Lake Bullen Merri Stocking

Looking back to go forward: Recreating a world class Chinook salmon fishery in Victoriaʹs western crater lakes

Taylor Hunt, Paul Brown and Khageswor Giri

November 2012 Fisheries Victoria Research Report Series 59

Recreating a world class Chinook salmon fishery i

If you would like to receive this Author Contact Details: Taylor Hunt information/publication in an Fisheries Research Branch, Fisheries Victoria accessible format (such as large PO Box 114, Queenscliff Vic 3225 print or audio) please call the Authorised by the Victorian Government, Customer Service Centre on: 2a Bellarine Hwy, Queenscliff, Victoria 3225 136 186, TTY: 1800 122 969, Printed by DPI Queenscliff, Victoria or email Published by the Department of Primary [email protected] Industries. © The State of Victoria, Department of Primary Copies are available from the website: Industries, 2012. www.dpi.vic.gov.au This publication is copyright. No part may be General disclaimer reproduced by any process except in accordance This publication may be of assistance to you but with the provisions of the Copyright Act 1968. the State of Victoria and its employees do not guarantee that the publication is without flaw of Preferred way to cite this publication: any kind or is wholly appropriate for your Hunt T.L., Brown P. and Giri K. (2012) Looking particular purposes and therefore disclaims all back to go forward: Recreating a world class liability for any error, loss or other consequence Chinook salmon fishery in Victoriaʹs western which may arise from you relying on any crater lakes. Fisheries Victoria Research Report information in this publication. Series No 59, 44 pages. Department of Primary Industries, Queenscliff, Victoria, Australia. ISSN 1448‐7373 ISBN 978‐1‐74326‐344‐0 (Print)

Recreating a world class Chinook salmon fishery ii

Executive Summary

The release of hatchery bred Chinook salmon o The catch rate of Chinook salmon in into Victoria’s western crater lakes in the mid Lake Purrumbete increased when fewer 1900’s (stocking) was successful in creating numbers of other species had been exceptional trophy fisheries in waters such as stocked in the lake over a four year Lake Bullen Merri and Lake Purrumbete period (Butcher 1947; Clements 1988). Particularly in o A trade off relationship between catch the late 1970s, 1980s and early 1990s, these rate and fish size from numbers stocked fisheries were heralded as one of only a few found for Lake Purrumbete will be land‐locked Chinook salmon fisheries in the valuable in helping fisheries managers world, generating extraordinary interest, angler and stakeholders plan fish stocking to participation and associated economic and social optimise fisheries management goals for benefits. More recently, it is thought the stocked crater lakes, and potentially, performance of these Chinook salmon fisheries other waters. has declined. o Density dependent growth with respect The recreational fishing community is keen to to stocking in Lake Purrumbete will be recreate a world class Chinook salmon fishery in suitable to use in a simulation model to Victoriaʹs western crater lakes. To do this, it is help refine the stocking strategies for the necessary to determine what factors contributed crater lakes. These data will be useful to to the decline of this fishery in the past. construct a multi‐species simulation model to investigate how stocking The objectives of this project were to: affects the performance of other species • Analyse available stocking, fisheries such as rainbow trout; Oncorhynchus assessment and angling club data to develop mykiss and brown trout; Salmo trutta. time‐series that describe the changes in the o Depending on the desired outcome of Chinook salmon fisheries over time. type of Chinook salmon fishery, three • Assess available data to determine if different options were suitable to be suitable to construct a simulation model that applied annually over the next three‐ can be used to inform stocking strategies. If year period in each lake: suitable, provide details and potential ¾ Maximum return to angler of costing of modelling project. Chinook salmon = 20,000 • Identify stocking strategies to re‐establish yearling Chinook salmon and high quality Chinook salmon fisheries at zero trout per year Lakes Bullen Merri and Purrumbete. If ¾ Optimal return to angler of suitable, recommend a three‐year stocking Chinook salmon at 50% of plan. current trout stocking = 15,000 The study found: yearling Chinook salmon and o Major fluctuations in fishery 15,000 yearling trout per year performance between 1978 and 2008 for ¾ Optimal return to angler of Lake Bullen Merri and 1969 and 2009 for Chinook salmon at current trout Lake Purrumbete stocking = 10,000 yearling o The more Chinook salmon yearlings Chinook salmon and 25,000 stocked into the lakes, the higher the yearling trout per year. catch rates (in the same year of stocking) o Evaluation of the revised stocking o The fewer Chinook salmon yearlings strategies using one of three options stocked into the lakes, the higher the provided will be essential to learn from return to anglers in terms of the size and improve these fisheries further. (weight) of fish caught

Recreating a world class Chinook salmon fishery iii

Table of Contents

Executive Summary...... iii

Introduction...... 1 Objectives...... 1

Methods...... 3 Fisheries data sources...... 3 Chinook salmon ...... 3 Redfin abundance ...... 3 Fish stocking data sources...... 3 Data analysis...... 3 Statistical analysis ...... 4 Successful analyses...... 4 Return to anglers of different stocking levels ...... 4

Results...... 5 Fishery performance...... 5 Lake Bullen Merri ...... 5 Lake Purrumbete ...... 5 Statistical analyses of fishery performance ...... 10 Lake Bullen Merri ...... 10 Lake Purrumbete ...... 10 Trade‐off between Chinook salmon catch rate and weight ...... 15

Discussion...... 18 Time‐series of fishery performance ...... 18 Potential for multi‐species simulation model ...... 19 Stocking strategies to re‐establish high quality Chinook salmon fisheries...... 20

Acknowledgements...... 24

References ...... 25

Appendix 1: History of Chinook salmon fisheries in Victoria ...... 27 Chinook salmon in Victoria...... 27 Introduction to Australia...... 27

Appendix 2: History of the study lakes...... 28 Crater Lakes ...... 28

Recreating a world class Chinook salmon fishery iv

Lake Bullen Merri...... 28 Lake Purrumbete...... 31

Appendix 3: Lake Bullen Merri stocking...... 34

Appendix 4: Lake Purrumbete stocking ...... 39

Appendix 5: Newspaper article 1978 ...... 44

Recreating a world class Chinook salmon fishery v

List of Tables Table 1. Physical characteristics of Lake Bullen Merri and Lake Purrumbete as reported in Barnham (1993)...... 2 Table 2. Estimates of parameters for Chinook salmon netting survey catch rate (fish caught/net/hour) from general linear regression model with number of Chinook salmon stocked same year in Lake Bullen Merri...... 11 Table 3. Estimates of parameters for Chinook salmon condition from general linear regression model with number of Chinook salmon stocked same year in Lake Bullen Merri...... 11 Table 4. Estimates of parameters for Chinook salmon angler catch rate (fish caught/angler/hour) from general linear regression model with number of Chinook salmon stocked same year in Lake Purrumbete...... 12 Table 5. Estimates of parameters for Chinook salmon netting survey catch rate (fish caught/net/hour) from general linear regression model with number of Chinook salmon stocked same year in Lake Purrumbete...... 12 Table 6. Estimates of parameters for Chinook salmon weight caught by anglers from general linear regression model with number of Chinook salmon stocked same year and total number of fish stocked for all other salmonids in the same year plus previous three years in Lake Purrumbete...... 13 Table 7. Recommended three‐year stocking strategy options for Lakes Bullen Merri and Purrumbete..... 22 Table 8. Evaluation options for stocking strategy and fishery performance. Pros, cons and relative costs.22 Table 9. Records of Chinook salmon from Lake Bullen Merri during the 1940s (Butcher 1947) ...... 33 Table 10. Records of Chinook salmon from Lake Purrumbete during the 1940s (Butcher 1947) ...... 33

List of Figures Figure 1. Location of Lake Bullen Merri and Lake Purrumbete in southwestern Victoria off the Princess Highway (line). Bathymetric information sourced from Timms (1976)...... 2 Figure 2. Catch rates of Chinook salmon from anglers and by fishery independent netting surveys from Lake Bullen Merri...... 6 Figure 3. Length of Chinook salmon caught by anglers and by fishery independent netting surveys from Lake Bullen Merri...... 6 Figure 4. Maximum and average weight of Chinook salmon caught by anglers from Lake Bullen Merri... 6 Figure 5. Condition Index of Chinook salmon caught by anglers and by fishery independent netting surveys from Lake Bullen Merri...... 7 Figure 6. Stocking history of Lake Bullen Merri...... 7 Figure 7. Catch rates of Chinook salmon by anglers and by fishery independent netting surveys from Lake Purrumbete...... 7 Figure 8. Length of Chinook salmon caught by anglers and by fishery independent netting surveys from Lake Purrumbete...... 8 Figure 9. Maximum and average weight of Chinook salmon by caught by anglers from Lake Purrumbete...... 8 Figure 10. Condition Index of Chinook salmon caught by anglers and by fishery independent netting surveys in Lake Purrumbete...... 8 Figure 11. Stocking regime for Lake Purrumbete...... 9 Figure 12. Catch rates of redfin by anglers and by fishery independent netting surveys from Lake Purrumbete...... 9

Recreating a world class Chinook salmon fishery vi

Figure 13. Relationship between angler catch rate of Chinook salmon (fish caught/net/hour) and number of yearling Chinook salmon stocked same year in Lake Bullen Merri...... 11 Figure 14. Relationship between angler Chinook salmon catch rate (fish caught/angler/hour) and number of yearling Chinook salmon stocked same year in Lake Purrumbete...... 12 Figure 15. Relationship between average weight of Chinook salmon (kg) caught by anglers and number of yearling Chinook salmon stocked same year in Lake Purrumbete...... 13 Figure 16. Relationship between average weight of Chinook salmon (kg) caught by anglers and the total number of salmonids stocked (both fingerlings and yearlings) in the same year plus the previous three years in Lake Purrumbete...... 14 Figure 17. Trade off relationship between angler catch rate (number of Chinook salmon caught/angler/hour) and average weight of caught fish (kg) with number of yearling Chinook salmon stocked same year in Lake Purrumbete...... 16 Figure 18. Return of Chinook salmon to angler (kg caught/angler/hour) from the number of yearling Chinook salmon stocked same year in Lake Purrumbete...... 17 Figure 19. Les Kennedy and his mounted 16 lbs (7.26 kg) Chinook salmon taken from Lake Bullen Merri in 1940. Photo taken 4 March 1982 and sourced from Clements (1988)...... 21 Figure 20. Skin of 23 lb 2 oz (10.49kg) Chinook salmon caught by Henry Rantall in March 1980, mounted and on display in the Lake Bullen Merri Angling Clubrooms. Photo taken June 2012 and sourced from Rob Hems...... 21 Figure 21. First known release of rainbow trout into Lake Bullen Merri in 1923. Leaving the hatcheries (top) and arriving at Camperdown (bottom). Photos sourced from Clements (1988) ...... 30 Figure 22. First known release of rainbow trout into Lake Bullen Merri in September 1923. Arrival at lake bank (top), Ready for liberation (bottom). Photos sourced from Clements (1988)...... 30

Recreating a world class Chinook salmon fishery vii

Introduction

Chinook salmon Oncorhynchus tshawytscha, is a Objectives northern American/north‐eastern Asian salmonid that was first introduced to Australia The objectives of this project were to: in the 1870s (Butcher 1947; Clements 1988). • Analyse available stocking, fisheries Recreational anglers target Chinook salmon for assessment and angling club data to develop it’s: time‐series that describe the changes in the • Fighting character when hooked Chinook salmon fisheries over time • Assess available data to determine if • Delicious rich‐flavoured flesh (Davies and McDowall 1996). suitable to construct a simulation model that can be used to inform stocking strategies. If The release of hatchery bred Chinook salmon suitable, provide details and potential into Victoria’s western crater lakes in the mid costing of modelling project 1900s (stocking) was successful in creating • Identify the stocking strategies which will exceptional trophy fisheries in waters such as re‐establish high quality Chinook salmon Lake Bullen Merri and Lake Purrumbete (Table fisheries at Lakes Bullen Merri and and Figure 1, Butcher 1947; Clements 1988). Purrumbete Particularly in the late 1970s, 1980s and early • Recommend a three‐year stocking plan. 1990s, these fisheries were heralded as one of only a few land‐locked Chinook salmon fisheries in the world, generating extraordinary interest, angler participation and associated economic and social benefits (Appendix 5, Nguyen and Ingram 2012). A history of the Chinook salmon fisheries in Victoria is presented in Appendix 1 and a history of the study lakes is presented in Appendix 2. More recently, it is thought the performance of these Chinook salmon fisheries has declined (Barnham 1993). While the reasons for this decline are unknown, it has been postulated that the following factors contributed: • Changes to the stocking regime • Changes to the genetic fitness of the Chinook salmon broodstock • Changes to the environmental conditions in the lakes. The recreational fishing community is keen to recreate a world class Chinook salmon fishery in Victoriaʹs western crater lakes. To do this it is necessary to determine what factors contributed to the decline of this fishery in the past.

