hawkesbury-Nepean River in studies conducted decades apart indicates that any anthropogenic impacts on this species appear to be equivalent across time, despite bans on commercial fishing for this species and stricter regulations on recreational fish take.

Fish from the tributaries were, however, on average, longer (mean = 251.63 mm) from tributaries than those from the main river channel (mean = 174.40 mm). These differences indicate that there is some segregation in preferred habit among fish of different sizes. Catchment-scale size differences have been observed by Van Der Walt et al. (2005). Macquaria novemaculeata caught in the Manning River had an average mean length of 330.0 mm. This substantially exceeded the length of fish in the

188 Hawkesbury-Nepean River (mean length 195.0 mm) while the average length of fish of the Williams River was intermediate between the other two rivers (mean length 215 mm). The length range of fish was also greater in the Manning (100 - 580 mm) and Williams rivers (50 - 510 mm) than in the Hawkesbury-Nepean River (50 - 425 mm). A closely related Australian species, Macc. peelii, was also observed to vary in size among habitats (Lake 1967). Within lake environments in the Murray-Darling River Basin, Macc. peelii had a longer average length than those caught in riverine habitats. This indicates that the mean size of at least these Australian fishes is lower in the main river channel than in associated waters, including open and obstacle-strewn tributaries. Since larger M. novemaculeata are more likely to be females (Harris 1986), this indicates that females may not be as prevalent in the main channel as they are in tributaries and the upper reaches of the river system.

The condition of Macquaria novemaculeata was similar in both tributary types. Harris (1987) recorded broadly similar findings as those in the current study in gorge and tidal freshwater habitats. In a lentic lagoon and farm dam habitats; however, the fish were in better condition than observed in gorge and tidal freshwater habitats. It was assumed that this was because fish were not able to migrate and thus had higher reserves than those in other habitats that were able to migrate (Harris and Gehrke 1993; Smith et al. 2011). As gonadal development for this species occurs between July and September (Harris 1986), female body condition can be exaggerated during this period (Harris 1987). Butler and Rowland (2008) examined the disparities in weight of Macc. ikei between winter and summer and identified timing of gonadal development as a principal contributor to weight. Prior to spawning in spring, Macc. ikei were observed to increase in weight in a progressive manner. As the spawning period came to an end the condition of fish was likely to be at its lowest point, and similar to other freshwater fishes post-spawning (Davis 1977; Rimmer 1985; Busacker et al. 1990; Meretsky et al. 2000). In the current study, no sampling was conducted during this period, therefore, no sampling bias should impact on fish condition due to spawning.

In New Zealand the condition of 350 - 500 mm shortfin eel Anguilla australis and 350-500 mm longfin eel Anguilla dieffenbachia was similar between lake and

189 backwater habitats (Chisnall 1989), contrasting with the Australian studies. In the Iberian Peninsula, lower fish condition was reported in chub Squalius laietanus and Mediterranean barbel Barbus meridionalis (Mas-Marti et al. 2010) when they occupied intermittent stream reaches.

Potentially, M. novemaculeata from obstacle-strewn tributaries could have been expected to be in better condition than those from open tributaries because migratory movement for spawning could have been impeded during low flow periods whereas it would not be in open tributaries and thus the energy expenditure associated with migration and spawning would have been less than when fish were not impeded by barriers to movement. Any impediment of migration for spawning did not, however, appear to increase M. novemaculeata condition in obstacle-strewn tributaries compared to open tributaries. It is therefore likely that M. novemaculeata of lotic habitats are unlikely to differ greatly between streams within the same catchment. Rather, differences are more likely to be observed when comparing lotic and lentic habitats (Harris 1987), habitats which are more dissimilar than those compared in the current study.

4.4.3 Age and Growth Harris (1987) recorded the oldest M. novemaculeata to be 22 years. Using equivalent techniques, the oldest fish identified in the current study was 28 years. Other percichthyids have also been reported to be long-lived. For example, the maximum recorded age of Macc. peelii was 48 years (Anderson et al. 1992), while golden perch M. ambigua has been recorded to live to 26 years (Mallen-Cooper and Stuart 2003), estuary perch M. colonorum to 41 years (Walsh et al. 2010), and Eastern freshwater cod Macc. ikei to 15 years (Butler and Rowland 2008).

The average age of Macquaria novemaculeata was similar in both open and obstacle strewn tributary types. Harris (1988) also found that the age frequencies of M. novemaculeata were similar across the habitats he studied (lagoon, gorge, tidal freshwater, farm dam) although individuals in the younger age groups were more frequent in freshwater tidal habitats than gorge habitats (Harris 1985a). He reported that from 1977 to 1982, the average age of M. novemaculeata in the Hawkesbury-

190 Nepean Catchment varied from 4.51 – 6.22 years (Harris 1988); whereas the average fish age of the current study was approximately 9 years from both tributary types. Despite this difference in average age, the mean length of fish was similar in the two studies (Harris 1985a – 230 – 250 mm; current study - 250 mm). Size truncation therefore appears to be occurring in the fish of the current study. This phenomenon typically occurs in fish as a result of size-selective harvesting whereby the larger individuals are targeted by recreational and/or commercial fishermen (Fenberg and Roy 2008). This is based on the assumption that slow growing fish are less likely to be retained than larger fish of the same age. This pattern of removal would select those individuals genetically pre-disposed to grow faster, and disproportionately replace them with slower-growing specimens (Johnson and Brown 1998).

Similar issues have arisen in the Atlantic cod Gadus morhua commercial fishery whereby the selective removal of the larger, most fecund fish affected the viability and sustainability of fish populations (Krohn and Kerr 1997). Populations of M. novemaculeata are, however, subjected to a variety of other impacts, in addition to recreational and commercial fishing that may also contribute to the potential for size truncation including river regulation (weirs - Hawkesbury-Nepean River, Harris 1986; dams – Shoalhaven River, Reinfelds et al. 2011), riparian disturbance (Growns et al. 1998) and pollutants (wastewater effluent – Growns and James 2005; oils - Cohen and Nugegoda 2000; Gulec and Holdway 2000).

Macquaria novemaculeata had equivalent growth between tributary types, indicating that neither habitat type supports faster-growing individuals. This is despite environmental characteristics that have been shown to influence fish growth in stream ecosystems. For example, Putman et al. (1995) found that growth of channel catfish Ictalurus punctatus was greatest in waterways with higher water velocity and instream cover. As with many Australian native fish (e.g., Macquarie perch M. australasica, Anderson et al. 1992), M. novemaculeata is generally considered a slow-growing species. It is the slowest of its genus (Harris 1987). Despite fish from both tributary types having similar growth, variability in growth of M. novemaculeata has been recorded in different habitats. Wilde and Sawynok (2005) found differential growth rates for M. novemaculeata. Growth rate was observed to be slowest in the

191 smallest/deepest impoundment and highest in the largest/shallowest impoundment. However, these dissimilar impoundment habitats are likely to have different productivity rates due to the nature of their construction. The current study was focused upon naturally occurring watercourses with similar depths.

Of the same genus, M. ambigua, have also shown no significant difference in growth rates between adjacent river basins (Roberts et al. 2008). In the U.S., growth of I. punctatus did not differ between high and low gradient stream reaches with different habitat conditions (Tyus and Nikirk 1990) while in Western Ireland, S. trutta growth did not vary with riparian vegetation type, despite greater fish densities in closed canopy streams (Dineen et al. 2007). As observed in the current study, these studies indicate, that despite apparent habitat differences, fish growth may remain equivalent under a variety of conditions.

Although overall there was not a difference between tributary types, there was a difference in the growth of M. novemaculeata among tributaries. The three slowest growing fish were collected from a waterway (Cattai Creek) that generally exhibits poor water quality, due largely to stormwater and sewage effluent discharge from the headwater reaches (Bailey et al. 2000). Since urbanisation began in the upper reaches of this Creek, it has been heavily altered (e.g. sedimentation), and much of the natural riparian vegetation has also been affected by these changes and from past clearing in the catchment (HNCMA 2007). Tyus and Nikirk (1990) found slow growth in I. punctatus in two U.S. rivers (Green and Yampa rivers) and suggested that this may have resulted from, for example, unfavourable riverine conditions. It is, therefore, likely that the slower growth of M. novemaculeata in Cattai Creek was due to unfavourable conditions caused by anthropogenic impacts.

4.4.4 Habitat selection, habitat selection by fish of different sizes, and density

In both tributary types, habitat near structure was selected most frequently by M. novemaculeata. Harris (1988) reported that this was typical behaviour for M. novemaculeata. He did not net any fish more than a few metres from structure, and did not catch any M. novemaculeata in open waters. He also observed that M.

192 novemaculeata dependence on structure persisted from juvenile stages where they tended to be observed around, for example, macrophytes, to adult stages when they were observed to tend to prefer coarse woody debris. Growns et al. (1998) also found that M. novemaculeata favoured habitat adjacent to vegetated, as opposed to degraded banks. It is likely, therefore, that as observed in Macc. peelii (Jones and Stuart 2007), M. novemaculeata are predators that lie-in-wait near structure, regardless of stream type occupied. Savino and Stein (1989) observed that predators such as largemouth bass M. salmoides and northern pike Esox lucius also preferred densely-vegetated sites, likely due to reduced energetic costs in ambushing prey as it passes their lie.

Other Australian fish species (e.g., blackfish Gadopsis marmoratus, Macc. peelii, trout cod Macc. macquariensis, M. ambigua) that are important for recreational fishing and maintenance of stream ecosystems have been observed to be strongly correlated with, and even reliant on, coarse woody debris (Koehn and O’Connor 1990). For example, Kennard (1995) showed that manipulating the amount of added woody debris in naturally-occurring floodplain lagoons modified the fish assemblage present. One major benefit of woody debris is that it may act as a refuge for fish that are prey of predatory species (e.g., barramundi Lates calcarifer, fork-tailed catfish Arius graeffei). In the Hawkesbury-Nepean River, Growns et al. (2003) found that freshwater mullet Mugil petardi were in greater abundance adjacent to well-vegetated banks than grassed banks. This preference for structure, therefore, extends to other species that occur sympatrically with M. novemaculeata in the Hawkesbury-Nepean River.

This preference for structure by fish has been observed in other studies. Johansen et al. (2005) found that Salmo salar actively sought small-sized tributaries with high levels of riparian cover while the bull trout Salvelinus confluentus has been observed to prefer coarse woody debris for cover (Swanberg 1997). Chara et al. (2006) also found that catfish Trichomycterus spp. in the Colombian Andes selected microhabitat based on cover suitability rather than water depth. In marine reef fish of the Adriatic Sea, habitat structure (e.g., seagrass, rocks) was preferred over areas of bare sand, and was regarded as one of the primary factors influencing nearshore fish assemblages (Guidetti 2000).

193

In the current study, habitat selection by fish of different sizes was equivalent between tributary types (Table 4.13). Mean fish length was greater in M. novemaculeata caught near structure, and this differed in each tributary type. In the Hawkesbury- Nepean River, Growns et al. (2003) found that larger M. novemaculeata occupied areas adjacent to vegetated banks. The dissimilarity observed between the studies was probably attributable to variation in habitat (or micro-habitat) preferences for fish of different sizes. Larger M. novemaculeata appeared to benefit from the habitat structure and canopy associated with the riparian zone. Growns et al. (2003) made the observation that M. novemaculeata were captured in greater numbers adjacent to grassed banks. It appears, therefore, that management of instream and riparian habitats is paramount for conservation of this species, as M. novemaculeata utilise varying habitats throughout life stages with a focus on structure in adult life. Juvenile and adult Sooty Grunter Hephaestus fuliginosus (Mulgrave River, QLD) also selected different habitat. Adults were typically found in areas of undercut banks and large snags, whereas juveniles were observed feeding in large loosely organised schools in open, flowing water (Pusey et al. 1995a; 1995b). Differential habitat selection between fish size classes was also reported by Collares-Pereira et al. (1995) in Portuguese lowland streams. They observed that larger fish favoured deeper areas with greater levels of riparian cover than smaller individuals. A study on brown trout S. trutta established that the quantity of overhanging riparian vegetation in well vegetated riparian zones directly correlated with the larger size of fish (Wesche et al. 1987).

No cannibalism has been recorded in M. novemaculeata (Harris 1985b; Smith et al. 2011). This may be an explanation for why smaller individuals less frequently utilised structure for habitat. They do not suffer the risk of being ambushed by larger M. novemaculeata which are often the apex predator in these aquatic environments (Harris 1983). Swimming freely in open water can therefore be performed with limited risk. Koehn (2009) observed that juvenile Macc. peelii preferred habitat with more coarse woody debris close to the bank than adult individuals. This habitat selection was considered to be a strategy to avoid predation by larger predatory fish, including adult Macc. peelii which do cannibalise younger individuals (Cadwallader

194 and Backhouse 1983). Likewise, Mittelbach (1981) predicted that larger bluegill sunfish Lepomis macrochirus were less constrained in their habitat selection due to lower predation risk.

Macquaria novemaculeata were present in equivalent density in the different tributary types. Harris (1988) also found no difference in M. novemaculeata density in his studies in the Sydney Basin. However, Harris (1988) did suggest that density of M. novemaculeata is more likely to be aligned with bank length as opposed to habitat surface area. Elsewhere, fish density has been reported to decrease as stream order increases (Weinstein 1979; Rozas and Odum 1987; Hettler 1989). It may have been expected then that as obstacle-strewn tributaries had a higher perimeter to area ratio of preferred habitat, fish density would be higher in this tributary type. As this did not occur, it can be assumed that both tributary types offer equivalent habitat benefits for this species.

In the U.S., I. punctatus occurred in higher densities in higher gradient streams (Layher and Maughan 1985; Tyus and Nikirk 1990). In Western Ireland, S. trutta densities were higher in streams with closed canopies (Dineen et al. 2007). Alternatively, Hawkins et al. (1983) found that the density of fish was lower in small streams with dense shading than more open streams with less shading. Obstacle- strewn tributaries exhibited denser canopy cover than open tributaries. Stronger differences in fish density that come from these contrasting habitats may not occur due to the variation in structure/cover made available from the riparian habitat. In obstacle-strewn tributaries, canopy trees provide cover, bind soil, and reduce erosion and the undercutting of banks. Open tributaries, which are more consistent with grassland streams, may be more susceptible to erosion and bank undercutting (Dineen et al. 2007). Undercut banks may, therefore, be utilised for habitat as readily as areas of, for example, coarse woody debris, which was typically more widespread in obstacle-strewn tributaries. The extent of preferred habitat available to M. novemaculeata may, therefore, be more complex than use of the more obvious structure (e.g., coarse woody debris).

195

4.5 Conclusions

Despite the habitat differences evident in each tributary type, parameters measured including fish length, weight, condition, age, growth, sex ratio, sex and growth, density and habitat selection were similar in both tributary types. The demographic similarities of the populations of M. novemaculeata between the two tributary types reinforces this species adaptability as a generalist, able to thrive in dissimilar habitats.

In comparing fish length between tributaries and the riverine channel, it was observed that longer fish typically occupied tributaries. This correlates to the female sex ratio bias in the tributaries, as this sex was larger than males. Males have been reported to occur more frequently in downstream riverine habitats (Harris and Rowland 1996). Maintaining tributary populations of M. novemaculeata is therefore paramount to the sustainability of the species as females inhabit these tributaries, potentially in greater abundance than in riverine habitats.

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212 5. Dietary analysis of the Percichthyidae Australian bass Macquaria novemaculeata in tributaries of the Hawkesbury-Nepean River

5.1 Introduction

Research into the dietary aspects of fishes is critical in establishing appropriate management practices which leads to their sustainable management, in both the long and short-term (Santos et al. 2001); however, there is a dearth of information on the diet of many species (Butler and Wooden 2012). Obtaining this dietary information for many fish species is often fraught with difficulties associated with logistical issues and diet variation in different waterways and habitats. Disparities in dietary components are chiefly attributed to (i) geographical isolation (Szepanski et al. 1999; Stehlik and Meise 2000; Olson et al. 2003), (ii) change in dietary preference as an individual attains greater sizes (Knutsen et al. 2001; Renones et al. 2002), (iii) seasonal movements to distinctly-different habitats (e.g., migrating from freshwater to saltwater in order to spawn) (Joyce et al. 2002; Jerry and Baverstock 1998), and (iv) limitation or seasonality of preferential food types leading to substitution with different food items (Munkittrick and Dixon 1989, Specziar et al. 1998).

For the management of predatory fish, information on diet in different aquatic habitats is informative. This is because by identifying the diet of fish under different stream characteristics, an understanding of what habitat variables influence the presence of prey can be ascertained (Smith et al. 2011b). Highly complex habitats exhibit a wider range of ecological niches than simple ones, and subsequently sustain a greater diversity of organisms (Pianka 1966; Grenouillet et al. 2002). Indeed, Chara et al. (2006) found that stream habitat characteristics (e.g., stream size, type of substratum, flow type) in the Colombian Andes had the strongest influence on macroinvertebrate communities present. Likewise, in the Satilla River in south-eastern Georgia, woody material supported 60% of the total invertebrate biomass despite representing only 4% of habitat surface. The fish studied relied strongly on these prey, and the authors reinforced the importance of such habitat traits at different trophic levels (Benke et al. 1985).

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Headwater streams are regarded as significant habitats for the production of macroinvertebrates (Wallace et al. 1986, 1997; Stone and Wallace 1998). The small size of these streams, and subsequent high-perimeter-to-area ratio, intensifies the aquatic-terrestrial interface (Polis et al. 1997; Wipfli 2005). In small forest streams, allochthonous input from streamside vegetation often contributes to the majority of matter consumed by benthic invertebrates, particularly in temperate regions (Fisher and Likens 1973; Vannote et al. 1980; Cummins et al. 1989; Wallace et al. 1997). The greater complexity at the aquatic-terrestrial interface in such regions can also supply invertebrates of terrestrial origin (e.g. Hymenoptera, Hemiptera, and Coleoptera) to the water body (Cadwallader et al. 1980; Nielsen 1992). This food source has been identified as contributing substantially to the diet of salmonids, with a higher contribution in forested stream reaches than grassland reaches (Wipfli 1997; Nakano et al. 1999b; Kawaguchi and Nakano 2001). Elsewhere, in streams of New Zealand, the diet of the banded kokopu Galaxias fasciatus consumed terrestrial prey in higher abundance in forested streams compared to other stream types (Main and Lyon 1988; West et al. 2005). West et al. (2005) suggested that this species preference for forested streams might therefore be influenced by its apparent preference for terrestrial prey. It has also been reported that the energy density of terrestrial invertebrates typically exceeds that of aquatic invertebrates (Cummins and Wuycheck 1971). This is because terrestrial invertebrates often have a more extensive exoskeleton, containing higher density energy. For example, Sweka and Hartman (2008) stated that if the terrestrial invertebrates of the diet of brook trout Salvelinus fontinalis were reduced by 100% it would take an increase of approximately 130% aquatic invertebrates to obtain the same energy for growth. This was supported by the observation that Salv. fontinalis grew slower when terrestrial invertebrate consumption was lower. However, their study did recognise that if much of this exoskeleton was indigestible the actual energy gain may be equivalent to that which can be obtained from aquatic invertebrates.

Compared to adjacent terrestrial vegetation, riparian vegetation has a higher abundance and diversity of terrestrial invertebrates (Jackson and Resh 1989; Lynch and Catterall 1999; Malanson 1993; Catterall et al. 2001). With riparian clearing, for

214 example, for farming or logging, the abundance of terrestrial invertebrates available to stream fish may be diminished, and in some situations lost due to the destruction of riparian habitat (Cummins 1975; Hynes 1975). This suggestion is supported by observations from a study in Victoria (Australia) where the number of terrestrial invertebrates used as a food source by fishes was greatest where there was overhanging terrestrial vegetation (Cadwallader et al. 1980). In assessing food intake of fish from forested streams in Japan it was observed that the fish diet consisted of 53% terrestrial invertebrates (Kawaguchi and Nakano 2001). This has also been observed elsewhere. For example, in a Sri Lankan stream, Moyle and Senanyake (1984) found that fish diet consisted of 44.0% terrestrial invertebrates. Garman (1991) also observed that when aquatic prey had diminished, cyprinids relied more heavily on terrestrial invertebrates than at other times. However, the relative importance of terrestrial invertebrates may vary with lifecycle stage. For example, older mountain galaxias Galaxias olidus rely more heavily on terrestrial invertebrates as a food source than younger fish. This highlights the importance of the riparian zone as a food source, at least for some fish species (Hunt 1975).

As alluded to above, the riparian zone and its health can also affect macroinvertebrate populations that occupy a given stretch of waterway. One study (Danger and Robson 2004) established macroinvertebrate community differentiation between two riparian zone categories that were equivalent to those in the current study (i.e., pasture and forested). These identifiable niches had a different suite of macroinvertebrates, with a transition zone in which both macroinvertebrate communities overlapped between the riparian zone types. Similarly, Scarsbrook and Halliday (1999) also focused on pasture-based and forested riparian zones adjacent to three waterways, in regards to differences in macroinvertebrate communities. The same shift of macroinvertebrates found in the study conducted by Danger and Robson (2004) was also observed. As little as 50 m into forested regions a macroinvertebrate community was comparable to areas 250 m into the forested regions. Arnaiz et al. (2011) also found a change in macroinvertebrate community diversity due to riparian vegetation type. They observed that these communities responded rapidly to riparian vegetation characteristics and associative woody material and allochthonous matter, despite only using this habitat indirectly.

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Many prey macroinvertebrates are readily affected by changes in water temperatures and this can affect their presence or absence in a particular stream reach. Shading of a waterway as a result of the presence of riparian vegetation and structure also potentially affects food available for fish by controlling the light that actually reaches the water’s surface (Bunn et al. 1997; 1999). This may subsequently affect how much a fish’s diet is comprised of certain prey (Davies and Nelson 1994; Rutherford et al. 1997, 2004). However, when prey is not limited higher water temperature usually results in enhanced fish growth rates although such increased water temperature may also result in excessive occurrence of filamentous green algae not generally consumed by macroinvertebrates. Its presence may therefore result in a fall in macroinvertebrate abundance. Such a drop in invertebrates could correlate to a potential loss of fish abundance when adequate food sources are not available to supplement the loss of macroinvertebrates (Bunn et al. 1999; Pusey and Arthington 2003).

When considering diet, ecologists consider two key divisions to aid them in defining feeding choices of animals such as fish - specialist or generalist. Predatory specialist feeders are defined as those that generally restrict their diet to a limited band of habitats and/or have limited diversity of prey in their diet. Predatory generalists are defined as those that can exist in a wide variety of habitats and can thrive on a diet consisting of a wide variety of prey (Bridcut and Giller 1995; Amundsen et al. 1996). Nevertheless, either feeding strategy is built upon the foundation that whilst foraging for food the total nutritional content/energy intake must either meet or exceed the total nutritional content/energy loss experienced in seeking, feeding upon, and digesting said prey (Werner et al. 1983a, 1983b, McIvor and Odum 1988, Turesson et al. 2002).

Whilst several factors may impact upon a fish’s dietary habits, it is ultimately the level of interaction that exists between a predator and prey that affects the actual consumption of particular food items (Schoener 1971; Floeter and Temming 2003). Hence, it is reasonable to assume that prey at higher densities are likely to elicit a greater response from predatory fish that feed upon them than when they are present at lower densities (Stewart and Jones 2001). This phenomenon was also observed by Davis (1985) who reported that dietary differences in barramundi Lates calcarifer

216 between tidal salt water and non-tidal fresh water habitats was likely attributed to prey availability rather than a shift in dietary preference. Elsewhere, in streams of the Colombian Andes, catfish Trichomycterus spp. did not appear to select prey, but rather consumed those macroinvertebrates that were most abundant (Chara et al. 2006). One study looked at the reestablishment of fauna in tidal creeks that had been rehabilitated. Of interest was the initial colonisation of these waterways by the shrimp species Acetes sibogae australis, followed by the colonisation of the predators Castlenaui’s herring Herklotsichthys castelnaui, goldspot mullet Liza argentea and sea mullet Mugil cephalus known to feed upon them. Whilst this could be seen as a coincidental occurrence during the faunal recolonisation of a vacated environment, it is more likely that these predatory fish had moved into this environment in a response to the prey availability (Boys et al. 2012).

Alternatively, some predatory fish, such as Eastern freshwater cod Maccullochella ikei, alternate readily between food sources. This generalist carnivore is an apex predator in the waterways in which it occurs naturally (Rowland 1993). In the Mann and Nymboida rivers of northern NSW, Butler (2001) reported that where Macc. ikei foraged for food items differed depending on prey availability. This variation within the species’ niche is likely to be attributable in some part to the seasonality of some dietary items. As a consequence, when preferred prey items are not readily available, this species will be less selective than when such prey is plentiful (Schoener 1971, Pyke 1984). Likewise, Butler and Wooden (2012) established that whilst Macc. ikei had an overall preference for crustaceans, in excess of an additional 30 species were also consumed as prey. These food items included both terrestrial and aquatic prey, and also larger items such as reptiles, fish, and mammals, together with smaller items such as insects. The related Murray cod Maccullochella peelii also exhibits similar dietary traits which have been further likened to the dietary traits of the introduced redfin perch Perca fluviatilis. During spring spawning in the Murray-Darling system, P. fluviatilis juveniles compete for prey with Macc. peelii larvae and potentially also prey on these fry (Lake 1967). This phenomenon is likely to be exacerbated during periods of limited rainfall when there is usually a reduction in available prey. This was supported by the catch data obtained between the years of 1919 and 1949, from the Kerang Lakes in Victoria. It was shown that when P. fluviatilis were more

217 common, native fish were less abundant. Estuary perch Macquaria colonorum is another Australian fish species that consumes a wide variety of prey throughout a range of habitats. In the Hopkins River (Victoria), Howell et al. (2004) categorised the broad range of prey taken by M. colonorum into five prey groups (freshwater shrimp Paratya australiensis; Amphipoda; freshwater crab Amarinus lacustrine; teleosts and tricopteran larvae) and found that, these groups made up 98% of this species’ diet. However, their primary prey was P. australiensis which contributed in excess of 38.5% to this species’ diet. These findings supported past observations made in the Hopkins River (Victoria). McCarraher and McKenzie (1986) found that shrimp and prawns made up 52% of the prey abundance for this species. Howell et al. (2004) stated that M. colonorum showed a preference for specific prey, not always the most common species in their habitat. They observed that while gastropods were the most commonly encountered potential prey in both freshwater and estuarine habitats, their contribution to the diet of M. colonorum was negligible.

To maintain this optimal feeding strategy there is generally a requirement to accommodate larger food items consistent with an increasing body size (Sagar and Eldon 1983, Werner et al. 1983a, Clapp et al. 1990, Beauchamp and Van Tassell 2001). Still, stream-resident salmonids have been shown to maintain growth if they have access to a highly abundant supply of smaller prey items (Steingrimsson and Gislason 2002). As fish grow, juveniles typically take advantage of prey sources by modifying their use of ecological niches.

Occasionally, habitat use and prey consumption is so distinct that populations can be divided into size classes where they play a different role within the ecosystem (King 2005). Such ontogenetic dietary shift is common in a range of fish species, especially in those that are piscivorous (Werner and Gilliam 1984; Olson 1996). Indeed, in a study on snakehead Channa limbata in Thailand, Ward-Campbell and Beamish (2005) identified ontogenetic dietary change as assisting in reducing inter-specific competition. This strategy limited overexploitation of certain taxa, until such time as the fish grow to a size where they can compete with others for particular food resources. In Australia, ontogenetic dietary shift has been observed in Macc. ikei where fish ≥ 551 mm consumed fewer crustaceans than fish ≤ 350 mm. The larger

218 fish also consumed more terrestrial animals and large fish compared to smaller fish which had a higher composition of aquatic insects in the diet (Butler and Wooden 2012). Similarly, barramundi Lates calcarifer also exhibited an ontogenetic dietary shift from crustacea to fish, with fish > 1000 mm consuming a diet that consisted of 87% fish (Davis 1985). Largemouth bass Micropterus salmoides also showed a dietary shift to a more piscivorous feeding strategy as they grow (Garcia-Berthou 2002). This Spanish study found that fish 25-75 mm fed mainly on amphipods and insects (e.g. ephemeropterans); fish 100-225 mm on freshwater shrimp, small fish, and insects; fish 250-300 mm on shrimp or crayfish; and fish > 300 mm on crayfish and large fish. An almost exclusively piscivorous diet in adulthood has also been observed in shortfinned eel Anguilla australis and longfinned eel A. dieffenbachii in New Zealand (Jellyman 1989), and in a range of tropical piscivores in Venezuela (Winemiller 1989).

5.1.1 Dietary aspects of Macquaria novemaculeata Macquaria novemaculeata is primarily a generalist carnivore, and this can influence the composition of lotic and lentic food-webs (Allen et al. 2002; Smith et al. 2011b). As observed in some other fishes (e.g., mulloway Argyrosomus japonicus; other percichthyids – Macc. peelii, golden perch Macquaria ambigua), the segment of its home range that an individual inhabits when not undertaking migration is generally a linear stretch of the riverine environment (Crook 2004; Taylor et al. 2006; Jones and Stuart 2007). It is assumed that this habit provides individuals with the advantage of being familiar with their surrounding habitat and prey availability. Other species, for example, European sea sturgeon Acipenser sturio, have also been shown to have similar site fidelity that is directly correlated to the presence of prey, predominantly immobile benthic organisms (Lepage et al. 2005).

Macquaria novemaculeata generally consume a variety of small fishes and invertebrates (e.g., aquatic - freshwater shrimp Paratya australiensis; terrestrial – members of the Cicadidae family) but rarely molluscs or sizeable crustaceans (e.g., adult Cherax spp. [yabby]). However, especially in tidally-influenced reaches, a large proportion of their diet is composed of burrowing decapods. In addition to dietary variation among sites, M. novemaculeata diet has been observed to vary with season

219 (Harris 1985b), although dietary preference appears to be more complex than simply seasonal. For example, teleost fish have been observed to be the most important prey, although invertebrates (terrestrial and aquatic) are commonly consumed, especially in summer months. The highest consumption of terrestrial invertebrates occurred in a gorge with limited riparian vegetation, and there were differences in diet among river reaches (estuarine to freshwater – Harris 1985b). In addition, despite being considered a generalist carnivore, M. novemaculeata may exhibit phases more attributable to a specialist predator. Smith et al. (2011b) found that during the cool month of August, approximately 80% of individuals had consumed a mean of 80% Daphnia sp. Similarly, in May, more than half the fish examined had 75% Chaoboridae larvae in their gut. These data indicate that M. novemaculeata is an opportunistic generalist predator. When a specific prey is in abundance, M. novemaculeata will switch diet. For example, Smith et al. (2011b) found that diet differed with month (e.g., fishes - May, December; insects - May, December; Chaoboridae - August; Ecnomidae - December; Chironmidae, Culicidae - March). Piscivory was highest in August for fish as small as 67 mm, although fish (e.g., flathead gudgeon Philypnodon spp.; Australian smelt Retropinna semoni) were only a common dietary component in individuals larger than 100 mm. The only prey that was restricted to a specific size category of fish was copepods and ostracods. These taxa were only consumed by individuals less than 100 mm (Smith et al. 2011b). The differences in diet are likely an adaptation to the multiplicity of M. novemaculeata habitats, coupled with the Australian environment, which is highly variable (Sternberg et al. 2008; Smith et al. 2011b). Pond-reared silver perch Bidyanus bidyanus were also observed to primarily feed on a specific prey but progressively targeted a greater diversity of prey as the available prey community moved to a more diverse state (Warburton et al. 1998). Harris (1985b) observed a similar pattern of prey selection by M. novemaculeata in riverine environments. The primary difference in diet was the higher composition of Daphnia sp. in impoundment populations throughout August. This correlated to abundance in zooplankton tows which were composed of 2350 ± 276 Daphnia spp. 100 m−3 near the edge and 5730 ± 2350 Daphnia sp. 100 m−3 recorded in the impoundment’s central region (Smith et al. 2011b).

