Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete Recreational Fishing Grants Program Research Report

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Chinook Salmon Fisheries Research

Evaluating performance at Lakes Bullen Merri and Purrumbete

September 2017

Recreational Fishing Grants Program Research Report

Published by the Victorian Government, Victorian Fisheries Authority (VFA), September 2017 © The State of Victoria, Victorian Fisheries Authority Melbourne, September 2017 This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968. Authorised by the Victorian Government, 1 Spring Street, Melbourne. Printed by VFA Queenscliff, Victoria. Preferred way to cite this publication: Ingram, B.A., Hunt, T.L. and Northey, M. (2017) Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete. Recreational Fishing Grants Program Research Report. Cover photos: Top left, Jason Castles with his 8.22kg (18lb) Chinook salmon from Lake Purrumbete in April 2017. Top right, Andrew Kompa with his 6kg brown trout from Lake Purrumbete in September 2013. Middle, rainbow trout caught by Ben Young from Lake Bullen Merri in March 2016. Bottom left, Finley of Geelong Fishing Charters with a young chinook salmon caught at Bullen Merri in June 2014. Bottom middle, Ben Bremer with his 2kg chinook salmon from Lake Bullen Merri in July 2014. Bottom right, Zoe Fifis with her first rainbow trout from Lake Purrumbete June 2017. Inset cover photo: Maz Stowlowski with his 5.62kg (12lb) chinook salmon from Lake Bullen Merri in March 2016. ISBN 978-1-925629-57-6 (Print) ISBN 978-1-925629-58-3 (pdf/online) Author Contact Details: Dr Brett Ingram Fisheries Management and Science Branch, Victorian Fisheries Authority PO Box 114, Queenscliff Vic 3225 Copies are available by emailing [email protected] For more information contact the VFA Customer Service Centre 136 186 Disclaimer

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Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program ii

Contents

Executive summary ______1

Introduction ______3

Methods ______7 Crater lakes 7 Angler catch data 7 Fishery independent data 9 Fish ageing 9 Data analysis 9

Results and discussion ______11 Angling club records 11 Social media postings 12 Lake Purrumbete angler creel survey 13 Angler catch composition 13 Angler catch rates 14 Size (length and weight), condition (K) and age of fish 15 Correlation analyses 26

Conclusions ______27

Acknowledgements ______29

References ______30

Appendix I. Crater lakes stocking history ______32

Appendix II. Crater lakes fishery management decisions ______33

Appendix III. Social media images of fish angled from Lake Bullen Merri and Lake Purrumbete ___ 36

Appendix IV. Correlation scatter plots ______38 Lake Purrumbete Brown trout 38 Lake Purrumbete Chinook salmon 39 Lake Purrumbete Rainbow trout 40 Lake Bullen Merri Chinook salmon 41 Lake Bullen Merri rainbow trout 42 Correlations between redfin and Chinook salmon in Lake Purrumbete 43

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program iii

Executive summary

The volcanic crater lakes of southern western Victoria, Lakes Purrumbete and Lake Bullen Merri have long supported high quality and productive recreational salmonid fisheries. Both lakes are regularly stocked with hatchery-bred rainbow trout, brown trout and chinook salmon to sustain popular and productive put-grow-and-take recreational fisheries. The study aimed to use available angler information (local angling club data catch records and creel surveys of public anglers) and fishery independent data to quantify the performance of brown trout, Chinook salmon and rainbow trout in Lake Purrumbete and Lake Bullen Merri during the trial stocking period between 2012 and 2016 and, compare this to previous years. Angler catch data were obtained from angling club records (2012-2016), a creel survey of Lake Purrumbete conducted during the present study (2013-2014), historical creel surveys (1962-2003) and social media. Fishery independent data were obtained from netting surveys conducted between 1978 and 2009. Angling club records provided valuable information on 2,367 caught fish (including 708 salmonids), which contributed to the assessment of fishery performance. During the 2013-14 creel survey of Lake Purrumbete, 1,112 anglers were interviewed and 2,367 fish (including 707 salmonids) were recorded. Most anglers (86%) targeted salmonids. Social media postings highlighted large (trophy) fish, being caught from Lake Purrumbete and Lake Bullen Merri in recent years. Other specific findings included: Chinook salmon

 The reintroduction of Chinook salmon into Lake Purrumbete and Lake Bullen Merri has been well received by most anglers and celebrated as highly successful as indicated by the presence of increasingly larger fish in angling club records from 2012-2015 and social media.  Social media reports from March 2016 onwards highlighted trophy Chinook salmon (4-8kg) catches by anglers.  The 2013/14 creel survey of Lake Purrumbete indicated that the catch rate for Chinook salmon was 0.1 fish/ angler hour, which was the same as the long term mean or average (LTM) value.  In the angling club records for Lake Purrumbete, average annual values of length, weight and condition factor (K ) values have increased between 2012 to 2015, but were below LTM values.  In the angling club records for Lake Bullen Merri, average annual values of length and weight records have increased between 2012 to 2015, whereas K values have declined.  Brown trout stocking in Lake Purrumbete appears to have had a negative effect on the Chinook salmon fishery as the angler catch rate, and length and weight of Chinook salmon have declined with increasing numbers of brown trout stocked in previous years.  The K factor of Chinook salmon angled in Lake Bullen Merri increased with increasing numbers of rainbow trout stocked, possibly suggesting that the newly stocked rainbow trout may be prey for larger Chinook salmon.  Based on the performance of Chinook salmon in the creel survey, angling club records and social media reports, it is recommended that stocking of Chinook salmon into both crater lakes be maintained. Brown trout  The catch rate of brown trout in the recent Lake Purrumbete creel survey (0.01 fish/angler hr) was lower than the LTM of 0.03 fish/angler hr, however, average annual lengths and weights of brown trout recorded in angling club records were higher than the LTM value.  Social media reports highlighted trophy brown trout (4.5kg+) catches by anglers during the study period, in particular at Lake Purrumbete from May 2016 onwards.  In Lake Bullen Merri, average annual length, weight and K factor estimated from angling club records increased from to 2012 to 2014, but declined in 2015, which may have reflected changes in stocking activities.  Angler catch rates of brown trout in Lake Purrumbete increased with increasing numbers of brown trout stocked in the previous two to four years, but declined with increasing numbers of rainbow trout stocked in the previous two to three years. Rainbow trout  The catch rate of rainbow trout estimated from the recent creel survey of Lake Purrumbete was 0.005 fish/ angler hr, which was considerably lower than the LTM of 0.05 fish/angler hr.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 1

 Social media reports highlighted well-conditioned rainbow trout (2kg+) were caught by anglers from March 2016 onwards.  Mean annual length, weight and K values of rainbow trout recorded in angling club records for Lake Purrumbete have generally declined since 2012.  Mean annual length and weight values for Lake Bullen Merri were generally consistent with LTM, but K values were variable and, apart from 2014, were generally lower than LTM. Redfin  Redfin were the most abundant species at Lake Purrumbete as evidenced by the creel survey and angling club catch records. It should be noted that the long term mean or average (LTM) comparison of catch rates takes into account a variety of fisheries management regimes, water levels and climatic periods, therefore its relevance needs to be carefully considered with respect to recent fishery performance. The information presented in this study was shared with fishers at a public consultation forum at Lake Purrumbete Angling Clubrooms on 12 March 2015 and as a result revised stocking plans for 2015 and 2016 for the Crater Lakes were agreed (Appendix II). This evaluation of the performance of the stocked fisheries of Lakes Bullen Merri and Purrumbete has improved the understanding of the effects of fish stocking strategies, and informed management decisions to improve outcomes for recreational fishers. In partnership with the Lake Purrumbete and Camperdown Angling Clubs and local anglers, further work is currently underway to better understand and further improve the Crater lakes fisheries including a rainbow trout strain stocking trial, brook trout stocking trial and modelling of redfin populations. In consultation with key stakeholder groups, such as through the annual rounds of the Vic Fish stock regional consultative meetings, these studies will help inform future decisions regarding the management (and stocking) of these popular and productive recreational fisheries.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 2

Introduction

The volcanic crater lakes of southern western Victoria, Lakes Purrumbete and Lake Bullen Merri (Figure 1) have long supported high quality and productive recreational salmonid fisheries (Tunbridge et al. 1991, Fisheries Victoria 1997, Department of Primary Industries 2008). Both lakes are stocked predominantly with hatchery-bred rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta) and Chinook salmon (Onchorynchus tshawytscha) to sustain popular and productive put-grow-and-take recreational fisheries (Barnham 1997, Department of Primary Industries 2008, Hunt et al. 2014) (Appendix I, Table 1). Stocking of the crater lakes provides a substantial return on investment, yielding significant economic and social benefits (Hunt et al. 2017). Lake Bullen Merri was first stocked in 1925 and since then in excess of 2.31 million fish have been released, most of which were rainbow trout (54%), Chinook salmon (25%) and brown trout (9%) (Appendix I). Lake Bullen Merri has also been stocked with Atlantic salmon (Salmo salar), Australian bass (Macquaria novemaculeata), golden perch (Macquaria ambigua) and silver perch (Bidyanus bidyanus). Lake Purrumbete was first stocked in 1879 with 198 brown trout, but regular stocking did not commence until 1931, and since then approximately 3.07 million fish have been released including rainbow trout (60%), Chinook salmon (27%) and brown trout (12%) (Appendix I). Small numbers of Atlantic salmon and brook trout (Salvelinus fontinalis) have also been released into the lake. Detailed salmonid stocking information for both lakes since the 1960s is provided in Table 2 and Table 3. The trial stocking period between 2012 and 2016 (Table 1) was the focus of this study. Summarised information on decisions regarding the management of the crater lakes fisheries, as summarised from Regional Fisheries Consultations meeting outcomes (2006 - 2009) and Vic Fish Stock meeting outcomes (2010 to current), is provided in Appendix II. Table 1. Number of fish stocked into Lake Purrumbete and Bullen Merri during the trial stocking period between 2012 and 2016 (*Note stocking plans for 2015 and 2016 were revised following a public consultation forum at Lake Purrumbete Angling Clubrooms on 12 March 2015).