Recreating a world class Chinook salmon fishery 1

Table 1. Physical characteristics of Lake Bullen Merri and Lake Purrumbete as reported in Barnham (1993) Lake Bullen Merri Purrumbete Surface area (ha) 490 585 Catchment surface area (ha) 878 4600 Shoreline length (km) 9.4 9.4 Volume (mL) 276,500 120,000 Average depth (m) 56 22 Annual rainfall (mm) 790 750

Figure 1. Location of Lake Bullen Merri and Lake Purrumbete in southwestern Victoria off the Princess Highway (line). Bathymetric information sourced from Timms (1976)

Recreating a world class Chinook salmon fishery 2

Methods

Fisheries data sources Data analysis To ensure data were as representative of the Chinook salmon total fishery as possible, years were only Quantitative metrics for fishery performance included if they had data from a minimum of included: three fish. • Catch rate of Chinook salmon by anglers All data were plotted as yearly time series of (number of fish caught per angler hour) and average catch rates (both Angler and FIS), in fishery independent surveys (FIS) average length, average and maximum weight (number of fish caught per net hour) and average condition index. • Length of Chinook salmon caught by anglers and in FIS (mm) Redfin abundance • Weight of Chinook salmon caught by club Redfin abundance data were extracted from the anglers (kg) Fisheries Victoria SAS Database and the following creel and netting survey reports: • Condition Index of Chinook salmon caught by anglers and in FIS (Barnham and Baxter • Baxter (1987) 1998) • Hume (1991) These data were sourced from: • Eddy and Smith (1995) • Fisheries assessment reports and databases, • Skene and Smith (1996) namely • Eddy (1998) o Baxter (1987) • Pomorin (2004) o Hume (1991) • Hall and Douglas (2010) o Eddy and Smith (1995) Data analyis o Skene and Smith (1996) Redfin catch rate data was plotted as yearly time o Brown and Vallis (1997) series. o Eddy (1998) Fish stocking data sources o Hall (2002) Stocking data were sourced from: o Hall (2003) • Barnham (1997) o Pomorin (2004) • Department of Primary Industries (2012) o Pomorin (2005) • DPI unpublished records (Ewan McLean, o Pomorin and Hall (2009) Fisheries Victoria Fish Liberations Officer o Hall et al. (2010) pers. comm.). o Hall and Douglas (2010) Data were reported on an annual basis and • Catch records from 35 logbooks (n= 4160 included month of release, species released, records) from the: weight (g) range of released fish and length (mm) range of released fish. o Lake Purrumbete Angling Club o Camperdown Angling Club. The stocking data are presented in Appendices 3 and 4. Angling club data Data recorded in angling club logbooks were Data analysis voluntarily reported by anglers and included Stocking data from 1976 to 2011 for Lake Bullen month of capture, species caught and the weight Merri and from 1969 to present for Lake (g) of gutted, gilled and cleaned fish. Purrumbete were plotted as yearly time series. Data were entered into an Excel database. Imperial weights recorded prior to 1980 were converted to metric (g).

Recreating a world class Chinook salmon fishery 3

Statistical analysis Successful analyses The fishery performance of the Chinook salmon Because limited data were available for both the fisheries in Lake Bullen Merri and Lake Lake Bullen Merri and Lake Purrumbete Purrumbete was evaluated statistically using an Chinook salmon fisheries only the following accumulated analysis of variance in a General analyses were successfully undertaken: Linear Regression model. • Lake Bullen Merri In this analysis, each measure of fishery o Catch rates of Chinook salmon from the performance (i.e. catch rate, length, weight, netting survey condition index) acted as a response variable o Condition index of Chinook salmon and was regressed against factors affecting from the netting survey fishery performance that acted as explanatory • Lake Purrumbete variables. o Catch rate of Chinook salmon from the Explanatory variables for fish stocking included netting survey the following categories: o Angler catch rate of Chinook salmon • Number of fingerlings stocked for each o Weight of Chinook salmon caught by species anglers. • Number of yearlings stocked for each The explanatory variables that were successfully species employed were: • Total number of fingerlings and yearlings stocked for all species • Lake Bullen Merri • Total number of fingerlings and yearlings o The number of yearling Chinook salmon stocked for all species except Chinook stocked in the same year as the fishery salmon. data was collected • Lake Purrumbete Due to the time it takes stocked fish to recruit to the fishery (and affect fishery performance); o The number of yearling Chinook salmon annual stocking data were also expanded to stocked in the same year as the fishery include the following time lags for each data was collected explanatory variable above: o The total number of all other salmonids • Number of fish stocked in the same year stocked in the same year plus the previous three years. • Number of fish stocked in the same year plus previous year Return to anglers of different stocking • Number of fish stocked in the same year levels plus previous two years The return of Chinook salmon to anglers at • Number of fish stocked in the same year different stocking levels was calculated by plus previous three years stocking. multiplying the angler catch rate by average weight of caught fish at specific numbers of On the basis that models with fewer terms are yearling Chinook salmon stocked (every 2,500 preferred to more complex models fish). (parsimonious), terms that added little to the fit of the model were progressively eliminated by stepwise regression (based on Wald F tests). Residuals versus fitted values plots were examined to check for any extreme outliers and judge the necessity of data transformation to satisfy the assumption of normality with constant variance. Regression parameters with statistical The return of Chinook salmon to anglers was probability values ≤5% (P≤0.05), were then plotted for a variety of stocking scenarios considered as statistically significant. (i.e. stocking average (167,836 fingerling and yearling trout), 75% of the average, 50% of the average and zero trout over the past three years).

Recreating a world class Chinook salmon fishery 4

Results

Chinook salmon stocking Fishery performance The stocking history of Lake Bullen Merri is Lake Bullen Merri shown in Figure 6. Metrics of fishery performance of Chinook salmon for Lake Bullen Merri included: Lake Purrumbete Metrics on fishery performance of Chinook • Fishery independent netting survey catch salmon for Lake Purrumbete included rates, length and condition extending between periods of 1978–1986, 1989–1994 • Fishery independent netting length and and 2002–2007. condition extending between periods of 1989–1994 and 2007, and catch rate in • Angler catch rates, length and condition patches between 1978–2009 from creel surveys conducted in 1993 and 1994 but catch rate also in 1984–85 and 2003. • Angler caught catch rate, length and condition from creel surveys conducted • The average and maximum weight of angler between 1993–1997 and 1999–2002, and caught fish from 1979 until 2008. catch rate also from 1984–1986 Chinook salmon catch rate • Angler caught average and maximum Catch rates of Chinook salmon in the fishery weight from 35 fishing club logbooks, 3996 independent netting surveys averaged 0.07 fish records extending from 1969 until 2009. per net hour (ranging from zero to 0.347 fish per net hour) (Figure 2). Chinook salmon catch rate Catch rates of Chinook salmon in the fishery Catch rates for Chinook salmon by anglers independent netting surveys averaged 0.019 fish averaged 0.018 fish per angler hour (ranging per net hour (ranging from 0.00 to 0.120 fish per from 0.001 to 0.041 fish per angler hour) (Figure net hour) (Figure 7). 2). Catch rates for Chinook salmon by anglers Chinook salmon length averaged 0.046 fish per angler hour (ranging The length of Chinook salmon caught in the from 0.005 to 0.084 fish per angler hour) (Figure fishery independent netting surveys averaged 7). 426 mm (ranging from 278 to 620 mm) (Figure 3). Chinook salmon length The length of Chinook salmon caught in the The length of Chinook salmon by anglers fishery independent netting surveys averaged averaged 365 mm (ranging from 359 to 371 mm) 466 mm (ranging from 364 to 718 mm) (Figure (Figure 3). 8). Chinook salmon weight The length of Chinook salmon by anglers The maximum weight of Chinook salmon averaged 334mm (ranging from 302 to 441 mm) caught by anglers averaged 2.98 kg (ranging (Figure 8). from 1.25 to 4.82 kg) (Figure 4). Chinook salmon weight The average weight of Chinook salmon caught The maximum weight of Chinook salmon by anglers averaged 1.94 kg (ranging from 0.84 caught by anglers averaged 3.30 kg (ranging to 3.75 kg) (Figure 4). from 0.47 to 6.07 kg) (Figure 9). Chinook salmon condition The average weight of Chinook salmon caught The condition index of Chinook salmon caught by anglers averaged 1.55 kg (ranging from 0.35 in the fishery independent netting surveys to 3.18 kg) (Figure 9). averaged 1.49 ‘good’ (ranging from 1.24 ‘fair’ to 1.72 ‘excellent’) (Figure 5). Chinook salmon condition The condition index of Chinook salmon caught The condition index of Chinook salmon caught in the fishery independent netting surveys by anglers averaged 1.60 ‘excellent’ (ranging averaged 1.33 ‘good’ (ranging from 1.08 ‘poor’ from 1.55 to 1.65 ‘excellent’) (Figure 5). to 1.67 ‘excellent’) (Figure 10).

Recreating a world class Chinook salmon fishery 5

Anglers Fishery independent netting surveys

0.3

0.2

0.1

Catch rate (fish per effort hour) effort per (fish rate Catch 0 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

Figure 2. Catch rates of Chinook salmon from anglers and by fishery independent netting surveys from Lake Bullen Merri.

Anglers Fishery independent netting surveys

650

550

450

350 Average length (mm) length Average

250 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

Figure 3. Length of Chinook salmon caught by anglers and by fishery independent netting surveys from Lake Bullen Merri.

Average Maximum

Weight of angled fish (kg) fish angled of Weight 0 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

Figure 4. Maximum and average weight of Chinook salmon caught by anglers from Lake Bullen Merri.

Recreating a world class Chinook salmon fishery 6

Anglers Fishery independent netting surveys

1.8

1.6

1.4

1.2 Condition Index (K) 1 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

Figure 5. Condition Index of Chinook salmon caught by anglers and by fishery independent netting surveys from Lake Bullen Merri.

Chinook salmon < 125 mm Chinook salmon > 125 mm Total fish

120

100

Number stocked (1,000) stocked Number 20

0 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

Figure 6. Stocking history of Lake Bullen Merri.

Anglers Fishery independent netting surveys

0.14

0.12

0.1

0.08

0.06

0.04

0.02 Catch rate (fish per effort hour) 0 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

Figure 7. Catch rates of Chinook salmon by anglers and by fishery independent netting surveys from Lake Purrumbete.

Recreating a world class Chinook salmon fishery 7

Anglers Fishery independent netting surveys

750 700 650 600 550 500 450 400

Average length (mm) length Average 350 300 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

Figure 8. Length of Chinook salmon caught by anglers and by fishery independent netting surveys from Lake Purrumbete.