In addition to prey availability, the size of prey and the gape width of the fish influence the predator’s target (i.e., the larger the gape, the larger the size of prey that

220 can be consumed - Pearre 1986; St John 1999; Scharf et al. 2000; Smith et al. 2011b). Smith et al. (2011b) confirmed that a progressive enlargement of M. novemaculeata gape resulted in progressively larger maximum prey size. However, the mean prey size taken has been found to usually be much smaller than the maximum size the individual’s gape would allow them to engulf. This is likely attributable to the ease with which smaller prey items (e.g., macroinvertebrates) can be consumed in comparison to larger, more mobile prey (e.g., fishes). Smaller prey may also be more abundant and available to M. novemaculeata than the larger prey items, depending upon season and/or waterway reach that the individual occupies (Harris 1985b; Smith et al. 2011b). In addition, larger prey items typically require higher energy expenditure for targeting and consumption, hence, M. novemaculeata may gain greater endpoint nutrition through consumption of smaller, less mobile organisms in greater quantities (e.g. burrowing decapods – Harris 1985b) than larger, potentially less abundant taxa. This has been shown in a study by Hansen and Wahl (1981) who found that yellow perch Perca flavescens actively targeted smaller water flea Daphnia pulex rather than larger prey that they were capable of consuming. They attributed this to the employment of an optimal foraging strategy whereby larger D. pulex with greater potential of predation escape were avoided.

Active feeding in M. novemaculeata has been shown to be highest in crepuscular periods (riverine - Harris 1985b; impoundment - Smith et al. 2011a). This strategy is probably due, in part, to the benefits of low-light hunting and the presence of appropriate active prey availability at dawn and dusk. Foraging during crepuscular periods is a common strategy for predatory fish that feed upon vertically-migrating zooplankton and/or zooplanktivorous fish, as do M. novemaculeata (Harris 1985b; Smith et al. 2011a). The predator/prey interaction may also be affected by the immediate aquatic thermal regimes. For example, successful capture of prey can depend on locomotor performance which is sensitive to variation in temperature. With a change in temperature regime, community structure can be altered due to variability in predatory pressure among prey species. Grigaltchik et al. (2012) established that mosquitofish Gambusia holbrooki had a lower tolerance for cooler waters than M. novemaculeata. Conversely, compared to M. novemaculeata, warmer temperatures did not affect locomotor performance and hence, at higher temperatures G. holbrooki were potentially more likely to evade predation than in relatively cooler waters. This

221 demonstrates that this species’ diet has the potential for certain prey species to be more readily targeted due to the water temperature in which M. novemaculeata reside.

Understanding habitat occupancy and associated diet of M. novemaculeata is important as only one other known study (Harris 1985b) has extended into isolated waterways when studying the feeding strategy of this species. In this chapter I investigate the diet of M. novemaculeata in two different tributary types in the Hawkesbury-Nepean River catchment; (i) ‘Obstacle-strewn’ tributaries, defined as irregularly connected pools, segregated by objects which were expected to impede M. novemaculeata migration under base flow conditions; and (ii) ‘Open’ tributaries lacking discernible obstacles that could impede the ability of M. novemaculeata to migrate under base flow conditions. The null hypothesis tested was that there was no significant difference in the diet of M. novemaculeata between obstacle-strewn and open stretches of waterway in the tributaries studied. Such information has the potential to play a key role in management of this species.

5.2 Methods

Site Description is described in Chapter 2, Section 2.1. Techniques used to capture fish are described under Sampling Method (Chapter 2, Section 2.2).

5.2.1 Dietary Analysis The fish were dissected in situ using a cut from the anal fin to the gill slits with an extra-wide blade boning knife (Victorinox™, Schwyz). The stomach, including contents, was then carefully removed from the fish. The stomach was slit open and the contents removed and placed in a jar of 96% ethanol and sealed. In addition to the contents collected from the stomach, food items from the throat and those that were regurgitated by the fish during capture were also collected and stored in the jar with the stomach contents, and the samples were taken to the laboratory for analyses.

All food items retrieved from a fish were analysed as ‘total stomach contents’. The wet mass of the contents of each stomach of each fish were weighed (g) using an electronic balance (resolution – 0.01; AND ek-300i, Bradford). Food items were identified with the aid of an externally-illuminated dissecting microscope (Nikon,

222 Lidcombe) at 10x magnification. To aid in identification the keys of Allen et al. (2002), Gooderham and Tsyrlin (2002), and Swanson (2007) were used.

All recently consumed food items (intact/undigested) were identified and counted. As M. novemaculeata rapidly digest prey (Harris 1985), stomach content often consisted of items that were not immediately identifiable. Such partly digested food items were identified, where possible, from shell fragments, antennae, legs and other remains (cf. Norderhaug et al. 2005) and, where possible, the number of individuals of each taxon was deduced. Vertebrates were subsequently classified to no greater than Order, and invertebrates to no greater than Family. The wet weight of each taxonomic group was subsequently determined to establish the wet mass dietary importance of each group (Labropoulou and Eleftheriou 1997).

All identified food items were also allocated to one of four categories; aquatic invertebrates, terrestrial invertebrates, aquatic vertebrates, and terrestrial vertebrates to determine the dietary contribution of each of these groups.

5.2.2 Data Analysis Data were visualised in PRIMERV6 using multidimensional scaling (MDS) to remove outliers (Clarke and Warwick 2001; Pelletier et al. 2010). One outlier was removed from the analysis. Stress levels of all MDS plots were interpreted as follows: <0.05 = an excellent representation of the data, <0.1 = a good representation of the data, <0.2 = a useful plot although the results should be considered with caution, and >0.3 = not an ideal representation of the data (Clarke and Warrick 2001).

5.2.2.1 Fish Length To determine if fish length differed between tributary type and among sites a nested analysis of variance (ANOVA) was conducted.

5.2.2.2 Fish Length and Stomach Content Weight To determine if stomach content weight differed with fish length (mm) a regression analysis and a one-way analysis of variance (ANOVA) was conducted.

223 5.2.2.3 Fish Length and Diet Shift To determine if prey consumed differed due to fish length (≥ 245 mm and < 245 mm) between tributary types a 2d non-metric MDS ordination was created to visually represent these data. This size partition was selected as it equated to the mean fish length in the study. The data remained untransformed. PRIMERV6 with PERMANOVA was used to analyse differences in diet of fish in these size classes between tributary type. To determine the contribution of taxa group abundance to the diet of M. novemaculeata ≥ 245 mm and < 245 mm in obstacle-strewn and open tributaries a SIMPER analysis was used.

5.2.2.4 Diversity and Abundance To determine if food abundance and diversity differed between tributary type and among sites a nested analysis of variance (ANOVA) was conducted.

5.2.2.5 Food item assemblage by weight and abundance To determine if the assemblage of prey items differed by abundance and weight between open and obstacle-strewn tributaries a 2d non-metric MDS ordination was created to visually represent these data. The data remained untransformed. PRIMERV6 with PERMANOVA was used to analyse the differences between open and obstacle-strewn tributaries. To determine the contribution that each taxon made to the diet of M. novemaculeata in obstacle-strewn and open tributaries, a SIMPER analysis was used.

5.2.2.6 Stomach Content Weight To determine if stomach content weight differed between tributary type and among sites a nested analysis of variance was conducted.

5.2.2.7 Stomach Fullness To determine differences in the number of fish with and without food items in the stomach between obstacle-strewn and open tributaries a Chi Square Goodness of Fit Analysis was conducted.

A stomach fullness index (SF) was calculated as SF = (wet weight of the stomach content / wet weight of the individual M. novemaculeata) x 100 (Hernández-García

224 1995). To determine if stomach fullness differed between tributary type and among sites a nested analysis of variance was conducted.

5.2.2.8 Food Type Diversity, Abundance, and Weight To determine if the diversity, abundance, and wet weight of food types (aquatic invertebrates; terrestrial invertebrates; aquatic vertebrates; terrestrial vertebrates) differed between tributary type and among sites a nested analysis of variance were conducted.

5.3 Results

Macquaria novemaculeata varied in length (114 – 390 mm); however, the difference was not significantly different between tributary types and sites. Of the 120 stomachs analysed, 101 contained at least one identifiable food item - 15.8% of fish had empty stomachs. Overall, there was no significant difference in the number of fish with and 2 without food items in the stomach between obstacle-strewn and open tributaries (χ 1 = 0.248, p = 0.619; n = 120).

In total 811 individual food items were categorised from the stomachs of fish. Overall, fish from obstacle-strewn tributaries contained a significantly greater number of food items (607); than had been consumed overall by fish caught in open tributaries (204; Figure 5.8; Table 5.1). Items included individuals from 65 identifiable taxonomic groups of which 40 were retrieved from the stomachs of fish from obstacle strewn tributaries whereas 25 taxa were retrieved from the stomachs of fish caught in open tributaries (Table 5.1). The size of food items ranged from small aquatic invertebrates (e.g. Tricoptera) to larger terrestrial vertebrates (e.g. Scincidae). Individuals of the orders Tricoptera (aquatic), Ephemeroptera (aquatic), Odonata (aquatic), and Amphipoda (aquatic) dominated abundance in obstacle-strewn tributaries whereas Atyidae (aquatic), Gerridae (aquatic), Isopoda (aquatic), and Odonata (terrestrial) were most commonly collected from the stomachs of fish caught in open tributaries (Table 5.1). Plant material was frequently present in stomachs.

225 Table 5.1 Abundance of food items and their type recorded in the stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia. Taxonomic Group Food Type Obstacle- Open strewn

Atyidae Aquatic Invertebrate 17 20 Gerridae Aquatic Invertebrate 3 26 Dytiscidae Aquatic Invertebrate 7 17 Belostomatidae Aquatic Invertebrate 0 16 Penaeidae Aquatic Invertebrate 0 5 Limnichidae Aquatic Invertebrate 0 5 Curculionidae Aquatic Invertebrate 2 1 Notonectidae Aquatic Invertebrate 3 0 Parastacidae Aquatic Invertebrate 2 0 Hydrophilidae Aquatic Invertebrate 2 0 Sialidae Aquatic Invertebrate 1 0 Carabidae Aquatic Invertebrate 1 0 Hydraenidae Aquatic Invertebrate 1 0 Tricoptera Aquatic Invertebrate 241 14 Ephemeroptera Aquatic Invertebrate 98 1 Odonata Aquatic Invertebrate 48 13 Amphipoda Aquatic Invertebrate 45 2 Isopoda Aquatic Invertebrate 4 30 Lepidoptera Aquatic Invertebrate 0 6 Diptera Aquatic Invertebrate 2 0 Plecoptera Aquatic Invertebrate 1 0 Gastropoda Aquatic Invertebrate 0 1 Platyhelminthes Aquatic Invertebrate 0 1 Nematomorpha Aquatic Invertebrate 34 0 Nematoda Aquatic Invertebrate 9 0

226 Taxonomic Group Food Type Obstacle- Open strewn

Gryllidae Terrestrial Invertebrate 11 2 Lycosidae Terrestrial Invertebrate 7 4 Tetragnathidae Terrestrial Invertebrate 6 1 Cicadidae Terrestrial Invertebrate 1 1 Scutelleridae Terrestrial Invertebrate 0 1 Cicadellidae Terrestrial Invertebrate 1 0 Blattidae Terrestrial Invertebrate 1 0 Cerambycidae Terrestrial Invertebrate 1 0 Megadrili Terrestrial Invertebrate 2 2 Caelifera Terrestrial Invertebrate 1 0 Hymenoptera Terrestrial Invertebrate 28 5 Odonata Terrestrial Invertebrate 1 20 Diptera Terrestrial Invertebrate 12 2 Lepidoptera Terrestrial Invertebrate 3 2 Mantodea Terrestrial Invertebrate 1 0 Diploda Terrestrial Invertebrate 3 0 Anguillidae Aquatic Vertebrate 3 0 Osteichthyes Aquatic Vertebrate 1 5 Scincidae Terrestrial Vertebrate 2 0 Aves Terrestrial Vertebrate 1 1

5.3.1 Fish Length There was no significant difference in the length of fish between open and obstacle- strewn tributary types (Figure 5.1; Table 5.2). There was also no significant difference in the length of fish among open and obstacle-strewn tributary sites (Figure 5.2; Table 5.2).

227

Table 5.2 Nested Analysis of Variance of the length of Macquaria novemaculeata recorded in obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia (ns = not significant). Sum of Squares d.f. Mean Square F Sign. Tributary type 73.633 1 73.633 0.009 0.930ns Tributary site (nested in 33880.067 4 8470.017 2.328 0.060ns tributary type) Total 414720.300 114 3637.897

228 5.3.2 Fish Length and Stomach Content Weight There was no significant linear relationship between the length of fish and stomach content weight (Figure 5.3; Table 5.4). The R squared value (0.000) did not account for any variability between fish length and stomach content weight (Table 5.3).

Table 5.4 Analysis of Variance between the length of Macquaria novemaculeata and stomach content weight recorded over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (ns = not significant). Sum of Squares d.f. Mean F Sign. Square Regression 0.001 1 0.001 0.001 0.981ns Residual 270.259 118 2.290 Total 270.260 119

229 5.3.3 Diversity of prey taken by Macquaria novemaculeata There was a significant difference in the diversity of prey in the stomachs of fish between open and obstacle-strewn tributary types (Figure 5.4; Table 5.5). Fish in obstacle-strewn tributaries had a higher diversity of prey in their stomachs when compared to open tributaries. There was no significant difference in the diversity of prey in the stomach contents of fish among open and obstacle-strewn tributary sites (Figure 5.5; Table 5.5).

35 30 25 20 15 10

5 Mean Taxonomic Groups MeanTaxonomic 0 Open Obstacle-strewn Tributary Type

230 Table 5.5 Nested Analysis of Variance of the food item diversity recorded in the stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (** = 0.01 significance, ns = not significant). Sum of Squares d.f. Mean Square F Sign. Tributary type 140.167 1 140.167 30.582 0.005** Tributary site (nested in 18.33 4 4.583 0.417 0.794ns tributary type) Total 8912.500 18 495.139

5.3.4 Food type diversity There was a significant difference in the aquatic invertebrate diversity and a highly significant difference in terrestrial invertebrate diversity recorded in the stomach contents of fish between tributary types. Fish from obstacle-strewn tributaries had a greater diversity of these two food types. Aquatic and terrestrial prey diversity recorded in the stomach contents of fish was equivalent (Figure 5.6; Table 5.6). There was no significant difference in food type diversity recorded in the stomach contents of fish among tributary sites (Figure 5.6; Table 5.6).

Figure 5.6 Mean food type diversity recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia (± S.E., n = 3).

231

Table 5.6 Nested Analysis of Variance of the food type diversity recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (** = 0.01 significance, * = 0.05 significance, ns = not significant). Source Food Type Sum of d.f. Mean F Sign. Squares Square Tributary Aquatic Invertebrate 40.042 1 40.042 8.308 0.010* Type Aquatic Vertebrate 0.42 1 0.042 0.231 0.637ns Terrestrial 28.167 1 28.167 12.675 0.002** Invertebrate Terrestrial 0.042 1 0.042 0.200 0.660ns Vertebrate Tributary Aquatic Invertebrate 6.833 4 1.708 0.354 0.838ns Site (nested in tributary type) Aquatic Vertebrate 1.667 4 0.417 2.308 0.098ns Terrestrial 9.667 4 2.417 1.088 0.392ns Invertebrate

232 Source Food Type Sum of d.f. Mean F Sign. Squares Square Terrestrial 0.167 4 0.042 0.200 0.935ns Vertebrate

Total 647.000 24

7.000 24

238.000 24

5.000 24

5.3.5 Abundance of prey taken by Macquaria novemaculeata There was a highly significant difference in food item abundance recorded in the stomach contents of fish due to tributary type. Obstacle-strewn tributaries had greater prey abundance than open tributaries (Figure 5.8; Table 5.7). There was no significant difference in food item abundance recorded in the stomach contents of fish among tributary sites (Figure 5.9; Table 5.7).

233

Table 5.7 Nested Analysis of Variance of the food item abundance recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (*** = 0.001 significance, ns = not significant). Sum of d.f Mean Square F Sign. Squares . 0.001** Tributary Type 7141.500 1 28153.500 176.373 * Tributary site (nested in 638.500 4 159.625 0.322 0.859ns tributary type) Error 8912.500 18 495.139

5.3.6 Food type abundance There was a highly significant difference in aquatic invertebrate abundance recorded in the stomach contents of fish between tributary types, with obstacle-strewn tributaries having a higher aquatic invertebrate abundance than open tributaries (Figure 5.10; Table 5.8). There was no significant difference in the abundance of any food types recorded in the stomach contents of fish among tributary sites (Figure 5.11; Table 5.8).

234

235 Table 5.8 Nested Analysis of Variance of the food type abundance recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (** = 0.01 significance, ns = not significant). Source Food Type Sum of d.f. Mean F Sign. Squares Square Tributary Aquatic 5460.167 1 5460.167 13.341 0.002** Type Invertebrate

Aquatic Vertebrate 0.000 1 0.000 0.000 1.000ns Terrestrial 63.375 1 63.375 2.702 0.118ns Invertebrate Terrestrial 0.042 1 0.042 0.200 0.660ns Vertebrate Tributary Aquatic 943.333 4 236.833 0.576 0.684ns Site (nested Invertebrate in tributary type) Aquatic Vertebrate 1.833 4 0.458 1.500 0.244ns Terrestrial 31.333 4 7.833 0.334 0.852ns Invertebrate Terrestrial 0.167 4 0.042 0.200 0.935ns Vertebrate

Total 33608.000 24

1107.000 24

10.000 24

5.000 24

5.3.7 Food type weight There was no significant difference in the weight of food types between open and obstacle-strewn tributaries (Figure 5.12; Table 5.9). There was also no significant difference in all food types by weight among tributary sites (Figure 5.13; Table 5.9).

236

Figure 5.13 Mean food type weight recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (± S.E.).

237

Table 5.9 Nested Analysis of Variance of the food type weight recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (ns = not significant). Source Food Type Sum of d.f. Mean F Sign. Squares Square Tributary Aquatic Invertebrate 0.516 1 0.516 0.284 0.600ns Type Aquatic Vertebrate 4.941 1 4.941 4.415 0.05ns Terrestrial 0.242 1 0.242 1.635 0.217ns Invertebrate Terrestrial 0.398 1 0.398 0.096 0.760ns Vertebrate Tributary Aquatic Invertebrate 5.543 4 1.386 0.763 0.563ns Site (nested in tributary type) Aquatic Vertebrate 10.363 4 2.591 2.315 0.097ns Terrestrial 0.750 4 0.188 1.267 0.319ns Invertebrate Terrestrial 18.116 4 4.529 1.094 0.389ns Vertebrate

Total 66.914 24

9.568 24

41.930 24

103.292 24

5.3.8 Stomach fullness There was no significant difference in the stomach fullness index of fish in open and obstacle-strewn tributary types and sites (Figure 5.14; Figure 5.15; Table 5.10).

238

239 Table 5.10 Nested Analysis of Variance of stomach fullness recorded in Macquaria novemaculeata from obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (ns = not significant). Sum of Squares d.f. Mean F Sign. Square Tributary Type 0.063 1 0.063 0.752 0.435ns Tributary Site (nested in 0.333 4 0.083 0.200 0.938ns tributary type) Error 47.40 114 0.416

5.3.9 Stomach content weight There was no significant difference in the mean weight of the stomach content of fish from open and obstacle-strewn tributary types and sites (Figure 5.16; Figure 5.17; Table 5.11).

1 Mean Stomach Contents Weight (g) Stomach Weight Mean Contents 0 Open Obstacle-strewn Tributary Type

240

Table 5.11 Nested Analysis of Variance of stomach content recorded in Macquaria novemaculeata from obstacle-strewn and open tributary types and sites over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (ns = not significant). Sum of Squares d.f. Mean F Sign. Square Tributary Type 0.251 1 0.251 0.355 0.435ns Tributary Site (nested in 2.833 4 0.708 0.302 0.938ns tributary type) Error 267.177 114 2.344

5.3.10 Food item assemblage by weight The assemblage of food items recorded in the stomach contents of fish measured by weight was highly significantly different between open and obstacle strewn tributaries (Figure 5.18 – MDS; Table 5.12).

241

Figure 5.18 Food item assemblage by weight recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia. Data remained untransformed (n = 3).

Table 5.12 Analysis of the food item assemblage by weight recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries by one-way PERMANOVA over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (** = 0.01 significance). Source d.f. Sum of Mean Pseudo P Perms Squares Square -F Tributary Type 1 8645.1 8645.1 2.1604 0.006** 997 Residual 22 88037 4001.7 Total 23 96683

Within tributary type, food item weight similarity ranged from 9.88% (open tributaries) to 13.73% (obstacle-strewn tributaries). In obstacle-strewn tributaries, Gryllidae contributed approximately 29% of the similarity. In open tributaries, Osteichthyes contributed approximately 44% of the similarity; Dytiscidae for approximately 28% (Table 5.13).

242 Table 5.13 The similarity of individual taxonomic group weight in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries by SIMPER over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia. × = aquatic invertebrate; ×× = terrestrial invertebrate; ××× = aquatic vertebrate. Tributary Ave. Taxonomic Av. Av. Sim/ Cont. Cum. Type Sim. Group Abu. Sim. SD (%) Cont. (%)

Obstacle- 13.73 Gryllidae×× 0.30 4.03 0.40 29.36 29.36 strewn

Tricoptera× 0.17 3.84 1.45 27.95 57.31 80.21 Nematomorpha× 0.15 3.15 0.57 22.91

Odonata× 0.08 0.91 0.54 6.62 86.83 89.74 Hymenoptera×× 0.04 0.40 0.32 2.91

Atyidae× 0.17 0.37 0.36 2.73 92.47 4.36 0.24 44.17 44.17 Open 9.88 Osteichthyes××× 0.94

Dytiscidae× 0.15 2.75 0.39 27.81 71.98 1.27 0.44 12.83 84.81 Belostomatidae× 0.26 0.67 0.31 6.73 91.55 Hymenoptera×× 0.05

5.3.11 Food item assemblage by abundance The assemblage of food items recorded in the stomach contents of fish measured by abundance was very highly significantly different between open and obstacle strewn tributaries (Figure 5.19 – MDS; Table 5.14).

243

Figure 5.19 Food item assemblage by abundance recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia. Data remained untransformed (n = 3).

Table 5.14 Analysis of the food item assemblage by abundance recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries by One-way PERMANOVA over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (*** = 0.001 significance). Source d.f. Sum of Mean Pseudo- P Perms Squares Square F Tributary Type 1 15821 15821 5.075 0.001*** 997 Residual 22 68584 3117.4 Total 23 84405

Within tributary type, food item similarity ranged from 13.0% (open tributaries) to 34.8% (obstacle-strewn tributaries). In obstacle-strewn tributaries, Tricoptera contributed approximately 60% of the similarity. In open tributaries, Belostomatidae contributed approximately 28% of the similarity (Table 5.15).

244 Table 5.15 The similarity of taxonomic group abundance recorded in stomach contents of Macquaria novemaculeata from obstacle-strewn and open tributaries by SIMPER over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia. × = aquatic invertebrate; ×× = terrestrial invertebrate; ××× = aquatic vertebrate. Tributary Ave. Taxonomic Av. Av. Sim/ Cont. Cum. Type Sim. Group Abu. Sim. SD (%) Cont. (%) Obstacle 34.8 Tricoptera× 20.92 20.91 1.99 60.16 60.16 -strewn Ephemeroptera× 8.17 4.22 0.36 12.13 72.29 Nematomorpha× 2.83 3.34 0.91 9.60 81.89 Odonata× 4.00 2.38 0.67 6.85 88.74 Gryllidae×× 0.92 0.97 0.62 2.78 91.52 Open 13.0 Belostomatidae× 1.33 3.65 0.38 28.12 28.12 Dytiscidae× 1.42 2.37 0.40 18.28 46.40 Isopoda× 2.50 1.71 0.43 13.16 59.56 Osteichthyes××× 0.42 1.64 0.34 12.64 72.19 Hymenoptera×× 0.42 1.54 0.40 11.82 84.01 Atyidae× 1.67 1.03 0.49 7.91 91.92

5.3.12 Fish size and diet There was a very highly significant difference in diet assemblage for fish < 245 mm and ≥ 245 mm in open and obstacle-strewn tributaries (Figure 5.20; Table 5.16). Pairwise PERMANOVA tests confirmed that open tributaries did not have a significantly different diet assemblage between fish that were < 245 mm and ≥ 245 mm (Table 5.17). Obstacle-strewn tributaries had a significantly different diet assemblage between fish that were < 245 mm and ≥ 245 mm. Open and obstacle- strewn tributaries had a significantly different diet assemblage for fish that were < 245 mm and ≥ 245 mm (Table 5.17).

245

Figure 5.20 Food item assemblage recorded in the stomach contents of Macquaria novemaculeata between fish < 245mm and ≥ 245mm from open and obstacle-strewn tributaries over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia. Data remained untransformed (n = 3).

Table 5.16 Analysis of the food item assemblage recorded in the stomach contents of Macquaria novemaculeata between fish < 245mm and ≥ 245mm from open and obstacle-strewn tributary types and sites by Nested PERMANOVA over approximately two years (December 2011 - April 2013) in the Hawkesbury- Nepean River, Australia (* = 0.05 significance, ns = not significant). Source d.f. Sum of Mean Pseudo P Perms Squares Square -F Tributary/Fish size 3 30400 10133 3.6189 0.001*** 997 Residual 44 1.232E5 2800.1 Total 47 1.536E5

Table 5.17 Pairwise analysis of the food item assemblage recorded in the stomach contents of Macquaria novemaculeata between fish < 245mm and ≥ 245mm from open and obstacle-strewn tributaries by PERMANOVA over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia (*** = 0.001 significance, * = 0.05 significance, ns = not significant). Groups T P (perm) Unique perms Open<245, Open>245 1.174 0.146ns 994 Open<245, Obstacle-strewn<245 1.657 0.014* 997 Open<245, Obstacle-strewn>245 2.645 0.001*** 998 Open>245, Obstacle-strewn<245 1.636 0.001*** 996 Open>245, Obstacle-strewn>245 2.580 0.001*** 996 Obstacle-strewn<245, Obstacle-strewn>245 1.464 0.042* 999

246

Within tributary type, food item similarity ranged from 7.94% (open tributaries < 245 mm) to 35.42% (obstacle-strewn tributaries ≥ 245 mm). In open tributaries, Isopoda made up approximately half of the diet of fish < 245 mm, whereas fish in open tributaries ≥ 245 mm fed on a combination of Belostomatidae and Osteichthyes. In obstacle-strewn tributaries, Tricoptera contributed over half of the diet of both smaller and larger fish (Table 5.18).

Table 5.18 Similarity of the food item assemblage recorded in the stomach contents of Macquaria novemaculeata between fish < 245mm and ≥ 245mm from open and obstacle-strewn tributaries by SIMPER over approximately two years (December 2011 - April 2013) in the Hawkesbury-Nepean River, Australia. × = aquatic invertebrate; ×× = terrestrial invertebrate; ××× = aquatic vertebrate. Tributary Ave. Taxonomic Av. Av. Sim/ Cont. Cum. Type and Sim. Group Abu. Sim. SD (%) Cont. Fish Size (%) Open 7.94 Isopoda× 0.83 4.58 0.41 57.77 57.77 <245mm Dytiscidae× 1.00 1.22 0.27 15.35 73.12 Tricoptera× 1.08 0.81 0.16 10.23 83.35 Belostomatidae× 0.75 0.74 0.17 9.34 92.69 Open 8.66 Belostomatidae× 0.58 2.08 0.29 24.04 24.04 ≥245mm Osteichthyes××× 0.42 1.79 0.36 20.71 44.75 Dytiscidae× 0.42 1.65 0.29 19.09 63.84 Odonata× 0.92 1.38 0.24 15.96 79.80 Atyidae× 1.50 0.90 0.28 10.44 90.23 Obstacle- strewn 13.70 Tricoptera× 4.08 8.33 0.63 60.83 60.83 <245mm Nematomorpha× 0.92 2.66 0.37 19.39 80.22 Ephemeroptera× 6.67 1.17 0.16 8.55 88.77 Odonata× 0.58 0.73 0.28 5.30 94.08 Obstacle- strewn 35.42 Tricoptera× 15.17 27.16 1.56 76.68 76.68 ≥245mm Nematomorpha× 1.67 2.04 0.65 5.75 82.44 Gryllidae×× 0.83 1.83 0.71 5.15 87.59 Odonata× 3.42 1.77 0.47 5.00 92.59

247 5.4 Discussion

Others (Harris 1985b; Smith et al. 2011b) have reported that Macquaria novemaculeata is an opportunistic carnivore. The results of the current study concur with these findings (Table 5.1). Overall, food items found in the stomachs of M. novemaculeata spanned 65 identifiable taxa, and included insects, fish, birds, and reptiles (Table 5.1). Fish from open tributaries fed chiefly on aquatic invertebrates (shrimp - Atyidae, water striders - Gerridae, water slaters - Isopoda, adult dragonflies and damselflies - Odonata). Fish from obstacle-strewn tributaries consumed a different aquatic suite of invertebrates (caddisflies - Tricoptera, mayflies - Ephemeroptera, amphipods – Amphipoda, and dragonflies and damselflies - Odonata). Since there was no identifiable reason why an opportunistic species would target different species in the different tributary types (e.g., there was no significant difference in the size of fish between habitat types, Table 5.2), it can be assumed that the differences reflected availability of prey in the different tributary types.