Lake Species 2012 2013 2014 2015 revised* 2016 revised* Chinook salmon 0 25,000 25,000 0 0 Rainbow trout 30,000 8,300 10,000 5,000 9,000 Purrumbete Brown trout 0 0 5,000 20,000 20,000 Brook Trout 0 0 0 0 3,000 Total 30,000 33,300 40,000 25,000 31,000 Chinook salmon 11,000 20,000 20,000 5,450 20,560 Rainbow trout 15,000 8,300 5,000 5,000 9,000 Bullen Merri Brown trout 0 0 5,000 5,000 5,000 Total 26,000 28,300 30,000 15,450 34,560

Stocking of Chinook salmon into Lake Purrumbete and Lake Bullen Merri was exceptionally successful in creating trophy fisheries, particularly in the late '70s to the '90s, which 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. More recently, however, the performance of these fisheries has declined, due to fewer Chinook salmon being available for stocking (none were released between 2008-2011). To make up for the shortfall in the numbers of other species (brown trout and rainbow trout) stocked into the lakes annually were increased. The recreational fishing community is keen to see the restoration of world class Chinook salmon fisheries in these crater lakes and subsequently the Camperdown and Lake Purrumbete Angling Clubs sought to engage assistance from Fisheries Victoria to achieve this objective. Following revitalisation of the chinook salmon breeding program at the Fisheries Victoria Snobs Creek Hatchery (see Nguyen and Ingram 2013) stocking recommenced in Lake Bullen Merri (in 2012) and Lake Purrumbete (in 2013), and Fisheries Victoria undertook a 3-4 year trial to assess restoration of the Chinook salmon fisheries in these lakes. In order to optimise the success of the chinook salmon stockings, stocking numbers for rainbow trout were reduced and stocking of brown trout was deferred for 2 years (2012-2013) during this trial period (Table 2 and Table 3). This stocking strategy was agreed upon at a consultative meeting with Fisheries Victoria and representatives of VRFish, Regional District Angling Associations, and the Camperdown and Lake Purrumbete Angling Clubs (Chinook Salmon Working Group Meeting, LPAC rooms, Aug. 9th 2012 - John Douglas, FV). It was further agreed that recreational fishers would

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 3

provide catch information to assist in monitoring the fisheries during the trial stocking period (Hunt et al. 2012).This study evaluates the performance of the two crater lakes Chinook salmon fisheries using outcomes of the recent stockings of Lake Bullen Merri and Lake Purrumbete. More specifically, the aims of the study were to use available angler information (local angling club data catch records and creel surveys of public anglers) and fishery independent data to: 1. Quantify the performance of Chinook salmon in the recreational fishery (catch rate and weight of fish) and compare to previous years 2. Quantify the performance of brown trout and rainbow trout in the recreational fishery (catch rate and weight of fish) and compare to previous years.

Above. Chinook salmon from Lake Bullen Merri during April 2015 by Ben Bremer.

Right. Maz Stowlowski with Chinook salmon and

rainbow trout from Lake Bullen Merri in March 2016.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 4

Table 2. Number of salmonids stocked into Lake Bullen Merri since the 1960s. Note stocking figures in 2015 and 2016 were adjusted after a consultative meeting on 12 March 2015 with anglers after reviewing trial results between 2012-2015. Additional information on fish stockings is provided in Appendix I. Information on management decisions regarding changes to fish stockings is provided in Appendix II. Period Water Atlantic salmon Chinook salmon Brown trout Rainbow trout Number Mean number Number Mean number Number Mean number Number Mean number years stocked per year years stocked per year years stocked per years stocked per year stocked (range) stocked (range) stocked year (range) stocked (range) 13,468 1960s 10 (750-41,715) 40,307 6,499 13,717 1970s 2 5 7 (20,613-60,000) (6,496-6,500) (6,500-28,474)

18,803 43,987 1980s 9 8 (1,700-29,340) (2,077-100,000) 12,070 15,493 1990s 7 1 10,000 8 (3,500-35,900) (1,400-21,980)

HISTORIC 4,560 11,365 11,144 11,000 2000s 5 6 9 10 (2,500-10,000) (1,839-22,300) (5,000-20,300) (10,000-15,000) 2010 1 10,000 1 29,023

2011 1 8,160 1 10,000 1 20,000

2012 1 11,000 1 15,000

2013 1 20,000 1 8,300

2014 1 20,000 1 5,000 1 5,000

2015 1 5,450 1 5,000 1 5,000

TRIALPERIOD 2016 1 20,560 1 5,000 1 9,000

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 5

Table 3. Number of salmonids stocked into Lake Purrumbete since the 1960s. Note stocking figures in 2015 and 2016 were adjusted after a consultative meeting on 12 March 2015 with anglers after reviewing trial results between 2012-2015. Additional information on fish stockings is provided in Appendix I. Information on management decisions regarding changes to fish stockings is provided in Appendix II. Period Water Atlantic salmon Chinook salmon Brown trout Rainbow trout Brook trout Number Mean number Number Mean number Number Mean number Number Mean number Number Mean number years stocked per year years stocked per year years stocked per year years stocked per year years stocked per stocked (range) stocked (range) stocked (range) stocked (range) stocked year (range) 30,643 29,625 1960s 2 6 (19,285-42,000) (9,252-89,100) 16,332 59,236 1970s 4 9 (14,917-20,000) (11,523-83,293)

18,131 49,736 1980s 10 1 3,500 10 (6,200-27,585) (20,000-80,000) 19,855 14,143 18,255 1990s 10 7 10

(1,000-71,050) (9,000-15,000) (5,000-40,000) HISTORIC 3,750 5,698 17,153 15,978 2000s 2 7 10 10 (2,500-5,000) (2,500-12,385) (10,806-25,000) (5,000-20,000) 2010 1 25,000 1 25,000 2011 1 7,845 1 15,000 1 15,000

2012 1 30,000 2013 1 25,000 1 8,300 2014 1 25,000 1 5,000 1 10,000 2015 1 20,000 1 5,000

TRIALPERIOD 2016 1 20,000 1 9,000 1 3,000

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 6

Methods

Crater lakes Lake Bullen Merri (490 ha, 66 m deep, 8 ppt salinity) and Lake Purrumbete (585 ha, 45 m deep, 0.4 ppt salinity) are two lakes located near Camperdown in south-western Victoria, Australia (Timms 1976, Figure 1). Both lakes belong to a series of highly productive volcanic maar lakes in the area (Ollier and Joyce 1964, Laurensen et al. 2012). Both lakes are stocked with a range of species to sustain recreational fisheries (Appendix I, Table 1). Redfin perch (Perca fluviatilis) are also a popular recreational species in Lake Purrumbete (Ingram 2016).

Figure 1. Location of Lake Bullen Merri and Lake Purrumbete in south- western Victoria.