Average Maximum 7

6 5

2 1 Weight of angled fish (kg) 0 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year Figure 9. Maximum and average weight of Chinook salmon by caught by anglers from Lake Purrumbete.

Anglers Fishery independent netting surveys

1.8

1.6

1.4

1.2 Condition Index (K) 1 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

Figure 10. Condition Index of Chinook salmon caught by anglers and by fishery independent netting surveys in Lake Purrumbete.

Recreating a world class Chinook salmon fishery 8

Chinook salmon < 125 mm Chinook salmon > 125 mm Total salmonids

120

100

Number stocked (1,000) 20

0 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

Figure 11. Stocking regime for Lake Purrumbete

Anglers Fishery independent netting surveys

1 0.9 0.8 0.7 0.6 0.5 0.4 effort hour) effort 0.3 0.2 0.1 0 redfin catch rate (redfin caught per per caught (redfin rate catch redfin 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

Figure 12. Catch rates of redfin by anglers and by fishery independent netting surveys from Lake Purrumbete.

Recreating a world class Chinook salmon fishery 9

The condition index of Chinook salmon caught Angler catch rate of chinook salmon by anglers averaged 1.37 ‘good’ (ranging from The number of yearling Chinook salmon 1.30 to 1.47 ‘good’) (Figure 10). stocked in the same year had a significant positive relationship on angler catch rate of Chinook salmon stocking Chinook salmon accounting for 31.4% of the The stocking history of Lake Purrumbete is variance (P = 0.034; Table 4, Figure 14). shown in Figure 11. The number of yearling Chinook salmon Redfin abundance stocked in the same year had a positive but Catch rates of redfin in the fishery independent statistically insignificant relationship with netting surveys averaged 0.266 fish per net hour netting survey catch rate of Chinook salmon (ranging from 0.012 to 0.921 fish per net hour) accounting for 13.0% of the variance (P = 0.055; (Figure 12). Table 5). Catch rates for redfin by anglers averaged 0.183 Chinook salmon weight fish per angler hour (ranging from 0.007 to 0.60 Average weight of angler caught Chinook fish per angler hour) (Figure 12). salmon in Lake Purrumbete exhibited Statistical analyses of fishery statistically significant negative relationships with: performance • The number of yearling Chinook salmon Lake Bullen Merri stocked in the same year (F = 16.50, P = The influence of stocking on the performance of 0.00061; Figure 15). the Chinook salmon fishery in Lake Bullen • The total number of fish stocked (both Merri was analysed using both the catch rates fingerlings and yearlings) for all other and condition index of fish caught in the netting salmonids in the same year plus previous survey. three years (F = 21.04, P = 0.00018; Figure Chinook salmon catch rate 16). The number of yearling Chinook salmon The most parsimonious model for average stocked in the same year had a significant weight of angler caught Chinook salmon positive relationship on catch rate of Chinook explained 57.0% of variance in the data (Table salmon from netting surveys (P = 0.044; Table 2). 6). The number of yearling Chinook salmon When fitted individually, the percentage of stocked in the same year accounted for 11.4% of variance explained by number of Chinook the variance in catch rate of Chinook salmon salmon yearling stocked same year was 15.9%, from netting surveys (Figure 13). whereas the percentage of variance explained by Chinook salmon condition total number of fish stocked for all other The number of yearling Chinook salmon salmonids in the same year plus previous three stocked in the same year had a negative but years was 25.2%. statistically insignificant relationship on condition of Chinook salmon from netting surveys (P = 0.077; Table 3). Lake Purrumbete The influence of stocking on the performance of the Chinook salmon fishery in Purrumbete was analysed using both the catch rates of fish caught by anglers and by the fisheries independent netting survey, and the weight of fish caught by anglers.

Recreating a world class Chinook salmon fishery 10

Table 2. Estimates of parameters for Chinook salmon netting survey catch rate (fish caught/net/hour) from general linear regression model with number of Chinook salmon stocked same year in Lake Bullen Merri.

Parameter Estimate Standard error t(26) P‐value Constant 0.0407 0.0194 2.10 0.045 Chinook salmon yearlings stocked 4.01×10‐06 1.89×10‐06 2.12 0.044

0.35

0.30

) r

u 0.25

e n

/ 0.20

(

t 0.15

c t

a 0.10 C

0.05

0.00

0 5000 10000 15000 20000 25000 30000 Number of Chinook salmon yearlings

Figure 13. Relationship between angler catch rate of Chinook salmon (fish caught/net/hour) and number of yearling Chinook salmon stocked same year in Lake Bullen Merri.

Average (straight full line) and 95% confidence intervals (curved dashed lines).

Table 3. Estimates of parameters for Chinook salmon condition from general linear regression model with number of Chinook salmon stocked same year in Lake Bullen Merri.

Parameter Estimate Standard error t(15) P‐value Constant 1.5563 0.0465 33.5 <.001 Chinook salmon yearlings stocked ‐8×10‐06 4.22×10‐06 ‐1.90 0.077

Recreating a world class Chinook salmon fishery 11

Table 4. Estimates of parameters for Chinook salmon angler catch rate (fish caught/angler/hour) from general linear regression model with number of Chinook salmon stocked same year in Lake Purrumbete.

Parameter Estimate Standard error t(10) P‐value

Constant 0.03218 0.00883 3.64 0.005 Chinook salmon yearlings stocked 2.16×10‐06 8.8×10‐07 2.46 0.034

0.12

) 0.10

r e

l 0.08

i f

( 0.06

h c

t 0.04

a C

0.02

0.00 0 5000 10000 15000 20000 25000 Number of Chinook salmon yearlings Figure 14. Relationship between angler Chinook salmon catch rate (fish caught/angler/hour) and number of yearling Chinook salmon stocked same year in Lake Purrumbete.

Average (straight full line) and 95% confidence intervals (curved dashed lines).

Table 5. Estimates of parameters for Chinook salmon netting survey catch rate (fish caught/net/hour) from general linear regression model with number of Chinook salmon stocked same year in Lake Purrumbete.

Parameter Estimate Standard error t(20) P‐value

Constant 0.00928 0.00732 1.27 0.219 Chinook salmon yearlings stocked 1.47×10‐06 7.2×10‐07 2.04 0.055

Recreating a world class Chinook salmon fishery 12

Table 6. Estimates of parameters for Chinook salmon weight caught by anglers from general linear regression model with number of Chinook salmon stocked same year and total number of fish stocked for all other salmonids in the same year plus previous three years in Lake Purrumbete.

Standard Parameter Estimate error t(20) P‐value

Constant 3.043 0.296 10.27 <0.001 Chinook salmon yearlings stocked ‐5.7×10‐05 0.000014 ‐4.06 <0.001 Total number of fish stocked ‐6.5×10‐06 1.42×10‐06 ‐4.59 <0.001

3.0

2.5

)

(

h 2.0

e g

a 1.5

d e

t 1.0

d A 0.5

0.0

0 5000 10000 15000 20000 25000 Number of Chinook salmon yearlings

Figure 15. Relationship between average weight of Chinook salmon (kg) caught by anglers and number of yearling Chinook salmon stocked same year in Lake Purrumbete.

Predicted average weights are adjusted for average stocking number of total fish except Chinook salmon in the same year plus previous three years (167,836). Average (straight full line) and 95% confidence intervals (curved dashed lines).

Recreating a world class Chinook salmon fishery 13

3.0

2.5

)

(

h g

i 2.0

a r

e 1.5

t s

u 1.0

d A

0.5

0.0 50000 100000 150000 200000 250000 300000 350000 Total number of fish in previous three years except Chinook salmon Figure 16. Relationship between average weight of Chinook salmon (kg) caught by anglers and the total number of salmonids stocked (both fingerlings and yearlings) in the same year plus the previous three years in Lake Purrumbete.

Predicted average weights are adjusted for average stocking number of yearling Chinook salmon stocked same year (6,811). Average (straight full line) and 95% confidence intervals (curved dashed lines).

Recreating a world class Chinook salmon fishery 14

Trade‐off between Chinook salmon Chinook salmon in the same year plus previous catch rate and weight three years is at 20,000 yearling Chinook salmon The analysis showed that in Lake Purrumbete (Figure 18). the number of yearling Chinook salmon stocked in the same year positively influences angler catch rates while negatively influencing the weight of the fish anglers’ catch. Stocking more yearling Chinook salmon leads to more fish being caught but they are on average lighter in weight (Figure 17). In contrast, stocking fewer yearling Chinook salmon leads to less fish being caught but they are on average heavier in weight (Figure 17).

In order to maximise both angler catch rate and average weight of caught Chinook salmon, this relationship suggests that providing average numbers of other species are being stocked (167,836 fingerling and yearling trout over the past three years), approximately 10,000 yearling Chinook salmon would need to be stocked in the same year. Return of Chinook salmon to angler from stocking The analysis showed that in Lake Purrumbete the number of trout (i.e. yearlings and fingerlings) stocked in the same year and in the previous three years in the same year negatively influences the weight of the anglers’ catch of Chinook salmon. The maximum return of Chinook salmon to angler at the current stocking number of total fish except Chinook salmon in the same year plus previous three years is at 10,000 yearling Chinook salmon. Stocking fewer trout over a period of four years, while maintaining a constant level of Chinook salmon stocking (i.e. 10,000 yearlings per year), will result in anglers catching larger (heavier) Chinook salmon (Figure 18). Stocking fewer trout over a period of four years, but maximising the return of Chinook salmon allows more Chinook salmon to be stocked. For example, the maximum return of Chinook salmon to angler at 75% of the current stocking number of total fish except Chinook salmon in the same year plus previous three years is at 12,500 yearling Chinook salmon. The maximum return of Chinook salmon to angler at 50% of the current stocking number of total fish except Chinook salmon in the same year plus previous three years is at 15,000 yearling Chinook salmon. The maximum return of Chinook salmon to angler at zero stocking of total fish except

Recreating a world class Chinook salmon fishery 15

Chinook salmon (kg) salmon Chinook Average weight of club angler caught caught angler club of weight Average

fish

2.5 2 1.5 1 0.5 0 caught

weight

(167,836)

average

years

and

three

plus

year

caught/angler/hour)

same

Average weight of caught Chinook salmon Chinook of caught weight Average the

salmon

salmon stocked per year salmon stocked salmon

Purrumbete.

Chinook

Chinook Lake of

except

year

fish

(number

total

same rate

catch

number stocked

Number of yearling Chinook yearling Number of angler

stocking

salmon

average

between

for

Angler catch rate of catch salmon Chinook Angler Chinook

adjusted

2,500 5,000 7,500 10,000 12,500 15,000 17,500 20,000 22,500 25,000 are yearling

relationship

off

0 weights

0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 Trade

number

average salmon caught/anglerhour) salmon

17.

Average angler catch rate (Chinook (Chinook rate catch angler Average with

(kg) Figure Predicted

Recreating a world class Chinook salmon fishery 16

three

Lake

year

plus

same

year

same

the stocked

salmon salmon

Chinook

Zero trout stocking except

fish

yearling

total

number

the

50% trout stocking trout 50% stocking

(0)

from

zero

and

(84,683)

75% trout stocking trout 75% average

caught/angler/hour)

50%

(kg

Number of yearling ChinookNumber salmonyearling of stocked per year angler (127,023),

average

75% salmon

Current trout stocking trout Current (167,836),

Chinook

2,500 5,000 7,500 10,000 12,500 15,000 17,500 20,000 22,500 25,000 average

0 Return

0.1

0.16 0.14 0.12 0.08 0.06 0.04 0.02

represent

Return to angler (kg/angler/hour) angler to Return 18.

