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Mo in V Nat Nito Victo Ive Oring Oria Fish G Monitoring fish stockinggs in Victoria: 2014 native fish surveys Recreational Fishing Grants Program Research Report Monitoring fish stockings in Victoria: 2014 native fish surveys Building Northern Native Fisheries, Lake Eildon Million Murray cod, Lower Goulburn River and Nagambie Lakes stocking initiative creel survey April 2015 Recreational Fishing Grants Program Research Report © The State of Victoria Department of Economic Development, Jobs, Transport and Resources This work is licensed under a Creative Commons Attribution 3.0 Australia licence. You are free to re-use the work under that licence, on the condition that you credit the State of Victoria as author. The licence does not apply to any images, photographs or branding, including the Victorian Coat of Arms, the Victorian Government logo and the Department of Economic Development, Jobs, Transport and Resources logo. To view a copy of this licence, visit http://creativecommons.org/licenses/by/3.0/au/deed.en Printed by DEDJTR Queenscliff, Victoria Preferred way to cite this publication: Ingram BA, Hunt TL, Lieschke J & Douglas J (2015). Monitoring fish stockings in Victoria: 2014 native fish surveys. Recreation Fishing Grants Program Research Report. ISBN 978-1-74146-536-5 (Print) Accessibility If you would like to receive this publication in an alternative format, please telephone the Customer Service Centre 136 186, email [email protected] , via the National Relay Service on 133 677 www.relayservice.com.au. This document is also available on the internet at www.depi.vic.gov.au 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. Monitoring fish stockings in Victoria: 2014 native fish surveys Recreational Fishing Grants Program ii Contents Executive summary 1 Conclusions and recommendations 3 Introduction 4 Background 4 Objectives of this report 4 Methods 6 Marking and stocking fish 6 Fish sampling 6 Catch per unit effort (CPUE) 10 Creel surveys 10 Detection of calcein in marked fish 11 Distance of stocked fish from stocking sites 11 Results and discussion 12 General information 12 Campaspe River 15 Gunbower Creek 17 Kow Swamp 18 Loddon River 19 Lake Eildon 21 Lower Goulburn River 23 Nagambie Lakes creel survey 25 Calcein marking 26 Conclusions 29 Recommendations 31 Acknowledgements 35 References 36 Appendix I. Sites surveyed and environmental data 39 Appendix II. Creel Survey questionnaire 41 Appendix III. Fish stocking history 44 Appendix IV. Species and number of fish observed in each waterbody during surveys 46 Appendix V: Age, total length and weight of golden perch and Murray cod captured during surveys 47 Monitoring fish stockings in Victoria: 2014 native fish surveys Recreational Fishing Grants Program iii Appendix VI: Percent of fish in each age bracket that were marked 48 Appendix VII: Detection of calcein in golden perch and Murray cod using different methods 50 Monitoring fish stockings in Victoria: 2014 native fish surveys Recreational Fishing Grants Program iv Executive summary Since the late 1980’s The Victorian government has invested considerably in native fish stocking aimed at improving recreational fishing. Since December 2010, three large-scale native fish stocking initiatives involving golden perch and Murray cod, and one major stocking initiative recreational fisher (creel) survey, have been conducted. Building Northern Native Fisheries initiative aimed to stock an extra 670,000 native fish fingerlings into the Campaspe River, Gunbower Creek, Loddon River and Kow Swamp, in addition to the regular allocation of 180,000 native fish. A further 425,000 native fingerlings are expected to be stocked into these waters in 2014. As part of the “Million Murray Cod” Program (MMC), it is expected that Lake Eildon will be stocked with 1,150,000 Murray cod. This program, which is considered to be the largest single-waterway stocking of Murray cod in Australia was funded entirely by recreational fishing license fees at a value of $800,000. Lower Goulburn River enhancement initiative will see 359,500 Murray cod and 527,700 golden perch released over a period of 4 years. The anglers of Nagambie Lakes have been creel surveyed to determine their perception of the native fish fishery and catch. The broad objective of this project was to address key knowledge gaps in the management of Victorian inland fisheries by answering recognised measures of stocking success including • Is there evidence of stocked fish survival? • What is the percentage contribution from fish stocking to the fish population and fishery? • Is there a net increase in fish abundance in the fish population and angler catch? • Is there a net increase in fisher target preference, participation and/or satisfaction from fish stocking? Golden perch and Murray cod fingerlings marked with calcein were released into the selected waters