5.4.1 Diversity and abundance of prey Although, as reported above, M. novemaculeata has been defined as a ‘generalist feeder’ (Harris 1985b; Allen et al. 2002; Smith et al. 2011b), they will focus on a single prey type when available in abundance (Smith et al. 2011b). In this study, the diversity and abundance of food items consumed by M. novemaculeata in obstacle- strewn tributaries was much greater than in open tributaries. The assemblage of food items by abundance also differed between open and obstacle-strewn tributaries. Harris (1985b) also observed substantial differences in the diet of this species between estuarine and freshwater habitats. For example, he observed that within the freshwater Gees Lagoon (NSW) some M. novemaculeata fed entirely on hemipterans and other insects whereas other individuals in the same wetland had consumed only fish and/or shrimp. In the estuary, fish fed primarily on Crustacea, including amphipods and isopods. These differences in the prey taken among habitats supports the suggestion that the differences in diet in the current study are due to differences in prey availability.

248 Optimal foraging theory predicts dietary specialisation as preferential prey items increase in abundance (Pyke 1984; Giske et al. 1998). This phenomenon has been observed in catfish Trichomycterus spp. in Colombia where the focus of consumption was on the most abundant macroinvertebrates available (Chara et al. 2006). This feeding strategy appears to be present in the current study, particularly in obstacle- strewn tributaries where, although a wide variety of prey was consumed, the immobile aquatic invertebrate larvae of taxa such as the caddisflies (Tricoptera) and mayflies (Ephemeroptera) dominated the fish diet (Table 5.1). Studying riverine and gorge regions of the Hawkesbury-Nepean River, Harris (1985b) also found that tricopteran larvae were common in the diet of M. novemaculeata. In contrast, he found that adult tricopterans were rarely consumed. These findings parallel the current study, in that there was an absence of terrestrial species of these taxa in the diet of M. novemaculeata. Consumption of stoneflies (Plecoptera) larvae was also rare in both the current study (Table 5.1), and that of Harris (1985b).

Despite being ubiquitous in sampled habitats, McDowall et al. (1996) found that Plecoptera was rare in the diet of the New Zealand fish shortjawed kokopu Galaxias postvectis. Previous research (Jackson 1978; Bishop and Tilzey 1978) reported that Plecoptera scarcely utilise the typically sandy and mobile stream beds of the Sydney Basin. They prefer waterways with a larger, more stable particle size. This further indicates that the difference between habitats of prey items consumed by fish that feed opportunistically can be due to the relative abundance of prey species of a specific type. Harris (1985b) found that Ephemeroptera was rare in the diet of M. novemaculeata, and this taxon was also rare in open tributaries in the current study although they were the second most frequently occurring dietary item consumed in obstacle-strewn tributaries. This indicates that the latter habitats likely acts as a suitable niche for this prey species where environmental characteristics, such as fast flowing water, rocks, logs, low disturbance, and detritus occur which provides them with preferred habitat (Hawking and Smith 1997; Gooderham and Tsyrlin 2002).

Based on the size range distribution and abundance of prey in the current study (Table 5.1), it is likely that M. novemaculeata take small organisms to conserve foraging energy, and ambush larger prey opportunistically. This feeding mode is supported by

249 the observation that the artificial lures the fish were caught on represented larger prey (e.g. fish, Cicadidae) than the sized prey that was predominantly found in the stomachs of fish. Harris (1985b) suggested that larger prey typically required higher energy expenditure to target and consume. Macquaria novemaculeata may, therefore, gain greater endpoint nutrition by focusing on the consumption of greater numbers of smaller, less mobile organisms (e.g., burrowing decapods – Harris 1985b) than larger, potentially less abundant taxa. Similar results were obtained by Hansen and Wahl (1981). They found that yellow perch Perca flavescens actively targeted the smaller water flea Daphnia pulex rather than focus on larger prey that they were capable of consuming. They attributed this to the employment of an optimal foraging strategy whereby larger D. pulex with greater potential to escape predation were avoided. Jellyman (1989) also found that the diet of two eel species consisted of small organisms (e.g. gastropods and amphipods) in high abundance, rather than larger organisms that their gape width theoretically allowed them to capture. It was suggested that the energetic gain due to consuming small items could be low in comparison to preying on larger individuals. In addition, Hynes (1970) suggested that in smaller order streams, including obstacle-strewn tributaries, the potential to capture invertebrate prey was higher per unit area than in larger waterways such as tributary- collecting rivers. Indeed, of the aquatic invertebrates consumed in abundance in open tributaries many were more mobile (e.g., Atyidae, Gerridae, Dytiscidae, Belostomatidae) than those consumed in abundance in obstacle-strewn tributaries (e.g., Tricoptera, Ephemeroptera) (Table 5.1). This higher mobility of prey species likely narrows the energetic gain a fish receives from targeting such prey items. This is supported by the observation that the relatively immobile aquatic invertebrate Isopoda was the most abundant of all food items consumed in open tributaries (Table 5.1). This indicated that when immobile organisms are available within these habitats M. novemaculeata will select them. However, it can be difficult to ascertain whether a fish species selects their preferred prey or if food items are merely consumed more often due to their higher abundance (Labropoulou and Eleftheriou 1997). Some softer- bodied animals (e.g., fish) may also be under-represented in stomach content analyses as they are digested at a more rapid rate than hard-bodied animals (Mattson 1990). However, as Steingrimsson and Gislason (2002) observed, larger food items were more readily recognised in the stomach contents, even in an advanced state of

250 digestion, so it is unlikely that softer-bodied animals were under-represented in the current study.

The higher diversity of prey in the diet of M. novemaculeata from obstacle-strewn tributaries (Figure 5.4; Figure 5.5) is likely a result of several factors that may differentiate the species from the open tributaries studied. Upland, forested streams have been reported to be biologically richer, more diverse environments that may offer suitable conditions for a range of biota that may not necessarily inhabit downstream areas (Harris 1985b; Pusey et al. 1995; Smith et al. 2011b). Such upland headwater streams exhibit food webs influenced by in situ primary productivity and terrestrial-derived allochthonous stream inputs (Vannote et al. 1980; Naiman and Decamps 1997). The riparian zones of headwater streams play a major role in the input of allochthonous plant detritus (Vannote et al. 1980; Kawaguchi and Nakano 2001). This detritus acts as an essential food resource for secondary production of benthic invertebrates (e.g. tricopterans, ephemeropterans), which form part of the diet of many aquatic animals higher in the food chain, including fish (Kaushik and Hynes 1971; Wallace et al. 1997). Downstream reaches are typically broader with less overhanging vegetation and associated allochthonous inputs (Pusey et al. 1995). These include such habitats as those found in the open tributaries analysed in the current study. Benstead et al. (2003) reported that streams draining deforested areas had lower instream insect community diversity than forested streams within Ranomafana National Park (Madagascar). In upland streams of Western Ireland, the diet of brown trout Salmo trutta had higher species richness in streams with deciduous riparian vegetation compared to grassland streams (Dineen et al. 2007). Open tributaries of the current study generally flowed through areas of grazed grassland. This could help explain the lower species richness recorded at these sites. It appears, therefore, that the maintenance of riparian vegetation in obstacle-strewn tributaries is of particular importance to the lifecycle of immobile aquatic invertebrates, which ultimately form a large part of the diet of M. novemaculeata in these environments.

The observation that the higher representation of terrestrial taxa, such as individuals of the orders Hymenoptera and Diptera that form part of the diet in obstacle-strewn tributaries (Table 5.1) could be expected based on a high-perimeter-to-area ratio,

251 enhancing the aquatic-terrestrial interface (Wipfli 2005). As observed in the current study, Harris (1985b) reported that terrestrial Hymenoptera, Orthoptera (e.g., Gryllidae), Blattodea, and Mantodea were included in the diet of M. novemaculeata from the Colo River Gorge (NSW). This reach of the Colo River was reported to have limited riparian vegetation. However, the aquatic-terrestrial interface of the Colo River Gorge was notable for its fluctuating water levels and associated rapids (Dunk 1999) which would serve to increase the wetted perimeter (O'Hop and Wallace 1983; Layzer et al. 1989). It does have some consistency, therefore, with obstacle-strewn tributaries where many of these prey species (e.g. Hymenoptera, Blattodea, and Mantodea) were also recovered from the stomach contents of fish in the current study. Upland tributaries are known for fluctuating water levels (O'Hop and Wallace 1983; Layzer et al. 1989), and this could influence the prey items available to M. novemaculeata due to a variation in wetted perimeter that does not occur in such frequency in open tributaries downstream. Furthermore, it was observed that the obstacle-strewn tributaries of this study had riffle and pool environments, high levels of overhanging vegetation, appeared to maintain cool water temperatures throughout hot periods, and there was extensive coarse woody material present instream. In the Satilla River (Georgia), woody material was estimated to support 60% of the total invertebrate biomass present despite representing only 4% of habitat surface. The fish studied relied strongly on the prey from these areas, and Benke et al. (1985) commented on the importance of such habitat traits at different trophic levels. These characteristics are likely to benefit a wide variety of biota, both aquatic and terrestrial, where they can occupy niches in the range of microhabitats available (Dineen et al. 2007).

Absent from the diet of fish in the current study was the terrestrial orders of Phasmatodea (e.g., stick insects), Dermaptera (earwigs) and Isoptera (termites). These prey were present in the Harris (1985b) study in the Colo River Gorge within the same river system although Isoptera consumption was correlated with infrequent summer swarming. In a stream in the U.S. with heavy riparian cover and shading, the minnow Notropis ardens consumed high numbers of terrestrial dipterans (Garman 1991). Of the terrestrial prey consumed in a forest reserve in Scotland, salmonids had a high abundance of Diptera and Hemiptera in the diet (Bridcut 2000). Hence, it

252 appears that the variable microhabitats that occur in obstacle-strewn tributaries support a wider range of prey for M. novemaculeata than open tributaries.

Obstacle-strewn tributaries had approximately twice the prey diversity (Table 5.1), prey abundance (Table 5.1), and prey items of a terrestrial origin compared to open tributaries (Figure 5.10). These upstream habitats may have greater or even fewer prey resources (e.g., Brainwood 2006), however, the competition for resources is likely to be lower than in downstream areas thus making them desirable (Harris 1985b). Similarly, a study by Pires et al. (1999) in the Guadiana River (Spain/Portugal) found that fish species richness/biomass increased with distance downstream, subsequently increasing resource competition. Harris (1986) noted that the reduced competition upstream was likely to be advantageous to M. novemaculeata. In a review of fish populations and associated migratory behaviours, Jonsson and Jonsson (1993) also recognised that this use of upland streams was likely to arise from fish seeking to maximise body size by entering areas with richer feeding grounds, and this aided improved fitness and condition. The high probability of reduced competition in obstacle-strewn tributaries is, therefore, likely to offer relatively unexploited food resources important for growth, unlike open tributaries where species such as yellowfin bream Acanthopagrus australis, dusky flathead Platycephalus fuscus and M. colonorum compete for food resources (Allen et al. 2002).

The differences in M. novemaculeata diet observed in the two tributary types (Table 5.1; Figure 5.4; Figure 5.8) is likely to be an adaptation to the multiplicity of habitats it occupies (Smith et al. 2011b), coupled with the Australian environment, which is highly variable (Sternberg et al. 2008). A similar suggestion was made by Davis (1985) in a study of the dietary differences of barramundi L. calcarifer in tidal and non-tidal river reaches. The differences he observed were attributed more to prey availability within each habitat than dietary preference.

The disparities in prey taken by fish has been commonly attributed to limitation or seasonality of preferential food types leading to substitution with different food items (Munkittrick and Dixon 1989, Specziar et al. 1998), and geographical isolation

253 (Szepanski et al. 1999; Stehlik and Meise 2000; Olson et al. 2003). In the current study, it is likely that, similar to L. calcarifer, the differences observed in the diet of M. novemaculeata between the two habitats studied could be largely attributable to prey availability (e.g., high consumption of Tricoptera and Ephemeroptera in obstacle-strewn tributaries), as opposed to selectivity or specialisation.

Similar to the observations of Harris (1985b), in this study, molluscs and larger-sized crustaceans (i.e. Parastacidae) were rarely consumed by M. novemaculeata (Table 5.1). He did find that, particularly in tidally-influenced reaches, a large proportion of M. novemaculeata diet was composed of burrowing decapods (e.g., shrimp, prawns). This is broadly equivalent to the findings of the current study. Atyidae and Penaeidae were more abundant in the tidally-influenced open tributaries than in the obstacle- strewn tributaries. However, Atyidae was also present in the stomachs of fish from obstacle-strewn tributaries although they did not contribute as substantially in abundance to the stomach contents (Table 5.1).

Harris (1985b) also observed that both terrestrial and aquatic invertebrates were commonly consumed by M. novemaculeata, especially in summer months, the period in which the majority of fish were analysed for diet in the current study. The previous study (Harris 1985b) also found that nematodes (Nematomorpha) were an important dietary component in gorge habitats. In the current study, this taxon was exclusively consumed by M. novemaculeata in obstacle-strewn tributaries where it occurred in moderate abundance in its diet. In the nearby Shoalhaven River, Bishop and Tilzey (1978) also observed that Nematomorpha was an important dietary component for Macquarie perch Macquaria australasica in gorge habitats. In contrast, Nematomorpha was rarely recorded in the diet of the New Zealand fish shortjawed kokopu G. postvectis in tributary environments (McDowall et al. 1996). It therefore appears that this taxon is a more frequently consumed prey item in gorge environments where appropriate habitat is present. Obstacle-strewn tributaries occasionally exhibited gorge-like regions, potentially providing suitable habitat for Nematomorpha which are consumed by M. novemaculeata.

254 As observed in the current study, Harris (1985b) found that adult coleopterans (e.g. Dytiscidae) and hemipterans (e.g. Notonectidae) were consumed by M. novemaculeata. In contrast, however, Belostomatidae (Hemiptera) was recorded exclusively in open tributaries although Harris (1985b) did not record them in his study. Odonata larvae were frequently recorded in both studies, with larvae most common in the diets of fish from obstacle-strewn tributaries, and adults most commonly retrieved from the stomachs of fish in open tributaries (Table 5.1). Harris (1985b) found that adult Odonata (e.g., dragonflies) were infrequent in the diet of M. novemaculeata. He reported that in estuarine reaches this species fed on amphipods and isopods. In the current study, M. novemaculeata fed on isopods; however, amphipods were far more likely to be eaten by fish in obstacle-strewn tributaries than in open tributaries (Table 5.1). Both studies indicated that Gerridae occurred in the diet only occasionally. This taxon was, however, more common in the diet of fish from open tributaries than from obstacle-strewn tributaries (Table 5.1). In the current study the majority of beetles consumed were aquatic forms (Table 5.1). However, this did not occur in Harris’s (1985b) study. He found that terrestrial beetles were a common dietary component, and were present in the stomach contents of M. novemaculeata in high diversity. Harris (1985b) also observed that flies (Diptera) occurred in the diet of this fish species. In the current study this taxon was most commonly consumed by M. novemaculeata in obstacle-strewn tributaries (Table 5.1). In contrast to the observations of Harris (1985b) who observed that Cicadidae was one of the most frequently encountered terrestrial invertebrates in the diet of M. novemaculeata, this taxon was only encountered in the diet of M. novemaculeata on one occasion in each tributary type (Table 5.1). In common with Harris (1985b), spiders (e.g. Lycosidae) were occasionally consumed by M. novemaculeata but were more likely to be in higher numbers in the diet of fish in obstacle-strewn tributaries than open tributaries (Table 5.1). It is possible that the complex vegetation adjacent to the obstacle-strewn tributaries may act as a more suitable microhabitat than the grazed areas surrounding the open tributaries (Leather et al. 1993). These findings reinforce the observation of M. novemaculeata, a generalist carnivore, typically consuming what is available in that environment, and this may vary over time.

255 It was observed that the consumption of vertebrates by M. novemaculeata was rare, with only two taxonomic groups, other than fish (Osteichthyes, Anguillidae) identified (Scincidae, Aves) (Table 5.1). Consumption of eel elvers was uncommonly observed in obstacle-strewn tributaries (Table 5.1) although Harris (1985b) did find that below the Warragamba Dam wall, M. novemaculeata consumed high numbers of elvers. This was presumably because of a surfeit of eels in this Region due to the restriction of upstream movement of this species due to the presence of the dam wall (Harris 1985b; Tsukamoto and Arai 2001). Consumption of Scincidae was also exclusive to, but uncommon, in obstacle-strewn tributaries (Table 5.1). Harris (1985b) also observed that skinks were occasionally consumed by M. novemaculeata.

A bird was found in the stomach of one M. novemaculeata in each tributary type (Table 5.1). Aves were also recorded as a dietary component of M. novemaculeata by Harris (1985b). As in the current study, they were also consumed infrequently. Harris (1985b) found that frogs occurred in the diet of M. novemaculeata, but none were retrieved from the stomach contents of fish in the current study. Rare consumption of vertebrates reported in this study and in the literature (Harris 1985b), indicates that M. novemaculeata are unlikely to actively seek this prey, but rather they are taken opportunistically.

Contrary to the observations of Harris (1985b), bony fish (Osteichthyes) were rarely consumed by M. novemaculeata, although piscivory was more common in fish from open tributaries than from obstacle-strewn tributaries (Table 5.1). These tidally influenced waterways were potentially more suitable habitat for a greater diversity of prey fish species, in higher abundance, than occurred in upland freshwater habitats (Pires et al. 1999; Allen et al. 2002). This finding correlates more generally to the literature whereby the more common prey items will be targeted more frequently (Pyke 1984; Smith et al. 2011b). Piscivory may also be more common in open tributaries due to the more limited terrestrial and aquatic invertebrates available as a food source (Table 5.1; Figure 5.10). Some individuals in these systems may target larger piscivorous prey more readily than they would be in obstacle-strewn tributaries where piscivory was low. This indicates that prey fish may be a more important food

256 source in open tributaries where alternative food sources are not as widely available (Table 5.1).

Prey fish in the stomachs of M. novemaculeata could not be identified to species level due to state of digestion, and therefore none was identified as M. novemaculeata. Although cannibalism could occur, it is unlikely to occur in this species (Harris 1985b; Smith et al. 2011b). Generally, cannibalism is considered most common amongst predatory fish (Davis 1985). Some species, such as peacock bass Cichla ocellaris are actually able to limit cannibalism through recognition of distinct colour banding (Zaret 1977). Although, M. novemaculeata do not exhibit distinct marks in adulthood, they do display dark blotches on the dorsal, anal, and pelvic fins as juveniles (Allen et al. 2002). This trait may act as a deterrent against cannibalism by adults.

In the current study, the abundance of shrimp and prawns in the diet of fish was low overall (obstacle-strewn – 2.8%; open – 12.3%), as was the consumption of fish (obstacle-strewn – 0.2%; open – 0.5%). No crab species were recorded in the diet of M. novemaculeata from either tributary type. In contrast, Harris (1985b) found that small crabs (Brachyurans) were the primary food source of M. novemaculeata in freshwater tidal habitats, and to a lesser extent in brackish reaches. These habitats, particularly the former, align strongly with the characteristics of open tributaries of the current study although there was no alignment with dietary intake (Table 5.1) and, as indicated previously, this is assumed to reflect opportunism rather than prey selection. The generalist feeding strategy employed by M. novemaculeata (Table 5.1) has been reported in other Australian freshwater fish. For example, M. colonorum consume a wide variety of prey items. Howell et al. (2004) investigated the diet of M. colonorum in the Hopkins River (VIC) and defined five prey groups (freshwater shrimp Paratya australiensis; Amphipoda; freshwater crab Amarinus lacustrine; teleosts, tricopteran larvae) that made up 98% of the species’ diet. These findings supported past observations made in the Hopkins River by McCarraher and McKenzie (1986) where shrimp and prawns made up 52% of the total abundance of the diet of M. colonorum. Tricopteran larvae, and to a lesser extent Amphipoda, were widely consumed by M. novemaculeata in obstacle-strewn tributaries, but not in open

257 tributaries. Howell et al. (2004) studied similar environments (i.e., open waterways with tidal influence). It is likely, therefore, that these two species select prey differently despite having access to similar resources. Howell et al. (2004) suggested that the fish they studied showed preference for targeting particular prey items, and that these species were not always the most common in their habitat. This phenomenon was also observed for gastropods. They were the most commonly encountered potential prey item in both freshwater and estuarine habitats, although their contribution to the diet of M. colonorum was negligible. A similar pattern occurred with M. novemaculeata. Only a single snail was found in the stomach contents of a fish in an open tributary and none were retrieved from obstacle-strewn tributaries (Table 5.1). Harris (1985b) also observed that gastropods were rare in the diet of M. novemaculeata. In contrast, gastropods made up half of the diet of the introduced mosquitofish Gambusia holbrooki in an Australian arid floodplain river (Balcombe et al. 2005), and dominated the diet of shortfinned eel Anguilla australis in Lake Pounui (New Zealand; Jellyman 1989). These studies indicate that gastropods are a viable food source but are likely not preferred by M. novemaculeata.

Eastern freshwater cod Macc. ikei also has a generalist diet and consumes a wide variety of prey. Of the 268 Macc. ikei individuals that Butler and Wooden (2012) investigated, stomach contents contained over 30 species of prey including crustaceans, mammals, insects, and reptiles. This prey originated from both aquatic and terrestrial habitats. The prey diversity and abundance in the current study (Table 5.1) was approximately double the number that Butler and Wooden (2012) found in the stomachs of Macc. ikei, and there were fewer empty stomachs. In contrast to the current study, crustaceans were the most common group in the diet of Macc. ikei. This indicated that they are of high dietary importance for Macc. ikei, unlike M. novemaculeata who consumed primarily Tricoptera and Ephemeroptera (Table 5.1).

A study by Ebner (2006) on the diet of the Murray cod Macc. peelii and golden perch M. ambigua in the Murray River (Australia) also revealed dietary differences to those found for M. novemaculeata in the current study. Maccullochella peelii fed primarily on fish (e.g. European carp Cyprinus carpio), and decapods (e.g. freshwater prawn Macrobrachium australiense). Fish did not occur as frequently in the diet of M.

258 ambigua, while decapods were in highest abundance in the diet. This is in strong contrast to the current study (Table 5.1), only 6% of M. ambigua stomach contents contained insects. In a study on the diet of a range of fishes in an Australian arid floodplain piscivory was uncommon. Only three of the seven fish species’ diets analysed contained fish (Balcombe et al. 2005). However in common with the current study, Australian smelt Retropinna semoni and Australian catfish Porochilus argenteus have been observed to occasionally consume terrestrial prey, although they tend to rely mainly on prey from their aquatic environment. However, one species, desert rainbowfish Melanotaenia splendida tatei, was shown to consume terrestrial prey items (e.g., ants, wasps, dipterans) in large quantities. This prey was also consumed by M. novemaculeata (Table 5.1) although most terrestrial prey was consumed in obstacle-strewn tributaries (Figure 5.10). This indicated that M. novemaculeata has a broadly similar feeding strategy to M. splendida tatei. Some Australian fish species, such as southern pygmy perch Nannoperca australis, apparently do not commonly consume terrestrial insects. Indeed, this species feeds mainly on aquatic Diptera, Tricoptera, and Ephemeroptera (Cadwallader 1979; Cadwallader et al. 1980). In the U.S., in a stream with heavy riparian cover and shading, the diet of minnow Notropis ardens had a high composition of aquatic Diptera, Tricoptera and Ephemeroptera (Garman 1991). These taxa also contributed substantially to the diet of G. postvectis (McDowall et al. 1996), koaro G. brevipinnis, and rainbow trout O. mykiss (Kusabs and Swales 1991) in New Zealand stream studies. In the current study, fish from open tributaries rarely consumed these taxa, but in obstacle-strewn tributaries tricopterans and ephemeropterans were the most commonly consumed taxa.

In the U.S., the feeding strategy of largemouth bass Micropterus salmoides was examined in purpose-built enclosures (Dibble and Harrel 1997). Fish fed primarily on macroinvertebrates (e.g., Odonata, Belostomatidae), with piscivory occurring at approximately half the frequency of consumption of these alternative taxa. A common theme occurs between this species and M. novemaculeata. Piscivory occurred less often than consumption of aquatic invertebrates (Table 5.1). However, this pattern was far stronger in the current study, indicating that aquatic invertebrates are of high

259 dietary importance to M. novemaculeata, particularly in obstacle-strewn tributaries (Figure 5.10).

In New Zealand, the diet of G. postvectis (McDowall et al. 1996) had a similarly high dietary diversity as found for M. novemaculeata in the current study (Table 5.1). Prey included Hymenoptera (e.g. ants, wasps), adult Lepidoptera, arachnids, and Cicadidae. Although contributing to the diversity of prey taken, these particular prey items typically occurred in low abundance within the diet. This was also observed in the current study (Table 5.1). In a U.S. stream with heavy riparian cover and shading, the diet of N. ardens was composed of few Hymenoptera, adult Lepidoptera and arachnids (Garman 1991). However, in the current study, other than Cicadidae, these taxa were consumed by M. novemaculeata more frequently in obstacle-strewn tributaries (Table 5.1). West et al. (2005) found that the diet of the related banded kokopu G. fasciatus also consumed both hymenopterans and hemipterans, but in higher abundance than the current study (Table 5.1). Cockroaches (Blattodea) were also present in the G. fasciatus diet, but occurred rarely. In the current study only one individual was recorded in the stomach contents of a single individual of M. novemaculeata (Table 5.1). It therefore appears that M. novemaculeata is definitely an opportunistic species, but it is likely that some potential prey species are simply not recognised as potential prey items by M. novemaculeata, or that this predator is simply not proficient at handling some potential prey for consumption.

5.4.2 Fish Size and Diet shift There was a very different diet assemblage in large and small fish between open and obstacle-strewn tributaries (Table 5.16). In open tributaries, smaller fish fed mainly on aquatic invertebrates, including isopods. In contrast, larger fish fed mainly on the aquatic invertebrate Belostomatidae and the aquatic vertebrate Osteichthyes. Within obstacle-strewn tributaries fish of all sizes fed mainly on the aquatic invertebrates, Tricoptera and Nematomorpha (Table 5.18).

To maintain an optimal feeding strategy there is generally a requirement to accommodate larger food items consistent with body size (Sagar and Eldon 1983, Werner et al. 1983a, Clapp et al. 1990, Beauchamp and Van Tassell 2001). There was

260 some indication that this did occur, at least in the open tributaries, where larger M. novemaculeata fed more frequently on fish than on invertebrates (Table 5.18). Harris (1985b) also found that teleosts were the most important prey item in the diet of M. novemaculeata, although Diptera formed 64% of the diet of young bass. In contrast, Diptera was rarely found to have been consumed in the current study, and terrestrial variants comprised most of these prey. No shift to the consumption of larger food items (e.g., fish) (Table 5.18) was apparent in obstacle-strewn tributaries compared to open tributaries. Whilst several factors (e.g., prey size, prey mobility) may impact on the prey that a fish consumes, it is ultimately the level of interaction that exists between predator and prey that affects the actual consumption of particular food items (Schoener 1971; Floeter and Temming 2003). Hence, it is reasonable to assume that when a prey species is in high density it is likely that predatory fish will consume more of the available prey than alternatives, regardless of prey size (Stewart and Jones 2001). Indeed, the mean prey size taken by M. novemaculeata has been found to usually be much smaller than the maximum size an individual is able to engulf (Harris 1985b; Smith et al. 2011b). As discussed above, this is likely attributable to the ease with which smaller prey items (e.g., macroinvertebrates) can be consumed in comparison to larger, more mobile prey (e.g., fishes) (Steingrimsson and Gislason 2002; Butler and Wooden 2012). Based on this premise, in the current study, smaller prey were presumably more abundant and available to M. novemaculeata than larger prey items, particularly in obstacle-strewn tributaries where Tricoptera dominated the diet of M. novemaculeata of all sizes (Table 5.18).

Small aquatic invertebrate prey has been observed to contribute significantly to the diet of the large predatory Macc. ikei in the Mann and Nymboida rivers (Australia) (Butler and Wooden 2012). It was suggested by Butler and Wooden (2012) that the discontinuous and dynamic attributes of these waterways demanded the consumption of smaller prey. They suggested that this was because, although not necessarily the preferred prey of this species, it was easier to catch and typically in higher abundance than larger prey. Their findings were broadly comparable to the obstacle-strewn tributaries of the current study. It is, therefore, likely that this feeding strategy (i.e., apparently preferring prey of less than optimum size) is an adaptation to the

261 multiplicity of habitats these species may occupy (Harris 1985b; Smith et al. 2011b; Sternberg et al. 2008; Butler and Wooden 2012).

Smith et al. (2011b) found that piscivory was highest in M. novemaculeata for fish as small as 67 mm, although prey fish (e.g., flathead gudgeon Philypnodon spp.; R. semoni) were only a common dietary component in individuals larger than 100 mm. Dietary analyses of L. calcarifer and L. niloticus showed similar trends. There was an ontogenetic shift from Crustacea (e.g., Isopoda, Amphipoda) to an almost exclusively fish-based diet (Hopson, 1972; Davis 1985). At least in open tributaries of the current study, piscivory was more common, although infrequent, in larger fish than in obstacle-strewn tributaries (Table 5.18). Elsewhere, steam-resident salmonids have been shown to maintain growth at larger sizes by consuming large prey or high numbers of smaller prey (Bachman 1982). Steingrimsson and Gislason (2002) suggested that S. trutta in the River Laxa (Iceland) likely placed high dietary importance on small prey in high abundance for stable growth than seeking less common, larger prey. Channel catfish Ictalurus punctatus in the Green and Yampa rivers (U.S.) also employ this foraging method whereby fish are rare in the diet (7%), but aquatic invertebrates (31%), and terrestrial insects (22%) were common (Tyus and Nikirk 1990). Holcik et al. (1988), however, claimed that large-stream resident salmonids can only maintain growth at larger sizes by becoming piscivorous or, at least, increasing piscivory. The rare employment of piscivory, as a choice or lack of opportunity, could therefore help to explain some of the factors contributing to the slow growth of M. novemaculeata (Harris 1985a). Indeed, in a study on snakehead Channa limbata in Thailand, Ward-Campbell and Beamish (2005) identified that an ontogenetic dietary change assisted in reducing inter-specific competition and limited overexploitation of some taxa (e.g., prey fish, Crustacea), until such time as the fish grew to a size where they could compete with others for particular prey taxa.

Ward-Campbell and Beamish (2005) observed broadly similar dietary patterns to the open tributaries in this study. Larger fish were highly piscivorous. An almost exclusively piscivorous diet in larger fish has also been observed in shortfinned eel Anguilla australis, and longfinned eel A. dieffenbachii in New Zealand (Jellyman 1989), in addition to a range of tropical piscivores in Venezuela (Winemiller 1989).