Angler catch data Angler catch data were obtained from angling club records (2012-2016), a creel survey of Lake Purrumbete conducted during the present study (2013-2014), historical creel surveys (1962-2003) and social media (Table 4). Angling club records Data recorded in angling club logbooks were voluntarily reported by anglers and included month of capture, species caught and the weight (g) of gutted, gilled and cleaned fish. Most information was provided by the Lake Purrumbete Angling Club and the Camperdown Angling Club, representing 35 logbooks (n= 4,160 records). Lake Purrumbete angler creel survey An on-site creel survey was conducted at Lake Purrumbete whereby anglers were intercepted and interviewed as they embarked or returned from a fishing expedition. Since the lake has one major access point (southern boat ramp), a standard access point creel survey was used with survey days stratified using a two stage stratified random sampling strategy (Robson 1991, Malvestuto 1996). Days were primary sampling units (PSUs) and were stratified into weekdays and weekend/public holidays. Morning and afternoon interview sessions (shifts) within a day were secondary sampling units (SSUs) and were selected with equal probability to reflect the similar fishing effort between two shifts. Table 5 and Table 6 present strata effort probabilities, which were determined through discussions with regular anglers of the lake operators of the local caravan park and tackle store owners regarding fishing effort. The survey was conducted over 91 days between 1 December 2013 and 30 November 2014, which represented 25% coverage of a full year.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 7

Historical creel surveys Historical creel surveys of Lake Purrumbete and Lake Bullen Merri were conducted by Fisheries Victoria between 1962 and 2003 (Table 4). Details on survey methods used to collect these data are provided in the published reports. Estimates of angler catch rates and size of fish caught by anglers were summarised for presentation in the current report. Social media data Weight and lengths of fish caught by recreational fishers in Lakes Bullen Merri and Purrumbete were recorded from descriptions of, or inquires about photos posted on social media (e.g. Facebook and fishing newsletters) by recreational fishers.

Table 4. Sources of angler catch information analysed in the current study.

Source Period Lake Lake Bullen Purrumbete Merri

Angling club logbooks (current study) 2012 - 2016  

Creel survey (Hume 1991b) 1961 - 1962 

Creel survey (Hume 1991a) 1984 - 1987  

Creel survey (Eddy and Smith 1994) 12/1992 – 11/1993  

Creel survey (Eddy and Smith 1995) 12/1993 – 11/1994  

Creel survey (Skene and Smith 1996) 12/1994 – 11/1995  

Creel survey (Eddy 1998) 12/1995 – 11/1997 

Creel survey (Pomorin 2004) 1999 - 2002 

Creel survey (Pomorin and Hall 2009) 09/2002 – 08/2003 

Creel survey (current study) 12/2013 – 11/2014 

Social media (current study) Current study  

Table 5. Strata effort distribution per day type between 1 December 2013 and 30 November 2014. Data type Estimated Total possible days Number of days % coverage proportional effort during period surveyed Weekday 0.3 250 35 14 Weekend/public holiday 0.7 115 56 49 Total 365 91 25

Table 6. Effort distribution per time of day (shifts) between 1 December 2013 and 30 November 2014. Time of day Definition Estimated proportional effort Morning An hour after sunrise until 0.5 midway through light hours Afternoon Midway through light hours until 0.5 an hour after sunset

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 8

Fishery independent data Fishery independent data were obtained from netting surveys conducted by Fisheries Victoria between 1978 and 2006, and unpublished survey information (Snobs Creek database) (1998-2009) (Table 7). Details on survey methods used to collect data are provided in the published reports. Estimates of angler catch rates and size of fish caught during surveys were summarised for presentation in the current report.

Table 7. Source of fishery independent survey information analysed in the current study.

Source Period Lake Bullen Lake Merri Purrumbete

Netting survey (Baxter 1987) 1978 - 1986  

Netting survey (Baxter et al. 1988) 1987  

Netting survey (Brown and Vallis 1997) 10/1997 

Netting survey (Hall 2002) 02/2000 – 02/2002 

Netting survey (Pomorin 2004) 11/1999 & 10/2000 

netting survey (Pomorin and Hall 2009) 1/2003 & 1/2004 

Netting survey (Hall and Douglas 2010) 1/2006 

Netting survey (Hall et al. 2010) 1/2006 

Netting survey (Unpublished Snobs Creek records) 1998 - 2009  

Fish ageing Age of fish in Lake Bullen Merri and Lake Purrumbete was determined from fish caught by recreational anglers. Both sagittal otoliths were extracted from donated fish (carcasses and frames), which were processed and the age estimated by the Fish Ageing Services Pty Ltd. (Portarlington, Victoria). This information was cross-matched against stocking records (year stocked and age of fish at stocking) to assign an age to each fish. Data analysis To ensure data were as representative of the total fishery in each lake, years were only included if they had data from a minimum of three fish. All data were plotted as yearly time series of average catch rates (fish per angler hour) estimated from total catch and number of fish caught by anglers (creel data survey only), size of fish (average, minimum and maximum length and weight), and fish condition (K) factor, which reflects the nutritional status or “well-being” of a fish, was calculated using the formula (Barnham and Baxter 1998): 퐾 = 105 × 푊⁄퐿3 where K = condition factor W = Weight (g) L = Length (mm)

Historically, Fisheries Victoria used K as a measure of salmonid quality and values of K determined from surveys assisted decisions regarding management of fisheries and stocking (Baxter and Vallis 1995, Barnham and Baxter 1998). For example, if K was consistently below 1.20 in a fishery maintained by stocking then stocking rates are reduced (Baxter 1991). For salmonids, K values usually fall between 0.8 and 2.2, with the majority between 1.0 and 1.4. Condition of salmonids for different K values is provided in Table 8. Long term mean (LTM) values for catch rate, length, weight and condition factor (K) of brown trout, Chinook salmon and rainbow trout were calculated from mean annual values.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 9

Table 8. Condition of salmonids at different K values (after Barnham and Baxter 1998).

K value Fish condition

1.6 Excellent condition, trophy class fishery

1.4 A good, well-proportioned fish

1.2 A fair fish, acceptable to many

1.0 A poor fish

0.8 Extremely poor fish

Correlation analyses Pearson’s correlation analysis (conducted using R software) was used to explore relationships between fishery performance measures and fish stocking. Fishery performance measures for brown trout, Chinook salmon and rainbow trout were:  Mean annual catch rate (fish/hour), estimated from angler creel surveys  Mean annual condition (K factor) of fish angled (angler creel and club records)  Mean annual size (length and weight) of fish angled (angler creel and club records) Fish stocking data were summarised as follows:  Number of fish stocked in the same year (Yr 0)  Number of fish stocked in the previous year (Yr -1)  Average number of fish stocked in the previous two years (Yr -1 and -2)  Average number of fish stocked in the previous three years (Yr -1, -2 and -3)

 Average number of fish stocked in the previous four years (Yr -1, -2, -3 and -4) for brown trout only. These values were determined for:  Brown trout  Chinook salmon  Rainbow trout

In addition, performance measures of the Chinook salmon fishery in Lake Purrumbete were correlated against the catch and size (length) of redfin caught by anglers (angler creel and club records).

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 10

Results and discussion

Angling club records Between June 2012 and May 2016 the Lake Purrumbete and Camperdown Angling Clubs recorded 2,367 fish of which 707 were salmonids (Table 9). Chinook salmon were the most frequently recorded salmonid species in both Lakes Bullen Merri (169 records) and Purrumbete (212 records). Rainbow trout (106 records) and brown trout (152 records) were the next most recorded salmonid in Lake Bullen Merri and Lake Purrumbete, respectively. Redfin, which were caught in Lake Purrumbete only, made up the majority (70%; 1,660 records) of all fish caught, however, only five fish contributed length and weight data. Further information on the size of fish recorded in angling clubs records is provided later in the report.

Table 9. Angling club catch records for June 2012 – May 2016.

Species Lake Bullen Lake Total Merri Purrumbete

Chinook Salmon 169 212 381

Brown trout 22 152 174

Rainbow trout 106 41 147

Atlantic Salmon 5 - 5

Redfin - 1,660 1,660

Total salmonids 302 405 707 Grand Total 302 2,065 2,367

Stephen Hill with a 5.25 kg (11.5 lb) Chinook salmon caught from Lake Bullen Merri in March 2016.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 11

Social media postings Social media postings of salmonids, caught in Lake Purrumbete and Lake Bullen Merri, highlighted large (trophy) fish were being caught in recent years (see Appendix III). Notable trophy catch periods include:  March 2016 when large Chinook salmon and well-conditioned rainbow trout were reported from Lake Bullen Merri,  May-September 2016 when large brown trout were reported from Lake Purrumbete,  May-June 2017 when large brown trout, Chinook salmon and smaller rainbow trout were reported from Lake Purrumbete.

Gordon Winter and Rod Reeves with their 7.7 kg (17 lb) and 5.4 kg (12 lb) Chinook salmon caught from Lake Purrumbete in March 2017 (Photo source: John Clements).