Figure Scenarios . Purrumbete. years

Recreating a world class Chinook salmon fishery 17

Discussion

Lake Bullen Merri and Lake Purrumbete have these changes are likely to have contributed to been reported to historically support exceptional the decline of the salmonid fisheries. Water world‐class salmonid fisheries with a reputation quality issues have occurred in Lake Bullen for growing large fish quickly (Hall 2003; Merri periodically causing fish kills and the Department of Primary Industries 2008). productivity of Lake Purrumbete is decreasing due to changes in water levels and the presence Since the early 1940s Chinook salmon have been of redfin. These changes are essentially a key component of the salmonid fisheries in irreversible and likely to continue to affect these crater lakes, where very large Chinook salmonid fisheries into the future. Similarly, salmon were reportedly caught (4.5–9 kg) general environmental conditions are likely to (Clements 1988; Figures 19 and 20). fluctuate in the future and freshwater fisheries The lakes’ reputation for producing large are well known as constantly changing Chinook salmon continued up to the mid‐2000s resources. One good year of fishing may be (Davies and McDowall 1996; Barnham 1998; followed by a period of bad years (Skene and Department of Primary Industries 2008) and Smith 1996; Eddy 1998). Despite the they are recognised as one of only a few land‐ environmental changes and fluctuations locked Chinook salmon fisheries in the world occurring throughout the time series of (Nguyen and Ingram 2012). information provided, we identified clear conditions of stocking that lead to high Concerns regarding the genetic fitness and fish performance of Chinook salmon fisheries in the production ability of Victorian Chinook salmon crater lakes. stocks have recently been alleviated through two studies. Nguyen and Ingram (2012) The finding that low stocking density described and characterised the genetic contributes to trophy fish is supported by the structure of the captive Chinook salmon conditions that existed when the trophy fish population at Snobs Creek and developed brood reputation in the crater lakes was strongest. stock management guidelines to ensure the Much of trophy Chinook salmon fishery long‐term genetic “fitness’ of the stock and reputation of Lakes Bullen Merri and viability of the fishery. The study states that Purrumbete appears to have been drawn from adoption of these recommendations will the periods of the 1940s (Butcher 1947) and the enhance production of more genetically “fit” late 1970s (Hume 1991), when these waters had seed stock for both breeding and release to the low stocking densities and low fishing pressure. recreational fishery. Landos (2012) implemented The early Chinook salmon stocking between improved Chinook salmon production 1936 and 1946 accompanied low numbers of techniques to ensure the availability of Chinook stocked rainbow trout and due to the war salmon for stocking in the future. This study period, most likely low fishing pressure. adds to this valuable work and moves us closer Similarly, the trophy fishery performance of the towards recreating a world class Chinook late 1970s consisted of almost exclusively salmon fishery in Victoriaʹs western crater lakes. Chinook salmon being stocked, plus a closed fishing season. These periods of when the crater Time‐series of fishery lakes got their trophy fish reputation highlight performance the contribution that low fishing pressure may also have on trophy fish. Although it was In this study, we successfully developed time‐ beyond the scope of this study to quantify series that describe the changes in the Chinook changes in fishing pressure, we suspect that salmon fisheries for both Lake Bullen Merri and fishing pressure is higher nowadays than it was Purrumbete. Our analysis found that fishery in the past; potentially making it more difficult performance between 1978 and 2008 in Lake for fish to live long enough to reach a trophy Bullen Merri and 1969 and 2009 in Lake size. Consequently, the expectations of Chinook Purrumbete fluctuated substantially. salmon re‐stocking (Appendix 5) to produce The historical information provided in this trophy size fish may need to be tempered by study established that large‐scale environmental considering the amount of fishing effort Lakes changes have occurred in the crater lakes and

Recreating a world class Chinook salmon fishery 18

Bullen Merri and Purrumbete are likely to the population has an infinite carrying capacity. receive. Density dependent growth relationships have been used in simulation modelling of fish A trade off between catch rate and fish size from species to determine suitable stocking strategies numbers stocked has been suggested in (Brown and Hall 2003). The negative previous studies of Lake Bullen Merri and relationships between stocking numbers and Purrumbete, but the present study is the first to weight of caught fish reported here could be demonstrate it. Hume (1991) speculated that one used in a simulation model to help refine the could reasonably expect that if, say 50% less fish stocking strategies for the crater lakes. were stocked into Lake Purrumbete, the catch would have been less but average size greater. This study has highlighted uncertainties that a Similarly, Eddy (1998) found that despite multi‐species simulation model could inform to doubling angler catch rate from increased refine stocking strategies at the crater lakes. stocking of Chinook salmon in 1996 and 1997, World‐class fisheries in the crater lakes were not the average weight of all Chinook salmon limited to Chinook salmon, as rainbow trout; caught in this period was between 364–504g Oncorhynchus mykiss and brown trout; also which was considered by most anglers as small. provided exceptional fishing from time to time Other studies have found similar trade offs. Fish (Clements 1988) but the impact of restocking (1968) found a close inverse relationship Chinooks salmon on these fisheries is not between numbers of rainbow trout supported in known. There is conjecture that brown and New Zealand lakes and average weight rainbow trout may directly compete and achieved by the trout. They concluded that influence the Chinook salmon fishery. The productive lakes would produce large‐size fish present study found no significant relationship if the trout population was kept relatively small. between the stocking numbers of brown trout More recently, Brown and Hall (2001) found that and fishery performance of Chinook salmon. when higher numbers of brown trout were However, Hall et al. (2010) point out that during stocked into Lake Toolondo, the trout were of the period when very large Chinook salmon poorer condition than when lower numbers were caught in Lake Bullen Merri in the late were stocked. Brown and Hall (2003) used 1970s to mid 1980s, brown trout and rainbow survey data of golden perch stocking and trout had not been stocked since 1974 and 1976 growth in Lake Eppalock to build a simulation respectively. Therefore from 1978 to 1980, model and demonstrate that if fewer fish were Chinook salmon were likely to be the main, if stocked, larger individuals would be available to not the only, predator present in the lake giving anglers in lower numbers; but if greater them an almost total monopoly over all of the numbers of fish were stocked then catch rates food resources in the lake (Hall et al. 2010). Eddy would rise but individuals would be smaller. (1998) added that brown trout are a long lived Demonstration of the stocking density trade off species and do not contribute to the fishery in relationship will be valuable in helping fisheries their first year of release. If Chinook salmon and managers and stakeholders plan fish stocking to brown trout do compete, depending on the optimise fisheries management goals for stocked desired outcome, the stocking of either species waters. could be manipulated to encourage the presence of larger individuals from one species. If, for Potential for multi‐species example, the presence of Chinook salmon was simulation model desirable, the stocking levels of brown trout could be reduced. Certainly, investigating how The available data were assessed as suitable to the restocked Chinook salmon will affect construct a simulation model that can be used to existing salmonid fisheries, is worthy of further inform stocking strategies. investigation. A simulation model would enable The negative relationship between stocking this question to be answered to help refine numbers and weight of caught fish is an stocking strategies for all species to re‐establish indication of density‐dependent growth, which high quality salmonid fisheries at Lakes Bullen is essential information in building a fish Merri and Purrumbete. population model. Density dependent growth is The potential costing of multi‐species simulation a key parameter that regulates fish populations modelling project would depend on the (Lorenzen and Enberg 2002) and a simulation management requirements from the information model without a density dependent growth outputs. relationship makes the incorrect assumption that

Recreating a world class Chinook salmon fishery 19

Stocking strategies to re‐establish kills occur more or less frequently or on a more or less severe scale than they have in the past, high quality Chinook salmon the relationships between fishery performance fisheries and stocking presented here may not hold true Fish stocking is an important tool in fisheries in the future. Therefore, periodic evaluation management that can be used to improve (every three years) of fishery performance with fisheries. The findings from this study provide a respect to stocking is advisable. Considering the rare opportunity to recreate a world class data gathered to identify the stocking strategies Chinook salmon fishery in Victoriaʹs crater provided here were from creel surveys, nettings lakes. We successfully identified stocking surveys and club anglers catch weights, we strategies to re‐establish high quality Chinook recommend that these are used to monitor salmon fisheries at Lakes Bullen Merri and and/or evaluate the stocking strategy. Each Purrumbete. Depending on the desired outcome method has different pros, cons and relative of type of Chinook salmon fishery, we provide costs (Table 8). three different options for stocking strategies (Table 7). The options are based on the assumption that the trade off between catch rate and fish size from numbers stocked detected for Lake Purrumbete also occurs in Lake Bullen Merri. Uncertainties within our data exist and assumptions were made in forming our stocking strategies, and it is appropriate that they are highlighted for consideration and future improvements. For example, the angling club records presented here were voluntarily recorded by anglers, and although unlikely, changes in the weight of caught fish could be an artefact of which fish were recorded, rather than the actual weight of fish in the catch. For the purposes of this study, we assumed that there were no systematic changes in the fish recording behaviour of anglers. Future research and monitoring using angling club records could improve on this by asking anglers to record all fish caught. Similarly, the netting survey data presented here was collected over long periods of time and for various purposes, not necessarily designed for long‐term comparisons in catch rate and length, weight and condition of caught fish. Although catch rates were standardised per unit effort (net hour), we assumed that netting survey sampling was applied spatially consistently over both lakes through time. Future research and monitoring using netting surveys could improve on this by ensuring netting surveys were applied consistently both spatially and temporally. The implementation of the suggested stocking strategies should be scientifically evaluated in order to learn from and improve these fisheries further. Different rates of environmental changes in the crater lakes in future could affect the accuracy of the recommended stocking strategies provided here. For example, if fish

Recreating a world class Chinook salmon fishery 20

Figure 19. Les Kennedy and his mounted 16 lbs (7.26 kg) Chinook salmon taken from Lake Bullen Merri in 1940. Photo taken 4 March 1982 and sourced from Clements (1988).

Figure 20. Skin of 23 lb 2 oz (10.49kg) Chinook salmon caught by Henry Rantall in March 1980, mounted and on display in the Lake Bullen Merri Angling Clubrooms. Photo taken June 2012 and sourced from Rob Hems.

Recreating a world class Chinook salmon fishery 21

Table 7. Recommended three‐year stocking strategy options for Lakes Bullen Merri and Purrumbete.

Fishery type Number of yearling Chinook Number of yearling salmon stocked per year trout stocked per year

Maximum return to angler from Chinook 20,000 zero salmon Optimal return from Chinook salmon at 15,000 15,000 50% of average trout stocking Optimal return from Chinook salmon at 10,000 25,000 average trout stocking

Table 8. Evaluation options for stocking strategy and fishery performance. Pros, cons and relative costs.

Method Creel survey Netting survey Angling club weigh stations

Pros Considerable past data to Considerable past data to compare Considerable past data to compare with with compare with Representative of fishery Representative of population Representative of club catch Engages many anglers Quick to conduct Ongoing Potential to add value with socio‐economic data Cons 6–9 months of data collection Doesn’t represent angler catch rate Doesn’t represent other angler catch Planning and data analysis Doesn’t engage anglers required Doesn’t consider catch rate Only engages club anglers Relative Cost $$$ $$ $

Recreating a world class Chinook salmon fishery 22

Conclusions

The project successfully: we provide three different options to be applied annually over the next three‐year • Analysed available stocking, fisheries period in each lake: assessment and angling club data and developed a time‐series that describe the o Maximum return to angler of changes in the Chinook salmon fisheries Chinook salmon = 20,000 yearling over time. We found: Chinook salmon and zero trout per year o Major fluctuations in fishery performance between 1978 and 2008 for o Optimal return to angler of Chinook Lake Bullen Merri and 1969 and 2009 for salmon at 50% of current trout Lake Purrumbete. stocking = 15,000 yearling Chinook salmon and 15,000 yearling trout

o The more Chinook salmon yearlings per year stocked into the lakes the higher the catch rates (in the same year of stocking) o Optimal return to angler of Chinook salmon at current trout stocking =

o The fewer Chinook salmon yearlings 10,000 yearling Chinook salmon and stocked into the lakes the higher the 25,000 yearling trout per year return to anglers in terms of the size (weight) of fish caught o Evaluation of the revised stocking strategies using one of three options

o The catch rate of Chinook salmon in provided will be essential to learn Lake Purrumbete increased when fewer from and improve these fisheries numbers of other species had been further. stocked in the lake over a four year period • Assessed the available data and determined them suitable to construct a simulation model that can be used to inform stocking strategies. We found: o A trade off relationship between catch rate and fish size from numbers stocked found for Lake Purrumbete will be valuable in helping fisheries managers and stakeholders plan fish stocking to optimise fisheries management goals for stocked crater lakes, and potentially, other waters. o The finding of density dependent growth with respect to stocking in Lake Purrumbete will be suitable to use in a simulation model to help refine the stocking strategies for the crater lakes. o These data will be useful to construct a multi‐species simulation model to investigate how stocking affects the performance of other species such as rainbow trout; Oncorhynchus mykiss and brown trout; Salmo trutta. • Identified stocking strategies to re‐establish high quality Chinook salmon fisheries at the crater lakes. Depending on the desired outcome of type of Chinook salmon fishery,

Recreating a world class Chinook salmon fishery 23

Acknowledgements

Thanks to Travis Dowling, Anthony Forster and John Douglas for commissioning the project.