262 Micropterus salmoides has also been shown to have a progressive shift in diet to a more piscivorous feeding strategy as they increase in size (Garcia-Berthou 2002). This Spanish study found that smaller fish (< 75 mm) fed mainly on amphipods and insects (e.g., Ephemeroptera), whereas intermediate sized fish (100-225 mm) fed on freshwater shrimp, insects and small fish. However, while larger fish included crayfish in their diet they increasingly preyed on larger fish. In the current study, fish in both open and obstacle-strewn tributaries tended to consume invertebrate prey equivalent to that taken by smaller Micro. salmoides (≤ 225 mm). Hodgson et al. (1989) described this species as preferring piscivory and suggested that they only adopted a generalist feeding strategy when required. Hickley et al. (1994) observed that past experimental angling spinning lures that represented prey fish produced Micro. salmoides of between 121 - 204 mm. A similar sampling methodology was employed in the current study. Many of the artificial lures were representative of prey fish. This is despite such prey being an infrequent occurrence in stomach contents, particularly in obstacle-strewn tributaries (Table 5.1). It would appear, therefore, that given the opportunity M. novemaculeata would target fish, and potentially any large prey, if the capture of prey presents itself.

5.4.3 Stomach Contents Weight and Fullness Despite the higher diversity and abundance of food items in the diet of M. novemaculeata from obstacle-strewn tributaries compared to open tributaries, the weight of stomach contents between tributary types and among sites was equivalent (Table 5.11). Labropoulo and Eleftheriou (1997) found that while small food items may exist in high dietary abundance, they may contribute little to the weight of food consumed by a fish. Indeed, the equivalent stomach content weight correlates to the lack of difference found in the length of fish between tributary types and among sites (Table 5.2). There was also an equivalent stomach fullness index between tributary types and among sites, also indicating equivalent food intake by M. novemaculeata between tributary types despite differences in the composition of the prey taken. However, in the current study, 83.3% of fish with empty stomachs were from open tributaries. In the Van Dieman Gulf (Australia), the diet of L. calcarifer consisted of different prey items in two habitat types (fresh non-tidal and salt-tidal). Despite this, the number of stomachs containing food was broadly similar between fresh and salt-

263 tidal habitats. Elsewhere, in Lake Ontario (U.S.) nearly half of the five trout and salmon species analysed for diet had empty stomachs (Brandt 1986). This is in contrast to the current study where approximately 84% of stomachs contained at least some animal matter. Consumption of prey by M. novemaculeata in the current study therefore appears to be a frequent event, which is consistent with the small prey size encountered in the diet which would require regular consumption for adequate energy for growth (Table 5.1).

5.4.4 Food item assemblage by weight The weight of prey assemblage was different between open and obstacle-strewn tributaries, indicating food items contribute disproportionately by weight to the diet of M. novemaculeata. An optimal feeding strategy is built upon the foundation that whilst foraging for food the total nutritional content/energy intake must either meet or exceed the total nutritional content/energy loss experienced in seeking, feeding upon, and digesting the prey captured (Werner et al. 1983a, 1983b, McIvor and Odum 1988, Turesson et al. 2002). Similar to the differences in abundance, weight contribution to stomach content in open tributaries was dominated by larger, more mobile taxa (Osteichthyes, Dytiscidae, and Belostomatidae) (Table 5.13). Garcia-Berthou (2002) also found that due to a larger size, prey fish and crayfish were more important by biomass to the diet of Micro. salmoides but were consumed infrequently. Macquaria novemaculeata may gain greater endpoint nutrition through consumption of smaller, less mobile organisms (Tricoptera and Nematomorpha) that were more frequently consumed in obstacle-strewn tributaries (Table 5.13). In New Zealand streams, the weight of prey in the diet of O. mykiss and G. brevipinnis was also dominated by immobile organisms including Ephemeroptera, Tricoptera, and Diptera larvae (Kusabs and Swales 1991). The weight contribution of Gryllidae to the diet of M. novemaculeata was also higher in obstacle-strewn tributaries than in open tributaries (Table 5.13) and, although these are highly-mobile animals on land, in water they are unlikely to readily evade fish predation or require high energy expenditure for the fish to capture. Indeed, Baxter et al. (2005) suggested that terrestrial prey were more vulnerable to predatory fish, compared to aquatic prey that typically have higher mobility and the ability to retreat into safe areas within familiar surroundings.

264 Terrestrial prey is likely, therefore, to be advantageous to the growth of M. novemaculeata, as it typically requires limited energy to consume.

The predator/prey interaction may also be affected by the immediate aquatic thermal regimes. For example, successful capture of prey can depend on locomotor performance which is sensitive to variation in temperature. With a change in temperature regime, community structure can be altered due to variability in predatory pressure among prey species. Grigaltchik et al. (2012) established that mosquitofish G. holbrooki had a lower tolerance for cooler waters than M. novemaculeata. Conversely, compared to M. novemaculeata, warmer temperatures did not affect locomotor performance and hence, at higher temperatures G. holbrooki were potentially more likely to evade predation than in relatively cooler waters. This demonstrates that M. novemaculeata diet has the potential for some prey species to be more readily targeted due to the water temperature in which the species resides. It is, therefore, likely that the upland obstacle-strewn tributaries in this study allow for more favourable water temperatures for capture and consumption of prey in the warmer months than in lowland open tributaries (Poole and Berman 2001; Whitledge et al. 2006; Grigaltchik et al. 2012).

5.4.5 Food type diversity, abundance and weight Prey diversity was dominated by aquatic and terrestrial invertebrates, with obstacle- strewn tributary aquatic/terrestrial invertebrate diversity greater than in open tributaries (Figure 5.6; Table 5.6). Similarly, abundance was dominated by aquatic invertebrates and to lesser extent terrestrial invertebrates. Obstacle-strewn tributaries had a greater number of aquatic invertebrates than in open tributaries (Figure 5.10).

Harris (1985b) found that M. novemaculeata consumed more terrestrial invertebrates in gorge habitats, compared to freshwater tidal habitats. In common with the current study, in New Zealand, Edwards and Huryn (1996) found that fish preyed upon terrestrial invertebrates less frequently than aquatic invertebrates, irrespective of landuse and vegetation type in the adjacent catchment. However, Dineen et al. (2007) found that the diet of Atlantic salmon Salmo salar and S. trutta consisted of fewer terrestrial invertebrate prey in grassland streams compared to streams with closed

265 canopies. Other research (Brewin and Ormerod 1984) has similarly reported that terrestrial invertebrates were rarely found during stream input assessments in Nepalese agricultural areas. In obstacle-strewn tributaries, M. novemaculeata stayed within close proximity to structure, and this was probably important because it is where a larger diversity of invertebrates originate from the terrestrial environment. Indeed, obstacle-strewn tributaries have a high-perimeter-to-area ratio, intensifying the aquatic-terrestrial interface (Wipfli 2005). Elsewhere, Nakano et al. (1999a) found that fishes readily shifted from preying upon benthic to terrestrial invertebrates when the latter was experimentally decreased. This finding potentially provides another reason why M. novemaculeata may prefer obstacle-strewn tributaries. If a particular prey source becomes limited, feeding effort may be readily switched to an alternative. For example, in obstacle-strewn tributaries aquatic invertebrates may be displaced or difficult to locate during flood periods while terrestrial invertebrates are likely to be washed into the stream and/or become easier to locate at the water/terrestrial interface.

It has also been reported that the energy density of terrestrial invertebrates typically exceeds that of aquatic invertebrates (Cummins and Wuycheck 1971). This is because, as previously mentioned, terrestrial invertebrates often have a more extensive exoskeleton that contains a higher energy density. For example, Sweka and Hartman (2008) observed that if terrestrial invertebrates in the diet of brook trout Salvelinus fontinalis were reduced by 100%, it would require an increase of approximately 130% of aquatic invertebrates to obtain the same energy for growth. This was supported by the observations on Salv. fontinalis. Their growth rate was slower when terrestrial invertebrate consumption was reduced. However, it was recognised that if much of the exoskeleton was indigestible, the actual energy gain may be equivalent to that which can be obtained from aquatic invertebrates. In a scenario likely similar to the fish in the current study Salv. fontinalis employs benthic foraging for aquatic invertebrates when terrestrial invertebrates are limited (Sweka and Hartman 2008).

Overall, the weight of individual terrestrial prey was, on average, higher than aquatic invertebrates. This indicated a disproportionately higher contribution to diet from the

266 terrestrial rather than aquatic food source (Figure 5.12). In a forested stream in Japan, targeting of terrestrial invertebrates by stream fishes was observed to be advantageous because this prey was four times as large than aquatic prey, making them more valuable energetically (Kawaguchi et al. 2003). Diet studies of S. salar and S. trutta in Western Ireland revealed that terrestrial invertebrates represented 33% of prey abundance but 58% prey weight (Dineen et al. 2007). Likewise, a study in New Zealand on the diet of G. fasciatus revealed that the average weight of terrestrial items in the diet was 4.5 mg while aquatic items contributed 1.5 mg (West et al. 2005). These fish targeted and consumed terrestrial prey and this represented 75% of the number, and 89% of the weight of the stomach contents. Macquaria novemaculeata more readily consumed more aquatic invertebrates (Figure 5.10) but their contribution to the weight of stomach contents was less than that of terrestrial prey (invertebrates and vertebrates; Figure 5.12). In New Zealand streams, Kusabs and Swales (1991) found a similar trend in the diet of G. brevipinnis and O. mykiss. They observed that aquatic prey was abundant, but was consumed less often than terrestrial prey which contributed more by weight. In another study on G. brevipinnis, terrestrial prey actually comprised the majority of the diet by weight (Main and Winterbourn 1987). In the current study, M. novemaculeata may gain substantial energy from items that are rarely consumed (e.g. Gryllidae; Aves). Because of their typically larger size, terrestrial invertebrates are thus likely to assist in supplementing a diet dominated in abundance by aquatic invertebrates (Figure 5.10).

Canopy removal in low-order streams and its effect on terrestrial invertebrate (e.g. adult Ephemeroptera, Diptera, and Tricoptera) habitat has been studied in the past (Jackson and Resh 1989; Wipfli 1997). However, most studies of food webs in these low-order streams have typically focused on the input of allochthonous matter, which acts as a food source for benthic invertebrates, which are subsequently preyed upon by predatory fish (Cummins et al. 1995; Wallace et al. 1997). However, terrestrial invertebrate input is typically greater in upland reaches where riparian vegetation dominates the canopy of streams in comparison to downstream reaches (Cloe and Garman 1996; Wipfli 1996). This is evident in obstacle-strewn tributaries where terrestrial invertebrate prey was in higher diversity, abundance and weight in the diet of fish than was observed in open tributaries (Figure 5.6; Figure 5.10; Figure 5.12). In

267 studying cutthroat trout Oncorhynchus clarki clarki in headwater streams of the U.S., Romero et al. (2005) suggested that the vegetation adjacent to waterways helped to sustain terrestrial invertebrate abundance, thereby providing a food resource for this species in an area where it may otherwise be impossible for them to persist. Leather et al. (1993) suggested that forested riparian zones are likely to provide a higher array of habitats suitable for prey than grasslands, which would be more consistent with open tributaries in the current study. Open tributaries were also characterised by a small- perimeter to area ratio. Cloe and Garman (1996) reported that terrestrial invertebrate inputs per unit area were higher in smaller second order streams in comparison to larger sixth order streams. The lower order streams would be equivalent to the streams of the current study where terrestrial invertebrates were more frequently recorded in the stomach contents of M. novemaculeata from obstacle-strewn tributaries than open streams.

Macquaria novemaculeata density may be typically higher in these temperate upland obstacle-strewn tributaries between late spring and early autumn (Harris 1983; Harris 1986; Harris and Rowland 1996) when terrestrial invertebrate prey availability is usually at its peak (Cloe and Garman 1996; Nakano et al. 1999b; Kawaguchi and Nakano 2001). In Japan, terrestrial invertebrates comprised > 70% of the prey items of salmonid diets in summer, but fell to only 1% during winter (Kawaguchi and Nakano 2001; Nakano and Murakami 2001). West et al. (2005) similarly suggested that if terrestrial invertebrates were a more available prey source to G. fasciatus within forested streams, this may help to explain the species habitation of such areas. Habitation of obstacle-strewn tributaries by M. novemaculeata between late spring and early autumn is therefore likely to be motivated, in part, by terrestrial invertebrate abundance which can be utilised as a food source.

5.5 Conclusions

The current study re-confirmed that M. novemaculeata is a generalist carnivore, opportunistically feeding on prey from a variety of taxonomic groups from both aquatic and terrestrial habitats. The different tributary types studied offered dissimilar habitats for prey, which appears to affect the dietary consumption of M.

268 novemaculeata. Despite the variation in diet between habitats this does not appear to affect this species ability to live and thrive in either habitat (i.e., obstacle-strewn or open tributaries), where fish length was equivalent.

Diversity and abundance of prey was higher in the stomachs of fish from obstacle- strewn tributaries compared to open tributaries. This indicated that these waterways have a complex array of environments able to sustain a wider range of prey in higher abundance than open tributaries. Although aquatic invertebrate diversity and abundance was high in both tributary types, aquatic vertebrates and terrestrial prey contributed disproportionately to the diet with these prey items weighing more on average than aquatic invertebrates and, therefore, would be expected to be of higher dietary importance per individual consumed.

Macquaria novemaculeata size was equivalent between tributary types, and this correlated to the lack of difference in stomach content weight and stomach fullness between tributary types. Fish size appeared to have a relationship with prey eaten. In open tributaries, large fish were more likely to consume more mobile items such as Belostomatidae and prey fish. Smaller fish from these tributaries consumed mainly the immobile benthic invertebrate Isopoda. Fish of all sizes from obstacle-strewn tributaries consumed mainly the aquatic invertebrates Tricoptera and Nematomorpha.

Based on the study undertaken here, it was concluded that degradation of the riparian zone at the aquatic/terrestrial interface is likely to result in reduction in the availability of terrestrial prey, and also indirectly aquatic prey, through a loss of allochthonous input. Whilst M. novemaculeata is unlikely to rely on terrestrial food sources as heavily as some species (e.g. salmonids), conservation and/or restoration of riparian vegetation would be important to accommodate food sources, particularly in upland obstacle-strewn tributaries where there may be a greater reliance on these food items for growth. The apparent importance of the riparian zone to primary and secondary production, and subsequently fish diet, highlights the unique feeding strategy of this species and the requirement to understand its complexities for suitable management of the species.

269

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295 6. Investigating migratory movements of the Percichthyidae Australian bass Macquaria novemaculeata in the Hawkesbury-Nepean River using otolith microchemistry

6.1 Introduction

6.1.1 Importance of fish movement Fish may move throughout a waterway for a number of reasons including small-scale (e.g., foraging for food) and large-scale movements for the purposes of dispersal or spawning migration (Lucas and Batley 1996; Jellyman and Sykes 2003). Understanding this movement is important in recognising fish habitat preference, particularly at different life stages, to better understand the ecology of the species and so effective development of management practices can be implemented to sustain populations (Jonsson et al. 1999; McDowall 1999).

In regards to migratory movements, one of the more commonly researched fish genera has been freshwater eels of the genus Anguilla. These fish occupy freshwater environments for much of their lifecycle but move to an ocean environment to breed (McDowall 1988; Tsukamoto and Arai 2001). For example, the early growth stages of Japanese eel Anguilla japonica were examined using otolith microchemistry to determine their migratory patterns. It was found that the eel leptocephali transformed into elvers in an ocean environment, before migrating inshore to freshwater streams to reach a near-adult stage. During growth in freshwater environments their gonads commence maturation. This triggers a return downstream and into an oceanic environment to spawn at their natal site. At the spawning site the eels have completed their migratory movements, and ultimately die (Tsukamoto 1992; Tsukamoto 1996; Fricke and Tsukamoto 1998). There are, however, exceptions to this migratory pattern among Japanese and European eels as shown in otolith studies. Some individuals lived their life in an oceanic environment without migration to freshwater habitats (Tsukamoto et al. 1998). This observation has implications for sustainability of commercial and recreational fisheries for diadromous fish populations, and highlights the need for a detailed understanding of the biology of such species (Tsukamoto and Arai 2001).

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Some fish migrations do not occur on such a large-scale as observed in the eels. For example, some individuals remain confined to a local area with their movement dictated by variable weather conditions. For example, fish may migrate during flood periods not usually available to them under typical hydrological conditions (Copp 1989; Benech and Penaz 1995). More generally, habitats that are repeatedly flooded in a seasonal manner are important to fish assemblages as they can play a key role in providing suitable breeding/juvenile sites and/or allow greater access to upstream waterways that would otherwise not be available (Lowe-McConnell 1975; Copp 1989; Benech and Penaz 1995). For example, during periodic flooding in Niger’s Central Delta, Benech et al. (1994) found that fish biomass increased ninefold compared to the biomass under typical hydrological conditions. The occurrence of flood events may, therefore, be essential in maintaining fish catch, catch size and sustaining larger population levels. Such upstream localities are also often rich in invertebrates (a potential prey for many species), but generally contain reduced numbers of predators (excluding piscivorous birds) that would be experienced in areas of alternative habitat (Neckles et al. 1990). However, movement into areas during flood may lead to fish being landlocked for the longer-term as the water recedes and reduces connectivity to other water bodies (Poizat and Crivelli 1997). This consequence can be advantageous to some fish (e.g. reduced competition; nursery area for juveniles), and result in mortality of others (Kushlan 1974; Lowe-McConnell 1975; Kushlan 1976; Riemer 1991; Loftus and Eklund 1994).

6.1.2 Natural Fish Barriers and Flow Naturally-occurring barriers to fish movement, such as elevated rock-shelfs, riffles, waterfalls, and long stretches of shallow water may impinge on the ability of fish to migrate within riverine systems and utilise different habitats (Ward et al. 2002). Variation in hydrology, coupled with these environmental attributes, may result in areas subjected to periods of ‘boom and bust’ for some populations as a result of isolation (Huey et al. 2008). Within Australia it has been shown that the annual occurrence of peak flows can connect waterholes, which Faulks et al. (2010) described as ‘essential’ for golden perch Macquaria ambigua to reach upstream waterholes. Without such peak flows, it would be impossible for these fish to occupy

297 such habitat. Elsewhere, in a study of fish movement in a stream, only a limited number of molly Poecilia gillii migrated upstream during flood events. It was hypothesised that more would have undertaken this migration if not for the characteristically steep topography of the waterway and its array of rapids and waterfalls acting as natural barriers (Chapman and Kramer 1991). Likewise, the journey for adult salmonoids returning into the headwaters of freshwater riverine systems after their marine life stage may also be impeded by the need to negotiate rapids, waterfalls and due to unstable hydrological events. For example, salmonid up- tributary movement is timed to reach the aggregate spawning grounds prior to ripening of the gonads. If in-stream conditions (barriers, water levels) preclude such movement, the potential for successful spawning is reduced (Banks 1969). The presence of barriers to movement may also result in the fragmentation of the fish population which may limit genetic variability, and exacerbate the potential for local extinction as a direct result of events such as long-term drought (Allendorf and Leary 1988; Lande 1988; Nagel 1991).

Fish movement through areas containing naturally-occurring barriers will typically involve negotiation through regions of high-velocity water. The ability of fish to perform such actions often contributes to the distribution of fish, including those that are diadromous (Peake et al. 1997; Warren and Pardew 1998). During upstream movement, some fish species may find that their swimming performance may not be sufficient to pass through an area due to water velocity. Such impediments to movement may ultimately regulate the distribution of species and individuals within the catchment. There are occasions where these natural barriers can work in the favour of some species, for example, by blocking the movement of others. For instance, native fish populations in an upstream region may be protected from exotic species that are not adapted to negotiate some natural barriers such as waterfalls (Bjornn and Reiser 1991). For example, the common native New Zealand fish, river galaxias Galaxias vulgaris, has been shown to exist primarily above waterfalls that limit movement upstream of brown trout Salmo trutta (Townsend and Crowl 1991). Such natural barriers to fish movement have been mimicked by the establishment of artificial barriers including weirs. While typically such structures have not been

298 specifically erected to limit the distribution of undesirable fish, it often occurs as a desirable by-product (Behnke and Zarn 1976).

Periods of heightened flow and a varying flow regime has the potential to influence fish assemblages and their resultant habitat use (e.g. Jowett and Duncan 1990, Fausch and Bramblett 1991). For example, differently structured fish assemblages may exist in areas that form part of the same catchment due to hydrological regimes isolated to singular regions. The catastrophic nature and seasonality of elevated flows in these regions can be integral in triggering fish spawning (Poff and Ward 1989, Biggs et al. 1990). Additionally, extreme flow events have been shown to shift, or even kill fish due to the violent momentum of the water (e.g. Harrell 1978; Harvey 1987). Fausch and Bramblett (1991) reported that after such events the reestablishment of fishes in regions depleted in this way can be limited by lack of flow which interferes with fish movement after the flood flows have dissipated. Nevertheless, swift reestablishment of fish in unoccupied stretches of water has been shown to occur when conditions are appropriate for their migration (e.g. Peterson and Bayley 1993). Reasons for this swift reestablishment are varied; however, Hynes (1970) suggested that in smaller-sized streams, the potential for invertebrate prey was higher per unit area compared to larger waterways such as tributary-collecting rivers. One study (Erkinaro and Niemela 1995) reported that juvenile salmon grew faster in small streams connected to a main river than in the main stream of the river. Anthropogenic alterations to these flows, such as climate change and water extraction may, therefore, lead to widespread modification of fish assemblages, including movement throughout waterways and the use of different habitats (Poff 1992).

6.1.3 Diadromy Fishes that exhibit a diadromous lifecycle undertake migrations that make them highly susceptible to anthropogenic impacts (Jonsson et al. 1999; McDowall 1999). Since European settlement of Australia, many once common diadromous fishes have declined in their distribution and abundance (Ingram et al. 1990; Faragher and Harris 1994; Miles et al. 2014). Despite this, much is unknown about the diadromous lifecycles of fish, a lifecycle commonly employed by fishes in Eastern Australia (Miles et al. 2014).

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Ensuring that natural passage for fish is maintained is especially important for diadromous species (Lucas and Baras 2001). Unnatural barriers to movement, for example, dam walls and weirs, can act as a limiting factor for the movement of fish (Castro-Santos 2006). The regulation of rivers through damming for potable water supply typically exhibits a flow regime that is invariable, with small volume releases of water that are not characteristic of the natural flow regime (Growns and Growns 2001). This factor has been identified as a significant contributor to the impacts received by diadromous fishes, which often require access to large stretches of waterways throughout their lifecycle (McDowall 1988; Helfman 2007).

Miles (2007) reviewed Australian fishes that exhibit diadromy. A total of 33 fish species were found to display this trait, including 15 amphidromous, 14 catadromous, and four anadromous species. The dearth of information on such species is chiefly due to the intricate nature of the lifecycles of this group of fishes (e.g. varied habitat occupancy, juvenile migration), making successful implementation of ecological field studies difficult (Closs et al. 2003; Pusey et al. 2004). Nevertheless, recent technological advancements provide the potential to extrapolate data from this group of fishes and, in particular, information relating to those species with complex lifecycles (e.g. Cooke et al. 2008; Elsdon et al. 2008; Ueda 2012).

6.1.4 Methods of Fish Movement Tracking The capacity to monitor animals and their associated life history traits has typically been restricted to larger, more conspicuous species (Hobson 1999; Miles et al. 2014). Generally, this has occurred as a result of technological restraints due to the use of external marker tags which often required physical re-recovery of the animal, or at least the need to come in close proximity with the individual (Hobson 1999). Despite the limitations, the utilisation of external tagging and capture-mark-recapture experiments have aided in gaining an understanding of fish migrations among varying localities and habitats (Morton et al. 1993). Some studies have also employed the elemental chemistry of fish saggital otoliths (or ear bones) (e.g. Gillanders 2005) as well as acoustic telemetry (e.g. Walsh et al. 2012) and PIT tagging (e.g. Baumgartner et al. 2010) experiments to better understand fish migration between habitats.

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PIT (Passive Integrated Transponder) can represent an efficient way of electronically monitoring movements of fish within waterways (Lucas and Baras 2000). Initial costs can be high to set up a monitoring program, but maintenance costs are typically low and do not require subsequent handling of fish beyond the PIT implant. This gear is not suitable to all localities, however, but may be useful for monitoring, for example, movement through constructed fishways (Baumgartner et al. 2012). The data attained from such a study could be used to establish occurrence of fish migrations, in addition to detecting fishway effectiveness over extensive periods of time (Castro-Santos et al. 1996; Baumgartner et al. 2010). Similarly, acoustic telemetry tags have been shown to be successful in understanding fish migratory behaviours (Eiler 1995; Lucas and Baras 2000). The tags used in this methodology are, however, costly and restricted to larger sized fish (> 12cm). Due to costs this method is also typically limited to tracking a small pool of fish (Lucas and Baras 2000).

Another approach to determining migratory movement is the use of otoliths. These ear bones develop in the inner ear of bony fishes. They show annual growth markings which are produced concurrently alongside micro-chemical levels associated with the occupied environment (Nelson et al. 1989). The elemental chemistry of fish saggital otoliths can therefore be utilised in determining waters frequented by an individual fish during its lifecycle. This can be established through strontium (Sr) levels present in the otolith layers because of strontium’s higher natural occurrence in seawater compared to freshwater (Kalish 1990; Secor and Rooker 2000; David et al. 2004). Conversely, barium (Ba) levels in otolith layers will be higher in freshwater environments where it occurs in higher concentration. With this knowledge, establishing fish movement between seawater and freshwater environments is achievable (Bath et al. 2000; Elsdon and Gillanders 2005a; 2005b: McCulloch et al. 2005; Crook et al. 2006). Otolith studies therefore provide greater potential for attaining long-term data over a larger area than acoustic telemetry and PIT tagging (Miles et al. 2014). In addition, cost-efficient and modern improvements to the technique have been made to the techniques used in otolith studies. For example, laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) has facilitated the collection of fish migration data (Miles et al. 2014). In South Eastern Australia,

301 otolith chemistry has enabled a greater understanding of the riverine movement of a range of fish species (Crook et al. 2006; Crook et al. 2008; Miles et al. 2009). Indeed, it has been used to confirm the diadromous lifecycle in Australian grayling Prototroctes maraena (Crook et al. 2006) and striped gudgeon Gobiomorphus australis (Miles et al. 2009). However, many Australian diadromous fishes, such as the catadromous Australian bass Macquaria novemaculeata, may only utilise saltwater environments for short periods during spawning events and early in their lifecycle (Miles et al. 2014). This has the potential to make patterns of migration between fresh and seawater less discernible, although recognisable. However, despite the benefits of this technique, careful interpretation of results was recommended by Miles et al. (2014) for fish species known for making rapid riverine movements. One example of this is with the species freshwater mullet Myxus petardi, whereby otolith chemistry suggested an amphidromous lifecycle (Miles et al. 2009). This assertion became less likely when acoustic telemetry indicated that catadromous movements had been rapid, and this was not readily detected through otolith chemistry (G. Butler and C. Walsh unpublished data). Otolith chemistry studies would benefit from studying diadromous fish populations throughout their distribution range within and among catchments (Walther and Limburg 2012).

6.1.5 Macquaria novemaculeata lifecycle and lifecycle interruption Harris (1986) established that, at least in the Hawkesbury River, M. novemaculeata spawn in waters that are approximately one-third the salinity of seawater (8-14 g/kg- 1), within water temperatures ranging from 11 to 16oC. Eggs are demersal and, once hatched, juveniles move to in-stream macrophytes before migration to upland freshwater reaches during the following spring-summer.

Males reside in these upland reaches for 2-4 years, females 5-6 years, before reaching maturity (van der Wal 1983). Outside of the winter-spawning period, in some catchments, adult females tend to move further upstream than males. This results in an apparent seasonal gender-separation (Harris and Rowland 1996). At least in the Snowy River (NSW), however, M. novemaculeata may make large-scale migrations up or down stream throughout the year. Large-scale movement is, therefore, apparently not only for spawning but perhaps also influenced by habitat use, prey

302 availability, and/or water quality and temperature. The suggestion that there is movement to a region with enhanced water quality was highlighted by Brown (2009) who suggested that an autumn peak-flow and associated turbidity downstream of the Buchan River tributary in the Snowy River may have been the cause of fish movement away from this area. However, in this system, most estuarine visits by M. novemaculeata were correlated with periodic increases in water temperature after the winter minima. This finding is somewhat contradictory to Reinfelds et al. (2011) who found that fish moving downstream at base flow in the Shoalhaven River (NSW) appeared to do so in response to progressively decreasing water temperatures at the end of autumn when water temperatures could fall below 15oC. This may be due to disparities in spawning periods between the two systems. Traditionally, spawning is thought to occur between May and July (Harris and Rowland 1996), however, Brown (2009) suggested that in the Snowy River the spawning season may extend from late July to late October. Nevertheless, simply because estuarine visits in the Snowy River were correlated to increases in water temperature does not mean that movement downstream does not occur at an earlier stage when temperatures are still falling before the winter minima. Indeed, in the Snowy River, M. novemaculeata moved greater distances in colder stream temperatures.

Effectively all rivers of the Australia’s eastern coastline have been subjected to multiple anthropogenic impacts. For example, river regulation by damming (e.g., Hawkesbury-Nepean River) has decreased flow and reduced the potential for migratory fish, such as M. novemaculeata, to move freely throughout the river length. This is because flow regulation caused by dams weakens the natural impact of increases in flow which, in essence, mimic drought. This lack of natural cues, even with environmental flows, is likely to reduce movement of M. novemaculeata and subsequent recruitment. The observation of reduced spawning in M. novemaculeata of Harris (1988) who undertook ichthyoplankton surveys during drought in 1979 and 1980 supported the reliance on flows for spawning. Such impediments to migration are problematic for M. novemaculeata. For example, naturally-occurring populations of M. novemaculeata in the Shoalhaven River have become isolated below the Tallowa Dam wall (Bishop and Bell 1978; Walsh et al. 2012). Such barriers to fish migration have also occurred in the Hawkesbury-Nepean River (NSW). This has

303 halved the potential for fish migration into up-stream habitats that would have naturally occurred in the past (Marsden and Gehrke 1996), although new technologies have seen improved fishways and fish passage in this waterway (Growns and James 2005). However, such isolation and the impediment to movement as a result of dam construction are likely to see this fish species excluded from areas with desirable resources (e.g. habitat - Reinfelds et al. [2011], prey – Harris [1985b]).

Females of this species are more likely to be impacted upon in catchments with dams as they apparently move further upstream than males in their natural lifecycle (Harris and Rowland 1996). In a review of fish populations and associated migratory behaviours, Jonsson and Jonsson (1993) also found that females tended to have a more extensive migration regime than males. These authors recognised that this is likely to arise from females attempting to maximise body size by entering areas with richer feeding grounds, which aids in improved fitness and condition that is advantageous for successful recruitment. In addition, these upstream habitats may have greater or even fewer resources (e.g., Brainwood 2006 – Hawkesbury-Nepean River). However, the competition for these resources in upstream areas is likely to be smaller than in downstream areas thus making them desirable, particularly for reproductive females of this species.