Darren John with a 5.1 kg and 4.2 kg brown trout caught in at Lake Purrumbete during May 2016.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 12

Lake Purrumbete angler creel survey A total of 616 groups equating to 1,112 anglers were interviewed over the 91 angler creel survey days at Lake Purrumbete. The estimated total number of angler fishing trips and days completed during the one year sampling frame at Lake Purrumbete was 3,628 ± 291 (SE) and 6,315 ± 531 (SE), respectively. Of the angler days, 2,273 ± 333 were during weekdays and 4,042 ± 414 were during weekends and public holidays (Table 10). (Table 5). The relative error estimate (standard error/total estimate) was 8.41% for total fishing days and 14.65% and 10.24% for weekdays and weekend/public holidays, respectively. The species target preference by visiting groups was dominated by stocked salmonid species (86.3%), with 13.74% of anglers preferring to target non-stocked species including redfin (13.6%) and short finned eel (0.17%). Based on these target preferences, the estimated total number of angler fishing trips and days completed for stocked species at Lake Purrumbete was 3,129 and 5,447 respectively. Fishing at Lake Purrumbete was the sole purpose of the trip for 89.3% of respondents. The remaining 10.7% of respondents said they were also fishing two nearby lakes; Lake Bullen Merri and Lake Elingamite on their trip. The majority (75.9%) of respondents stated they were satisfied with their fishing experience at Lake Purrumbete on the day of the interview, with 20.0% unsatisfied and 4.1% unsure.

Table 10. Estimated fishing days, standard error (SE) and relative error estimate of SE (%) between 1 December 2013 and 30 November 2014 at Lake Purrumbete.

Data type Estimated fishing Estimated Standard Relative Error days Error Estimate (%) Weekday 2,272.62 332.59 14.63 Weekend/public holiday 4,042.16 414.06 10.24 Total 6,314.78 531.10 8.41

Angler catch composition Information from creel surveys conducted between 1976 and 2016 in Lake Purrumbete has shown that redfin perch dominated the catch in recent years, representing 27-83% of fish caught since 1993 (Figure 2a). Chinook salmon were in highest proportions (71-97%) of the catch in the late 1970s, while rainbow trout were in highest proportions (72-76%) in the mid-1980s. Brown trout represented a small proportion (4-20%) of the angler catch during the late 1990s and early 2000s, noting that regular stocking of brown trout did not start until 1994 (Appendix I). In the most recent creel survey of Lake Purrumbete conducted in 2014 (this study), angler catch was dominated by redfin perch (78%) followed by Chinook salmon (18%) (Figure 2a). Catch composition data from creel surveys of Lake Bullen Merri were available for three years only (1993, 1994 and 2003) (Figure 2b). Chinook salmon, and rainbow trout were only species in the creel survey in 1993 and 1994, while small numbers of brown trout, Australian bass and Atlantic salmon were present in the catch in 2003, which is a reflection of stockings in the years prior (Appendix I). In 1995 there were a number of fish kills in the lake due to poor water quality and as a result the salmonid fishery collapsed (Eddy 1998). Consequently, stocking of salmonids into the lake was greatly reduced while stocking on native species, particularly Australian bass and golden perch, was increased (Appendix I). The information provided above does not take into account targeting by anglers.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 13

100 (a)

80

60

40

20

Percent catch of (%)

0 1975 1980 1985 1990 1995 2000 2005 2010 2015 100

(b)

80

60

40

20

Percent Percent catch of (%) 0

1975 1980 1985 1990 1995 2000 2005 2010 2015

Redfin Short fin eel Rainbow trout Chinook salmon Brown trout Australian bass Atlantic salmon

Figure 2. Percent of catch recorded during creel surveys (a) Lake Purrumbete and (b) Lake Bullen Merri (data source: creel surveys).

Angler catch rates Angler catch rates for each species and lake, estimated from creel surveys, provided below does not take into account targeting preferences by anglers. Chinook salmon Mean annual catch of Chinook salmon in Lake Purrumbete ranged from 0.02 – 0.36 fish/ angler hr (Figure 3). Catch rates were highest in late 1970s (0.13 – 0.36 fish/ angler hr), while rates were lower (0.02 - 0.1 fish/ angler hr) during the 1990s and early 2000s. In the most recent creel survey of Lake Purrumbete (this study), the catch rate was 0.1 fish/ angler hr, which was the same as the LTM (Figure 3). Catch rates of Chinook salmon in Lake Bullen Merri were generally low (long term mean 0.01 fish/ angler hr), with the highest rate being recorded in 1993 (0.04 fish/ angler hr) (Figure 4). Despite continued stocking of Lake Bullen Merri with Chinook salmon throughout the early 1990s there was an appreciable decline in the catch rate of Chinook salmon between 1993 and 1995, which may reflect the deteriorating environmental conditions that led to a collapse of the salmonid fishery in 1995 (Eddy 1998). Brown trout Mean annual catch of brown trout in Lake Purrumbete ranged from 0 - 0.09 fish/ angler hr (Figure 7). The rate was highest during the early 2000s (0.03-0.09 fish/ angler hr), which is not surprising since large numbers of brown trout were stocked into the lake during the mid 1990s (Appendix I). The catch rate increased steadily from 1993 until 2001, however, in the most recent creel survey of Lake Purrumbete conducted in 2014 (this study), the catch rate was 0.01 fish/ angler hr, which was below the LTM of 0.03 fish/ angler hr (Figure 7). Historical records indicated that catch rates of brown trout in Lake Bullen Merri were lower than for Lake Purrumbete, ranging from 0-0.03 fish / angler hr (Figure 8).

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Rainbow trout Mean annual catch of rainbow trout in Lake Purrumbete ranged from 0 – 0.22 fish/ angler hr (Figure 11). Catch rates were highly variable during the 1970s and 1980s (0.004 - 0.22 fish/angler hr). During the 1990s and early 2000s catch rates were generally lower (0.03 – 0.08 fish/ angler hr), perhaps reflecting a reduction in stocking numbers during the early 1990s. The catch rate in the recent survey was 0.005 fish/ angler hr, which was considerably lower than the LTM of 0.05 fish/angler hr (Figure 11). Mean annual catch rates in Lake Bullen Merri ranged from 0 – 0.17 fish/ angler hr and the LTM was 0.07 fish/angler hr (Figure 12).

Size (length and weight), condition (K) and age of fish Chinook salmon Mean annual lengths and weights of Chinook salmon caught in Lake Purrumbete ranged from 175 - 718 mm and 0.18 - 2.12 kg, respectively (Figure 3). Both the longest (740 mm) and heaviest (6.2 kg) fish were caught during fishery netting surveys conducted in 1987 and 1994, respectively (Table 11). In angling club records, mean annual values of length, weight and K were below LTM values, but have increased from 2012 to 2015 (Figure 3). Chinook salmon length and weight data from angling club records from 2014 were generally larger than for the creel survey conducted the same year (Table 12). Mean annual lengths and weights of Chinook salmon caught in Lake Bullen Merri ranged from 278 - 603 mm and 0.29 - 4.01 kg, respectively (Figure 4). Fish were generally larger during the late 1980s and early 1990s, and both the longest (755 mm) and heaviest (7.4 kg) fish were caught during fishery netting surveys conducted in 1988 (Table 11). In recent angling club records (2012-2015), the mean annual values for fish length and weight have generally increased over time whereas K values have declined (Figure 4). Over the long term, the condition of Chinook salmon in Lake Bullen Merri has generally been greater than for Lake Purrumbete. A total of 25 Chinook salmon were aged, 20 from Lake Bullen Merri and five from Lake Purrumbete. Fish from all stocking events each year since 2012 were represented in aged fish. In Lake Bullen Merri, fish from stockings in 2012- 2013, 2014 and 2015 were recaptured (Figure 5a), while in Lake Purrumbete fish from both 2013 and 2014 were recaptured (Figure 5b). The relationship between age and length of Chinook salmon in crater lakes is provided in Figure 6 and Table 13. There were insufficient data across age groups to estimate growth rates of Chinook salmon stocked into the crater lakes in recent years, and there is very little historic age data from the crater lakes to compare with the results from the current study. Brown trout Mean annual values of the length and weight of brown trout caught in Lake Purrumbete ranged from 323 - 585 mm and 0.36 - 2.72 kg, respectively (Figure 7). The longest fish recorded was 760 mm, which was recorded in angling clubs records from 2015, while the heaviest was 6.168 kg caught during a fishery survey in 2009 (Table 11). Recent social media postings reported brown trout up to 6.0 kg being caught in the lake. Mean annual lengths and weights of brown trout recorded in angling club records from 2013-2015 were above the LTM of 507 mm and 1.72 kg, respectively (Figure 7). Rather than being indicative of the size range of the brown trout population present in the lake, angling club records may reflect a tendency of anglers to select larger fish for weigh-in at club events. In contrast, however, mean annual K values estimated from angling club records have declined from 1.11 in 2013 to 0.95 in 2015, all of which were below the LTM of 1.21 (Figure 7). Length and weight data from the creel survey conducted in 2014 were comparable to data recorded in angling club records for the same year (Table 12). Mean annual values of the length and weight of brown trout caught in Lake Bullen Merri ranged from 337 - 690 mm and 0.59 - 5.23 kg, respectively (Figure 8). Both the longest (690 mm) and heaviest (5.28 kg) were recorded in angling clubs records from 2014 (Table 11), whereas recent social media postings reported brown trout up to 5.3 kg being caught in the lake. Mean annual length, weight and K values estimated from angling club records increased from to 2012 to 2014, but declined in 2015 (Figure 8). This trend may reflect changes in stocking activities. Between 2012 and 2013, no brown trout were stocked into the lake which meant that the catch of brown trout between 2012 and 2014 was not influenced by the presence of smaller (yearlings) stocked fish, whereas the stockings in 2014 and 2015 may have contributed to reducing the overall size of fish caught by anglers in 2015. Sixteen brown trout caught from Lake Bullen Merri were aged, which represented 4 – 6 year old fish from stockings undertaken between 2008 and 2010 (Figure 9). No fish were aged for fish stocked in 2007, 2014 and 2015, which may