Rob Hems, Roger Tolman, Gary Cronin and members of the Purrumbete and Camperdown Angling Clubs for providing the angling club data and helpful comments on the project.

Brett Ingram, Marc Ainsworth, Steve Eddy,

Corey Green and Fabian Trinnie, DPI; Phil Weigall, Geoff Wilson, Geoff Cramer, Steve Cooper, David Dwyer; and Mike Allen and Dan Gwinn, University of Florida, for helpful comments on the project. Also special thanks to Leanne Gunthorpe and Andy Longmore for their thorough and helpful comments drafts of this report.

Recreating a world class Chinook salmon fishery 24

References

Barnham, C. (1977). Ten‐year effort to Freshwater Division, Fisheries and Habitat acclimatise quinnat salmon pays off. Australian Assessment Program, Marine and Freshwater Fisheries 36. Resources Institute, Snobs Creek. Barnham, C. (1993). ʹInternal Operations Butcher, A. B. (1947). ʹQuinnat salmon in Document No. 1: Consultation and Managment Victorian inland waters.ʹ Fisheries Pamphlet No. Summary.ʹ Freshwater Fish Management 4. Fisheries and Game Department Victoria. Branch, Fisheries Division, Victoria. Cadwallader, P. and Eden, A. K. (1982). Barnham, C. (1997). ʹFisheries Information Observations on the food of rainbow trout, report No. 2: Summary of immediately available Salmo gairdneri Richardson, in Lake Purrumbete, records of non‐indigenous and indigenous fish Victoria. Bulletin of the Australian Society of stockings in Victorian public waters 1871‐1996.ʹ Limnology 8, 17‐21. Freshwater Fish Management Branch, Fisheries Cadwallader, P. L. and Eden, A. K. (1981). Food Division, Victoria. and growth of hatchery‐produced chinook Barnham, C. (1998). ʹFreshwater Fish of Victoria salmon, Oncorhynchus tshawytscha (Walbaum), in ‐ Chinook Salmon.ʹ Fisheries Notes. Department landlocked Lake Purrumbete, Victoria, of Natural resources and Environment, East Australia. J. Fish Biol. 18, 321‐330. Melbourne. Clements, J. (1988). ʹSalmon at the Antipodes. A Barnham, C. and Baxter, A. (1998). ʹCondition History and Review of Trout, Salmon and Char Factor, K, for Salmonid Fish.ʹ Fisheries Notes. and Introduced Coarse Fish in Australia.ʹ (John State of Victoria, Department of Primary Clements Publisher) Industries. Davies, P. E. and McDowall, R. M. (1996) Baxter, A. F. (1987). ʹCatch and effort data for all Salmons, trout and chars. In ʹFreshwater fishes the major angling species caught by the Trout of south‐eastern Australiaʹ. (Ed. R. M. Management Group during gill netting surveys McDowall). (Reed Books: Sydney) conducted between 1978 and 1986 inclusive.ʹ Department of Primary Industries (2008). Fisheries Management Report No. 6. Freshwater ʹCorangamite Fishery Management Plan.ʹ Fisheries Management Branch, Fisheries Fisheries Victoria Management Report Series Division. No. 59. Department of Primary Industries, Brown, C. E. and Cocomazzo, M. A. (1994). ʹThe Melbourne. distribution and sexual development of forage Department of Primary Industries (2012) Fish fish species in Lake Purrumbete.ʹ A report to the Stocking Reporting. In. (Fisheries Victoria: Deaprtment of Conservation and Natural Melbourne) Resources. School of Aquatic Science and Natural Resource Management, Deakin Douglas, J. and Brown, P. (2010). ʹTriploid University, Colac. brown trout for roach control and a trophy fishery.ʹ Fisheries Victoria Techinical Report No. Brown, P. and Hall, K. (2001). ʹToolondo 85. Department fo Primary Industries, Reservoir Fisheries Assessment July 1998 ‐ Queenscliff. December 2000, including a review of brown trout growth, condtion and stocking density Eddy, S. (1998). ʹReport on Creel Surveys Lake since 1989.ʹ MAFRI Freshwater Fisheries Report Purrumbete, Lake Murdeduke and Lake Bullen 00/05. Department of Natural Resources and Merri 1 December 1995 to 30 November 1997.ʹ Environment, Snobs Creek. Fisheries Management Report ‐ No. 62. Victorian Fisheries, Department of Natural Resources and Brown, P. and Hall, K. (2003). ʹLake Eppalock Environment, Colac. Golden Perch Stock Assessment.ʹ Fisheries Victoria Research Report Series No. 6. Eddy, S. and Smith, I. (1995). ʹReport on Creel Department of Primary Industries, Snobs Creek. Surveys Lake Purrumbete and Lake Bullen Merri 1 December 1993 to 30 November 1994.ʹ Brown, P. and Vallis, S. (1997). ʹLake Bullen Fisheries Management Report ‐ No. 53. Victorian Merri Fishery Assessment October 1997.ʹ MAFRI Freshwater Division Fish Survey 97/12.

Assessment of the Victorian sea urchin fishery 25

Fisheries, Department of Natural Resources and Research Report Series No. 55. Fisheries Environment, East Melbourne. Victoria, Department of Primary Industries, Queenscliff. Fish, G. R. (1968). An examination of the trout population of five lakes near Rotorua, New Pomorin, K. (2004). ʹRainbow Trout Stocking Zealand. New Zealand Journal of Marine and Evaluation Lake Purrumbete 1999‐2002.ʹ Freshwater Research 2, 333‐362. Fisheries Victoria Research Report Series No. 05. Department of Primary Industries, Queenscliff. Hall, K. (2002). ʹLake Bullen Merri Fisheries Assessments ‐ DNRE South West Region, 2000‐ Pomorin, K. (2005). ʹLake Bullen Merri Fisheries 2002.ʹ Marine and Freshwater Resources Assessment.ʹ Department of Primary Industries, Institute Freshwater Fisheries report No. 02/3. Snobs Creek. Department of Natural Resources and Pomorin, K. and Hall, K. (2009). ʹLake Bullen Environment, Snobs Creek. Merri Fisheries Assessment: September 2002 ‐ Hall, K. (2003). ʹLake Bullen Merri Fisheries January 2004.ʹ Fisheries Revenue Allocation Assessment ‐ DNRE South West Region, 2002‐ Committee Final Report. Department of Primary 2003.ʹ Marine and Freshwater Resources Industries, Queenscliff. Institute Freshwater Fisheries Report No. 03/7. Skene, W. and Smith, I. (1996). ʹReport on Creel Marine and Freshwater Resources Institute, Surveys Lake Purrumbete, Lake Bullen Merri Snobs Creek. and Lake Murdeduke 1 December 1994 to 30 Hall, K. and Douglas, J. (2010). ʹLake November 1995.ʹ Fisheries Management Report ‐ Purrumbete Stock Assessment.ʹ Fisheries No. 55. Victorian Fisheries, Department of Victoria Report Series No. 35. Department of Natural Resources and Environment, East Primary Industries, Alexandra. Melbourne. Hall, K., Douglas, J. and Pomorin, K. (2010). Stoessel, D. (2009). ʹArtificial aeration of Lake ʹLake Bullen Merri 2005 and 2006 Stock Bullen Merri: review of operations.ʹ Recreational Assessments.ʹ Fisheries Victoria Assessment Fishing Grant Program ‐ Research Report. Report Series No. 58. Department of Primary Department of Primary Industries, Queenscliff. Industries, Alexandra. Timms, B. V. (1976). A Comparative Study of the Hames, F. (1990). ʹChinook salmon project 1980‐ Limnology of Three Maar Lakes in Western 1987.ʹ. Snobs Creek Freshwater Fisheries Victoria I. Physiography and Physicochemical Research Station and Hatchery, Alexandra, Features. Australian Journal of Marine and Victoria. Freshwater Research 27, 35‐60. Hume, D. (1991). ʹReport on three years of creel Tunbridge, B. R., Rogan, P. L. and Barnham, C. surveys: 1984 to 1987.ʹ Technical report series no. A. (1991). ʹA guide to the inland angling waters 122. Arthur Rylah Institute for Environmental of Victoria.ʹ (Inland Fisheries Management Research. Department of Conservation and Branch, Fisheries Management Division, Environment, Victoria. Department of Conservation and Environment: Melbourne) Landos, M. (2012). ʹChinook Salmon Production Review 2011‐2012.ʹ Future Fisheries Veterinary Williams, W. D. (1992). ʹThe biological status of Science. Lake Corangamite and other lakes in western Victoria.ʹ A report to the Department of Lorenzen, K. and Enberg, K. (2002). Density‐ Conservation and Environment. Department fo dependent growth as a key mechanism in the Zoology, University of Adelaide, Colac. regulation of fish populations: evidence from among‐population comparisons. Proceedings of the Royal Society of London B 269, 49‐54.

Nguyen, T. T. T. and Ingram, B. A. (2012). ʹGenetic status of Chinook Salmon held at Snobs

Creek and implications from improved broodstock management.ʹ Fisheries Victoria

Recreating a world class Chinook salmon fishery 26

Appendix 1: History of Chinook salmon fisheries in Victoria

Between 1936 and 1946 Chinook salmon were Chinook salmon in Victoria released into 16 Victorian lakes in an attempt to In Victoria, only ’landlocked’ populations of develop ‘landlocked’ populations. While little Chinook salmon exist. These populations do not data was collected by which the success or breed naturally. otherwise of the stockings could be determined Chinook salmon are artificially breed by scientifically, it was anecdotally accepted that stripping eggs from ripe females and milt from the stocking was successful in Lake Bullen Merri ripe males, hatching and rearing the fish to a and Lake Purrumbete. In these lakes, the suitable size for release. Victorian Chinook Chinook salmon populations showed acceptable salmon also die after spawning or attempted growth rates and flourishing fisheries spawning (Butcher 1947; Barnham 1998). developed. Chinook salmon are one of the most highly The success of stocking at Lake Bullen Merri and sought after game species (Clements 1988; Lake Purrumbete encouraged local angling Davies and McDowall 1996). clubs to provide financial assistance to the then Fisheries Department, to import Chinook Land‐locked Chinook salmon in Victoria have salmon from New Zealand for further stocking. been known to grow to 89 cm and 11.4 kg It is reported that local anglers also attempted to raise their own Chinook salmon in local Introduction to Australia hatcheries, through these ventures were thought Chinook salmon has been introduced to many to be unsuccessful. locations outside of its natural range including New Zealand and Australia. Accounts of early Lakes Bullen Merri and Purrumbete were Chinook salmon hatchery production and stocked periodically between 1952 and 1967 stocking liberation in Australia are provided by with eggs imported from either New Zealand or Butcher (1947), Barnham (1977), Hames (1990), Oregon, U.S.A. Cadwallader and Eden (1981), Clements (1988), A ban on the importation of live salmonid fish Davies and McDowall (1996) and Nguyen and and eggs into Australia because of disease risks Ingram (2012). in 1967 resulted in the establishment of a Chinook salmon were first shipped from population of Chinook salmon at the Snobs California to Australia in 1874, but the eggs died Creek hatchery. This population has been used in transport. A second shipment of 50,000 ova in to breed all Chinook salmon released in Victoria 1877 via New Zealand was more successful. waterways (since 1976) and the following Chinook salmon fry were stocked into Victorian generations of breeding stock. coastal rivers but failed to establish sea‐run Hatchery reared Chinook salmon were released populations. Between 1910 and 1936 Chinook in a variety of other Victorian waters during the salmon were imported from New Zealand and 1970s, 1980s and 1990s. with little success. Since stocked into Tasmanian waters. 2000, the stocking of Chinook salmon has focussed on Lake Bullen Merri and Purrumbete.