Reinfelds et al. (2011) found that downstream of Tallowa Dam (Shoalhaven River, NSW), 84% of tagged M. novemaculeata migrated downstream from freshwater reaches to estuarine habitats for spawning. Of these fish, 62% moved in conjunction with periods of flow elevation due to dam releases, and 38% moved downstream under typical baseflow conditions. However, at least some of these baseflow-moving fish did take advantage of elevated flow regimes and thus moved more efficiently in their downstream migration into estuarine spawning grounds. The elevated flows thus generally allowed for more efficient passage of fish past obstacles as higher flows can effectively drown out impediments to fish movement (Reinfelds et al. 2011).

In contrast, Harris (1986) found that while falling water temperature in autumn initiated gonadal development (onset of spermatogenesis and oocyte maturation), M. novemaculeata relied on floods to stimulate downstream migration to estuarine

304 habitats. It appears that to initiate downstream migration in regulated rivers, adequate flow is important to provide suitable passage for migration. However, to ensure that a substantial proportion of M. novemaculeata achieve downstream movement to the estuary spawning grounds, also requires conditions of natural base flow (Reinfelds et al. 2011). Taking advantage of elevated flows, including those due to flood, has also been shown to result in successful recruitment in other Australian percichthyids (e.g. Murray cod Macc. peelii) (Harris 1986; Walsh et al. 2011). Seasonally variable movement also occurs in other species. For example, use of seasonally flooded marshes by fish for reproductive purposes occurs in Southern France (Poizat and Crivelli 1997) and in curimba Prochilodus scrofa in the upper Parana River (Brazil) whose reproductive success correlates with flood events throughout summer and autumn (Gomes and Agostinho 1997).

Under typical flow conditions, M. novemaculeata readily move through pool-riffle zones during the dawn/dusk period, minimising the chance of predation (Reinfelds et al. 2010). Even below fast-spilling and flowing water released from an upstream dam, Bishop and Bell (1978) reported that M. novemaculeata had the potential to swim against the flow at speeds in excess of 2-4 m/s, although this may only have been possible for short bursts before the fish succumbed to exhaustion. This finding correlates to more recent observations where at water velocities of 1.5-2.0 m/s over lengths of approximately 10 m, mature M. novemaculeata had difficulty proceeding upstream (Badenhop et al. 2006). Reinfelds et al. (2010) observed that while negotiating shallow riffle areas at a flow rate of 130MLd-1, mature and potentially exhausted M. novemaculeata were readily predated upon by piscivorous birds. Downstream of Tallowa Dam, environmental flows may have improved conditions for M. novemaculeata movement, especially in the post-spawning period during their upstream migration in late winter and early spring. These environmental flows resulted in greater depths which facilitated fish movement across extensive shallow- riffle zones.

To negotiate natural riffle zones, M. novemaculeata require depths of 0.1 m (juveniles) and 0.2 m (adults) (Koehn and O’Connor 1990; Badenhop et al. 2006). Environmental flows also aided in improved movement through the higher-gradient

305 rapids, which provide a secondary pathway[s] along the margins of rapids where there is typically lower water velocity of a more suitable depth for fish to migrate than the shallows (Walsh et al. 2010; Reinfelds et al. 2010).

Because migration from freshwater to estuaries to spawn can be influenced by water flow (i.e., floods), M. novemaculeata often experience diminished recruitment during drought periods (Harris 1988). These impacts can be further exacerbated by the presence of weirs with inappropriately constructed fishways that are based on those used internationally for salmonid migration, and are sub-optimal for M. novemaculeata. With recent advancements in weir design (e.g. suitable fishways) that have been introduced to Australia, some migratory issues that have occurred in the past because of such man-made obstacles have been lessened. For these to work successfully, depths of more than 0.3-0.4 m may be necessary for successful passage of adult M. novemaculeata (Mallen-Cooper 1992), however, not all migrating individuals of this species are adults. A high proportion of M. novemaculeata migrants are juveniles or fish that have not attained a large adult size, usually making their way upstream after spawning in the estuaries (Harris 1984a; b). Immature M. novemaculeata, in particular, do not possess the swimming capability crucial to passing weirs that lack a suitable fishway (Bainbridge 1958, Mallen-Cooper 1992). For example, Mallen-Cooper (1992) observed that as immature M. novemaculeata (40-94 mm) migrated upstream they grew, and with that came commensurate improvement in their swimming ability and hence they were subsequently able to swim upstream more efficiently against the increased water velocities than at a smaller size.

Successful population management of migratory fish also requires specific comprehension of their population density and carrying capacity across their range of habitats (Baumgartner et al. 2012). For example, during M. novemaculeata recruitment events between 1990 and 1992 (Hawkesbury-Nepean River) the potential for recruitment was not reached despite apparently suitable conditions. It was suggested (Harris and Gehrke 1993) that perhaps when the population was at carrying capacity, M. novemaculeata restrict spawning and in this way the density of the population is regulated (Harris and Gehrke 1993). This behaviour may correlate to

306 year-round site fidelity observed in this species in the Shoalhaven River. With a selected cohort of tagged fish, Walsh et al. (2012) found that spawning in M. novemaculeata occurred less frequently than in M. colonorum. No spawning occurred in fish from some reaches, perhaps as a result of population carrying capacity. Similarly, high density within a population of the guppy Poecilia reticulata during the spawning season has been associated with female egg retention (Dahlgren 1979).

Migratory movement within catchments also provides greater potential for gene flow among localities than would be experienced if M. novemaculeata was more sedimentary (Jerry and Baverstock 1998). In addition to within river migration, M. novemaculeata have been captured offshore. This indicates that they have the ability to move among catchments (Jerry 1997). Grimes and Kingsford (1996) assumed that during flood events they could move offshore within the flood plume of waters that were diluted with freshwater. When individual plumes at the catchment mouth meet with the plumes of adjacent river systems, there is the potential for fish to move between catchments and enable gene flow between normally isolated populations. Jerry (1997) reported that no M. novemaculeata eggs or larvae have ever been encountered in salinities exceeding that used in estuarine spawning, hence, their contribution to gene flow between catchments at this life stage is likely to be insignificant, if not non-existent. Nevertheless, the observation that M. novemaculeata populations of each catchment have only subtly different genetic attributes does indicate that some gene flow occurs among catchments (Jerry and Baverstock 1998). This assumption is supported by the observations of Jerry and Baverstock (1998) who found that as the distance of separation increased between catchments, genetic differentiation among populations became greater. Since spawning and migratory events in diadromous fish species commonly occur under advantageous abiotic conditions, including flooding, the scenario of flood plume-mediated exchange of genetic material between catchments is therefore feasible (Pusey et al. 2004; Clark et al. 2005).

Overall, there is a dearth of data available on the migrations of M. novemaculeata that occupy tributary systems for at least part of their lifecycle. With the apparent likelihood that the recreational fishermen cohort that targets this species is increasing

307 in size (Chapter 3), understanding this species ability to recolonise these habitats is essential to maintaining sustainable populations. Modern advancements in LA- ICPMS otolith chemistry analytical techniques offers an avenue to better understand the complex movements of this species in habitats rarely studied.

The purpose of this study is to determine migratory movement by M. novemaculeata between freshwater and estuarine habitats using otolith microchemistry. Only one other study (Macdonald and Crook 2010) has focused on the otolith microchemistry of M. novemaculeata. This was an in vitro study examining the response of Sr:Ca and Ba:Ca in otoliths of the species. It confirmed that using these elemental ratios as indicators of periodic waterway occupancy showed potential movement across salinity gradients.

In this chapter I investigate migratory movements of M. novemaculeata between two different tributary types in the Hawkesbury River catchment; (i) ‘Obstacle-strewn’ tributaries were defined as irregularly connected pools, segregated by objects which were expected to impede M. novemaculeata migration under base flow conditions and (ii) ‘Open’ tributaries lacking discernible obstacles that could impede the ability of M. novemaculeata to migrate under base flow conditions. The null hypothesis tested is that there is no significant difference in the migratory movements to estuaries by M. novemaculeata from obstacle-strewn and open stretches of waterway in the tributaries studied.

6.2 Methods

6.2.1 Collection of fish for analysis Site Description is described in Chapter 2, Section 2.1. Techniques used to capture fish are described under Sampling Method (Chapter 2, Section 2.2).

A stratified criterion was employed in the selection of fish from which otoliths were analysed. An excess of females was obtained because the otolith microchemistry focus was tailored towards females of this species for a number of reasons: 1) more females than males were encountered in sampling; hence, they represented most of

308 the sampled population; 2) past research (Harris 1987) showed that females of this species typically grow larger and faster than males and, therefore females have a greater likelihood of being more vulnerable to recreational fisherman take; and 3) a species can generally flourish with some reduction of males within a population and is likely to suffer more if female numbers are impacted (Harris 1987; Krohn and Kerr 1997). Knowledge of female migratory habits, therefore, has a greater potential to contribute valuable data to underpin the sustainable management of M. novemaculeata populations than focusing on the movements of males.

Five females and one male were selected at random from each tributary type (Table 6.1). After capture, fish were taken to the laboratory for processing and analysis.

6.2.2 Otolith Microchemistry Analysis

6.2.2.1 Preparation of otoliths for analysis Otoliths were removed from the heads of sampled fish in vitro using the boning knife. This procedure was a modification of Harris (1985a) which involved extraction of the gills and viscera, by parting of the vertebral column from the skull. The bulbous posteroventral component of the basioccipital bone was then removed surgically using scissors. Physical handling was subsequently used to remove excess flesh still attached to the removed segment, and to lever open the cavity housing the otoliths. Once removed, the otoliths were rinsed with Milli-Q water and stored dry in separate jars.

Where possible, otoliths were measured (mm) with digital callipers (resolution = 0.01; Whitworth, California) in both a longitudinal and transverse dimension. The saggital otoliths were embedded within epoxy resin (Epofix, Struers, Denmark) and were cut centrally utilising an isomet low speed diamond band saw (Buehler, Illinois), ran at low speed, with lubrication provided by water (Elsdon and Gillanders 2002; Crook et al. 2006). The cutting was aimed centrally through the core of the otolith which is denoted by a cloudy white spot. The thickness of the sections was measured with callipers (mm) (resolution = 0.001; Mitutoyo, Japan) to approximately 0.40 mm. These segments were subsequently rinsed with Milli-Q water and allowed to dry on

309 glass slides. After preparation, a sectioned otolith was placed on glass microscope slide and affixed with additional epoxy resin and/or heated crystal bond around the edge of the hardened resin. Otoliths were then lightly polished with an aluminium oxide (Al2O3) paste (20 M; 3 M; 0.3 M) in a sequential manner on a series of 6 inch (approx. 154 mm) microcloths (Buehler, Illinois) to remove any residual resin on the otolith surface and, in addition, to create a smooth surface for analysis. At the completion of this process sectioned otoliths were approximately 0.30 mm thick. They were then rinsed with Milli-Q water and sonicated for five minutes. The prepared slides were subsequently dried in a laminar flow cabinet before storage in glass specimen containers prior to analysis of age (Chapter four) and microchemistry (Miles 2007).

6.2.2.2 Microchemistry analysis Microchemistry analysis involved the use of a micro-chemical procedure, involving a LA-ICPMS. The equipment used a laser ablation unit (New Wave Research UP213 – Kenelec Technologies, Victoria, Australia) run in conjunction with an inductively coupled plasma-mass spectrometer (Agilent Technologies 7500 cx – Agilent Technologies Australia, Victoria, Australia). The laser utilised an Nd:YAG solid-state laser source, which emitted a 213 nm laser pulse in the fifth harmonic. Affixed to the laser unit was a Large Format Cell (LFC). The laser unit was joined to the ICP-MS by means of polyvinylchloride tubing. To improve reading sensitivity, the 7500 cx ICP- MS was affixed with a ‘cs’ lens system.

Before each experiment, the LA-ICPMS operating system was retuned for appropriate sensitivity. Reference standards (NIST 612 glass) were measured regularly to calibrate the relative sensitivity of each analyte mass (Norman et al. 1996; Elsdon and Gillanders 2002; Elsdon and Gillanders 2004; Crook et al. 2006). The standard was measured each time the sealed sample stage was opened, and again mid-way through each sample set. Laser ablation of the samples was conducted using a continuous scan across the otoliths from one edge to the other using an automated stage. Two different settings were used; 1) for otolith transects a single line was used to pass from the edge of the otolith through the core and to the other edge using a 10-Hz pulse rate, a 30µm diameter spot and a scan rate of 5µm per second and 2) in order to produce otolith

310 maps, a series of transects were used to ensure coverage of the otolith (e.g., a scan every 30 µm down the otolith) using a 20 Hz pulse, 30 µm diameter spot. Due to the large area and number of scans required, the speed was increased to 61 µm per second. A pre-ablation pass was run before all scans to ensure the surface was free from any contamination. In order to determine if otolith Sr:Ca and Ba:Ca transects alone provide sufficient information to determine differences in migratory movements of M. novemaculeata, a pilot study involving two individuals was initially conducted.

Colour was used to allude to the strength of the signal, which is obtained after transfer of the ablated otolith section to the ICPMS. The output was correlated to the concentration of elements. The elements tested included Sr88 and Ba137. These elements were standardised to Ca and expressed as a ratio (i.e. Sr:Ca). Life history patterns of the fish were investigated by examining symmetric patterns in the Sr:Ca and Ba:Ca profiles. This was conducted in order to attain data in relation to how M. novemaculeata vary in obstacle-strewn and open waterways with a focus on the number of estuarine visits individuals from the two tributary types undertook. Total estuarine visits were compared to the minimum age of fish between tributary types by Chi square analysis. Where estuarine occupancy appeared constant over a period of years, estuary returns were rated at one per year.

6.3 Results

6.3.1 Efficiency of results The two sample transects taken typically exhibited similar patterns for both chemical ratios studied (Sr:Ca; Ba:Ca). That is, a drop or spike in one chemical usually occurred in conjunction with the other (Figure 6.1; Figure 6.2). This demonstrated that the method lacked the ability to clearly define migration patterns in M. novemaculeata. An alternative method was therefore adopted using a map of the entire otolith showing Sr:Ca and Ba:Ca across the entire cross-section of the otolith. This method also allowed for more ease in determining the association of the age of fish with time of migration.

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Figure 6.1 Transect of a female fish from Wrights Creek highlighting variation in otolith microchemistry (Sr:Ca; Ba:Ca) in the Hawkesbury-Nepean River, Australia.

Figure 6.2 Transect of a female fish from Wheeny Creek highlighting variation in otolith microchemistry (Sr:Ca; Ba:Ca) in the Hawkesbury-Nepean River, Australia.

Whole otolith maps produced from the LA-ICPMS analysis showed that the interior core of the otolith typically exhibited low Ba:Ca, with increased concentration in the outer areas. Patterns of Sr:Ca were less distinct in this core region; however, the core of the otolith often had a high elemental concentration of Sr:Ca. The high levels of Sr:Ca and low levels of Ba:Ca in the interior core of the otolith, indicated estuarine residency in the larval/juvenile stage for fish sampled (Figure 6.5; Figure 6.6).

312

Concentrations in the region outside of the core of the otolith were highly variable for both Sr:Ca and Ba:Ca, with the elemental composition of otoliths often exhibiting no consistent pattern across both ratios. It would be expected that peaks in Sr:Ca in the region outside of the core would represent occupancy of estuarine environments and, therefore, a negative relationship would occur with Ba:Ca. This did not necessarily occur. Increases in Sr:Ca extending outside of the core in the LA-ICPMS scans, often occurred in parallel with increases in Ba:Ca (Figure 6.5; Figure 6.6). However, in the otolith maps Ba:Ca appear to display clearer, more distinguishable banding patterns to make interpretations of fish migration from although occasionally Sr:Ca displayed clearer results of the change in ratios (fish e and f - Figure 6.5).

6.3.2 Comparison of fish age and migration between stream types Macquaria novemaculeata analysed in the study varied in length from 243-337 mm, with the age of fish varying from 6–16 years (Table 6.1).

Webbs Creek (a) 288 Female 9

Webbs Creek (b) 287 Female 16

Wrights Creek (c) 319 Female 14

Wrights Creek (d) 311 Female 13

Wrights Creek (e) 282 Female 6

Webbs Creek (f) 296 Male 6

Little Wheeny Creek (g) 249 Female 13

Wheeny Creek (h) 315 Female 7

Wheeny Creek (i) 271 Female 7

Wheeny Creek (j) 337 Female 11

313 Site Fish Code Length (mm) Sex Age (Years)

Wheeny Creek (k) 276 Female 8

Popran Creek (l) 243 Male 7

While migration did not necessarily occur annually, most fish did visit the estuary each year (Figure 6.3; Figure 6.4). Estuary returns by M. novemaculeata were not 2 significantly different between tributary types (χ 1 = 0.393, p = 0.53; n = 12).

314

Figure 6.4 Estimated number of estuary returns by six Macquaria novemaculeata from obstacle-strewn tributaries (g-k = female; l = male) of the Hawkesbury- Nepean River, based on analysis of otolith chemistry. *Where estuarine occupancy appeared constant over a period of years, estuary returns were rated at one per year.

The lifecycle of fish from open tributaries exhibited occupancy in estuarine habitats after emergence from the egg before, typically, movement to freshwater reaches in the first year of life (Figure 6.5; Table 6.2). Two fish apparently made multiple trips to and from the estuary within this period (a, d; Figure 6.5; Table 6.2). After the first year, all fish made estuary returns although the frequency at which this occurred varied. The oldest fish (b, c, d) made estuary returns less frequently in ratio to their age than younger fish. One female fish (a) migrated to the estuary every year, and the male analysed (f) visited the estuary five times in its six years of life (Figure 6.5; Table 6.2).

315 (a)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >60 0 >8

(b)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >200 0 >10

(c)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >140 0 >5

(d)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >175 1.5 >10.5

(e)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >180 0 >10

(f)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >180 0 >7

316 Table 6.2 Interpretation of migration frequency of six Macquaria novemaculeata from open tributaries (Figure 6.5) using Ba:Ca (a-d) and Ba:Ca/Sr:Ca (e-f) elemental concentrations. < Estuary = return to estuary; > Freshwater = > migration to freshwater. (a) Year 0-1: Fish emergence from egg and growth in estuary > freshwater < estuary > freshwater

Years 1-3: < estuary > freshwater < estuary

Year 3-6: > freshwater < estuary > freshwater > estuary > freshwater > estuary > freshwater

Year 6-9: < estuary

(b) Year 0-1: Fish emergence from egg and growth in estuary > freshwater

Year 1-16: < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater

Year 1-2: < estuary

Year 2-5: > freshwater

Year 5-14: < estuary > freshwater < estuary > freshwater < estuary > freshwater

(d) Year 0-1: Fish emergence from egg and growth in estuary > freshwater < estuary > freshwater < estuary > freshwater

Year 1-13: < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater

(e) Year 0-2: Fish emergence from egg and growth in estuary > freshwater

Year 2-5: < estuary > freshwater < estuary > freshwater

(f) Year 0-2: Fish emergence from egg and growth in estuary > freshwater

Year 2-6: < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary

All fish from obstacle-strewn tributaries remained in estuarine habitats after emergence from the egg before movement to freshwater reaches (Figure 6.6; Table 6.3). Two fish (i, l) apparently made multiple trips to and from the estuary within this initial period (Figure 6.6; Table 6.3). The length of estuarine occupancy in this initial period fluctuated with one fish moving to freshwater reaches almost immediately and another taking more than three years to move into the freshwater reaches of the catchment (Figure 6.6; Table 6.3). The oldest fish (g, j, k) made estuary returns less frequently in ratio to their age than younger fish. Two fish (a, l) made six estuary returns in their seven years of life (Figure 6.6; Table 6.3).

317 (g)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >250 0 >6

(h)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >800 0 >8

(i)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >225 0 >9

(j)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >225 0 >10

(k)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >375 0 >6

(l)

Ba:Ca µmol mol Sr:Ca mmol mol 0 >100 0 >4

318 Table 6.3 Migration interpretations of six Macquaria novemaculeata from obstacle-strewn tributaries (Figure 6.6) using Ba:Ca (g-k) and Ba:Ca/Sr:Ca (l) elemental concentrations. < Estuary = return to estuary; > Freshwater = > migration to freshwater. (g) Year 0-2: Fish emergence from egg and growth in estuary > freshwater < estuary > freshwater

Year 2-13: < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater

(h) Year 0-1: Fish emergence from egg and growth in estuary

Year 1-2: < estuary > freshwater > freshwater < estuary

Year 3–7: > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater < estuary > freshwater

(i) Year 0-1: Fish emergence from egg and growth in estuary > freshwater < estuary

Year 1-2: > freshwater < estuary > freshwater

Year 2-4: < estuary

Year 4-7: > freshwater < estuary > freshwater < estuary > freshwater

(j) Year 0-3: Fish emergence from egg and growth in estuary

Year 3-4: > freshwater

Year 4: < estuary

Year 4-5: > freshwater

Year 5-6: < estuary

Year 6: > freshwater

Year 7-11: < estuary > freshwater < estuary > freshwater

(k) Year 0-4: Fish emergence from egg and growth in estuary > freshwater < estuary > freshwater < estuary > freshwater

Year 4-8: < estuary > freshwater < estuary > freshwater

(l) Year 0-1: Fish emergence from egg and growth in estuary > freshwater < estuary > freshwater

Year 1-2: < estuary > freshwater < estuary

Year 2-3: > freshwater < estuary

Year 3-4: > freshwater < estuary

Year 4-6: > freshwater < estuary

Year 7: > freshwater

6.4 Discussion

The study reconfirmed that M. novemaculeata is catadromous. It lives predominantly in the freshwater reaches of rivers and migrates to the estuary to spawn (Figure 6.5; Figure 6.6). However, some fish may make additional trips to the estuary or even stay in the estuary for prolonged periods.

319

Harris (1986) established that once hatched, juvenile M. novemaculeata move to in- stream macrophytes in the estuary before migration to upland freshwater reaches during the following spring-summer. Mugil cephalus has also been recorded to remain in estuaries during juvenile growth before movement to upland habitats (Wells 1984). The fry of other catadromous species also initially remain in the estuarine regions of the river. For example, L. calcarifer juveniles initially move into saline coastal swamps and creeks before movement upstream to freshwater environments (Moore 1982). In the current study after hatching, fry typically remained in estuarine habitats for less than a year before migrating upstream to freshwater reaches (Table 6.2; Table 6.3). The length of M. novemaculeata estuarine occupancy in this initial period did; however, fluctuate. Some fish moved to freshwater reaches almost immediately after hatching, while one took more than three years (Table 6.3). This is consistent with the observations of McDowall (1999) who found that juvenile amphidromous and catadromous fish species will occupy lower riverine reaches, taking anywhere from months to years to eventually move to upland habitats. Similar to M. novemaculeata, the catadromous Australian L. calcarifer has been shown to occupy marine waters anywhere from two months to four years (Milton et al. 2008). Indeed some L. calcarifer populations apparently lack a freshwater phase in their lifecycle (Pender and Griffin 1996; Milton et al. 2008), although it has been recognised that restrictive access to freshwater rivers likely played a role in this species habitat use (Pender and Griffin 1996).

Some fish from the current study made return trips to the estuary, apparently before they were at an age of sexual maturity (females, 5-6 years, Harris 1986) although age of maturity does vary. For example, Harris (1986) determined that 4% of female M. novemaculeata were mature at less than three years of age (21% < 4; 33% ≥ 5). Indeed, one fish remained in the estuary for at least three years, where it could have potentially matured to become part of the estuarine spawning cohort without prior movement to freshwater. This variation in the age of maturation times has also been exhibited in other species such as vendace Coregonus albula (Amundsen et al. 2012) and in winter ﬂounder Pseudopleuronectes americanus. Indeed, McBride et al. (2013) observed that there was more variation between age-at-maturity than size-at-maturity

320 in P. americanus. This phenomenon has also been observed in another Australian percichthyid, Macc. peelii (Gooley et al. 1995).

The two males analysed in the current study made estuarine visits more frequently than females (Table 6.2; Table 6.3). This could be because males become sexually mature earlier than females (2-4 years compared to 5-6 years - Harris 1986). Males also do not have the requirement to improve their condition as much as females in order to spawn. It may, therefore, be beneficial for females to spawn only when they are in good condition so that they maximise the number of eggs for each visit to the estuary, whereas biologically males need to maximise their chance of breeding (Jonsson and Jonsson 1993).

As previous researchers have reported (e.g., Harris 1986; Reinfelds et al. 2011; Walsh et al. 2012), M. novemaculeata does not necessarily spawn annually. It has been suggested (Harris and Gehrke 1993) that perhaps when the population was at carrying capacity, M. novemaculeata restrict spawning and the density of the population is, therefore, regulated (Harris and Gehrke 1993). Harris (1986) found that 10.7% of female M. novemaculeata aged > 5 showed no ovarian development between June and October. This supports the suggestion that this species does not necessarily spawn annually. These data are compatible with the observations in the current study. Not all females visited the estuary annually. This has also been observed to occur in some other fish species. For example, previous researchers (Walsh et al. 1986; Schwalme and Chouinard 1999; Rideout et al. 2000) have observed that between 20-50% of mature Atlantic cod Gadus morhua do not spawn annually. In the current study, no fish spawned annually (Table 6.2; Table 6.3).

6.4.1 Differences between obstacle-strewn and open tributaries There is no apparent difference between the number of estuarine fish migrations between obstacle-strewn and open tributaries (Table 6.2; Table 6.3). This indicates that obstacle-strewn streams do not present a major migratory barrier to fish migration. Since obstacle-strewn tributaries are the ‘natural’ condition for many tributaries of Australian East Coast rivers this species would be adapted to movement through such environments. As already indicated, some populations of L. calcarifer

321 exhibit near exclusive freshwater life histories (Pender and Griffin 1996). This was attributed to migration upstream during flood events and the subsequent ‘land- locking’ of individuals in lagoons or unnavigable waterway reaches for extended periods of time. However, generally, fish typically exhibit high mobility, and have been shown to swiftly recolonise vacated habitats when available (Peterson and Bayley 1993; Sheldon and Meffe 1995; Boys et al. 2012). Indeed, as has been observed in L. calcarifer (Pender and Griffin 1996; Milton et al. 2008), it is likely that M. novemaculeata wait for large flow events to make spawning movements regardless of their location in the riverine system (Reinfelds et al. 2011). This may, at least in part, explain why they do not make annual migratory trips to the estuary to spawn. This is consistent with the observations of other percichthyid species of Australia. Typically such species have evolved distinctive life-histories to deal with extreme conditions due to weather fluctuations in both the short and long-term. Such erratic conditions typically consist of wide-scale flooding events and extended periods of drought (Puckridge et al. 1998; Roberts et al. 2008). Upland reaches, such as high- gradient tributaries, typically experience higher peaks in water levels than more expansive floodplain rivers where flow impacts are weakened. These waterways are more receptive to isolated rainfall events due primarily to steep topography. This assists in the creation of short-term, although powerful, water surge events (Meffe 1984). This phenomenon likely aids M. novemaculeata to move out of obstacle- strewn tributaries where water is funneled and highly concentrated and thus water levels are raised to allow fish to move over structures that chocks the river at base flow levels (Meffe 1984; Chapman and Kramer 1991).

The characteristics of these waterways therefore likely play an important ecological role in the lifecycle of M. novemaculeata. This is because females typically occur in reaches higher in the catchment than males rather than lower in the catchment where streams are often less chocked by debris, even during low-flow periods (Harris and Rowland 1996). Females are therefore more likely to have a life cycle that is adapted to movement downstream at appropriate times from these upper, often obstacle- strewn, tributaries to reach the estuary to spawn and contribute to the population and the genetic diversity of the species (Jerry 1997).

322 McDowall (1988; 1999) suggested that amphidromous and catadromous fish species with substantial migratory capabilities disperse further inland than those that have lesser migratory ability, but may also occupy habitat at lower elevation in the catchment. Why M. novemaculeata expend considerable energy to reach obstacle- strewn tributaries rather than occupy tidal reaches and open tributaries is likely to be influenced by a number of factors. For example, there is a greater likelihood for ease in establishing territories and reduced predation in upper reaches where M. novemaculeata is often the apex predator (Harris 1983). The tidal nature of open tributaries may also render certain territories inaccessible as the tide recedes, resulting in movement to other areas where territoriality and predation risks are higher, ultimately increasing energy expenditure (Desmond et al. 2000). Avoiding predators and lower levels of intraspecific competition is also regarded as an important factor in catadromous Anguillid eels seeking freshwater habitats (Inoue et al. 2010). Likewise, movement to freshwater swamps is believed to enhance survival rates of juvenile L. calcarifer (Russell and Garrett 1985; Milton et al. 2008). Macquaria novemaculeata is likely motivated to reach obstacle-strewn tributaries for similar habitat benefits.

Although previous studies have shown that natural barriers to movement may result in fish assemblage changes in particular stream reaches (Ross et al. 1985; Poff and Allan 1995), this does not appear to be the situation for M. novemaculeata. They did not appear to be impeded in their movement to the estuary to spawn from either obstacle- strewn or open tributaries. The reason for not moving to the estuary annually may, therefore, be related to other factors associated with the ecology of this species.

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340 7. Discussion

The Australian bass Macquaria novemaculeata is a species of high importance within its environment. It is an apex predator that can live throughout the entirety of river catchments within its natural range, including the riverine channel, estuarine reaches and tributaries (Harris 1983; Harris 1988). The species presence in these ecosystems has also been important as a commercial fishery, with more recent fishing effort focused on recreational fishing (Gray et al. 2003; Dowling et al. 2010). Despite the cessation of commercial exploitation of M. novemaculeata, a threat still exists from recreational anglers who target it throughout waterways which spans rivers of the Australian East Coast between the Mary River (Queensland) to Lakes Entrance (Victoria; Williams 1970; Lake 1978; Harris 1983) (Figure 1.1), including the Hawkesbury-Nepean River, the focus of the current study.

Despite M. novemaculeata being one of the most studied freshwater finfish species in Australia (e.g., Harris 1988; Walsh et al. 2012), research with a specific focus on population differences in tributary habitats has been neglected, although some themes have been previously explored more generally (e.g., Harris 1985a; Harris 1988). Based on prior knowledge of the fish, it was hypothesised that M. novemaculeata would thrive better in obstacle-strewn tributaries than in those that were open. This was because, primarily, there was likely to be a higher diversity and abundance of prey where the habitat was more complex and thus there was a wider range of microhabitats for aquatic life compared to open tributaries which would have less habitat complexity and were, therefore, likely to sustain lower prey diversity (Pianka 1966; Benke et al. 1985; Grenouillet et al. 2002; Chara et al. 2006). It was observed, however, that when obstacle strewn tributaries were compared with those that were open (i.e., not obstacle strewn), fish were of equivalent size, condition, age range and sex ratio (Chapter four). There was also a substantial bias towards females in both tributary types. This finding deviates, at least marginally, from the suggestion that female fish move further upstream for more advantageous habitat, leading to faster growth (Harris 1986; Jonsson and Jonsson 1993). If this were the situation, it would be expected that the obstacle-strewn tributaries would be more favourable habitat than

341 the open tributaries. It therefore appears that females merely prefer lower-order stream reaches than males, whether open or obstacle strewn.