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 15

be due to the small sample size. The relationship between age and length of brown trout in crater lakes is provided in Figure 10 and Table 13. There were insufficient data across age groups to estimate growth rates of brown trout stocked into the crater lakes in recent years, and there was insufficient historic age data from the crater lakes to compare with the results from the current study. Rainbow trout Mean annual values of the length and weight of rainbow trout caught in Lake Purrumbete ranged from 246 - 487 mm and 0.26 – 2.17 kg, respectively (Figure 11). Fish caught during netting surveys in the late 1980s and early 1990s tended to be larger and more variable in size than fish recorded in creel surveys, although both the longest (670 mm) and heaviest (4.34 kg) fish were recorded in a creel survey conducted in 1994 (Table 11). Mean annual length, weight and K values of rainbow trout recorded in angling club records have generally declined since 2012 (Figure 11), although it is noted that just one fish was recorded in 2012, 2014 and 2015. Due to the small sample size, no comparison can be drawn between the size of rainbow trout recorded in angling club records and fish reported in the creel survey of 2014 (Table 12). Mean annual values of the length and weight of rainbow trout caught in Lake Bullen Merri ranged from 236 - 465 mm and 0.3 – 1.57 kg, respectively (Figure 12). Fish caught during netting surveys in the late 1980s and early 1990s were generally larger and more variable than fish recorded in creel surveys and angling club records. The longest (670 mm) was recorded during a fishery netting survey in 1989, but heaviest (4.4 kg) fish were recorded in a creel survey conducted in 2003 (Table 11). In angling club records, mean annual length (336-402 mm) and weight (0.57-0.96 kg) values were generally consistent with LTM values (length = 365 mm, weight 0.83 kg). On the other hand, K values were variable and, apart from 2014, were generally lower than the LTM (Figure 12). Four rainbow trout only were donated by anglers for aging, which was insufficient to undertake an assessment.

Table 11. Maximum length and weight records for brown trout, Chinook salmon, and rainbow trout caught in Lake Purrumbete and Lake Bullen Merri between 1975 and 2015 (data source: angling club records (ACR), creel surveys (CS) and fishery independent surveys (FIS)).

Species Water Length Weight mm Year Source Kg Year Source Brown trout Lake Purrumbete 760 2015 ACR 6.17 2009 FIS Lake Bullen Merri 690 2014 ACR 5.23 2014 ARC Chinook salmon Lake Purrumbete 740 1987 FIS 6.2 1994 FIS Lake Bullen Merri 755 1988 FIS 7.4 1988 FIS Rainbow trout Lake Purrumbete 670 1994 CS 4.34 1994 CS Lake Bullen Merri 585 1989 FIS 4.4 2003 CS

Table 12. Comparison between length, weight and condition (K) of salmonids recorded angling club records and a creel survey of Lake Purrumbete in 2014 (1 December 2013 and 30 November 2014).

Species Angling club records Creel survey Mean Range Number Mean Range Number measured measured Brown trout Length (mm) 566 460-680 18 559 470-710 47 Weight (kg) 1.91 1.1-3.06 19 1.82 1.13-3.27 45 K factor 1.04 0.62-1.25 1.02 Chinook salmon Length (mm) 381 300-600 31 349 250-510 140 Weight (kg) 628 0.26-2.2 41 436 140-1.1 117 K factor 1.07 0.77-2.05 0.97 Rainbow trout Length (mm) 390 1 483 380-570 5 Weight (kg) 0.68 1 1.31 0.66-2.23 5 K factor 1.14 1.08

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 16

Table 13. Age and length of Chinook salmon and brown trout angled from Lake Bullen Merri and Lake Purrumbete between January 2014 and April 2016.

Age Chinook salmon Brown trout (years old) Number Total Length (cm) Number Total Length (cm) Range Mean Range Mean 1 1 29 29 2 13 40.8-56.0 48.4 3 8 52-65 59.9 4 11 46.1-60 54.1 5 2 58.2-59.7 59.0 6 2 70.4-79.0 73.2

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 17

Number stocked

Figure 3. Chinook salmon in Lake Purrumbete. Catch rate (mean ± s.e of seasonal data), numbers stocked, length (mean ± range), weight (mean ± range) and condition (K) factor (mean ± range).

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Number stocked

Figure 4. Chinook salmon in Lake Bullen Merri. Catch rate (mean ± s.e of seasonal data), numbers stocked, length (mean ± range), weight (mean ± range) and condition (K) factor (mean ± range).

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Figure 5. Estimates of age and length of Chinook salmon stocked into, and angled from, Lake Bullen Merri (a) and Lake Purrumbete. (YO = years olds).

Figure 6. Age and length of Chinook salmon angled from Lake Bullen Merri and Lake Purrumbete

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 20

Number stocked

Figure 7. Brown trout in Lake Purrumbete. Catch rate (mean ± s.e of seasonal data), numbers stocked, length (mean ± range), weight (mean ± range) and condition (K) factor (mean ± range).

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Number stocked

Figure 8. Brown trout in Lake Bullen Merri. Catch rate (mean ± s.e of seasonal data), numbers stocked, length (mean ± range), weight (mean ± range) and condition (K) factor (mean ± range).

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 22

Figure 9. Estimates of age and length of brown trout stocked into, and angled from, Lake Bullen Merri. (YO = years olds).

Figure 10. Age and length of brown trout angled from Lake Bullen Merri

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 23

Number stocked

Figure 11. Rainbow trout in Lake Purrumbete. Catch rate (mean ± s.e of seasonal data), numbers stocked, length (mean ± range), weight (mean ± range) and condition (K) factor (mean ± range).

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 24

Number stocked

Figure 12. Rainbow trout in Lake Bullen Merri. Catch rate (mean ± s.e of seasonal data), numbers stocked, length (mean ± range), weight (mean ± range) and condition (K) factor (mean ± range).

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 25

Correlation analyses Plots of relationships between fish stocking numbers and fishery performance measures are provided in Appendix IV. Specific significant trends (P<0.05) are described below. Chinook salmon Angler catch rates of Chinook salmon in Lake Purrumbete declined with increasing numbers of brown trout stocked in Yr 0 and Yr -1 (P<0.05) (a trend that was also observed in historic lake Purrumbete netting data). This trend, however, was not observed in Lake Bullen Merri. This may be due, in part, to limited data. The K factor of Chinook salmon angled in Lake Bullen Merri increased with increasing numbers of rainbow trout stocked. Fish are a major part of the diet of Chinook salmon (Cadwallader and Eden 1981), and newly released trout may be contributed to the diet of these fish, having a positive influence on their condition. The K factor of Chinook salmon in Lake Bullen Merri declined with increasing numbers of Chinook salmon and brown trout stocked, but this trend was opposite in Lake Purrumbete. Both length and weight of chinook salmon angled in Lake Purrumbete declined with increasing numbers of brown trout stocked in previous years (Yr -1 to Yr -4) (P<0.05). However, this trend was inconsistent or absent for Lake Bullen Merri, partly due to limited data Hunt et al. (2014) suggested that the number of yearling Chinook salmon stocked in the same year positively influenced angler catch rates, while negatively influencing the weight of fish caught by anglers, implying a trade-off relationship between catch rate and fish size in the fishery. There were no significant relationships between Chinook salmon performance measures and redfin catch rate in Lake Purrumbete, however the K factor declined and catch rate increased with increasing size of redfin. Large redfin in Lake Purrumbete may be competing with Chinook salmon for food, reducing condition and increasing susceptibility to angling. Previous analyses suggested that the size of redfin declined with increasing numbers of brown trout and Chinook salmon stocked in the same year of surveys and number of brown trout stocked in the previous year (Ingram 2016). Brown trout Angler catch rates of brown trout in Lake Purrumbete increased with increasing numbers of brown trout stocked in the previous two to four years, but declined with increasing numbers of rainbow trout stocked in the previous two to three years. The K factor of brown trout were also positively correlated with brown trout stocked in the previous two years. There were no significant relationships between the size of brown trout angled and number of fish stocked. There was insufficient data available to assess brown trout stockings in Lake Bullen Merri. Rainbow trout Angler catch rates of rainbow trout in Lake Purrumbete increased with increasing numbers of rainbow trout stocked in the same year (Yr 0) (a trend also observed in historic netting data), which suggests that anglers are catching recently stocked fish. Both length and weight of rainbow trout in Lake Purrumbete was negative correlated with the number of brown trout stocked in the same year (Yr 0). There was insufficient data available to assess brown trout stockings in Lake Bullen Merri. Comments of correlation analyses The use of correlation analyses provides an indication of direction and magnitude of relationship between pairs of parameters, in this case performance measures and levels of fish stocking. However, there are limitations in the use of this analyses as it is difficult to identify direct cause and effect. Although there were a number of significant relationships identified (as described above), trends were not always consistent between species and lakes, and do not take into account other factors influencing fishery performance. Aquatic communities in lakes are both complex and dynamic, and incorporate a series of interconnected trophic levels, from bacterial and algal communities to predators, such as brown trout and Chinook salmon. The bottom-up: top-down trophic model for freshwater pelagic ecosystems (McQueen et al. 1986) proposes influences of both resource availability (food) (bottom-up) and predators (top-down) on the community. Predatory fish can regulate lower trophic levels while processes at lower trophic levels may influence the fish community. Other factors, which were not included in the present study, may have influenced interactions between the parameters. These may include environmental conditions (water quality, water level, temperature, habitat availability and climate), biological factors (the number and species of fish stocked, health and condition of stocked fish and food availability) and harvest pressure (take by anglers).