Assessment of the Victorian sea urchin fishery 27

Appendix 2: History of the study lakes

Crater Lakes cope with fluctuating water quality and provide summer fishing opportunities. Of these, Both Lake Bullen Merri and Lake Purrumbete stockings only the Australian bass established a are crater lakes which were formed by volcanic population (Pomorin and Hall 2009), but to date explosions (Timms 1976; Barnham 1993). no popular fishery for this species has Lake Bullen Merri and Lake Purrumbete are developed. highly productive and contain a diverse Increased stocking of Chinook salmon occurred community of forage fish species (Butcher 1947; in 1991 when records from Consultation Cadwallader and Eden 1981; Clements 1988) meetings between the Fisheries Department and such as: anglers (CONS) in 1991 state “Chinook salmon • Common galaxid; Galaxias maculates appear to do better in Lake Bullen Merri compared • Pigmy perch, Nannoperca australis with Lake Purrumbete, and there appeared to be good • Big‐headed Gudgeon; Philypnodon grandiceps reason to concentrate more heavily on the Chinook salmon fishery in this lake. Results of current These forage fish formed a major part of the diet stocking program were good and returns to anglers of Chinook salmon in these lakes (Cadwallader also good although the lake was not subject to the and Eden 1981). Butcher (1947) described the same fishing pressure at Lake Purrumbete. Brief growth in Chinook salmon stocked 1936 and soundings on a ‘trophy’ fishery were not well 1946 as ‘remarkably uniform throughout the received.” The Fisheries Department proposed an year because of great supplies of available food’. increase in Chinook salmon and an equivalent reduction of rainbow trout and stocking records Lake Bullen Merri indicate an increase in Chinook salmon stocking Lake Bullen Merri is described as a popular in 1991 to 11,900 (Barnham 1993). angling water (Department of Primary Decreases in stocking of Chinook salmon have Industries 2008) that contains large populations of galaxiids, gudgeon and invertebrates, also occurred due to production failures. In 1993 particularly caddis, on which trout and salmon there were insufficient Chinook salmon to meet the total stocking commitment for both Lakes feed (Tunbridge et al. 1991; Barnham 1993). Bullen Merri and Purrumbete due to continuing The high availability of prey is thought to problem with a Nocardia infection at Snobs account for the extraordinary salmonid growth Creek. Apart from 1,000 fish, all 6,600 remaining rates and popular fisheries observed here (Hall Chinook salmon produced in 1993 were stocked 2002). into Lake Bullen Merri (Barnham 1993). Fish stocking Triploid rainbow trout were trialled in Lake Lake Bullen Merri has been stocked with fish Bullen Merri between 1987–1995 to see if they since at least 1923 (Clements 1988; Barnham grew faster and lived longer than other 1997) (Figure 21 and 22). The main fish species salmonids (Hall 2002). Consultation meetings released into Lake Bullen Merri are: between the Fisheries Department and anglers • Rainbow trout in 1986 first highlighted the potential of a 50/50 stocking of triploid rainbow trout and Chinook • Chinook salmon salmon and this occurred for rainbow trout in • Brown trout 1987. In 1991 there appeared to be no • Atlantic salmon (Salmo salar) substantive result from stocking triploid The stocking program for Lake Bullen Merri has rainbow trout, although there was also no focussed principally on rainbow trout. Stocking information available from Snobs Creek to of Chinook salmon occurred periodically indicate the extent of the triploiding. It is unclear stocked between 1936 and 1946, 1952, 1954 and from the document if this averages that testing 1978 (Appendix 2). Golden perch; Macquaria was performed to confirm triploidy or not ambigua, silver perch; Bidyanus bidyanus and (Douglas and Brown 2010). The stocking of Australian bass: Macquaria novemaculeata were triploid rainbow trout continued until 1995 stocked in the late 1990s in an attempt to despite an inability to determine by surveys the establish alternative species that might better

Recreating a world class Chinook salmon fishery 28

contribution of triploid fish to the fishery 1992 and October 1993, and February–March (Barnham 1993). 1995. Fishery performance While the cause of the fish kills has not been The performance of the trout fisheries in Lake determined, the following factors have been Bullen Merri is characterised by periods of high implicated: productivity inter‐dispersed with periods of • Low dissolved oxygen levels poor returns. • High pH The trout fishery in Lake Bullen Merri • High temperature commenced in 1924 (Clements 1988). • Chemical contamination from the runoff of In the 1940s first records of an exceptionally herbicides high performing Chinook salmon fishery occur • Elevated nutrient s and associated algal (Butcher 1947). These reports indicate very large blooms (Hume 1991; Tunbridge et al. 1991; Chinook salmon were being taken from Lake Eddy 1998). Bullen Merri (Table 9). After each fish kill, stocking was suspended and During the early 1990s, reports again indicated later resumed when the conditions in the Lake the fishery was performing well, for both for the were deemed suitable to sustain fish (Barnham trout fishery in general and for the Chinook 1993; Eddy and Smith 1995; Skene and Smith salmon fishery. The 1991 reports indicated there 1996; Brown and Vallis 1997). was a good return to anglers (Barnham 1993), while in 1993, the Trout Management Group described Lake Bullen Merri as high value for rainbow trout and Chinook salmon fishery. Very large specimens of Chinook salmon were reported to have been caught from Lake Bullen Merri in those years (Barnham 1993). From 1993 to 1998 the performance of the trout and Chinook salmon fishery in Lake Bullen Merri declined, and this was attributed to poor water quality (Eddy and Smith 1995; Skene and Smith 1996; Eddy 1998). Habitat and productivity Lake Bullen Merri is a brackish crater lake that is becoming more saline each year (Williams 1992; Eddy 1998; Hall et al. 2010). This is due to the continued deposition of salt and the steady lowering of it’s water level (Tunbridge et al. 1991; Barnham 1993). Butcher (1947) stated that the lake is falling by approximately 9 inches (229 mm) each year. Since 1898 the lake level is believed to have fallen by approximately 14 m (Williams 1992). Water quality issues are well documented for Lake Bullen Merri. Between 1955 and 1983 seventeen fish kills were reported, and netting surveys indicated the disappearance of a number of year classes of Chinook salmon during this time (Hume 1991). An aerator was installed in 1985 in an effort to reduce fish kills by mixing well‐oxygenated surface waters with the oxygen‐depleted bottom waters (Hume 1991). Despite the installation of the aerator, fish kills occurred during February

Assessment of the Victorian sea urchin fishery 29

Figure 21. First known release of rainbow trout into Lake Bullen Merri in 1923. Leaving the hatcheries (top) and arriving at Camperdown (bottom). Photos sourced from Clements (1988)

Figure 22. First known release of rainbow trout into Lake Bullen Merri in September 1923. Arrival at lake bank (top), Ready for liberation (bottom). Photos sourced from Clements (1988).

Recreating a world class Chinook salmon fishery 30

ranging from 10 lb to 19 lb were taken from Lake Lake Purrumbete Purrumbete (Table 10). Local environment and habitat Lake Purrumbete is a popular angling water for During the 1960s, fishery performance in Lake salmonids (Barnham 1993; Department of Purrumbete widely fluctuated. Anecdotal Primary Industries 2008). information provided from anglers and angling clubs in Hume (1991) included: The lake contains large numbers of common • Oct 1959 – 5 people took 21 fish galaxids that support high growth of salmonids. • 1960/61 – Very good season Fish stocking • 1963 – Very poor season – no good catches Lake Purrumbete has been stocked with fish • since at least 1879 (Clements 1988; Barnham 1964 – Very poor season 1997). The main fish species released into Lake • 1965 – Excellent season Bullen Merri are: • 1967 – Very poor season • Rainbow trout • 1968 – Very good fishing during opening • Chinook salmon • 1969 – Very good Chinook salmon season, • Brown trout but otherwise quiet. • Atlantic salmon. During the 1970s, reports again indicated the The stocking program for Lake Purrumbete has fishery was performing well, for both for the focussed principally on rainbow trout. Stocking trout fishery in general and for the Chinook of Chinook salmon occurred periodically salmon fishery. The stocking of rainbow trout in stocked between 937 and 1946, 1952 and 1958, Lake Purrumbete is reported to have resulted in 1967, and 1976 until 2007. Stocking of Chinook the formation of a successful sport fishery and salmon ceased after 2007 (Appendix 3). the growth rates of Chinook salmon in Lake Purrumbete, while not attaining the levels seen Substantial changes in fish stocking have in the 1940s, compared favourably with that of occurred at Lake Purrumbete over time. For other landlocked Chinook salmon populations example, an increased stocking of rainbow trout (Cadwallader and Eden 1981).. for five years (1984–1988) was reviewed by Hume (1991) and found to be of little value. The early 1990s appears to be a period of poorer Hume (1991) and Barnham (1993) stated that fishery performance, where the quality of even when the return of rainbow trout to fishing had declined since the early 1980s anglers was high in 1984/85, the average size (Barnham, (1993); Eddy and Smith, (1995). was less than what most ‘serious’ anglers The releases of Chinook salmon in the mid 1990s expected from this lake. provided good results in 1996 and 1997. Another major change in stocking occurred in However Eddy (1998) explained that although 1987 when the stocking of Chinook salmon these stockings more than doubled the return to changed from fingerlings to yearlings to the angler from previous years, the average promote greater survival and returns to anglers weight of all Chinook salmon caught in this (Barnham 1993). Brown trout were re‐ period was considered to be small by most introduced to the fishery in 1993 (Barnham anglers. 1993), and described as a valuable addition to Habitat and productivity the fishery, particularly as the return of rainbow Lake Purrumbete is a deep freshwater lake that trout remained below expectation (Eddy 1998). is surrounded by grazing land (Williams 1992; Fishery performance Barnham 1993; Eddy 1998). The performance of the trout fisheries in Lake The productivity of Lake Purrumbete is believed Purrumbete is characterised by periods of high to be declining and this decline has been productivity inter‐dispersed with periods of compounded by changes to water levels and the poor returns. establishment of growing self‐supporting First records of an exceptionally high population of redfin (Perca fluviatilis) (Tunbridge performing Chinook salmon fishery occur in the et al. 1991; Barnham 1993). 1940s (Butcher 1947). These reports indicate that Several studies discuss works on an outlet drain ‘appreciable numbers’ of large Chinook salmon in 1982 that is believed to have caused permanent lowering of the water level and