Despite similarities in size and condition, as predicted, prey taken by the fish were very different between tributary types (Chapter five). Although few fish were found to have an empty stomach, and the fish from the two tributary types had equivalent weight of food in their stomachs, the diet of those caught in open tributaries was much lower in diversity than those in the obstacle-strewn tributaries. This finding is indicative of this species generalist behaviour (Harris 1985b). It is able to thrive in either tributary type despite quite different prey diversity and species composition.

On average, fish in the main riverine channel were smaller than those caught in both tributary types. This size difference is, therefore, unlikely to be attributable to differences in diet, as fish of the different tributary types consumed different diversities of prey, and no difference in size was observed. However, small fish frequently consumed a different diversity of prey to larger fish (Chapter five). River regulation and water extraction has previously been observed to be a primary cause for such differences between the river and its tributaries (Gray et al. 1990; Growns and Growns 2001). However, in the study reaches of the Hawkesbury-Nepean River (originally named the Hawkesbury River below its confluence with the Grose River), weirs are rare and water extraction is substantially lower than in the upstream Nepean River reaches (above the confluence with the Grose River). Indeed, fish migration to the estuary was equivalent between the tributary types despite dissimilar hydrological regimes in the different tributary types (i.e., obstacle-strewn tributaries experience rapid spikes in water level) (Chapter six).

A previous study (Van Der Walt et al. 2005) showed that M. novemaculeata of the Hawkesbury-Nepean River were smaller than those of the Manning and Williams rivers, indicating that there is some size differentiation between these catchments, presumably caused by anthropogenic influence (e.g. river regulation, commercial/recreational fishing). One reason for this assumption is that the Hawkesbury-Nepean River Catchment is central to the species natural distribution and, therefore, this size discrepancy is unlikely to be naturally-occurring. Evidence that it is more likely to be a result of over-fishing is supported by observations of fish

342 morphormetrics in M. colonorum (Walsh et al. 2010) and G. morhua that have, together with M. novemaculeata, been commercially fished. The selective removal of larger fish affected the viability and sustainability of fish populations due to fishing- impacts resulting from the extraction of the most fecund individuals from the population (Krohn and Kerr 1997). Outside of spawning periods, female M. novemaculeata also apparently prefer to move further upstream (Harris 1986), and this was supported by the current study where females were more common in the tributaries studied than males.

This difference in sex ratio in the tributaries may impart some bias on previous catchment-scale size differences observed in M. novemaculeata and the difference between fish caught in the tributaries compared to those in the main channel. The Williams and Manning rivers both exhibit less tributary habitat than the Hawkesbury- Nepean River. Larger females, therefore, may not have the same options to seek lower order streams in the Williams and Manning rivers and thus fish would be somewhat more restricted to the riverine channel in these rivers than in the Hawkesbury-Nepean River. This provides one explanation for the discrepancy in M. novemaculeata size between the river and tributaries of the Hawkesbury-Nepean River (Chapter four).

In the current study, some M. novemaculeata, were determined to be older than 20 years, with one individual determined to be 28 years of age, the oldest age recorded for this species. This species is therefore long-lived, an adaptive trait that presumably counteracts the effects of unfavourable spawning conditions such as drought (Harris 1986) that occurs intermittently in the Region of the study. This species also experiences limited natural predation beyond the juvenile stage because it spends much of its time in freshwater habitats where it is the apex predator (Harris 1983).

The average age of fish in the current study was approximately double those caught by Harris (1988) in the same river system, but were of a similar mean length, and the same aging technique was utilised. One explanation for this difference is that size truncation has occurred, at least in the intervening decades between the two studies. This phenomenon typically occurs in fish as a result of size-selective harvesting whereby the larger individuals are targeted by recreational and/or commercial fishermen (Fenberg and Roy 2008). This is based on the assumption that slow

343 growing fish are less likely to be retained than larger fish of the same age when fishermen practice catch-and-release. This removal would select those individuals genetically pre-disposed to grow faster, and disproportionately increase those pre- disposed to grow slower (Johnson and Brown 1998). This may occur when there has been heavy fishing pressure for an extended period, as has occurred with commercial fishing in the lower reaches of the Hawkesbury-Nepean River where larger specimens have been targeted (Gray et al. 2003) and recreational fishing occurs in the main stream and tributaries (Van Der Walt et al. 2005). However, commercial fishing pressure no longer occurs due to a ban on commercial fishing of the species. As a result of the genetic bottleneck that may occur under prolonged heavy fishing pressure on larger fish, a change to the genetic structure of the fish population may have occurred. Removal of fishing pressure with the ban of commercial fishing, revised restrictions on angler fish take to protect fecund females (i.e., only one fish can be taken that is ≥ 35 cm), and the switch to catch-and-release among recreational fishers thereafter, would then be expected to result in fish being, on average, smaller for their age than in the population when commercial fishing commenced and actively targeted larger specimens of this species, exacerbated by the additional pressure from recreational anglers retaining their catch. The observation that the fish in the Hawkesbury-Nepean River were smaller than other rivers within their endemic range (Van Der Walt et al. 2005), but older than previously captured (within this River) does support this concept. Evidence that this may be occurring can be gleaned from the work of Swain et al. (2007). They observed that there were genetic changes in growth of Atlantic cod Gadus morhua as a result of size-selective harvesting. This was attributed to the observed small size-at-age of fish despite otherwise suitable environmental conditions (e.g., food and habitat availability). Although anglers surveyed in the current study reported that they typically caught-and-released their fish, they also claimed that over time they had moved to a more sport-orientated basis when angling for M. novemaculeata since they initially commenced recreational fishing (Chapter three). This indicates that there is now less pressure on the fishery than previously, and that even large fish are being released rather than retained.

Female M. novemaculeata of this study were typically larger than males, and they were more frequently encountered than males during sampling (Chapter four). Observations of Harris (1985a) on M. novemaculeata support this distribution of the

344 sexes within the riverine system. He observed that 60% of fish from freshwater tidal habitats were males, and 87% of fish caught in gorge and lagoon habitats were female. This does suggest that the size difference between tributaries and the riverine channel may be due primarily to differences between the sexes in preferred habitat. Since there is sexual dimorphism with females attaining a larger maximum size than males, and there were a substantially higher number of females than males caught in both tributary types studied, this could explain the difference between the smaller average length of fish in the main riverine channel than those caught in the tributaries. The observation by Harris (1987) that females in the headwaters of the catchment were often larger than those elsewhere further indicates that females may be attracted to the most productive habitats or where there is less competition from other fish (i.e., lower order reaches of the river including tributaries) (Harris 1986).

Males were also observed to move more frequently to the estuary than females. Since male fish move through the riverine environment from the tributaries and headwaters to reach the estuary for spawning more frequently, males would spend more time in association with reaches in the main channel than females. The observation that males are more commonly encountered in the riverine channel could merely reflect the more frequent migration of males within the river system. Males in the main channel are also likely to have an advantage over tributary or gorge-based males in being better able to determine the migratory movements of females to the estuary where spawning takes place. A similar pattern of distribution to that of M. novemaculeata has also been observed in three New South Wales rivers for the longfin eel Anguilla dieffenbachia. The sex ratio of this species was observed to be skewed strongly. There was a female bias of approximately 97% in freshwater (non-tidal) reaches, although the bias was weaker in the tidal reaches (Walsh et al. 2004).

Energetic input to spawning for males is lower than for females and subsequently they do not need to attain the same condition as females to successfully reproduce (Harris 1986). For example, males of the North American Atlantic sturgeon Acipenser oxyrinchus were observed to require one year to re-establish breeding condition whereas females required three years (Smith 1985). Despite M. novemaculeata taking a different diversity of prey in the different tributary types, fish from both tributary types contained the same weight of food in their stomachs (Chapter five). This

345 indicates that although the composition of prey differed, both tributary types provided the fish with equivalent dietary requirements to maintain equivalent condition.

Macquaria novemaculeata from the different tributary types also made equivalent numbers of estuarine visits (Chapter six). This indicated that any fish taken by anglers is unlikely to differentially affect populations in the two tributary habitat types studied. This is evidenced by succession rates, density, and the sex ratio in the current study that were similar in both tributary types. This is somewhat different to a study that focused on the abundance of black bream Hephaestus jenkinsi and barramundi Lates calcarifer in intermittent river-floodplain systems of Northern Australia (Close et al. 2014). Individuals of these fish species were observed to be restricted to discontinuous habitats in the dry season and were thus more susceptible to fishing pressure. This was observed to have led to reduced abundance of L. calcarifer overall. In the current study there were no observed differences between fish from obstacle- strewn tributaries that would be expected to inhibit movement in and out of the tributary compared with those fish that inhabited the open tributaries where movement between the tributary and the main channel would not have been impeded. However, unlike Northern Australia where fish may be trapped until the following wet season in the pools left when flow in the river ceases, the tributaries of the Hawkesbury-Nepean River would likely be isolated at baseflow for shorter periods of the year (Harris 1986; Harris 1988; Reinfelds et al. 2011). Nevertheless, there is potential for M. novemaculeata to become isolated in obstacle-strewn tributaries, at least, during drought periods (Harris 1986).

In the current study, most fishing club anglers that targeted M. novemaculeata do so in the Hawkesbury-Nepean River Catchment. Most anglers who responded to the survey did not retain their catch but typically released the fish at point of capture (Chapter three). This was particularly prevalent in difficult to access areas, such as obstacle-strewn tributaries, where catch and-release of fish was more common amongst anglers than in more readily accessible areas of the river system.

The recreational angling survey for M. novemaculeata indicated that the removal of fish for consumption was rare and has been declining over time (Chapter three). Despite this overall trend anglers who fished in easy access areas, such as the riverine

346 channel, were more likely to retain their catch (or a larger proportion of it) than those who fished elsewhere in the river. Anglers that fished in secluded areas more often, for example, in tributaries such as those that were sampled in the current study, seldom retained any of their catch. However, recreational fishing cannot be excluded as an impact on the population since a large number of Australians fish without affiliation with clubs (Henry and Lyle 2003). Extension of the survey to those not affiliated with fishing clubs may therefore have shown that the non-club affiliated angler was more likely to retain at least a portion of their catch for consumption than those who were club affiliated. For example, anglers were more likely to harvest muskellunge Esox masquinongy in regions that lacked fishing clubs than where there was a club influence. It was assumed that this was because fishing clubs are likely to endorse employment of catch-and-release angling for this species (Gasbarino 1986; Oehmke et al. 1986). If the same trend as observed for E. masquinongy occurred for M. novemaculeata it may, at least in part, account for the much smaller size of fish in the Hawkesbury-Nepean River than in other catchments north and south of this river catchment. This is because the potential impacts from non-club affiliated anglers may be substantial, due to the large number of anglers in Australia who are not affiliated with a fishing club. For example, only 4.3% of anglers who responded to the Australian National Recreational and Indigenous Fishing Survey had a fishing club/association membership (Henry and Lyle 2003).

The observation that most respondents to the questionnaire were between the ages of 25 and 44 years, indicates that this is somewhat of a mature recreational fishing population (Chapter three). If young entrants to the fishery are not initially exposed to the club demographic that encourages catch-and-release employment there is likely to be other avenues of influence. These influences may range from fishing-based publications, both online and in hard-copy, and fishing-themed television shows which commonly stress the importance of catch-and-release sustainable fishing (Martin et al. 2012). These avenues of influence are likely imparting some effect on new entrants to this fishery as they also employ catch-and-release fishing frequently.

347 7.1 Recommendations and further research

It is essential that M. novemaculeata survive into adulthood and beyond to maximise recruitment to the population (Reinfelds et al. 2011). Adult longevity and their ability to grow to a large size are particularly important as fecundity is typically highest amongst females of a greater size (Harris 1986). In general, this study indicated that tributary habitat played a more crucial role in the presence of females than inherent habitat complexity. In managing this species it is desirable to recognise the importance of tributary habitat, both open and obstacle-strewn, as important for females and thus for the maintenance of viable populations of M. novemaculeata.

Selective removal of larger, faster-growing M. novemaculeata, leaving a population of slow-growing individuals has been demonstrated elsewhere for other species (e.g., G. morhua – Swain et al. 2007) and appears to have occurred in the Hawkesbury- Nepean River. Despite current laws to protect M. novemaculeata from over- exploitation, it is further recommended that zero take of larger M. novemaculeata (at least within natural waterways) is considered for effective sustainable management of the species. In addition, the permittance of targeted catch and release fishing for this species from May to August in riverine environments below freshwater impoundments should also be reviewed. However, angler employment of catch and release techniques during spawning periods, has been shown to have minimal impact on spawning success in other species (e.g. S. salar - Booth et al. 1995 and common snook Centropomus undecimalis – Lowerre-Barbieri 2003).

The potential for future re-introduction of a commercial fishery for this species is also not recommended as this could further exacerbate current size truncation. There is a need to monitor across the catchments where M. novemaculeata occurs on the East Coast of Australia, and particularly in those catchments that have the most rapidly growing human populations to ensure that the loss of large fish and the age-size ratio is not changing so that remedial action can occur more efficiently than has apparently happened in the Hawkesbury-Nepean River Catchment. The relevance of this issue extends to other potentially exploited fisheries throughout the world where impacts occur and research-based management is required for long-term sustainability of the fish populations.

348

The past shift of recreational fishers who target M. novemaculeata to more frequent employment of catch-and-release fishing than previously (Chapter three) warrants attention in management of fisheries internationally because fish stocks are currently diminishing worldwide (Torres and Felthoven 2014). With an increasing human population and presumably more recreational fishers, understanding this shift and what has led to it is likely to benefit the successful sustainable management of recreational fisheries. Indeed, angling in the modern world may actually accommodate a positive influence on the sustainability of fish species, which may otherwise go unnoticed without an angler’s vested interest. Specifically, in the case of M. novemaculeata, it would likely benefit the fishery’s sustainability if there was to be a more concerted effort to encourage people to join fishing clubs so that they are able to learn from others, for example, to encourage a greater level of release rather than retaining catches, and to ensure that recreational anglers learn proper handling techniques of fish from hook to release.

Regular fishing competitions, such as the Basscatch competition that provided size data for this study (Chapter four) also provides an option for monitoring the species and thus should be encouraged. Such data are important because they support the understanding of the ecological complexities of a species, such as M. novemaculeata, which is an essential component of sustainable management of the species and, therefore, the dynamics of the ecosystem it inhabits, particularly in areas of increasing urbanisation.

However, as a generalist species, able to thrive equally on very different dietary regimes available in the different tributary types (Chapter five), this presumably allows the species some flexibility to cope with such changes (i.e., urbanisation). Maintaining tributary populations of M. novemaculeata and the habitats in which they reside, in addition to understanding the potential for angler impact is important in considering the needs of the species. It is therefore essential to utilise a holistic approach to this species management encompassing anglers and management groups to drive positive and long-term change that ultimately benefits this species (Arlinghaus 2006). Although, significant difficulties exist in satisfying the interests of an entire angling cohort, what is known is that successful management programs

349 incorporate an understanding of not only how fish respond to exploitation but also what drives an angler’s fishing behaviour (Johnson and Carpenter 1994; Radomski et al. 2001; Post et al. 2008).

The prevalence of the Australian bass, M. novemaculeata in Eastern Australia’s increasingly urbanised areas, and its need to migrate to estuaries to breed, makes it an aquatic species worthy of attention for management. Baseline data for long-term studies on M. novemaculeata such as those instigated by Harris (1985a; 1985b; 1986; 1987; 1988), in addition to studies that make ad hoc contributions to science (e.g., the current study; Reinfelds et al. 2011; Walsh et al. 2012) are important to have implemented for an apex predator such as M. novemaculeata, which is an integral component across a broad range of stream habitats in the coastal flowing rivers of Eastern Australia. Disseminating this information more widely in a transparent, clear manner to the average angler through avenues such as fishing themed magazines and online resources is also likely to benefit the long-term sustainability of this species. Indeed, the reasons for adoption of catch-and-release by anglers were typically rooted in science.

7.2 References

Arlinghaus, R. 2006, 'Overcoming human obstacles to conservation of recreational fishery resources, with emphasis on central Europe', Environmental Conservation, vol. 33, pp. 46-59.

Benke, A.C., Henry III, R.L. Gillespie, D.M. and Hunter, R.J. 1985, 'Importance of Snag Habitat for Animal Production in Southeastern Streams', Fisheries, vol. 10, pp. 8-13.

Booth, R.K., Kieffer, J.D., Bruce, L.T., Davidson, K. and Bielak, A.T. 1995, ‘Effects of late-season catch and release angling on anaerobic metabolism, acid–base status, survival, and gamete viability in wild Atlantic salmon (Salmo salar)’, Canadian Journal of Fisheries and Aquatic Sciences, vol. 52, pp. 282-290.

350 Chara, J.D., Baird, D.J., Telfer, T.C. and Rubio, E.A. 2006, 'Feeding ecology and habitat preferences of the catfish genus Trichomycterus in low-order streams of the Colombian Andes', Journal of Fish Biology, vol. 68, pp. 1026–1040.

Close, P.G., Dobbs, R.J., Tunbridge, D.J., Speldewinde, P.C., Warfe, D.M., Toussaint, S. and Davies, P.M. 2014, ‘Customary and recreational fishing pressure: large-bodied fish assemblages in a tropical, intermittent Australian river’, Marine and Freshwater Research, vol. 65, pp. 466–474.

Dowling, C.E., Hall, K.C. and Broadhurst, M.K. 2010, ‘Immediate fate of angled-and- released Australian bass Macquaria novemaculeata’, Hydrobiologia, vol. 641, pp. 145-157.

Fenberg, P.B. and Roy, K. 2008, 'Ecological and evolutionary consequences of size- selective harvesting: how much do we know?', Molecular Ecology, vol. 17, pp. 209- 220.

Gasbarino, P. 1986. Catch and release of muskellunge philosophy and methods. In: G. Hall (ed.) Managing Muskies. American Fisheries Society, Special Publication 15, Bethesda, MD. Pp. 300–308.

Gray, C.A., Kennelly, S.J. and Hodgson, K.E. 2003, ‘Low levels of bycatch from estuarine prawn seining in New South Wales, Australia’, Fisheries Research, vol. 64, pp. 37-54.

351 Gray, C.A., Johnson, D.D., Broadhurst, M.K. and Young, D.J. 2005, 'Seasonal, spatial and gear-related influences on relationships between retained and discarded catches in a multi-species gillnet fishery', Fisheries Research, vol. 75, pp. 56-72.

Growns, I. and James, M. 2005, ‘Relationships between river flows and recreational catches of Australian bass’, Journal of Fish Biology, vol. 66, pp. 404-416.

Harris, J.H. 1983, 'The Australian bass, Macquaria novemaculeata, PhD Thesis, University of New South Wales.

Harris, J.H. 1985a. 'Age of Australian bass, Macquaria novemaculeata (Perciformes: Percichthyidae) in the Sydney Basin', Australian Journal of Marine and Freshwater Research, vol. 36, pp. 235–246.

352 Harris, J.H. 1987, 'Growth of Australian bass Macquaria novemaculeata (Perciformes, Percichthyidae) in the Sydney Basin', Australian Journal of Marine and Freshwater Research, vol. 38, pp. 351–361.

Harris, J.H. and Rowland, S.J. 1996, 'Family Australian freshwater cods and basses' In: R. McDowall (ed.) Freshwater Fishes of South-Eastern Australia, Sydney, Reed Books. pp 150-163. pp. 150–163, Sydney, Reed Books.

Henry, G.W. and Lyle, J.M., 2003, The national recreational and indigenous fishing survey. NSW Fisheries, Cronulla, Australia, ISSN 1440-3544, pp. 188.

Jonsson, B. and Jonsson, N. 1993, 'Partial migration: niche shift versus sexual maturation in fishes', Reviews in Fish Biology and Fisheries, vol. 3, pp. 348–365.

Johnson, B.M. and Carpenter, S.R. 1994, 'Functional and numerical responses: a framework for fish-angler interactions?’, Ecological Applications, vol. 4, pp. 808-821.

Johnson, P.D. and Brown, K.M. 1998, ‘Intraspecific life history variation in the threatened Louisiana pearlshell mussel, Margaritifera hembeli’, Freshwater Biology, vol. 40, pp. 317–329.

Krohn, M.M. and Kerr, S.R. 1997, ‘Declining Weight-at-age in Northern Cod and the Potential Importance of the Early Years and Size-selective Fishing Mortality’, NAFO Scientific Council Studies, vol. 29, pp. 43-50.

Lake, J.S. 1978, 'Australian Freshwater Fishes', Nelson, Melbourne.

353 Lowerre-Barbieri, S.K., Vose, F.E. and Whittington, J.A. 2003, ‘Catch-and-Release Fishing on a Spawning Aggregation of Common Snook: Does it Affect Reproductive Output?’, Trasactions of the American Fisheries Society, vol. 132, pp. 940-952.

Martin, D.R., Pracheil, B.M., DeBoor, J.A., Wilde, G.R. and Pope, K.L. 2012, 'Using the Internet to Understand Angler Behaviour in the Information Age', Fisheries, vol. 37, pp. 458-463.

Oehmke, A.A., Stange, D., Ogden, K., Addis, J.T. and Mooradian, S.R. 1986. The role of anglers and private organizations in muskellunge management. In: G. Hall (ed.) Managing Muskies. American Fisheries Society, Special Publication 15, Bethesda, MD. pp. 323–334.

Pianka, E.R. 1966, ‘Convexity, desert lizards, and spatial heterogeneity’, Ecology, vol. 47, pp. 1055-1059.

Planning and infrastructure undated, Metropolitan Plan 2036. Available at http://strategies.planning.nsw.gov.au/MetropolitanStrategyforSydney.aspx (Accessed 8 July 2013).

Radomski, P.J., Grant, G.C., Jacobson, P.C. and Cook, M.F. 2001, 'Visions for recreational fishing regulations', Fisheries, vol. 26, pp. 7-18.

Reinfelds, I.V., Walsh, C.T., Van der Meulen, D.E., Growns, I.O. and Gray, C.A. 2011, ‘Magnitude, frequency and duration of instream flows to stimulate and facilitate catadromous fish migrations: Australian bass (Macquaria novemaculeata Perciformes, Percichthyidae), River Research and Applications, vol. 29, pp. 512-527

354

Smith, T.I.J. 1985, ‘The fishery, biology, and management of Atlantic sturgeon, (Acipenser oxyrinchus), in North America’, Environmental Biology of Fishes, vol. 14, pp. 61–72.

Swain, D.P., Sinclair, A.F. and Hanson, J.M. 2007, ‘Evolutionary response to size- selective mortality in an exploited fish population’, Proceedings of the Royal Society B, vol. 274, pp. 1015-1022.

Torres, M.D.O, and Felthoven, R.G. 2014, ‘Productivity growth and product choice in catch share fisheries: The case of Alaska pollock’, Marine Policy, vol. 50, pp. 280- 289.

355 Williams, N.J. 1970, 'A comparison of the two species of the genus Percalates Ramsey and Ogilby (Percomorphi: Macquariidae) and their taxonomy', N.S.W. State Fisheries Research Bulletin. No. 11.

356 8. Appendices

8.1 Appendix I - complete template of the recreational fisherman questionnaire

357 Two-minute QUESTIONNAIRE

- Your help is required -

- Australian Bass and Recreational Fisherman -

The following questionnaire is to be answered anonymously and used for my PhD on Ecology of Australian Bass in tributaries of the Hawkesbury-Nepean River.

Where applicable, please circle the answer you feel is most correct. By completing this questionnaire you are consenting to having this information used for research purposes.

Completion of questionnaire implies content for use of data for research purposes. You must be over 18 years or older to complete this questionnaire.

After completing this survey please hand it to your club president/secretary.

1. What is your age in years? 1.  18-24 2.  25-34 3.  35-44 4.  45-54 5.  55+

2. What is your gender? 1.  Male 2.  Female

3. What is the postcode of the suburb that you live in? What state do you live in?

4. What percentage of your fishing effort is focused around capture of Australian Bass? 1.  <10% 2.  11-30% 3.  31-50% 4.  51%-70% 5.  71-90% 6.  91%+

358 5. From this percentage, what river system/s is your main recreational fishing focus for bass?

6. On average, how frequently do you fish for Australian Bass? 1.  At least weekly 2.  Fortnightly 4.  Monthly 5.  Every 6 months 6.  Less than once a year

7. Through what means do you conduct the majority of your fishing for Australian Bass? 1.  Kayak/Canoe/Boat 2.  On foot

8. When fishing for bass, how many people do you normally fish with: 1.  Usually go alone 2.  Usually with one other 3.  Usually with 2 or 3 others 4.  Usually with a larger group

9. What is the most common size of the bass you catch? (Include all of the bass you catch - including those you throw back). 1.  10-15cm 2.  16-21cm 3.  22-27cm 4.  28-33cm 5.  34cm+

10. Would you say you mainly fish rivers or creeks for Australian bass? 1.  Creeks 2.  Rivers 3.  Both evenly

11. What types of fishing sites do you generally prefer? 1.  Easy access areas. 2.  More secluded (generally difficult to access) areas.

359 12. How many years have you been fishing for Australian Bass? 1.  0-4 2.  5-9 3.  10-14 4.  15-19 5.  20+

13. How do you generally identify locations to fish? (Tick all that apply) 1.  Word of mouth in a bait and tackle shop 2.  Googlemaps 3.  Other (please specify)

14. What proportion of Australian Bass captured by you is kept for consumption? 1.  0% 2.  1-5% 3.  6-20% 4.  21-50% 5.  50%+

15. In your experience do most fishermen keep bass or catch and release them? 1.  Catch-and-release 2.  Fishing for consumption 3.  Both evenly

16. Has your general attitude towards the angling capture of Australian Bass switched since you first commenced fishing for Australian Bass? 1.  Switch has become more sport-oriented; 2.  Switch has become more focused on capture for consumption 3.  No change in attitude.

------THANK YOU FOR COMPLETING THIS QUESTIONNAIRE------

After completing this survey please hand it to your club president/secretary.

Thank you for your time, Alan Midgley University of Western Sydney Ph: 4570 1183 (work) [email protected]

360 8.2 Appendix II - recreational fisherman questionnaire results

361 Age Gender State of Residence Percentage Fishing effort towards Bass? 25-34 Male NSW 71-90% 25-34 Male NSW 71-90% 45-54 Male NSW 51%-70% 35-44 Male NSW 31-50% 35-44 Male NSW 31-50% 45-54 Male NSW 71-90% 55+ Male NSW 91%+ 55+ Male NSW 51%-70% 25-34 Male NSW 71-90% 25-34 Male NSW 31-50% 25-34 Male NSW 71-90% 18-24 Male NSW 71-90% 35-44 Male NSW 51%-70% 25-34 Male NSW 51%-70% 25-34 Male NSW 71-90% 25-34 Male NSW 31-50% 45-54 Male NSW 71-90% 55+ Male NSW 71-90% 35-44 Male QLD 91%+ 25-34 Male QLD 91%+ 25-34 Male NSW 71-90% 35-44 Male NSW 51%-70% 45-54 Male NSW <10% 25-34 Male NSW 91%+ 35-44 Male NSW 31-50% 35-44 Male NSW 51%-70% 35-44 Male NSW 51%-70% 25-34 Male NSW 51%-70% 25-34 Male NSW 31-50% 35-44 Male NSW 11-30% 25-34 Male NSW 51%-70% 25-34 Female NSW 11-30% 25-34 Male NSW 11-30% 55+ Male No answer 51%-70% 55+ Male No answer 51%-70% 55+ Male NSW 91%+ 55+ Male NSW 91%+ 45-54 Male No answer 31-50% 25-34 Male NSW 71-90% 25-34 Male NSW 71-90% 35-44 Male NSW 51%-70% 18-24 Male NSW <10% 35-44 Male NSW 11-30%

362 Age Gender State of Residence Percentage Fishing effort towards Bass? 18-24 Male NSW 51%-70% 35-44 Male No answer 11-30% 55+ Male No answer 51%-70% 25-34 Male NSW <10% 25-34 Male NSW <10% 25-34 Male NSW 31-50% 55+ Male NSW <10% 35-44 Male No answer 51%-70% 35-44 Male NSW 71-90% 25-34 Male NSW 51%-70% 35-44 Male NSW 11-30% 35-44 Male NSW <10% 18-24 Male NSW 51%-70% 45-54 Male NSW 11-30% 35-44 Male NSW 11-30% 25-34 Male NSW 51%-70% 18-24 Male NSW 11-30% 45-54 Male NSW 31-50% 18-24 Male NSW 31-50% 25-34 Male NSW 11-30% 18-24 Male NSW 71-90% 55+ Male NSW 51%-70% 35-44 Male NSW 11-30% 45-54 Male NSW 51%-70% 35-44 Male NSW <10% 55+ Female NSW <10% 25-34 Male NSW 51%-70% 35-44 Male NSW 11-30% 55+ Male NSW <10% 35-44 Male NSW 51%-70% 35-44 Male NSW 71-90% 35-44 Male NSW 51%-70% 18-24 Male NSW 71-90% 55+ Male NSW 91%+ 18-24 Male NSW 91%+ 35-44 Male ACT 11-30% 18-24 Male NSW 91%+ 55+ Male QLD 91%+ 25-34 Male NSW 11-30% 35-44 Male NSW 91%+ 18-24 Male NSW 31-50% 18-24 Male NSW 91%+ 55+ Male NSW <10%

363 Age Gender State of Residence Percentage Fishing effort towards Bass? 25-34 Male NSW 11-30% 25-34 Male NSW 11-30% 45-54 Male NSW <10% 18-24 Male NSW 51%-70% 18-24 Male NSW 51%-70% 55+ Male NSW 31-50% 45-54 Male NSW 11-30% 55+ Male No answer 91%+ 18-24 Male NSW 51%-70% 45-54 Male NSW 11-30% 18-24 Male NSW 51%-70% 25-34 Male NSW 31-50% 35-44 Male NSW 31-50% 45-54 Male NSW 11-30% 45-54 Male NSW 31-50% 18-24 Male NSW 11-30% 25-34 Male NSW <10% 18-24 Male NSW <10% 25-34 Male NSW 11-30% 45-54 Male NSW 71-90% 18-24 Male QLD 91%+ 25-34 Male No answer 51%-70% 45-54 Male VIC 31-50% 18-24 Male NSW 51%-70% 35-44 Male NSW 71-90% 45-54 Male NSW <10% 18-24 Female NSW 31-50% 25-34 Male NSW <10% 18-24 Male NSW 51%-70% 45-54 Male NSW 51%-70% 25-34 Male NSW <10% 55+ Male NSW 71-90% 25-34 Male QLD 51%-70% 35-44 Male NSW 31-50% 25-34 Male NSW 51%-70% 55+ Male NSW <10% 55+ Male No answer 51%-70% 35-44 Male No answer 11-30% 55+ Female NSW 91%+ 18-24 Male NSW 31-50% 55+ No answer NSW 71-90% 45-54 Female NSW 71-90% 25-34 Male NSW 71-90%