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 26

Conclusions

General comments  This report builds on previous assessments on the fisheries of Lake Purrumbete and Lake Bullen Merri (e.g. Brown and Vallis 1997, Hall 2002, Pomorin 2004, Pomorin and Hall 2009, Hall and Douglas 2010, Hall et al. 2010, Hunt et al. 2013, Hunt et al. 2014).  Angling club records and an angler creel survey conducted in the crater lakes in recent years have provided valuable information, which contributed to assessment of fishery performance in Lake Purrumbete and Lake Bullen Merri. Combining this information with historic creel information and fishery independent survey data has allowed for a more detailed review of the status of the fisheries and effects of stocking thereon.  Angling club size records were generally consistent with creel size records for brown trout, but lengths and weights of chinook salmon from angling club records were generally larger than for the creel survey data.  Social media postings highlighted large (trophy) fish, being caught from Lake Purrumbete and Lake Bullen Merri in recent years.  Correlation analyses conducted as part of this study provided an indication of direction and magnitude of relationship between fishery performance measures and levels of fish stocking. However, the results should be viewed with caution as this type of analysis does not take into account complex interactions between multiple variables. Other factors influencing the fishery performance may include environmental conditions (water quality, water level, temperature, habitat availability and climate), biological factors (the number and species of fish stocked, health and condition of stocked fish and food availability) and harvest pressure (take by anglers).  Compared to previous years, the performance of the recreational fishery for brown trout, Chinook salmon and rainbow trout in Lake Purrumbete and Lake Bullen Merri has been generally consistent, as indicated by recent measures of size and fish condition (K) being close to LTM values. Specific findings included: Chinook salmon o The reintroduction of Chinook salmon into Lake Purrumbete and Lake Bullen Merri has been well received by most anglers and celebrated as highly successful as indicated by the presence of increasingly larger fish in angling club records from 2012-2015 and social media. o Social media reports from March 2016 onwards highlighted trophy Chinook salmon (4-8kg) catches by anglers. o The 2013/14 creel survey of Lake Purrumbete the catch rate for Chinook salmon was 0.1 fish/ angler hour, which was the same as the LTM value. o In the angling club records for Lake Purrumbete, average annual values of length, weight and K values have increased between 2012 to 2015, but were below LTM values. o In the angling club records for Lake Bullen Merri, average annual values of length and weight records have increase between 2012 to 2015, whereas K values have declined. o Brown trout stocking in Lake Purrumbete appears to have had a negative effect on the Chinook salmon fishery as the angler catch rate, and length and weight of Chinook salmon have declined with increasing numbers of brown trout stocked in previous years. o The K factor of Chinook salmon angled in Lake Bullen Merri increased with increasing numbers of rainbow trout stocked, possibly suggesting that the newly stocked rainbow trout may be prey for larger Chinook salmon. o There were no significant relationships between Chinook salmon performance measures and the redfin catch rate in Lake Purrumbete. However, the K value declined and catch rate increased with increasing size of redfin. Large redfin in Lake Purrumbete may be competing for food with Chinook salmon, reducing condition and increasing susceptibility to angling. o Based on the performance of Chinook salmon in the creel survey, angling club records and social media reports, it is recommended that stocking of Chinook salmon into both crater lakes be maintained.

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Brown trout o The catch rate of brown trout in the recent Lake Purrumbete creel survey (0.01 fish/angler hr) was considerably lower than the LTM of 0.03 fish/angler hr, however, average annual lengths and weights of brown trout recorded in angling club records were above the LTM value. o Social media reports highlighted trophy brown trout (4.5kg+) catches by anglers during the study period, in particular at Lake Purrumbete from May 2016 onwards. o Catch rates of brown trout in Lake Bullen Merri were historically lower than for Lake Purrumbete, as indicated by LTM values. o In Lake Bullen Merri, average annual length, weight and K factor estimated from angling club records increased from to 2012 to 2014, but declined in 2015, which may have reflected changes in stocking activities. o Angler catch rates of brown trout in Lake Purrumbete increased with increasing numbers of brown trout stocked in the previous two to four years, but declined with increasing numbers of rainbow trout stocked in the previous two to three years. Rainbow trout o The catch rate of rainbow trout estimated from the recent creel survey of Lake Purrumbete was 0.005 fish/ angler hr, which was considerably lower than the LTM of 0.05 fish/angler hr. o Social media reports highlighted well-conditioned rainbow trout (2kg+) were caught by anglers from March 2016 onwards. o Mean annual length, weight and K values of rainbow trout recorded in angling club records for Lake Purrumbete have generally declined since 2012. o Mean annual length and weight values for Lake Bullen Merri were generally consistent with LTM, but K values were variable and, apart from 2014, were generally lower than LTM. Redfin o Redfin were the most abundant species at Lake Purrumbete as evidenced by the creel survey and angling club catch records. It should be noted that the long term mean or average (LTM) comparison of catch rates takes into account a variety of fisheries management regimes, water levels and climatic periods, therefore its relevance needs to be carefully considered with respect to recent fishery performance. Fisheries managers utilise information from a range of sources to inform decisions regarding the management of recreational fisheries. In the case of the crater lakes, managers rely heavily on information and options from anglers, and science-based surveys and experiments, such as the current study. The information presented in this study was shared with fishers at a public consultation forum at Lake Purrumbete Angling Clubrooms on 12 March 2015 and as a result revised stocking plans for 2015 and 2016 for the Crater Lakes were agreed (Appendix II). This evaluation of the performance of the stocked fisheries of Lakes Bullen Merri and Purrumbete has improved the understanding of the effects of fish stocking strategies, and has informed management decisions aimed at improved fishing outcomes for recreational fishers. In partnership with the Lake Purrumbete and Camperdown Angling Clubs and local anglers, further work is currently underway to better understand and further improve the Crater lakes fisheries including a rainbow trout strain stocking trial, brook trout stocking trial and modelling of redfin populations. In consultation with key stakeholder groups, such as through the annual rounds of the Vic Fish stock regional consultative meetings, these studies will help inform future decisions regarding the management (and stocking) of these popular and productive recreational fisheries.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 28

Acknowledgements

This project was instigated by Lake Purrumbete Angling Club with funds from the Victorian Government to improve recreational fishing in Victoria through revenue from Recreational Fishing Licences. The efforts of Rob Hems of the Lake Purrumbete Angling Club are especially acknowledged for establishing and commissioning the project. Lake Purrumbete and Camperdown Angling Clubs and the members are thanked for their ongoing support in collection of angling club records that contributed to this project. Although we can’t name all those who contributed records, members who contributed large number records included Brian Nygaard, Don Swayn, Hans Bongart, James Reid, Robert Reid, Kerry Cannad, Ross Winstanley, Simon Andrus and Les Broughton. Anglers who contributed caught fish for otolith aging including Scott Gray, Maz Stowlowski, Brian Nygaard and Jason Andrus. Rob Hems, Dave Ritchie, Glen Place, Bob Liddle, Gary Cronin and other members of the Lake Purrumbete and Camperdown Angling Clubs for providing advice on the angler creel survey questionnaire. Scott Gray for conducting the angler creel survey interviews, and Pieta Lindburg for assistance with data entry. Anthony Forster and John Douglas provided constructive comments throughout the project. John Clements is thanked for assistance with providing photos and social media reports of catches.