Assessment of the Victorian sea urchin fishery 31

reduced productivity. Hume (1991), Barnham when redfin numbers were low and just (1993), Eddy and Smith (1995), Skene and Smith beginning to increase. Eddy (1998) speculated (1996) and Eddy (1998) explain that the lowering that brown trout may control redfin to some of the water level by about 0.3m reduced the extent as the introduction of brown trout to Lake amount of flooded grassland by at least five Purrumbete in 1993 coincided with reduced hectares during high‐level periods and reduced numbers of redfin in angler catch, and redfin spawning area for forage fish such as galaxids had been observed in the stomachs of brown resulting in the loss of nutrient input. trout during this time. Redfin control by removal through netting was discussed as Cadwallader and Eden (1981) found that difficult and most likely ineffective due to the galaxids made up a significant proportion of size of the lake, the potential of stocked Chinook salmon diet and suggested that the salmonids to be caught as bycatch and the issue availability of forage fish, particularly galaxids, of disposing of caught redfin (Barnham 1993). appeared to be the major factor affecting the growth of Chinook salmon in Lake Purrumbete. A later study by Brown and Cocomazzo (1994) confirmed that the success of spawning of forage fish is closely related to water levels. A fall in water level reduces the amount of habitat available for use as nursery areas and may lead to a decrease in the number of forage fish. A decrease in the abundance of forage fish has been suggested to occur in Lake Purrumbete coinciding with a decline in the fishery. Anecdotal reports suggest that prior to the reduction in water level in 1978, galaxids were much less abundant in Lake Purrumbete than formerly (Cadwallader and Eden 1981). Eddy and Smith (1995) state that during the period 1982 and 1993 there was an undocumented but noticeable decline in the numbers of common galaxids, that could have been due to reduced water levels or increased redfin predation. A further cause for the decline in productivity is believed to be the increasing abundance of redfin. Cadwallader and Eden (1981) wrote that redfin had become established and first recorded in Lake Purrumbete in 1976. Hume (1991) explained that the increasing dominance of redfin caught in netting surveys was alarming and Tunbridge et al. (1991) said that redfin continue to expand in both number and total weight of fish. Barnham (1993) suggested the expansion was probably at the cost of the salmonid fisheries through competition for food. Reducing redfin abundance through the stocking of salmonids to encourage predation and/or netting redfin for biomass reduction has been discussed as unsuitable. Barnham (1993) raised that predation of redfin by salmonids was not likely to be a useful factor in controlling redfin. Redfin were not recorded in the stomach contents of Chinook salmon and rainbow trout in Lake Purrumbete (Cadwallader and Eden 1981; Cadwallader and Eden 1982), but these dietary studies were conducted in 1978 and 1976

Recreating a world class Chinook salmon fishery 32

Table 9. Records of Chinook salmon from Lake Bullen Merri during the 1940s (Butcher 1947) Time period Metric Data 1941 Weight Range 9–17 lb 4.1–7.7 kg

Average unknown

Age unknown October–November, 1943 Weight Range 4–12 lb 1.8–5.4 kg

Average 7 lb 6 oz 3.3 kg n=6 Age 2+ September, 1947 Weight Range 8 oz–2 lb 0.2–0.9 kg

Average 1 lb 3 oz 0.5 kg n=9 Age 1+

Table 10. Records of Chinook salmon from Lake Purrumbete during the 1940s (Butcher 1947) Time period Metric Data 1940 Weight Range 10 lb 4.5 kg Average na n=1 Age unknown July, 1943 Weight Range 4–10 lb 1.8–4.5 kg Average 3 lb 10 oz 1.6 kg n=10 Age 2+ 1944 Weight Range 18 lb 2 oz 8.2 kg Average na n=1 Age unknown December, 1946 Weight Range 3.5–7.5 lb 1.6–3.4 kg Average 4 lb 14 oz 2.2 kg n=4 Age 1+ July, 1947 Weight Range 1–10 lb 0.5–4.5 kg Average 5 lb 7 oz 2.5 kg n=13 Age 2+

Assessment of the Victorian sea urchin fishery 33

Appendix 3: Lake Bullen Merri stocking

Fish stocking history for Lake Bullen Merri. Length Chinook Rainbow Brown Atlantic Australian Silver Golden Weight (g) Year Month Fish size (mm) salmon trout trout salmon bass perch perch range range 1923 9 4100 Yearling ND ND 1925 6 4000 ND ND ND 1925 8 1250 Yearling ND ND 1927 ND 2750 ND ND ND 1927 8 1500 Yearling ND ND 1927 ND 7000 Fry 20–35 ND 1928 ND 350 ND ND ND 1928 ND 1000 ND ND ND 1928 ND 10000 Fry 20–35 ND 1929 ND 1000 ND ND ND 1929 5–6 2000 Yearling ND ND 1930 ND 500 ND ND ND 1931 ND 1500 ND ND ND 1932 ND 1000 ND ND ND 1933 ND 1500 ND ND ND Eyed 1933 8 15000 Ova trout eggs ND 1934 ND 2000 ND ND ND Eyed 1934 8 20000 Ova trout eggs ND 1935 ND 4500 ND ND ND Eyed 1935 8 20000 Ova trout eggs ND 1936 ND 2500 ND ND ND 1936 ND 2500 Fry 20–35 ND Eyed 1936 8 20000 Ova trout eggs ND 1937 ND 2000 ND ND ND 1937 ND 2700 Yearling ND ND 1937 9 20000 Fry 20–35 ND 1938 ND 5082 1500 ND ND ND Eyed 1938 9 10000 Ova trout eggs ND 1939 ND 5000 ND ND ND Eyed 1939 9 21000 Ova trout eggs ND 1940 ND 5000 2000 ND ND ND 1941 ND 11000 1000 ND ND ND 1941 5 2000 Yearling ND ND 1942 ND 4500 ND ND ND 1945 ND 3690 ND ND ND 1946 ND 11000 ND ND ND 1948 ND 5500 ND ND ND

Recreating a world class Chinook salmon fishery 34

Length Chinook Rainbow Brown Atlantic Australian Silver Golden (mm) Weight (g) Year Month salmon trout trout salmon bass perch perch Fish size range range Eyed 1949 8 20000 Ova trout eggs ND 1949 ND 5000 ND ND ND 1950 ND 7500 ND ND ND 1951 ND 5000 ND ND ND 1952 ND 500 ND ND ND 1952 ND 14928 Fry 20–35 ND 1953 ND 42000 Fry 20–35 ND 1954 ND 30000 ND ND ND 1955 ND 19080 ND ND ND 1956 ND 34100 ND ND ND 1957 ND 14550 ND ND ND 1958 8 10000 Std 50–125 ND 1959 10–11 26500 Advanced 126–175 ND 1960 1 3000 Advanced 126–175 ND 1961 1 750 Advanced 126–175 ND 1962 5 15000 Std 50–125 ND 1963 6 17000 Std 50–125 ND 1964 8–9 16876 Advanced 126–175 ND 1965 4 5350 Std 50–125 ND 1965 12 2835 Advanced 126–175 ND 1966 7 7920 Std 50–125 ND 1967 ND 8050 Std 50–125 ND 1967 ND 3000 Advanced 126–175 ND 1968 ND 41715 4 102–127 ND 1969 11 13180 5 127–152 ND 1970 8 6500 6500 4 102–127 ND 1971 ND 19435 6496 ND ND ND 1972 8 6500 6500 4 102–127 ND 1973 4 11500 6565 3–5 76–127 ND 1974 4 6500 6500 3 76–101 ND 1975 5–9 17109 1–2 125–150+ ND 1976 8–10 28474 1 150+ ND 1978 5 20613 1 150+ ND 1979 11 60000 3 90–124 ND 1980 7 6809 7 151–175 41–62 1980 12 20000 4 76–100 5.1–12 1981 8–10 2077 9 201–225 92–133 1981 8 100 ND ND ND 1981 10 20000 3 51–75 1.6–5 1982 5–6 20000 7 151–175 41–62 1982 6 1800 9 201–225 92–133 1982 6–7 922 ND ND 1000

Assessment of the Victorian sea urchin fishery 35

Length Chinook Rainbow Brown Atlantic Australian Silver Golden (mm) Weight (g) Year Month salmon trout trout salmon bass perch perch Fish size range range 1982 10 22700 3 51–75 1.6–5 1983 3–9 35098 5–9 101–225 12.1–133 1983 10 20000 2 26–50 0.3–1.5 1984 4–5 30000 6–7 126–175 24–62 1984 11 20900 3–8 51–200 1.6–91 1985 4–7 40000 7 151–175 41–62 1985 11 480 6 126–150 24–40 1986 9–10 25650 6 126–150 24–40 1986 ND 3690 2YO ND ND 1986 ND 100000 2 26–50 0.3–1.5 1987 10–11 S– 50000 20000 3 51–75 1.6–5 1987 ND 35000 3 35–50 1.6–3 1987 11 T – 50000 3/Fingerling 50 1.5 1987 11 50000 Fingerling 50 1.5 1989 4 T – 9700 Yearling 250 188 1989 6–10 14100 Yearling 250 188 1989 4–5 5880 Yearling 250 188 1990 4–5 T – 10300 Yearling 250 188 1990 6–10 11700 Yearling 250 188 1990 4–5 10000 Yearling 250 188 1991 4–5 T – 10000 Yearling 250 188 1991 5–7 10050 Yearling 250 188 1991 4–7 11900 Yearling 250 188 1992 5–6 T– 6300 Yearling 250 188 1992 5–9 15200 Yearling 250 188 1993 3–8 12400 Yearling 250 188 1993 4–5 T – 7600 Yearling 250 188 1993 3 6600 Yearling 250 188 1994 5–7 10000 Yearling 250 188 1994 6–9 T – 10600 Yearling 250 188 1994 5 6300 Yearling 250 188 1994 10 29500 Fingerling 50 1.5 1995 8 4615 Yearling 250 188 1995 8–9 T – 1705 Yearling 250 188 1995 11 5000 Fingerling 50 1.5 1996 4 3500 Yearling 176–200 63–91 1996 4 1400 8 176–200 63–91 1996 12 2500 2.1 ND 2.1 1996 12 2500 4.5 ND 4.5 1996 12 2500 0.54 ND 0.54 1997 3 10000 1.32 ND 1.32 1998 4 10000 1.55 ND 1.55

Recreating a world class Chinook salmon fishery 36

Length Chinook Rainbow Brown Atlantic Australian Silver Golden (mm) Weight (g) Year Month salmon trout trout salmon bass perch perch Fish size range range 1998 4 10000 0.77 ND 0.77 1998 10 10000 1 ND 1 1999 3 12000 1.34 ND 1.34 1999 3 10000 0.91 ND 0.91 1999 4 35000 0.85 ND 0.85 1999 9–11 10000 9–10+ 201–250+ 92–189+ 1999 9–11 15000 9–10+ 201–250+ 92–189+ 1999 12 10000 0.2 ND 0.2 1999 12 20000 3 51–75 1.6–5 2000 10–12 15000 8–10+ 176–250+ 63–189+ 2000 5 5300 5 101–125 12.1–23 2001 6–9 10000 8–10 176–250 63–188 2001 6–9 15000 8–10 176–250 63–188 2001 8 1839 9 201–225 92–133 2001 11 10000 1 ND 1 2002 7–10 10000 8–9 176–225 63–133 2002 7–10 10000 8–9 176–225 63–133 2002 6 10000 9 201–225 92–133 2002 11 10000 1.2 ND 1.2 2003 7 10000 2 ND 10–49 2003 8 10000 3 ND 50–99 2003 7 2500 2 ND 10–49 2003 6 7250 4 ND 100–199 2004 6 10000 3 ND 50–99 2004 7–10 10000 3 ND 50–99 2004 5 2550 5 ND 200–299 2004 4–8 17500 3 ND 50–99 2004 11 10000 1.5 ND 1.5 2005 7 10000 3–4 ND 50–199 2005 10 10000 3–5 ND 50–299 2005 6 2500 2 ND 11–49 2005 11 22300 3–4 ND 50–199 2006 5 5000 ND ND ND 2006 5 5000 ND ND ND 2006 6 5000 ND ND ND 2006 4 4680 ND ND ND 2006 6 4000 ND ND ND 2006 7 4500 ND ND ND 2006 8 2470 ND ND ND 2007 1 3650 82 ND 82 2007 1 1900 160 ND 160 2007 2 3100 125 ND 125