364 Age Gender State of Residence Percentage Fishing effort towards Bass? 55+ Male NSW 31-50% 55+ Male NSW 11-30% 35-44 Male NSW 91%+ 25-34 No answer NSW 31-50% 25-34 Male NSW 71-90% 18-24 Male NSW 71-90% 35-44 Male NSW 71-90% 18-24 Male NSW 71-90% 18-24 Male NSW 31-50% 35-44 Male NSW 11-30% 35-44 Male NSW 11-30% 25-34 Male NSW 11-30% 55+ Male NSW 11-30% 18-24 Male NSW 71-90% 18-24 Male NSW 11-30% 25-34 Male NSW <10% 25-34 Male NSW 51%-70% 45-54 Male NSW 71-90% 35-44 Male NSW 51%-70% 25-34 No answer NSW 11-30% 35-44 Male NSW 71-90%

365 River System where your conduct majority of Bass fishing frequency? How is the majority of Bass fishing your recreational fishing for bass conducted? Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat + On foot Hunter River Fortnightly Kayak/Canoe/Boat Broga River + Bega River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hastings River + Camden Haven River + Fortnightly Kayak/Canoe/Boat Macleay River Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Williams River + Macleay River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River + Georges River + At least weekly On foot Woronora River Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Richmond River At least weekly On foot Hastings River Monthly Kayak/Canoe/Boat Shoalhaven River Fortnightly Kayak/Canoe/Boat Shoalhaven River At least weekly On foot Richmond River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly On foot Hastings River + Myall River + Williams River Fortnightly Kayak/Canoe/Boat + Karuah River + Paterson River + Hunter River No specific answer At least weekly Kayak/Canoe/Boat Tweed River Fortnightly Kayak/Canoe/Boat No specific answer At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Clyde River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Clarence River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Georges River Fortnightly Kayak/Canoe/Boat Tuggerah Lakes System At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River + Lane Cove River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly On foot Hawkesbury-Nepean River + Macleay River Monthly Kayak/Canoe/Boat No answer At least weekly Kayak/Canoe/Boat Macleay River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Narrabeen Lakes System At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River +Narrabeen Lakes At least weekly Kayak/Canoe/Boat System Hawkesbury-Nepean River Less than once a year On foot

366 River System where your conduct majority of Bass fishing frequency? How is the majority of Bass fishing your recreational fishing for bass conducted? No Specific answer Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly On foot Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat + On foot Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat No answer Less than once a year Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Less than once a year Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly On foot Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Every 6 months Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat No answer Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly On foot Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Brogo River Less than once a year Kayak/Canoe/Boat No answer Less than once a year Kayak/Canoe/Boat No answer Fortnightly Kayak/Canoe/Boat No answer Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Every 6 months Kayak/Canoe/Boat Manning River Every 6 months Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Tweed River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Less than once a year On foot No answer Fortnightly On foot Richmond River At least weekly Kayak/Canoe/Boat No answer Monthly On foot Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hunter River Fortnightly Kayak/Canoe/Boat Richmond River Fortnightly Kayak/Canoe/Boat Deau River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Maroochy River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly On foot Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Wyong River At least weekly Kayak/Canoe/Boat

367 River System where your conduct majority of Bass fishing frequency? How is the majority of Bass fishing your recreational fishing for bass conducted? No answer Every 6 months Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River Every 6 months Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat No answer Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly On foot No answer At least weekly On foot Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Lane Cover River Monthly On foot Georges River Less than once a year On foot Hawkesbury-Nepean River Monthly On foot Hawkesbury-Nepean River Monthly On foot Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat No answer At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly On foot Myall River Every 6 months Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly On foot Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly On foot Hawkesbury-Nepean River Fortnightly On foot Hawkesbury-Nepean River Every 6 months Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat No answer Fortnightly On foot Hawkesbury-Nepean River Monthly On foot No answer Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River + Macleay River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly On foot No answer Every 6 months Kayak/Canoe/Boat No answer Monthly Kayak/Canoe/Boat No answer At least weekly Kayak/Canoe/Boat Parramatta River At least weekly On foot Hawkesbury-Nepean River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly On foot Hawkesbury-Nepean River + Colo River Fortnightly Kayak/Canoe/Boat

368 River System where your conduct majority of Bass fishing frequency? How is the majority of Bass fishing your recreational fishing for bass conducted? Hawkesbury-Nepean River + Colo River + Lane Fortnightly Kayak/Canoe/Boat Cove River Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Every 6 months On foot Hawkesbury-Nepean River + Macleay River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly On foot Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River Every 6 months Kayak/Canoe/Boat Hawkesbury-Nepean River Every 6 months Kayak/Canoe/Boat Hawkesbury-Nepean River Monthly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly On foot Hawkesbury-Nepean River Fortnightly On foot Hawkesbury-Nepean River Less than once a year On foot Hawkesbury-Nepean River At least weekly On foot Hawkesbury-Nepean River + Macleay River Fortnightly Kayak/Canoe/Boat Hawkesbury-Nepean River At least weekly Kayak/Canoe/Boat Hawkesbury-Nepean River Fortnightly On foot Paterson River + Williams River + Hunter River Every 6 months Kayak/Canoe/Boat

369 Number of people normally Bass Size of Average Bass Caught? Fish in Rivers or Creeks for Bass? fishing with? Usually with one other 22-27cm Creeks Usually go alone 22-27cm Rivers Usually with one other 34cm+ Rivers Usually go alone 28-33cm Rivers Usually go alone 22-27cm Rivers Usually with 2 or 3 others 28-33cm Rivers Usually with 2 or 3 others 22-27cm Both evenly Usually with one other 16-21cm Rivers Usually with one other 28-33cm Rivers Usually with one other 22-27cm Both evenly Usually go alone 22-27cm Rivers Usually with one other 28-33cm Creeks Usually with one other 28-33cm Rivers Usually go alone 22-27cm Both evenly Usually go alone 28-33cm Creeks Usually with one other 28-33cm Both evenly Usually go alone 22-27cm Rivers Usually go alone 28-33cm Both evenly Usually go alone 34cm+ Both evenly Usually go alone 34cm+ Creeks Usually go alone 28-33cm Creeks Usually go alone 16-21cm Rivers Usually go alone 22-27cm Rivers Usually with a larger group 16-21cm Rivers Usually with one other 28-33cm Rivers Usually with one other 28-33cm Creeks Usually go alone 16-21cm Creeks Usually go alone 16-21cm Creeks Usually with one other 16-21cm Creeks Usually with one other 16-21cm Creeks Usually go alone 22-27cm Both evenly Usually with one other 16-21cm Creeks Usually with one other 16-21cm Creeks Usually with one other 16-21cm Rivers Usually with 2 or 3 others 22-27cm Rivers Usually with 2 or 3 others 28-33cm Rivers Usually with 2 or 3 others 16-21cm Rivers Usually go alone 22-27cm Both evenly Usually with one other 22-27cm Creeks Usually with one other 28-33cm Creeks Usually with one other 22-27cm Creeks No answer 22-27cm Rivers Usually with one other 28-33cm Rivers

370 Number of people normally Bass Size of Average Bass Caught? Fish in Rivers or Creeks for Bass? fishing with? Usually with 2 or 3 others 16-21cm Rivers Usually with one other 10-15cm Rivers Usually with one other 28-33cm Rivers Usually with one other 10-15cm Both evenly Usually with 2 or 3 others 10-15cm Rivers Usually with 2 or 3 others 22-27cm Creeks Usually go alone 10-15cm Rivers Usually go alone 16-21cm Rivers Usually go alone 22-27cm Rivers Usually with one other 22-27cm Both evenly Usually with one other 28-33cm Rivers Usually with one other 16-21cm Creeks Usually with 2 or 3 others 22-27cm Rivers Usually with one other 22-27cm Rivers Usually with one other 22-27cm Rivers Usually go alone 28-33cm Rivers Usually with 2 or 3 others 22-27cm Rivers Usually with one other 34cm+ Both evenly Usually with 2 or 3 others 16-21cm Both evenly Usually go alone 16-21cm Both evenly Usually with 2 or 3 others 22-27cm Both evenly Usually with 2 or 3 others 22-27cm Rivers Usually with one other 16-21cm Both evenly Usually with one other 16-21cm Rivers Usually with 2 or 3 others 16-21cm Creeks Usually with 2 or 3 others 28-33cm Both evenly Usually with one other 16-21cm Rivers Usually go alone 28-33cm Both evenly Usually with one other 10-15cm Creeks Usually go alone 28-33cm Creeks Usually go alone 28-33cm Rivers Usually with one other 28-33cm Creeks Usually with one other 28-33cm Both evenly Usually with one other 28-33cm Both evenly Usually with one other 28-33cm Rivers Usually with one other 28-33cm Both evenly Usually with one other 22-27cm Rivers Usually go alone 28-33cm Both evenly Usually with 2 or 3 others 16-21cm Rivers Usually go alone 16-21cm Rivers Usually with one other 16-21cm Rivers Usually with one other 28-33cm Both evenly Usually go alone 22-27cm No answer

371 Number of people normally Bass Size of Average Bass Caught? Fish in Rivers or Creeks for Bass? fishing with? Usually go alone 16-21cm Rivers Usually with 2 or 3 others 10-15cm Rivers Usually go alone 28-33cm Rivers Usually with 2 or 3 others 22-27cm Both evenly Usually with 2 or 3 others 22-27cm Rivers Usually with one other 16-21cm Rivers Usually go alone 28-33cm Creeks Usually with a larger group 28-33cm Both evenly Usually with 2 or 3 others 22-27cm Rivers Usually with one other 22-27cm Rivers Usually go alone 34cm+ Both evenly Usually with one other 16-21cm Rivers Usually with one other 16-21cm Both evenly Usually with one other 16-21cm Rivers Usually with one other 16-21cm Rivers Usually with one other 22-27cm Both evenly Usually with 2 or 3 others 16-21cm Both evenly Usually with one other 16-21cm Creeks Usually go alone 16-21cm Rivers Usually with 2 or 3 others 28-33cm Rivers Usually go alone 22-27cm Creeks Usually go alone 22-27cm Creeks Usually go alone 28-33cm Creeks Usually with one other 22-27cm Rivers Usually with one other 28-33cm Both evenly Usually with one other 34cm+ Both evenly Usually with one other 22-27cm Rivers Usually with one other 22-27cm Rivers Usually with 2 or 3 others 16-21cm Rivers Usually with 2 or 3 others 22-27cm Rivers Usually with 2 or 3 others 16-21cm Both evenly Usually with 2 or 3 others 16-21cm Rivers Usually with one other 28-33cm Rivers Usually with 2 or 3 others 16-21cm Both evenly Usually with 2 or 3 others 22-27cm Rivers Usually go alone 28-33cm Rivers Usually with one other 22-27cm Rivers Usually with one other 22-27cm Both evenly Usually with a larger group 34cm+ Both evenly Usually go alone 16-21cm Rivers Usually with 2 or 3 others 28-33cm No answer Usually with 2 or 3 others 16-21cm Both evenly Usually with one other 28-33cm Both evenly

372 Number of people normally Bass Size of Average Bass Caught? Fish in Rivers or Creeks for Bass? fishing with? Usually with a larger group 22-27cm Rivers Usually with one other 10-15cm Both evenly Usually with one other 16-21cm Rivers Usually with one other 22-27cm Rivers Usually go alone 22-27cm Rivers Usually with one other 22-27cm Both evenly Usually with one other 22-27cm Both evenly Usually with 2 or 3 others 10-15cm Both evenly Usually with 2 or 3 others 28-33cm Rivers Usually with one other 10-15cm Rivers Usually with one other 16-21cm Rivers Usually with one other 10-15cm Rivers Usually go alone 16-21cm Both evenly Usually with one other 22-27cm Rivers Usually with 2 or 3 others 10-15cm Rivers Usually go alone 10-15cm Creeks Usually with 2 or 3 others 22-27cm Rivers Usually with one other 28-33cm Both evenly Usually go alone 22-27cm Both evenly Usually with one other 10-15cm Rivers Usually go alone 22-27cm Creeks

373 Easy access or secluded areas preferred to fish? Number of Years How are Bass Fishing spots Identified? Bass fishing? More secluded (generally difficult to access) areas. (5-9) Googlemaps/Nearmap + Bushwalking/Exploring More secluded (generally difficult to access) areas. (20+) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (15-19) Googlemaps/Nearmap + Bushwalking/Exploring Easy access areas. (0-4) Googlemaps/Nearmap + Fishing club discussion No answer (5-9) Googlemaps/Nearmap + Internet-based Fishing Forums discussion Easy access areas. (10-14) Local knowledge More secluded (generally difficult to access) areas. (10-14) Fishing club discussion Easy access areas. (15-19) Googlemaps/Nearmap + Discussion with friends Easy access areas. (0-4) Googlemaps/Nearmap + Discussion with friends More secluded (generally difficult to access) areas. (10-14) Googlemaps/Nearmap Easy access areas. (0-4) Googlemaps/Nearmap + Fishing club discussion More secluded (generally difficult to access) areas. (5-9) Bushwalking/Exploring + Topographical hard copy maps More secluded (generally difficult to access) areas. (5-9) Topographical hard copy maps + Discussion with friends More secluded (generally difficult to access) areas. (5-9) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap Easy access areas. (0-4) Googlemaps/Nearmap + Local knowledge Easy access areas. (20+) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (15-19) Googlemaps/Nearmap + Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (15-19) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap + Discussion with friends Easy access areas. (5-9) Word of mouth in a bait and tackle shop + Bushwalking/Exploring + Internet-based Fishing Forums discussion More secluded (generally difficult to access) areas. (20+) Word of mouth in a bait and tackle shop Easy access areas. (5-9) Fishing club discussion More secluded (generally difficult to access) areas. (15-19) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (0-4) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap Easy access areas. (0-4) Word of mouth in a bait and tackle shop + Internet-based Fishing Forums discussion + Fishing Videos/books More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap + Local knowledge More secluded (generally difficult to access) areas. (10-14) Googlemaps/Nearmap + Discussion with friends More secluded (generally difficult to access) areas. (0-4) Discussion with friends More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap + Fishing club discussion More secluded (generally difficult to access) areas. (0-4) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (10-14) Googlemaps/Nearmap Easy access areas. (15-19) Googlemaps/Nearmap Easy access areas. (10-14) Word of mouth in a bait and tackle shop Easy access areas. (10-14) Fishing club discussion More secluded (generally difficult to access) areas. (15-19) Googlemaps/Nearmap + Discussion with friends More secluded (generally difficult to access) areas. (20+) Fishing club discussion

374 Easy access or secluded areas preferred to fish? Number of Years How are Bass Fishing spots Identified? Bass fishing? More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap + Fishing club discussion More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap + Fishing club discussion More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap + Fishing club discussion Easy access areas. (0-4) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap More secluded (generally difficult to access) areas. (10-14) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (0-4) No Answer More secluded (generally difficult to access) areas. (10-14) Word of mouth in a bait and tackle shop Easy access areas. (5-9) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap Easy access areas. (0-4) Word of mouth in a bait and tackle shop Easy access areas. (0-4) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (10-14) Word of mouth in a bait and tackle shop Easy access areas. (0-4) Word of mouth in a bait and tackle shop Easy access areas. (0-4) No Answer Easy access areas. (15-19) Bushwalking/Exploring More secluded (generally difficult to access) areas. (10-14) Googlemaps/Nearmap Easy access areas. (15-19) Word of mouth in a bait and tackle shop Easy access areas. (0-4) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (10-14) No Answer Easy access areas. (20+) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (20+) No Answer More secluded (generally difficult to access) areas. (5-9) No Answer Easy access areas. (10-14) Word of mouth in a bait and tackle shop Easy access areas. (20+) Googlemaps/Nearmap Easy access areas. (0-4) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap Easy access areas. (20+) Word of mouth in a bait and tackle shop Easy access areas. (10-14) Word of mouth in a bait and tackle shop Easy access areas. (5-9) Word of mouth in a bait and tackle shop Easy access areas. (20+) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (20+) Word of mouth in a bait and tackle shop Easy access areas. (5-9) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (5-9) Discussion with friends Easy access areas. (15-19) Bushwalking/Exploring Easy access areas. (0-4) Bushwalking/Exploring Easy access areas. (0-4) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (0-4) Discussion with friends More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (5-9) Bushwalking/Exploring More secluded (generally difficult to access) areas. (0-4) Bushwalking/Exploring Easy access areas. (0-4) Googlemaps/Nearmap + Discussion with friends More secluded (generally difficult to access) areas. (15-19) Bushwalking/Exploring + Discussion with friends

375 Easy access or secluded areas preferred to fish? Number of Years How are Bass Fishing spots Identified? Bass fishing? More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap + Topographical hard copy maps More secluded (generally difficult to access) areas. (20+) Googlemaps/Nearmap + Bushwalking/Exploring Easy access areas. (0-4) Googlemaps/Nearmap + Internet-based Fishing Forums discussion More secluded (generally difficult to access) areas. (5-9) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap Easy access areas. (0-4) Internet-based Fishing Forums discussion More secluded (generally difficult to access) areas. (0-4) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap Easy access areas. (0-4) Word of mouth in a bait and tackle shop Easy access areas. (20+) Local knowledge More secluded (generally difficult to access) areas. (0-4) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap Easy access areas. (15-19) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (20+) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (5-9) Fishing club discussion More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (20+) Discussion with friends More secluded (generally difficult to access) areas. (10-14) Googlemaps/Nearmap Easy access areas. (0-4) Googlemaps/Nearmap + Bushwalking/Exploring Easy access areas. (20+) Word of mouth in a bait and tackle shop Easy access areas. (0-4) Word of mouth in a bait and tackle shop Easy access areas. (0-4) Local knowledge More secluded (generally difficult to access) areas. (0-4) Bushwalking/Exploring + Discussion with friends Easy access areas. (0-4) Word of mouth in a bait and tackle shop Easy access areas. (0-4) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (15-19) Local knowledge More secluded (generally difficult to access) areas. (5-9) Googlemaps/Nearmap + Bushwalking/Exploring More secluded (generally difficult to access) areas. (5-9) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap + Discussion with friends More secluded (generally difficult to access) areas. (15-19) Word of mouth in a bait and tackle shop Easy access areas. (10-14) No answer More secluded (generally difficult to access) areas. (20+) No answer Easy access areas. (0-4) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap More secluded (generally difficult to access) areas. (20+) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (5-9) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (20+) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap More secluded (generally difficult to access) areas. (5-9) No answer Easy access areas. (0-4) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (20+) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap + Discussion with

376 Easy access or secluded areas preferred to fish? Number of Years How are Bass Fishing spots Identified? Bass fishing? friends More secluded (generally difficult to access) areas. (0-4) Googlemaps/Nearmap Easy access areas. (5-9) Googlemaps/Nearmap Easy access areas. (20+) Word of mouth in a bait and tackle shop Easy access areas. (10-14) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (20+) No answer No answer (0-4) Internet-based Fishing Forums discussion Easy access areas. (10-14) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap Easy access areas. (20+) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (5-9) Discussion with friends More secluded (generally difficult to access) areas. (10-14) Word of mouth in a bait and tackle shop Easy access areas. (20+) Fishing club discussion Easy access areas. (20+) Bushwalking/Exploring More secluded (generally difficult to access) areas. (20+) Bushwalking/Exploring More secluded (generally difficult to access) areas. (15-19) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap Easy access areas. (0-4) No answer More secluded (generally difficult to access) areas. (0-4) Word of mouth in a bait and tackle shop + Googlemaps/Nearmap More secluded (generally difficult to access) areas. (10-14) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (0-4) Bushwalking/Exploring Easy access areas. (0-4) Word of mouth in a bait and tackle shop Easy access areas. (5-9) Word of mouth in a bait and tackle shop Easy access areas. (20+) Word of mouth in a bait and tackle shop Easy access areas. (5-9) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (20+) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (0-4) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (0-4) Word of mouth in a bait and tackle shop Easy access areas. (0-4) Word of mouth in a bait and tackle shop Easy access areas. (5-9) Googlemaps/Nearmap More secluded (generally difficult to access) areas. (20+) Bushwalking/Exploring + Topographical hard copy maps Easy access areas. (0-4) Word of mouth in a bait and tackle shop Easy access areas. (0-4) Word of mouth in a bait and tackle shop More secluded (generally difficult to access) areas. (20+) Googlemaps/Nearmap + Discussion with friends + Hard copy topographical maps

377 Bass kept for Other fisherman keep bass or Switch more sport-orientated or for capture for consumption? catch and release them? consumption? 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 1-5% Catch-and-release Switch has become more sport-oriented 0% Both evenly No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Both evenly Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 1-5% Both evenly No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 1-5% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Both evenly No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 1-5% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude.

378 Bass kept for Other fisherman keep bass or Switch more sport-orientated or for capture for consumption? catch and release them? consumption? 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more focused on capture for consumption 1-5% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 1-5% Fishing for consumption Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 1-5% Both evenly No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Both evenly No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Both evenly Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 6-20% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 6-20% Catch-and-release Switch has become more sport-oriented

379 Bass kept for Other fisherman keep bass or Switch more sport-orientated or for capture for consumption? catch and release them? consumption? 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No answer 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 1-5% Catch-and-release No change in attitude. 1-5% Both evenly No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 1-5% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 6-20% Fishing for consumption Switch has become more focused on capture for consumption 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 1-5% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 50%+ Fishing for consumption No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude.

380 Bass kept for Other fisherman keep bass or Switch more sport-orientated or for capture for consumption? catch and release them? consumption? 0% Catch-and-release No change in attitude. 6-20% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 6-20% Both evenly Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Both evenly Switch has become more sport-oriented 6-20% Catch-and-release Switch has become more focused on capture for consumption 0% Both evenly Switch has become more sport-oriented 1-5% Fishing for consumption No change in attitude. 1-5% Fishing for consumption No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release Switch has become more sport-oriented 0% Catch-and-release Switch has become more sport-oriented 0% Fishing for consumption Switch has become more sport-oriented 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 0% Catch-and-release No change in attitude. 50%+ Fishing for consumption No change in attitude.

381 8.3 Appendix III – fieldwork results

382 Creek

Fish Weather/ Time type Creek Map Date no. Barometer (obstacle name Locality or open) 1 17/01/12 Windy 3pm Open Wright’s Gareth’s Sunny Cloudy 1023 hpa 2 “ “ 3:05pm “ “ “ 3 “ “ 3:25pm “ “ “ 4 “ “ 3:30pm “ “ “ 5 “ “ 4pm “ “ “ “ “ 5:30pm “ “ “ “ “ 5:40pm “ “ “ “ “ 6:00pm “ “ “ “ “ 6:05pm “ “ “ “ “ 6:30pm “ “ “ “ “ 8:00pm “ “ “ 6 19/01/12 Sunny then 1:50pm Obstacle Little McMahons Cloudy Wheeny D/stream 1018hpa 7 “ “ 2:05pm “ “ “ 8 “ “ 2:35pm “ “ “ 9 “ “ 5:40pm “ “ “ 10 “ “ 6:55pm “ “ “ 11 24/01/12 Overcast/rain 1:30pm Open Webbs Webbs 1020hpa Creek Mountain Rd 12 “ “ 1:40pm “ “ “ 13 “ “ 2:00pm “ “ “ 14 “ “ 2:30pm “ “ “

383 Creek

Fish Weather/ Time type Creek Map Date no. Barometer (obstacle name Locality or open) 15 “ “ 4:45pm “ “ “ “ “ 4:50pm “ “ “ “ “ 4:55pm “ “ “ “ “ 5:00pm “ “ “ “ “ 5:25pm “ “ “ 16 16/02/12 1020 hpa 11:35 Obstacle Popran Ironbark Rd Sunny then am to overcast after this fish 17 “ “ 12:25 “ “ “ pm 18 “ “ 12:55 “ “ “ pm 19 “ “ 2:30 pm “ “ “ 20 “ “ 2:50 pm “ “ “ “ “ 3:00 pm “ “ “ “ “ 3:15 pm “ “ “ “ “ 3:35 pm “ “ “ “ “ 3:45 pm “ “ “ 21 18/03/12 Overcast to 10:50am Obstacle Popran Ironbark Rd sunny 1020 22 18/03/12 “ 11:20am “ “ “ 23 18/03/12 “ 11:55am “ “ “ 24 18/03/12 “ 12:30pm “ “ “ 25 18/03/12 “ 1:10pm “ “ “ 18/03/12 “ 1:15pm “ “ “ 18/03/12 “ 1:20pm “ “ “

384 Creek

Fish Weather/ Time type Creek Map Date no. Barometer (obstacle name Locality or open) 18/03/12 “ 1:25pm “ “ “ 18/03/12 “ 1:45pm “ “ “ 18/03/12 “ 2:00pm “ “ “ 18/03/12 “ 2:25pm “ “ “ 26 20/03/12 1020 falling 11:30am Open Wrights Gareth’s 27 “ “ 11:35am “ “ “ 28 “ “ 11:45am “ “ “ 29 “ “ 12:10pm “ “ “ 30 “ “ 1:00pm “ “ “ “ “ 2:25pm “ “ “ “ “ 2:45pm “ “ “ 31 27/03/12 Sunny to 11:30pm Open Webbs Webbs cloudy Creek 1022 Steady Mountain Rd 32 “ “ 12:25pm “ “ “ 33 “ “ 1:00pm “ “ “ 34 “ “ 1:25pm “ “ “ 35 “ “ 1:35pm “ “ “ 36 29/03/12 1020 falling 8:00am Obstacle Little McMahons Wheeny

37 “ “ 12:00pm “ “ “ 38 “ “ 1:35pm “ “ “ 39 “ “ 2:55pm “ “ “ 40 “ “ 4:00pm “ “ “ 41 14/04/12 Sunny to 10:00am Obstacle Wheeny Above overcast Comleroy

385 Creek

Fish Weather/ Time type Creek Map Date no. Barometer (obstacle name Locality or open) 1030 42 “ “ 10:36am “ “ “ 43 “ “ 11:00am “ “ “ 44 “ “ 11:55am “ “ “ 45 “ “ 12:00pm “ “ “ “ “ 1:05pm “ “ “ “ “ 1:10pm “ “ “ “ “ 2:00pm “ “ “ “ “ 2:15pm “ “ “ “ “ 2:15pm “ “ “ “ “ 2:20pm “ “ “ 46 08/10/2012 Sunny 8:30am Open Cattai Newmans Light cloud 47 08/10/2012 “ 8:45am “ “ “ 48 08/10/2012 “ 8:55am “ “ “ 49 08/10/2012 “ 9:20am “ “ “ 50 08/10/2012 “ 9:35am “ “ “ 51 18/10/12 Sunny, 1:00pm Open Webbs Crossing partly cloudy 1022 rising

52 “ “ 1:05pm “ “ “ 53 “ “ 1:35pm “ “ “ 54 “ “ 2:40pm “ “ “ 55 “ “ 2:45pm “ “ “ “ “ 4:00pm “ “ “ “ “ 4:10pm “ “ “ “ “ 4:15pm “ “ “

386 Creek

Fish Weather/ Time type Creek Map Date no. Barometer (obstacle name Locality or open) “ “ 4:25pm “ “ “ “ “ 4:25pm “ “ “ “ “ 4:40pm “ “ “ “ “ 4:40pm “ “ “ “ “ 4:55pm “ “ “ “ “ 5:00pm “ “ “ “ “ 5:15pm “ “ “ “ “ 5:30pm “ “ “ “ “ 5:35pm “ “ “ 56 23/10/12 Sunny 11:05am Open Cattai Newmans 1025 Rising 57 “ “ 11:25am “ “ “ 58 “ “ 11:40am “ “ “ 59 “ “ 12:15pm “ “ “ 60 “ “ 12:30pm “ “ “ 61 25/10/12 Sunny/windy 11:10am Open Wrights Gareth’s 1010 steady 62 “ “ 11:25am “ “ “ 63 “ “ 2:45pm “ “ “ 64 “ “ 3:10pm “ “ “ 65 “ “ 3:35pm “ “ “ 66 30/10/12 Sunny 1:30pm Obstacle Popran Ironbark 1020 Rising Downstream 67 “ “ 3:00pm “ “ “ 68 “ “ 3:50pm “ “ “ 69 “ “ 4:10pm “ “ “ 70 “ “ 4:25pm “ “ “ 71 03/11/12 Cloudy 7:50am Open Cattai Mitchell

387 Creek

Fish Weather/ Time type Creek Map Date no. Barometer (obstacle name Locality or open) 1020 steady Upstream 72 “ “ 8:50am “ “ “ 73 “ “ 9:05am “ “ “ 74 “ “ 9:45am “ “ “ 75 “ “ 10:30am “ “ “ 76 20/11/12 Overcast 1:00pm Obstacle Little D/stream 1020^ Wheeny McMahons 77 27/11/12 Overcast 10:10am “ “ Tim’s 1015^ 78 “ “ 11:00am “ “ “ 79 “ “ 11:15am “ “ “ 80 “ “ 12:30pm “ “ “ 81 29/11/12 Overcast 8:00am Obstacle Wheeny Above 1015 steady Comleroy 82 “ “ 8:35am “ “ “ 83 “ “ 9:10am “ “ “ 84 “ “ 9:50am “ “ “ 85 “ “ 10:45am “ “ “ 86 11/12/12 Overcast 10:15am Open Webbs Webbs Ck Windy Mountain 1025 Steady Rd 87 “ “ 10:45am “ “ “ 88 “ “ 11:55am “ “ “ 89 “ “ 12:30pm “ “ “ 90 “ “ 12:45pm “ “ “ 91 12/01/13 1010 steady 10:05am Obstacle Popran Peats Ridge Sunny Rd d/stream

388 Creek

Fish Weather/ Time type Creek Map Date no. Barometer (obstacle name Locality or open) 92 “ “ 10:25am “ “ “ 93 “ “ 11:00am “ “ “ 94 “ “ 11:15am “ “ “ 95 “ “ 12:30pm “ “ “ “ “ 12:25pm “ “ “ “ “ 12:30pm “ “ “ “ “ 12:40pm “ “ “ “ “ 12:55pm “ “ “ “ “ 1:00pm “ “ “ “ “ 1:20pm “ “ “ 96 15/01/13 Overcast/ 10:00am Obstacle Little D/S Tim’s Sunny Wheeny 97 “ “ 10:05am “ “ “ 98 “ “ 10:15am “ “ “ 99 “ “ 10:25am “ “ “ 100 “ “ 10:55am “ “ “ “ “ 11:05am “ “ “ “ “ 11:20am “ “ “ “ “ 11:40am “ “ “ “ “ 11:40am “ “ “ “ “ 12:05pm “ “ “ “ “ 12:05pm “ “ “ “ “ 12:25pm “ “ “ “ “ 12:30pm “ “ “ “ “ 12:40pm “ “ “ 101 22/01/13 Sunny 10:30am Open Wrights Gareth’s