The Lake Purrumbete and Camperdown Angling Clubs were presented with a mounted Chinook salmon and plaque in appreciation of their support for monitoring salmonid fisheries in the Crater Lakes over many years. The Chinook Salmon was caught at Lake Bullen Merri in 1980, which was 9kg (20lb) in weight and 2 years and 10 months old. Pictured from left: Rob Hems, Glen Place, David Richie and Bob Liddell.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 29

References

Barnham, C. (1997). Summary on Researched Available Records of Non-indigenous and Indigenous Fish Stockings into Victorian Public Waters. Ninth Edition: 1871-1996. Department of Natural Resources and Environment, Victorian Fisheries, Internal Operations Document No. 2. Barnham, C. and Baxter, A. (1998). Condition Factor, K, for Salmonid Fish. Fisheries Notes No. FN0005. State of Victoria, Department of Primary Industries. 4 pp. Baxter, A. (1991). Management of the recreational salmonid fishery in Lake Wendouree, Ballarat, Victoria Fisheries Management Report No. 39. Victorian Fisheries, Department of Conservation and Environment. 36 pp. Baxter, A. and Vallis, S. (1995). A Summary of Trout Management Group Fish Population Surveys 1994. Fisheries Management Report No. 52. Victorian Fisheries, Department of Conservation and Natural Resources. Baxter, A., Vallis, S. and Barnham, C.A. (1988). A Summary of Trout Management Group Fish Population Surveys 1987. Fisheries Management Report No. 21. Fisheries Division, Department of Conservation, Forests and Lands. Baxter, A.F. (1987). Catch and effort data for all the major angling species caught by the Trout Management Group during gill netting surveys conducted between 1978 and 1986 inclusive. Fisheries Management Report No. 6. Freshwater Fisheries Management Branch, Fisheries Division. Brown, P. and Vallis, S. (1997). Lake Bullen Merri Fishery Assessment, October 1997. MAFRI Freshwater Division Fish Survey 97/12. Cadwallader, P.L. and Eden, A.K. (1981). Food and growth of hatchery-produced Chinook salmon, Oncorhynchus tshawytscha (Walbaum), in landlocked Lake Purrumbete, Victoria, Australia. Journal of Fish Biology 18: 321-330. Department of Primary Industries (2008). Corangamite Fishery Management Plan. Fisheries Victoria Management Report Series No. 59. 49 pp. Eddy, S. (1998). Report on Creel Surveys Lake Purrumbete, Lake Murdeduke and Lake Bullen Merri 1 December 1995 to 30 November 1997. Fisheries Management Report No. 62. Victorian Fisheries, Department of Natural Resources and Environment, Colac. Eddy, S. and Smith, I. (1994). Report on creel surveys : Lake Purrumbete and Lake Bullen Merri 1 December 1992 to 30 November 1993 Fisheries Management Report No. 50. Victorian Fisheries, Department of Natural Resources and Environment, East Melbourne. 25 pp. Eddy, S. and Smith, I. (1995). Report on Creel Surveys Lake Purrumbete and Lake Bullen Merri 1 December 1993 to 30 November 1994. Fisheries Management Report No. 53. Victorian Fisheries, Department of Natural Resources and Environment, East Melbourne. Fisheries Victoria (1997). Victorian inland fisheries strategy. Fisheries Victoria, Department of Natural Resources and Environment. Hall, K. (2002). Lake Bullen Merri Fisheries Assessments - DNRE South West Region, 2000-2002. Marine and Freshwater Resources Institute Freshwater Fisheries Report No. 02/3. 18 pp. Hall, K. and Douglas, J. (2010). Lake Purrumbete Stock Assessment. Fisheries Victoria Assessment Report No. 35. Department of Primary Industries, Alexandra. Hall, K., Douglas, J. and Pomorin, K. (2010). Lake Bullen Merri 2005 and 2006 Stock Assessments. Fisheries Victoria Assessment Report Series No. 58. Department of Primary Industries, Alexandra. Hume, D. (1991a). Report on three years of creel surveys: 1984 to 1987. Arthur Rylah Institute for Environmental Research Technical Report Series No. 122. Department of Conservation & Environment, Heidelberg. 115 pp. Hume, D. (1991b). Results of the diary creel survey for the 1961/62 fishing season in Victoria. Fisheries Management Report No. 20. Freshwater Fish Management Branch, Fisheries Division, Victoria. Hunt, T.L., Brown, P. and Giri, K. (2012). Looking back to go forward: Recreating a world class Chinook salmon fishery in Victoria's western crater lakes. Fisheries Victoria Research Report Series No. 59. Department of Primary Industries, Victoria, Queenscliff. 44 pp. Hunt, T.L., Brown, P. and Giri, K. (2013). Chinook salmon stocking and fishery performance review. Recreational Fishing Grants Research Report, Department of Primary Industries Victoria. 1-44 pp. Hunt, T.L., Giri, K., Brown, P., Ingram, B.A., Jones, P.L., Laurenson, L.J.B. and Wallis, A.M. (2014). Consequences of fish stocking density in a recreational fishery. Canadian Journal of Fisheries & Aquatic Sciences 71: 1554-1560. Hunt, T.L., Scarborough, H., Giri, K., Douglas, J.W. and Jones, P. (2017). Assessing the cost-effectiveness of a fish stocking program in a culture-based recreational fishery. Fisheries research 186: 468-477.

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Ingram, B.A. (2016). Options for managing redfin perch in Lake Purrumbete to improve recreational fishing. Recreational Fishing Grants Program Report Department of Economic Development, Jobs, Transport and Resources, Melbourne 31 pp. Laurensen, L.J.B., French, R.P., Jones, P.L., Lerodiaconou, D., Gray, S.C., Versace, V.L., Rattray, A., Brown, S. and Monk, J. (2012). Aspects of the biology of Galaxias maculatus. J. Fish. Biol 81: 1085-1100. Malvestuto, S.P. (1996). Sampling the recreational fishery. In: Fisheries Techniques (Murphy, B.R. and Willis, D.W. eds.), pp. 591-623. American Fisheries Society, Bethesda, Maryland. McQueen, D.J., Post, J.R. and Mills, E.L. (1986). Trophic relationships in freshwater pelagic ecosystems. Canadian Journal of Fisheries and Aquatic Sciences 43: 1571-1581. Nguyen, T.T.T. and Ingram, B.A. (2013). Managing genetic viability of Chinook salmon. Recreational Fishing Grants Program Research Report. Department of Primary Industries Victoria. Australia. 25 pp. Ollier, C.D. and Joyce, E.B. (1964). Volcanic physiography of the western plains of Victoria. Proceedings of the Royal Society of Victoria 77: 357-376. Pomorin, K. (2004). Rainbow Trout Stocking Evaluation Lake Purrumbete 1999-2002. Fisheries Victoria Research Report Series No. 5. Department of Primary Industries, Queenscliff. Pomorin, K. and Hall, K. (2009). Lake Bullen Merri Fisheries Assessment: September 2002 - January 2004. Fisheries Revenue Allocation Committee Final Report. Department of Primary Industries, Queenscliff. Robson, D.S. (1991). The roving creel survey. American Fisheries Society Symposium 12: 19-24. Skene, W. and Smith, I. (1996). Report on Creel Surveys Lake Purrumbete, Lake Bullen Merri and Lake Murdeduke 1 December 1994 to 30 November 1995. Fisheries Management Report No. 55. Victorian Fisheries, Department of Natural Resources and Environment, East Melbourne. Timms, B.V. (1976). A Comparative study of the limnology of three maar lakes in western Victoria. I. Physiography and physicochemical features. Australian Journal of Marine and Freshwater Research 27 (1): 35-60. Tunbridge, B.R., Rogan, P.L. and Barnham, C.A. (1991). A guide to the inland angling waters of Victoria. Department of Conservation and Environment, Melbourne. 119 pp.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 31

Appendix I. Crater lakes stocking history

120,000 Atlantic salmon Lake Purrumbete

100,000 Chinook salmon

Brook trout 80,000 Brown trout 60,000 Rainbow trout

40,000

Number stocked Number 20,000

0

1927 1929 1931 1933 1935 1937 1939 1941 1943 1945 1947 1949 1951 1953 1955 1957 1959 1961 1963 1965 1967 1969 1971 1973 1975 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 1925 140,000 Atlantic salmon Australian bass Lake Bullen Merri 120,000

Chinook salmon Golden perch

100,000 Brown trout Silver perch Rainbow trout 80,000

60,000

40,000 Number stocked Number

20,000

0

1927 1929 1931 1933 1935 1937 1939 1941 1943 1945 1947 1949 1951 1953 1955 1957 1959 1961 1963 1965 1967 1969 1971 1973 1975 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 1925

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 32

Appendix II. Crater lakes fishery management decisions

Regional Fisheries Consultations meeting outcomes (2006 - 2009) and Vic Fish Stock meeting outcomes (2010 to current). Lake Year Management decision notes Source Lake 2006 Surveys indicated that brown trout condition factor was consistent with Fisheries Purrumbete previous surveys. Catch rates for Chinook salmon and rainbow trout were low, Management but no conclusions can be drawn from these species. Paper No. 41 (2006) New stocking rates to be in place for at least 2 years unless conditions change.

