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