102 “ “ 10:35am “ “ “

389 Creek

Fish Weather/ Time type Creek Map Date no. Barometer (obstacle name Locality or open) 103 “ “ 11:15am “ “ “ 104 “ “ 11:30am “ “ “ 105 “ “ 11:55am “ “ “ 106 23/03/13 Fine/Sunny 11:30am Obstacle Wheeny Above Comleroy 107 “ “ 11:45am “ “ “ 108 “ “ 12:10pm “ “ “ 109 “ “ 12:30pm “ “ “ 110 “ “ 1:05pm “ “ “ “ “ 1:40pm “ “ “ “ “ 1:45pm “ “ “ “ “ 1:45pm “ “ “ “ “ 2:30pm “ “ “ “ “ 2:55pm “ “ “ “ “ 3:05pm “ “ “

111 24/03/13 Fine/Sunny 1:15pm Obstacle Wheeny Above Occasional Comleroy Showers 112 “ “ 1:25pm “ “ “ 113 “ “ 1:45pm “ “ “ 114 “ “ 2:15pm “ “ “ 115 “ “ 2:25pm “ “ “ “ “ 2:55pm “ “ “ “ “ 3:00pm “ “ “ “ “ 3:05pm “ “ “ “ “ 3:35pm “ “ “ “ “ 3:40pm “ “ “

390 Creek

Fish Weather/ Time type Creek Map Date no. Barometer (obstacle name Locality or open) “ “ 4:15pm “ “ “ “ “ 4:20pm “ “ “ 116 26/03/13 Fine/sunny 2:00pm Open Cattai Newmans With occasional cloud 117 “ Cloudy 2:30pm “ “ “ 118 “ “ 3:30pm “ “ “ 119 “ “ 5:30pm “ “ “ 120 “ “ 5:35pm “ “ “

391 Fish Length Weight (g) Gape Gape Capture Total Cast no. (mm) Height Width Position for 5 fish (mm) (mm) (open or and Sex near structure) 1 223 162.5 30 30 S Female 2 224 179.2 29 28 S Female 3 213 150.4 27 26 S Male 4 201 128.0 30 25 O Male 5 282 361.5 36 38 O Female 77 228 S 177 O 251 S 231 O 211 O 284 S 6 205 154.2 26 27 S Male 7 196 112.9 24 22 S Female 8 168 79.2 23 20 S Male 9 133 40.4 16 17 S Male 10 200 131.6 23 25 O Female 199 11 280 321.1 34 31 S Male 12 215 150.0 28 26 S Male 13 288 369.8 41 36 S Female 14 175 81.1 19 17 S Male 15 269 291.3 32 30 S Female 130 170 O 192 O 250 S

392 Fish Length Weight (g) Gape Gape Capture Total Cast no. (mm) Height Width Position for 5 fish (mm) (mm) (open or and Sex near structure) 198 S 16 280 301.7 31 34 S Male 17 259 267.7 29 33 S Female 18 269 297.4 31 31 S Male 19 236 193.2 28 30 S Female 20 341 506.9 42 46 S Female 125 131 S 160 S 365 O 310 S 21 214 156.4 27 28 S Female 22 320 493.1 40 41 S Female 23 302 410.2 35 38 O Female 24 220 118.0 25 25 S Female 25 267 352.2 42 37 S Female 125 271 O 173 S 186 O 390 S 320 S 261 S 26 271 350.1 31 32 S Female 27 352 623.2 42 44 S Female 28 325 610.7 43 41 S Female 29 307 471.6 42 37 S Female

393 Fish Length Weight (g) Gape Gape Capture Total Cast no. (mm) Height Width Position for 5 fish (mm) (mm) (open or and Sex near structure) 30 275 387.5 34 34 O Female 79 309 S 252 S 31 251 249.2 31 31 S Female 32 246 245.4 34 34 O Female 33 173 87.6 24 24 O Female 34 153 56.9 19 16 O Male 35 204 158.1 28 25 O Male 195 36 374 742.9 43 52 S Female 37 196 111.7 22 23 S Female 38 375 996.4 43 44 S Female 39 263 374.8 34 30 S Female 40 141 44.9 16 15 O Male 340 41 344 823.1 43 45 S Female 42 232 200.9 28 29 S Female 43 194 138.9 23 24 S Male 44 226 183.2 26 28 S Female 45 243 244.9 29 33 S Female 50 315 S 212 S 280 O 175 S 120 S

394 Fish Length Weight (g) Gape Gape Capture Total Cast no. (mm) Height Width Position for 5 fish (mm) (mm) (open or and Sex near structure) 130 S 46 305 450.9 42 40 S Female 47 234 195.7 27 33 S Male 48 297 432.5 31 38 S Female 49 176 80.4 19 24 S Male 50 188 118.1 22 28 S Male 183 51 234 172.9 30 32 S Male 52 296 420.1 35 44 S Male 53 251 227.1 28 30 S Female 54 276 377.1 36 42 S Female 55 229 185.7 31 31 O Male 79 131 O 305 S 221 O 321 S 214 O 316 S 197 S 187 S 154 S 163 O 221 O 159 S 56 239 229.5 31 34 S Female 57 309 456.1 22 26 S Female

395 Fish Length Weight (g) Gape Gape Capture Total Cast no. (mm) Height Width Position for 5 fish (mm) (mm) (open or and Sex near structure) 58 175 87.5 35 43 S Male 59 202 123.2 23 27 S Female 60 217 151.6 25 30 S Male 211 61 315 522.6 38 49 S Female 62 237 223.1 30 36 S Male 63 274 387.0 36 40 S Female 64 265 345.7 32 37 S Female 65 235 268.2 28 33 S Female 450 66 345 642.9 41 49 S Female 67 203 154.6 25 26 S Male 68 236 218.5 27 33 S Male 69 238 280.5 28 33 S Male 70 248 270.3 32 30 S Male 560 71 185 109.0 22 24 S Male 72 217 136.6 24 27 S Male 73 160 63.7 20 23 S Male 74 315 564.0 36 46 S Female 75 205 141.9 27 32 S Male 379 76 163 76.0 20 22 S Male 77 146 52.9 19 11 S Male 78 215 155.2 25 29 O Male 79 291 358.9 30 36 S Female 80 227 175.8 29 30 S Male

396 Fish Length Weight (g) Gape Gape Capture Total Cast no. (mm) Height Width Position for 5 fish (mm) (mm) (open or and Sex near structure) 556 81 271 333.2 32 34 S Female 82 251 290.5 28 32 S Female 83 276 373.0 37 38 S Female 84 285 433.6 35 41 S Female 85 269 433.7 38 39 S Female 323 86 300 460.6 37 44 S Female 87 280 347.4 36 42 O Female 88 287 404.4 35 43 S Female 89 293 409.2 40 43 S Female 90 216 166.4 27 27 S Male 261 91 348 668.1 36 43 S Female 92 307 457.1 29 40 S Female 93 297 432.3 31 39 S Female 94 206 144.8 23 28 O Male 95 243 236.7 30 30 S Male 138 380 S 209 S 274 S 232 O 252 O 244 S 96 174 96.1 20 23 O Male 97 234 250.7 25 30 S Male

397 Fish Length Weight (g) Gape Gape Capture Total Cast no. (mm) Height Width Position for 5 fish (mm) (mm) (open or and Sex near structure) 98 165 91.4 19 23 S Male 99 221 190.0 24 30 O Male 100 249 289.3 28 33 S Female 65 216 O 183 S 217 S 245 S 162 S 151 S 253 S 142 S 204 S 101 319 524.8 42 45 S Female 102 305 474.8 38 44 S Female 103 311 496.4 42 49 S Female 104 285 406.2 39 46 S Female 105 254 264.8 35 40 S Female 153 106 261 310.6 31 33 S Female 107 237 244.9 28 31 S Female 108 337 588.8 39 39 S Female 109 114 31.9 16 16 S Unsexable 110 291 382.4 37 38 S Female 80 167 O 281 S

398 Fish Length Weight (g) Gape Gape Capture Total Cast no. (mm) Height Width Position for 5 fish (mm) (mm) (open or and Sex near structure) 311 S 296 S 189 S 321 S 111 231 201.7 25 28 S Male 112 315 556.8 37 42 S Female 113 209 139.4 27 29 S Female 114 264 322.5 31 34 S Female 115 272 458.5 36 38 S Female 75 232 S 211 S 157 O 297 S 277 S 305 S 322 S 116 335 660.1 44 50 S Female 117 337 690.5 45 45 S Female 118 172 91.7 22 22 S Male 119 283 407.4 38 44 S Female 120 277 401.3 37 43 S Female 402

399 8.4 Appendix IV – raw diet data

400 Total Aquatic or Taxa Total Wet Fish Terrestrial Aquatic or Terrestrial Wet Weight No. Vertebrates Vertebrate Freq. Invertebrates Invertebrate Freq. Weight (g) (g) 1 Belostomatidae Aquatic Invertebrate 4 0.76 0.76 Terrestrial 2 Aves (Class) Vertebrate 1 9.39 9.39 3 Belostomatidae Aquatic Invertebrate 2 0.31 0.36 4 Empty 5 Empty Nematomorpha 6 (Phylum) Aquatic Invertebrate 1 0.01 0.44 Odonata (Order) Aquatic Invertebrate 1 0.01 Curculionidae Aquatic Invertebrate 1 0.03 7 Unidentifiable 0.14 8 Unidentifiable 0.9 9 Tetragnathidae Terrestrial Invertebrate 1 0.01 0.14 10 Diploda (Class) Terrestrial Invertebrate 1 0.02 0.79 Nematomorpha (Phylum) Aquatic Invertebrate 2 0.01 Odonata (Order) Aquatic Invertebrate 1 0.05 Tricoptera (Order) Aquatic Invertebrate 3 0.03 11 Unidentifiable 0.52 12 Unidentifiable 0.2 13 Belostomatidae Aquatic Invertebrate 2 0.49 2.33 Cicadae Terrestrial Invertebrate 1 0.75 Atyidae Aquatic Invertebrate 1 0.05 14 Atyidae Aquatic Invertebrate 1 0.09 0.86 Isopoda (Order) Aquatic Invertebrate 1 0.02 15 Atyidae Aquatic Invertebrate 99 4.8 7.46 Ephemeroptera (Order) Aquatic Invertebrate 1 0.01 Belostomatidae Aquatic Invertebrate 1 0.03 Gryllidae Terrestrial Invertebrate 1 0.04 Gryllidae Terrestrial Invertebrate 1 1.26 Diploda (Class) Terrestrial Invertebrate 1 0.04 Nematoda (Phylum) Aquatic Invertebrate 1 0.01 Tricoptera (Order) Aquatic Invertebrate 1 0.03 Nematomorpha (Phylum) Aquatic Invertebrate 2 0.01 Nematomorpha 17 (Phylum) Aquatic Invertebrate 3 0.06 1.9 Tricoptera (Order) Aquatic Invertebrate 13 0.09 Nematomorpha 18 (Phylum) Aquatic Invertebrate 3 0.09 3.11 Atyidae Aquatic Invertebrate 1 0.12 Tricoptera (Order) Aquatic Invertebrate 27 0.24 Odonata (Order) Aquatic Invertebrate 1 0.02 Tricoptera 19 (Order) Aquatic Invertebrate 11 0.05 0.58 Tricoptera 20 (Order) Aquatic Invertebrate 3 0.02 1.11 Ephemeroptera (Order) Aquatic Invertebrate 1 0.01 Parastacidae Aquatic Invertebrate 1 0.01 Diptera (Mosquito) Terrestrial Invertebrate 1 0.01 21 Empty Tricoptera 22 (Order) Aquatic Invertebrate 1 0.01 0.39 Terrestrial Aves (Class) Vertebrate 1 0.1 23 Gryllidae Terrestrial Invertebrate 1 0.56 2.62

401 Total Aquatic or Taxa Total Wet Fish Terrestrial Aquatic or Terrestrial Wet Weight No. Vertebrates Vertebrate Freq. Invertebrates Invertebrate Freq. Weight (g) (g) Nematomorpha (Phylum) Aquatic Invertebrate 1 0.27 Tricoptera (Order) Aquatic Invertebrate 6 0.03 24 Gryllidae Terrestrial Invertebrate 1 0.11 0.42 Nematomorpha (Phylum) Aquatic Invertebrate 1 0.02 Nematomorpha 25 (Phylum) Aquatic Invertebrate 1 0.08 0.41 26 Unidentifiable 0.2 27 Empty 28 Belostomatidae Aquatic Invertebrate 1 0.53 5.76 Osteichthyes Aquatic (Class) Vertebrate 1 4.69 29 Empty 30 Belostomatidae Aquatic Invertebrate 1 0.24 0.24 Osteichthyes Aquatic 31 (Class) Vertebrate 1 0.9 1.09 32 Gerridae Aquatic Invertebrate 26 0.39 2.31 Isopoda (Order) Aquatic Invertebrate 1 0.01 33 Atyidae Aquatic Invertebrate 1 0.06 0.06 34 Isopoda (Order) Aquatic Invertebrate 1 0.01 0.08 35 Belostomatidae Aquatic Invertebrate 2 0.1 0.58 Isopoda (Order) Aquatic Invertebrate 1 0.01 Osteichthyes Aquatic 36 (Class) Vertebrate 1 0.6 1.96 Mantodea (Order) - Praying Mantis Terrestrial Invertebrate 1 0.18 Odonata (Order) Terrestrial Invertebrate 1 0.02 Ephemeroptera (Order) Aquatic Invertebrate 1 0.02 Tricoptera (Order) Aquatic Invertebrate 2 0.02 37 Unidentifiable 0.05 Scincidae - Terrestrial 38 Water Skink Vertebrate 1 1.82 3 Tricoptera (Order) Aquatic Invertebrate 6 0.07 Hymenoptera (Order) - ant Terrestrial Invertebrate 1 0.02 Ephemeroptera (Order) Aquatic Invertebrate 1 0.01 Nematomorpha 39 (Phylum) Aquatic Invertebrate 1 0.01 3.91 Odonata (Order) Aquatic Invertebrate 3 0.13 Gryllidae Terrestrial Invertebrate 1 0.03 Atyidae Aquatic Invertebrate 2 0.25 Tricoptera (Order) Aquatic Invertebrate 4 0.06 Gerridae Aquatic Invertebrate 2 0.01 Lycosidae Terrestrial Invertebrate 4 0.08 Ephemeroptera (Order) Aquatic Invertebrate 4 0.04 Notonectidae Aquatic Invertebrate 1 0.07 Ephemeroptera 40 (Order) Aquatic Invertebrate 1 0.03 0.19 Megadrili (Superorder) - 41 Terr. Earthworm Terrestrial Invertebrate 1 0.71 4.82 Nematomorpha (Phylum) Aquatic Invertebrate 3 0.4 Tricoptera (Order) Aquatic Invertebrate 25 0.36 Odonata (Order) Aquatic Invertebrate 1 0.02 Ephemeroptera (Order) Aquatic Invertebrate 1 0.01

402 Total Aquatic or Taxa Total Wet Fish Terrestrial Aquatic or Terrestrial Wet Weight No. Vertebrates Vertebrate Freq. Invertebrates Invertebrate Freq. Weight (g) (g) Plecoptera (Order) Aquatic Invertebrate 1 0.01 42 Unidentifiable 0.04 Tricoptera 43 (Order) Aquatic Invertebrate 3 0.04 0.09 Tricoptera 44 (Order) Aquatic Invertebrate 4 0.02 0.41 Megadrili (Superorder) - Terr. Earthworm Terrestrial Invertebrate 1 0.12 Hydraenidae Aquatic Invertebrate 1 0.01 Hymenoptera (Order) - 2x 45 wasps, 2x ants Terrestrial Invertebrate 4 0.12 0.37 Tricoptera (Order) Aquatic Invertebrate 1 0.01 Odonata (Order) Aquatic Invertebrate 2 0.09 Osteichthyes Aquatic 46 (Class) Vertebrate 1 1.66 2.24 Belostomatidae Aquatic Invertebrate 1 0.47 47 Unidentifiable 0.59 48 Odonata (Order) Aquatic Invertebrate 2 0.2 0.31 Diptera (Order) Terrestrial Invertebrate 1 0.03 49 Empty 50 Dytiscidae Aquatic Invertebrate 1 1.22 1.28 Isopoda (Order) Aquatic Invertebrate 1 0.02 Tricoptera 51 (Order) Aquatic Invertebrate 2 0.01 0.08 Lycosidae Terrestrial Invertebrate 1 0.04 52 Dytiscidae Aquatic Invertebrate 1 0.03 0.44 Tricoptera (Order) Aquatic Invertebrate 1 0.01 Odonata (Order) Aquatic Invertebrate 1 0.04 Amphipoda 53 (Order) Aquatic Invertebrate 1 0.04 0.3 Lepidoptera (Order) Terrestrial Invertebrate 1 0.26 54 Odonata (Order) Aquatic Invertebrate 1 0.07 0.28 Tricoptera 55 (Order) Aquatic Invertebrate 5 0.05 0.39 Tricoptera 56 (Order) Aquatic Invertebrate 5 0.05 2.78 Dytiscidae Aquatic Invertebrate 4 0.08 Lycosidae Terrestrial Invertebrate 1 0.54 Hymenoptera 57 (Order) Terrestrial Invertebrate 1 0.09 2.7 Diptera (Order) Terrestrial Invertebrate 1 0.11 Belostomatidae Aquatic Invertebrate 1 0.13 Dytiscidae Aquatic Invertebrate 2 0.02 Lepidoptera (Order) Terrestrial Invertebrate 1 0.03 Gastropoda 58 (Class) Aquatic Invertebrate 1 0.01 2.21 Dytiscidae Aquatic Invertebrate 1 0.01 Curculionidae Aquatic Invertebrate 1 0.03 59 Dytiscidae Aquatic Invertebrate 1 0.03 0.54 Amphipoda (Order) Aquatic Invertebrate 1 0.01 60 Dytiscidae Aquatic Invertebrate 2 0.08 0.46 Osteichthyes Aquatic 61 (Class) Vertebrate 1 3.97 3.99 62 Odonata (Order) Terrestrial Invertebrate 15 0.05 1.48 Platyhelminthes (Phylum) Aquatic Invertebrate 1 0.01 Dytiscidae Aquatic Invertebrate 1 0.01

403 Total Aquatic or Taxa Total Wet Fish Terrestrial Aquatic or Terrestrial Wet Weight No. Vertebrates Vertebrate Freq. Invertebrates Invertebrate Freq. Weight (g) (g) 63 Atyidae Aquatic Invertebrate 3 0.26 0.26 64 Atyidae Aquatic Invertebrate 2 0.12 1.53 Odonata (Order) Aquatic Invertebrate 6 0.74 Dytiscidae Aquatic Invertebrate 1 0.01 65 Belostomatidae Aquatic Invertebrate 1 0.03 0.74 Odonata (Order) Terrestrial Invertebrate 3 0.12 Odonata (Order) Aquatic Invertebrate 2 0.06 Tricoptera (Order) Aquatic Invertebrate 1 0.01 Tricoptera 66 (Order) Aquatic Invertebrate 18 0.12 1.42 Amphipoda (Order) Aquatic Invertebrate 2 0.01 Dytiscidae Aquatic Invertebrate 1 0.01 Hymenoptera (Order) Terrestrial Invertebrate 1 0.04 Diptera (Order) Terrestrial Invertebrate 1 0.01 Tetragnathidae Terrestrial Invertebrate 1 0.01 Isopoda (Order) Aquatic Invertebrate 1 0.01 Amphipoda 67 (Order) Aquatic Invertebrate 37 0.9 1.9 Tricoptera (Order) Aquatic Invertebrate 4 0.01 Curculonidae Aquatic Invertebrate 1 0.01 68 Diptera (Order) Terrestrial Invertebrate 2 0.02 0.11 69 Dytiscidae Aquatic Invertebrate 2 0.1 4.04 Blattidae - Methana marginalis Terrestrial Invertebrate 1 0.53 Hydrophilidae Aquatic Invertebrate 1 1.07 Diploda (Class) Terrestrial Invertebrate 1 0.19 70 Dytiscidae Aquatic Invertebrate 1 0.01 0.14 71 Isopoda (Order) Aquatic Invertebrate 1 0.01 0.57 Gryllidae Terrestrial Invertebrate 1 0.11 Hymenoptera 72 (Order) Terrestrial Invertebrate 1 0.01 1.21 73 Dytiscidae Aquatic Invertebrate 1 0.08 0.22 74 Dytiscidae Aquatic Invertebrate 1 0.09 1.1 75 Dytiscidae Aquatic Invertebrate 1 0.08 0.38 76 Atyidae Aquatic Invertebrate 1 0.01 0.77 Odonata (Order) Aquatic Invertebrate 2 0.04 77 Diptera (Order) Terrestrial Invertebrate 1 0.01 0.29 Diptera (Order) Aquatic Invertebrate 2 0.01 Ephemeroptera (Order) Aquatic Invertebrate 42 0.04 78 Cicadae Terrestrial Invertebrate 1 0.16 1.24 Lepidoptera (Order) Terrestrial Invertebrate 1 0.01 Ephemeroptera (Order) Aquatic Invertebrate 2 0.01 Tricoptera (Order) Aquatic Invertebrate 5 0.03 Nematoda (Phylum) Aquatic Invertebrate 4 0.01 79 Odonata (Order) Aquatic Invertebrate 1 0.16 1.73 Amphipoda (Order) Aquatic Invertebrate 1 0.02 Gryllidae Terrestrial Invertebrate 1 0.01 Diptera (Order) Terrestrial Invertebrate 2 0.01 Tetragnathidae Terrestrial Invertebrate 1 0.01 Tricoptera (Order) Aquatic Invertebrate 9 0.24 Aquatic 80 Anguillidae Vertebrate 1 3.24 3.52

404 Total Aquatic or Taxa Total Wet Fish Terrestrial Aquatic or Terrestrial Wet Weight No. Vertebrates Vertebrate Freq. Invertebrates Invertebrate Freq. Weight (g) (g) Carabidae Aquatic Invertebrate 1 0.2 81 Odonata (Order) Aquatic Invertebrate 8 0.62 1.61 Tricoptera (Order) Aquatic Invertebrate 11 0.12 Isopoda (Order) Aquatic Invertebrate 1 0.01 Amphipoda (Order) Aquatic Invertebrate 1 0.01 Lepidoptera (Order) Terrestrial Invertebrate 1 0.27 Tricoptera 82 (Order) Aquatic Invertebrate 15 0.08 0.15 Tetragnathidae Terrestrial Invertebrate 1 0.01 Tricoptera 83 (Order) Aquatic Invertebrate 1 0.01 0.9 Parastacidae Aquatic Invertebrate 1 0.14 Tetragnathidae Terrestrial Invertebrate 1 0.01 Hymenoptera (Order) - ants Terrestrial Invertebrate 2 0.02 Dytiscidae Aquatic Invertebrate 1 0.01 Tricoptera 84 (Order) Aquatic Invertebrate 7 0.09 2.97 Odonata (Order) Aquatic Invertebrate 8 0.29 Nematomorpha (Phylum) Aquatic Invertebrate 1 0.18 Lycosidae Terrestrial Invertebrate 1 0.01 Tricoptera 85 (Order) Aquatic Invertebrate 2 0.01 1.63 Scincidae - Terrestrial Water Skink Vertebrate 1 1.14 Nematoda (Phylum) Aquatic Invertebrate 1 0.01 Odonata (Order) Aquatic Invertebrate 4 0.02 Penaeidae - Metapenaeus 86 macleayi Aquatic Invertebrate 1 4.07 4.43 87 Penaeidae Aquatic Invertebrate 3 0.29 2.1 Tetragnathidae Terrestrial Invertebrate 1 0.01 Isopoda (Order) Aquatic Invertebrate 7 0.02 Scutelleridae - Scutiphora pedicellata Terrestrial Invertebrate 1 0.02 Lepidoptera (Order) Aquatic Invertebrate 5 0.01 88 Atyidae Aquatic Invertebrate 11 1.77 6.48 Isopoda (Order) Aquatic Invertebrate 11 0.26 Odonata (Order) Aquatic Invertebrate 1 0.01 Megadrili (Superorder) - earthworm Terrestrial Invertebrate 1 0.55 Megadrili (Superorder) - 89 earthworm Terrestrial Invertebrate 1 0.41 1.06 Isopoda (Order) Aquatic Invertebrate 1 0.01 90 Isopoda (Order) Aquatic Invertebrate 5 0.08 0.28 Lepidoptera (Order) Aquatic Invertebrate 1 0.01 91 Isopoda (Order) Aquatic Invertebrate 2 0.01 0.43 Tricoptera (Order) Aquatic Invertebrate 1 0.01 Hymenoptera (Order) - 1x ant 2x flying ants Terrestrial Invertebrate 2 0.01 Gerridae Aquatic Invertebrate 1 0.01 Dytiscidae Aquatic Invertebrate 1 0.01 92 Gryllidae Terrestrial Invertebrate 1 0.12 2.73

405 Total Aquatic or Taxa Total Wet Fish Terrestrial Aquatic or Terrestrial Wet Weight No. Vertebrates Vertebrate Freq. Invertebrates Invertebrate Freq. Weight (g) (g) Atyidae Aquatic Invertebrate 1 0.05 Nematoda (Phylum) Aquatic Invertebrate 1 0.01 Nematomorpha (Phylum) Aquatic Invertebrate 1 0.01 Tricoptera (Order) Aquatic Invertebrate 2 0.03 Odonata (Order) Aquatic Invertebrate 6 0.11 Dytiscidae Aquatic Invertebrate 1 0.01 Hydrophilidae Aquatic Invertebrate 1 0.04 Tricoptera 93 (Order) Aquatic Invertebrate 8 0.04 1.46 Amphipoda (Order) Aquatic Invertebrate 4 0.05 Tetragnathidae Terrestrial Invertebrate 1 0.01 Hymenoptera (Order) - 5 x flying ants Terrestrial Invertebrate 5 0.01 Gryllidae Terrestrial Invertebrate 1 0.01 Odonata (Order) Aquatic Invertebrate 5 0.01 Lepidoptera (Order) - Moth Terrestrial Invertebrate 1 0.16 Diptera (Order) - Fly Terrestrial Invertebrate 1 0.06 Nematomorpha (Phylum) Aquatic Invertebrate 1 0.01 Cerambycidae Terrestrial Invertebrate 1 0.17 Tricoptera 94 (Order) Aquatic Invertebrate 2 0.04 0.04 Tricoptera 95 (Order) Aquatic Invertebrate 2 0.02 1.74 Nematomorpha (Phylum) Aquatic Invertebrate 1 0.01 96 Unidentifiable 0.03 97 Lycosidae Terrestrial Invertebrate 1 0.02 0.48 Hymenoptera (Order) - ant Terrestrial Invertebrate 1 0.01 Ephemeroptera (Order) Aquatic Invertebrate 34 0.02 Sialidae Aquatic Invertebrate 1 0.01 Tricoptera 98 (Order) Aquatic Invertebrate 5 0.01 0.03 Hymenoptera (Order) - flying ant Terrestrial Invertebrate 1 0.02 Tricoptera 99 (Order) Aquatic Invertebrate 7 0.04 0.57 Diptera (Order) - fly Terrestrial Invertebrate 1 0.03 Lycosidae Terrestrial Invertebrate 1 0.01 Cicadellidae - Leafhopper Terrestrial Invertebrate 1 0.01 Nematomorpha 100 (Phylum) Aquatic Invertebrate 1 0.01 1.27 Tricoptera (Order) Aquatic Invertebrate 7 0.06 Gryllidae Terrestrial Invertebrate 1 0.33 Caelifera (Suborder) - Grasshopper Terrestrial Invertebrate 1 0.11 101 Penaeidae Aquatic Invertebrate 1 0.57 0.57 102 Atyidae Aquatic Invertebrate 1 0.08 0.08 Odonata (Order) - 103 Adult dragonfly Terrestrial Invertebrate 1 0.39 2.17 Osteichthyes Aquatic 104 (Class) Vertebrate 1 0.46 0.46 105 Odonata (Order) - Terrestrial Invertebrate 1 0.5 1.71

406 Total Aquatic or Taxa Total Wet Fish Terrestrial Aquatic or Terrestrial Wet Weight No. Vertebrates Vertebrate Freq. Invertebrates Invertebrate Freq. Weight (g) (g) Adult dragonfly Lycosidae Terrestrial Invertebrate 2 0.26 106 Odonata (Order) Aquatic Invertebrate 1 0.13 2 Nematomorpha (Phylum) Aquatic Invertebrate 1 0.47 Gryllidae Terrestrial Invertebrate 1 0.93 Tricoptera 107 (Order) Aquatic Invertebrate 2 0.04 0.48 Nematomorpha (Phylum) Aquatic Invertebrate 3 0.13 Diptera (Order) - fly Terrestrial Invertebrate 1 0.03 Odonata (Order) Aquatic Invertebrate 1 0.04 Nematoda 108 (Phylum) Aquatic Invertebrate 2 0.01 0.24 Nematomorpha (Phylum) Aquatic Invertebrate 1 0.03 Odonata (Order) Aquatic Invertebrate 3 0.1 Tricoptera (Order) Aquatic Invertebrate 3 0.05 109 Unidentifiable 0.03 Tricoptera 110 (Order) Aquatic Invertebrate 1 0.02 0.13 Hymenoptera (Order) - 1x 111 Wasp, Ants x 9 Terrestrial Invertebrate 10 0.23 0.92 Nematomorpha (Phylum) Aquatic Invertebrate 3 0.03 Notonectidae Aquatic Invertebrate 1 0.01 Aquatic 112 Anguillidae Vertebrate 1 0.13 1.14 Tricoptera (Order) Aquatic Invertebrate 13 0.12 Ephemeroptera (Order) Aquatic Invertebrate 10 0.05 Diptera (Order) - fly Terrestrial Invertebrate 1 0.02 Gryllidae Terrestrial Invertebrate 1 0.01 113 Atyidae Aquatic Invertebrate 12 1.52 2.93 Ephemeroptera (Order) Aquatic Invertebrate 1 0.01 114 Gryllidae Terrestrial Invertebrate 1 0.2 0.61 Diptera (Order) - mosquito Terrestrial Invertebrate 1 0.01 Tricoptera (Order) Aquatic Invertebrate 3 0.01 Notonectidae Aquatic Invertebrate 1 0.03 Nematomorpha 115 (Phylum) Aquatic Invertebrate 3 0.18 1.47 Aquatic Anguillidae Vertebrate 1 0.06 Hymenoptera (Order) - flying ant Terrestrial Invertebrate 1 0.01 Tricoptera (Order) Aquatic Invertebrate 3 0.02 Hymenoptera 116 (Order) - wasp Terrestrial Invertebrate 1 0.06 3.66 Limnichidae Aquatic Invertebrate 5 0.35 117 Unidentifiable 0.56 118 Unidentifiable 0.02 Hymenoptera 119 (Order) - wasps Terrestrial Invertebrate 2 0.37 0.44 120 Unidentifiable 0.21

407