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 Recreational Fishing Grants Program Research Report 0 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 This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. Accessibility If you would like to receive this publication in an accessible format, such as large print or audio, please telephone 136 186, or email [email protected] Deaf, hearing impaired or speech impaired? Call us via the National Relay Service on 133 677 or visit www.relayservice.com.au 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,