Brown trout: stocking increased from 15,000 to 20,000. Chinook salmon: stocking reduced from 10,000 to 5,000. Rainbow trout: no change (20,000). Atlantic salmon: stocking not supported. 2007 Retain stocking rates as per 2006. Fisheries Management Paper No. Brown trout: no change (20,000). 49 (2007) Chinook salmon: No change (5,000) Rainbow trout: No change (20,000) 2008 Surveys indicated that current salmonid condition is within those seen Fisheries previously from the lake. Management Paper No. Changes in stocking numbers due to shortfall in Chinook salmon in 2008. 61 (2008) Changes in place until Chinook salmon become available again.

Brown trout: stocking increased to 25,000. Chinook salmon: nil (substituted for brown trout) Rainbow trout: no change (20,000). 2009 Changes in stocking numbers due to shortfall in Chinook salmon. Changes in Fisheries place until Chinook salmon become available again. Management Paper No.

72 (2009) Brown trout: no change (25,000) Chinook salmon: nil (substituted for brown trout) Rainbow trout: no change (20,000). 2010 Note rebuilding capacity to breed Chinook salmon at Snobs Creek. Fisheries Management Brown trout: no change (25,000). Paper No. 77 (2010) Chinook salmon: 5,000 if available (otherwise substitute with rainbow trout) Rainbow trout: Increased to 25,000 (20,000 if Chinook salmon are available) 2011 Two year Atlantic salmon stock trial in lieu of Chinook salmon. Continued Fisheries stocking of Atlantic salmon dependent on performance and supply of Chinook Management Paper No. salmon. 82 (2011)

Brown trout: reduced to 15,000 (number substituted for Atlantic salmon) Chinook salmon: nil Rainbow trout: reduced to 15,000 (number substituted for Atlantic salmon) Atlantic salmon: Increased to 15,000. 2012 Future fishery stocking to be discussed out of session. Fisheries Management Paper No. 85 (2012) 2013 Brown trout: 5,000 (resume in 2014). Vic Fish Chinook salmon: 25,000 Stock (2013)

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 33

Lake Year Management decision notes Source Rainbow trout: 10,000 2014 Brown trout: no change (5,000) (no change until program assessment). Vic Fish Chinook salmon: subject to availability (45,000 across Lake Purrumbete and Stock (2014) Lake Bullen Merri). Rainbow trout: no change (10,000) (no change until program assessment). Brook trout: nil (trial stocking supported but deferred until current program completed and assessed). 2015 Feedback from anglers has indicated a strong desire to maintain the high Vic Fish performance of the Chinook salmon fishery in Lake Bullen Merri and for Stock (2015) increased catch rates in Lake Purrumbete. Consequently fisheries managers will adjust stocking plans for the lakes to optimise what each can deliver for freshwater anglers. The focus will be further building the Chinook salmon fishery in Lake Bullen Merri where they have done best.

Brown trout: increased to 20,000 Chinook salmon: 10,000. Rainbow trout: no change (5,000) Brook trout: TEP approved and stocking plan being developed 2016 Brown trout: no change (20,000) Vic Fish Chinook salmon: increased to 20,000. Stock (2016) Rainbow trout: increased t0 9,000 Brook trout: 3,000 Lake Bullen 2006 Surveys indicated that brown trout condition factor was consistent with Fisheries Merri previous surveys, but condition factor of Chinook salmon had declined. Management Paper No. Brown trout: stocking reduced from 10,000 to 5,000. 41 (2006) Chinook salmon: stocking reduced from 17,500 to 15,000 Rainbow trout: 10,000 Atlantic salmon: stocking not supported. 2007 Retain stocking rates as per 2006. Fisheries Management Paper No. Brown trout: no change (5,000). 49 (2007) Chinook salmon: No change (15,000) Rainbow trout: No change (10,000) Atlantic salmon: nil, will not be considered. 2008 Surveys indicated that current salmonid condition is within those seen Fisheries previously from the lake. Management Paper No. Changes in stocking numbers due to shortfall in Chinook salmon in 2008. 61 (2008) Changes in place until Chinook salmon become available again.

Brown trout: stocking increased to 20,000. Chinook salmon: nil (substituted for brown trout) Rainbow trout: 10,000. 2009 Changes in stocking numbers due to shortfall in Chinook salmon. Changes in Fisheries place until Chinook salmon become available again. Management Paper No. 72 (2009) Brown trout: Increased to 20,000. Chinook salmon: nil (substituted for brown trout) Rainbow trout: 10,000. 2010 Change in species mix. Note rebuilding capacity to breed Chinook salmon at Fisheries Snobs Creek. Management Paper No. Brown trout: reduced to 10,000. 77 (2010) Chinook salmon: 15,000 if available (otherwise substitute with rainbow trout) Rainbow trout: Increased to 30,000 (15,000 if Chinook salmon are available) 2011 Two year Atlantic salmon stock trial in lieu of Chinook salmon. Continued Fisheries

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 34

Lake Year Management decision notes Source stocking of Atlantic salmon dependent on performance and supply of Chinook Management salmon. Paper No. 82 (2011)

Brown trout: no change (10,000). Chinook salmon: nil Rainbow trout: reduced to 20,000 (number substituted for Atlantic salmon) Atlantic salmon: Increased to 10,000. 2012 Future fishery stocking to be discussed out of session. Fisheries Management Paper No. 85 (2012) 2013 Brown trout: 5,000 (resume in 2014). Vic Fish Chinook salmon: 20,000 Stock (2013) Rainbow trout: 10,000 2014 Brown trout: no change (5,000) (no change until program assessment). Vic Fish Chinook salmon: subject to availability (45,000 across Lake Purrumbete and Stock (2014) Lake Bullen Merri). Rainbow trout: reduced to 5,000 (no change until program assessment). 2015 Feedback from anglers has indicated a strong desire to maintain the high Vic Fish performance of the Chinook salmon fishery in Lake Bullen Merri and for Stock (2015) increased catch rates in Lake Purrumbete. Consequently fisheries managers will adjust stocking plans for the lakes to optimise what each can deliver for freshwater anglers. The focus will be further building the Chinook salmon fishery in Lake Bullen Merri where they have done best.

Brown trout: no change (5,000). Chinook salmon: 20,000 Rainbow trout: no change (5,000). 2016 Brown trout: no change (5,000). Vic Fish Chinook salmon: no change (20,000) Stock (2016) Rainbow trout: increase to 9,000.

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 35

Appendix III. Social media images of fish angled from Lake Bullen Merri and Lake Purrumbete

Photos of Chinook salmon, brown trout and rainbow trout caught by anglers at the Crater Lakes between 2015-2017 (Photo source: John Clements).

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 36

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 37

Appendix IV. Correlation scatter plots

Lake Purrumbete Brown trout

BT = Brown trout. CS = Chinook salmon. RT = Rainbow trout. All data. 2012-2015 data. Linear regressions no. fish stocked in: Yr 0 Yr -1 Yr -1 & -2 Yr -1, -2 & -3 Yr -1, -2, -3 & -4 Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 38

Lake Purrumbete Chinook salmon

BT = Brown trout. CS = Chinook salmon. RT = Rainbow trout. All data. 2012-2015 data.

Linear regressions no. fish stocked in: Yr 0 Yr -1 Yr -1 & -2 Yr -1, -2 & -3 Yr -1, -2, -3 & -4

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 39

Lake Purrumbete Rainbow trout

BT = Brown trout. CS = Chinook salmon. RT = Rainbow trout. All data. 2012-2015 data. Linear regressions no. fish stocked in: Yr 0 Yr -1 Yr -1 & -2 Yr -1, -2 & -3 Yr -1, -2, -3 & -4

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 40

Lake Bullen Merri Chinook salmon

BT = Brown trout. CS = Chinook salmon. RT = Rainbow trout. All data. 2012-2015 data.

Linear regressions no. fish stocked in: Yr 0 Yr -1 Yr -1 & -2 Yr -1, -2 & -3 Yr -1, -2, -3 & -4

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 41

Lake Bullen Merri rainbow trout

BT = Brown trout. CS = Chinook salmon. RT = Rainbow trout. All data. 2012-2015 data.

Linear regressions no. fish stocked in: Yr 0 Yr -1 Yr -1 & -2 Yr -1, -2 & -3 Yr -1, -2, -3 & -4

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 42

Correlations between redfin and Chinook salmon in Lake Purrumbete

CS = Chinook salmon. All data. Linear regression

Chinook Salmon Fisheries Research – Evaluating performance at Lakes Bullen Merri and Purrumbete  Recreational Fishing Grants Program 43

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