over four years from 2010/11. In 2014 electro-fishing surveys were conducted to capture fish from the stocked sites. Sampled fish were measured, aged and analysed for the presence of a calcein mark. Results from these surveys were compared with surveys conducted before the stocking events. Between December 2013 and April 2014, anglers fishing at Lake Eildon and the Nagambie Lakes were interviewed to assess catch and satisfaction. These results were compared with surveys conducted during 2010 and 20-11. Key findings In waters that were stocked with calcein-marked golden perch, the percent of fish that were stocked ranged from 11% (lower Goulburn R.) to 54% (Campaspe R.) (overall mean 22%). The percent of Murray cod that were stocked ranged from 11% (lower Goulburn R.) to 100% (Campaspe R.) (overall mean 50%). Based on the proportion of stocked fish amongst sampled fish (as above), the distribution of stocked fish across sites sampled and change in abundance of fish, information on the contribution of stocked fish to wild stocks was provided for the water bodies assessed (see table below). Species Water Contribution Comments of stocked fish to wild stocks Golden perch Campaspe R. Likely Current project supports past studies suggesting that regular stocking is maintaining the golden perch population. Presence of marked fish may be underestimated due to non- marked fish being released. No appreciable change in electro-fishing CPUE. Kow Swamp Inconclusive The contribution of stocking to the population is uncertain as sample size was too small for assessment and non-marked fish were released. Results were confounded by most marked fish being from the 2013/14 stocking that were captured 3 weeks after release. These fish also inflated the CPUE. Loddon R. Likely The high percentage of stocked fish present along with an appreciable change in electro-fishing CPUE suggests that golden perch stocking is making a substantial contribution to the population. Presence of marked fish may be underestimated due to non-marked fish being released. Monitoring fish stockings in Victoria: 2014 native fish surveys Recreational Fishing Grants Program 1 Species Water Contribution Comments of stocked fish to wild stocks Golden perch Lower Goulburn R. Unlikely Results suggest that stocking is contributing little to the population, which is more likely being supported by immigration and natural recruitment. Sample size was too small for assessment and marked fish caught at small number of surveyed sites only. Murray cod Campaspe R. Unlikely The sample size was too small to assess the contribution of stockings to the population. Marked fish caught in small number of surveyed sites only. No appreciable change in electro-fishing CPUE. Gunbower Ck Inconclusive The contribution of stocking to the population is uncertain as the sample size was too small for assessment and non- marked fish were released. Electro-fishing CPUE greater than for 2012 survey, but no appreciable change when historic data considered. Kow Swamp Inconclusive The contribution of stocking to the population is uncertain as sample size too small for assessment and non-marked fish were released. Results confounded as most marked Murray cod caught were thought to be fish that moved from Gunbower Ck to Kow Swamp (released 3 weeks before the survey occurred). Lake Eildon Yes Stocked Murray cod have made a significant contribution to the Murray cod population. Marked fish were caught at all sites surveyed. Loddon R. Unlikely No conclusions can be made regarding the contribution of stocking Murray cod to the population as the sample size was small and marked fish were caught in a small number of sites only. Presence of marked fish may be underestimated due to non-marked fish being released. Lower Goulburn R. Likely Small numbers of stocked fish were caught which are likely to contribute to the population, along with immigration and natural recruitment. Marked fish caught in a small number of surveyed sites only. Building northern rivers A high percent of stocked golden perch and Murray cod were present within the Campaspe River, suggesting that stocking is likely to contribute to the Campaspe River recreational fishery as the stocked fish reach legal size. The presence of a high percentage of marked Murray cod suggests that stocking has had a positive impact in Gunbower Creek. Further monitoring will be required to determine if the large number of 0 and 1 year old fish observed in Kow swamp will recruit to the recreational fishery. No conclusions can be made regarding the contribution of stocking to Murray cod populations in the Loddon River as many of fish in the target age group (<4 years old) may have been stocked fish that were not marked with calcein. Lake Eildon Million Murray Cod Stocked Murray cod represented the vast majority (98%) of Murray cod caught in Lake Eildon.
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