Assessment of the Victorian sea urchin fishery 37

Length Chinook Rainbow Brown Atlantic Australian Silver Golden (mm) Weight (g) Year Month salmon trout trout salmon bass perch perch Fish size range range 2007 4 10000 30 ND 30 2008 6 5,000 55 ND 55 2008 6 5,000 66 ND 66 2008 7 3,050 128 ND 128 2008 8 5,000 74 ND 74 2008 9 1,950 57 ND 57 2008 9 5,000 78 ND 78 2008 10 4,400 88 ND 88 2008 10 600 102 ND 102 2008 12 300 990 ND 990 2009 5 4,200 63 ND 63 2009 8 5,000 62 ND 62 2009 8 2,647 68 ND 68 2009 8 2,465 73 ND 73 2009 8 3,270 110 ND 110 2009 8 2,700 144 ND 144 2009 9 2,135 81 ND 81 2009 9 2,630 71 ND 71 2009 10 4,030 70 ND 70 2009 10 923 75 ND 75 2010 4 5,000 72 ND 72 2010 5 5,000 54 ND 54 2010 5 4,000 60 ND 60 2010 5 5,000 55 ND 55 2010 6 5,540 65 ND 65 2010 7 1,000 48 ND 48 2010 7 4,955 68 ND 68 2010 8 5,000 73 ND 73 2010 10 2,750 150 ND 150 2010 10 778 147 ND 147 2011 6 8,480 46 ND 46 2011 6 6430 56 ND 56 2011 6 1910 233 ND 233 2011 7 6,000 47 ND 47 2011 7 2765 34 ND 34 2011 8 6250 53 ND 53 2011 8 5520 52 ND 52 2011 9 805 54 ND 54 ND is Not Defined, T is Triploid

Recreating a world class Chinook salmon fishery 38

Appendix 4: Lake Purrumbete stocking

Fish stocking history for Lake Purrumbete. Chinook Rainbow Brown Atlantic Length Weight (g) Year Month Fish size salmon trout trout salmon (mm) range range 1879 ND 198 ND ND ND 1931 7 1500 Yearling ND ND 1932 6 2000 Yearling ND ND Eyed trout 1933 9 20000 Ova eggs ND 1933 ND 1500 ND ND ND Eyed trout 1934 8 25000 Ova eggs ND Eyed trout 1934 10 10000 Ova eggs ND 1934 ND 10900 ND ND ND Eyed trout 1935 8–9 48000 Ova eggs ND 1935 ND 3400 ND ND ND 1935 7 500 Yearling ND ND 1936 ND 2000 ND ND ND 1937 ND 1000 1000 ND ND ND 1937 4 2000 2000 Yearling ND ND 1937 ND 3920 Yearling ND ND 1938 ND 1500 ND ND ND 1939 ND 5000 ND ND ND 1940 ND 5000 2000 ND ND ND 1941 ND 10160 1000 ND ND ND 1942 ND 5500 ND ND ND 1944 ND 3000 ND ND ND 1945 ND 3200 ND ND ND 1946 ND 11000 ND ND ND 1948 ND 5650 ND ND ND 1949 ND 5000 ND ND ND 1950 ND 7500 ND ND ND 1951 ND 5000 ND ND ND 1952 ND 21928 Fry 20–35 ND 1952 ND 500 ND ND ND 1953 ND 8000 Fry 20–35 ND 1954 ND 57255 ND ND ND 1955 ND 17880 ND ND ND 1956 ND 10000 Fry ND ND 1956 ND 48500 ND ND ND 1957 ND 100000 Fry 20–35 ND 1958 10 62000 Fry 20–35 ND 1959 11 3500 Advance 126–175 ND 1959 9 8000 Std 50–125 ND

Assessment of the Victorian sea urchin fishery 39

Chinook Rainbow Brown Atlantic Length Weight (g) Year Month salmon trout trout salmon Fish size (mm) range range 1960 1 3000 Advance 126–175 ND 1960 8 15000 Std 50–125 ND 1961 2–3 14700 Advance 126–175 ND 1961 8 60000 Std 50–125 ND 1961 9 14400 Std 50–125 ND 1962 3–4 39600 Std 50–125 ND 1964 1 42000 Std 50–125 ND 1965 11–12 9252 Advance 126–175 ND 1966 1 830 Advance 126–175 ND 1966 7 10500 Std 50–125 ND 1967 ND 19285 ND ND ND 1969 ND 10470 ND ND ND 1970 ND 73512 ND ND ND 1971 ND 83293 ND ND ND 1972 4 72600 3 76–101 ND 1973 4–7 72000 3 76–101 ND 1974 3 56080 4 102–127 ND 1975 3–5 72000 1–3 90–150+ ND 1976 4–5 14908 1 150+ ND 1976 3–6 50010 1–3 90–150+ ND 1977 5 15105 1 150+ ND 1978 4 20000 1 150+ ND 1978 9–11 11550 1 150+ ND 1979 11 15000 3 90–124 ND 1979 2–3 25000 2–3 90–149 ND 1980 3 30000 5 101–125 12.1–23 1980 7 7584 7 151–175 41–62 1980–1981 12–10 42957 4–9 76–225 5.1–133 1981 6 3464 ND ND 400 1981 2–10 80000 3–9 51–225 1.6–133 1982 9 50000 2 26–50 0.3–1.5 1982 9 25300 3 51–75 1.6–5 1982 7–8 20000 6–7 126–175 24–62 1983 10 20000 2 26–50 0.3–1.5 1983 3 20000 5 101–125 12.1–23 1984 11 20000 3 51–75 1.6–5 1984 4–5 50000 6–7 126–175 24–62 1985 11 18800 2 26–50 0.3–1.5 1985 6–7 50000 7 151–175 41–62 1986 10 20000 3 51–75 1.6–5 1986 4–8 51550 7–10 ND ND 1987 4 10000 Yearling 250 188 1987 4–8 49300 Yearling 250 188

Recreating a world class Chinook salmon fishery 40

Chinook Rainbow Brown Atlantic Length Weight (g) Year Month salmon trout trout salmon Fish size (mm) range range 1987 4 10000 6 126–150 24–40 1987 4–8 49300 6–8 126–200 24–91 1988 5–6 7500 Yearling 250 188 1988 4–7 50000 Yearling 250 188 1988 4–7 50000 7–9 151–225 92–133 1988 5–6 7400 10 ND ND 1989 4 7000 Yearling 250 188 1989 4–9 50000 Yearling 250 188 1990 4 19600 Yearling 161.7 73.3 1990 4–7 40000 Yearling 250 188 1991 4–7 30000 Yearling 250 188 1991 4–7 20000 Yearling 250 188 1992 3–6 36700 Yearling 250 188 1993 3 1000 Yearling 250 188 1993 6–9 15000 Yearling 250 188 1993 ND 15000 Yearling 250 188 1994 3 4000 Yearling 250 188 1994 3–8 15000 Yearling 250 188 1994 ND 15000 Yearling 250 188 1995 11 65000 Fingerling 50 1.5 1995 3–7 15000 Yearling 250 188 1995 3–9 15000 Yearling 250 188 1995 ND 10000 Yearling 250 188 1996 5–11 15000 Yearling 250 188 1996 ND 10000 Yearling 250 188 1996 5–9 15000 Yearling 176–225 63–133 1997 4–10 25000 Yearling 151–250 41–188 1997 4–11 15000 Yearling 151–250 41–188 1997 ND 10000 Yearling 151–250 41–188 1998 5–10 15000 7–10 151–250 41–188 1998 5–10 10000 7–10 151–250 41–188 1998 4–10 15000 9–10+ 201–250+ 92–189+ 1999 10 63672 2 26–50 0.3–1.5 1999 12 20000 3 51–75 1.6–5 1999 5–10 15000 8–9 176–225 63–133 1999 5–10 5000 8–9 176–225 63–133 1999 5–8 9200 8–10 176–250 63–188 2000 9 100000 3 51–75 1.6–5 2000 11 2500 9 201–225 92–133 2000 8–12 15000 9–10+ 201–250+ 92–189+ 2000 8–12 5000 9–10+ 201–250+ 92–189+ 2001 10 100000 3 51–75 1.6–5 2001 7–8 15000 8–9 176–225 63–133

Assessment of the Victorian sea urchin fishery 41

Chinook Rainbow Brown Atlantic Length Weight (g) Year Month salmon trout trout salmon Fish size (mm) range range 2001 7–8 5000 8–9 176–225 63–133 2001 7 5000 9–10 201–250 92–188 2002 6–8 15000 8–9 176–225 63–133 2002 6–8 15000 8–9 176–225 63–133 2002 6 5000 9 201–225 92–133 2003 6 15000 2 ND 10–49 2003 7 2500 2 ND 10–49 2003 6–7 15000 2 ND 10–49 2003 6 2500 4 ND 100–199 2004 6–7 10000 4 ND 100–199 2004 6–11 20000 3 ND 50–99 2004 7–11 15000 3 ND 50–99 2005 11 10000 4 ND 100–199 2005 11 12385 3–4 ND 50–199 2005 6 10000 3 ND 50–99 2005 9 15000 3 ND 50–99 2006 5 5200 ND ND ND 2006 5 4000 ND ND ND 2006 6 8000 ND ND ND 2006 7 6000 ND ND ND 2006 8 14800 ND ND ND 2006 9 2000 ND ND ND 2006 11 5000 ND ND ND 2007 5 17000 35 ND 35 2007 4 3000 37 ND 37 2007 4 4400 40 ND 40 2007 1 2500 82 ND 82 2007 2 4290 119 ND 119 2007 11 1900 760 ND 760 2007 7 216 1400 ND 1400 2008 8 5,000 56 ND 56 2008 10 5,000 60 ND 60 2008 10 1,200 60 ND 60 2008 6 5,500 68 ND 68 2008 9 3,100 69 ND 69 2008 8 5,000 70 ND 70 2008 7 4,000 75 ND 75 2008 9 1,900 79 ND 79 2008 10 1,100 82 ND 82 2008 7 4,200 86 ND 86 2008 7 3,900 91 ND 91 2008 10 2,300 102 ND 102 2008 10 2,800 103 ND 103

Recreating a world class Chinook salmon fishery 42

Chinook Rainbow Brown Atlantic Length Weight (g) Year Month salmon trout trout salmon Fish size (mm) range range 2009 3 5,000 5,000 36 ND 36 2009 5 5,000 50 ND 50 2009 5 5,000 54 ND 54 2009 5 66 ND 66 2009 7 5,000 68 ND 68 2009 10 620 75 ND 75 2009 10 2,500 78 ND 78 2009 9 103 ND 103 2009 6 2,750 108 ND 108 2009 8 3,130 115 ND 115 2009 8 2,500 144 ND 144 2010 4 6,900 52 ND 52 2010 5 2,794 55 ND 55 2010 5 5,000 58 ND 58 2010 5 3,274 63 ND 63 2010 7 5,375 67 ND 67 2010 5 5,000 69 ND 69 2010 7 5,570 70 ND 70 2010 10 5,306 70 ND 70 2010 7 4,875 80 ND 80 2010 8 4,750 82 ND 82 2010 10 1,156 151 ND 151 2011 5 3490 43 ND 43 2011 6 8,370 202 ND 202 2011 7 2250 34 ND 34 2011 7 11510 47 ND 47 2011 8 6630 60 ND 60 2011 8 5285 51 ND 51 2011 8 330 39 ND 39 ND is Not Defined, T is Triploid

Assessment of the Victorian sea urchin fishery 43

Appendix 5: Newspaper article 1978

Recreating a world class Chinook salmon fishery 44