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John Cannon ESPM 5242 – November 2007

Evaluating the effectiveness of the MNDNR’s walleye stocking program at creating a better walleye fishery. John Cannon ESPM 5242 – November 2007. Why do an evaluation?.

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John Cannon ESPM 5242 – November 2007

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  1. Evaluating the effectiveness of the MNDNR’s walleye stocking program at creating a better walleye fishery John Cannon ESPM 5242 – November 2007

  2. Why do an evaluation? • “Fish stocking is ubiquitous in Minnesota but generally lacks direct monitoring of its consequences. This makes it hard to distinguish positive and negative effects statewide…” – Statewide Conservation and Preservation Plan • “What are the overall effects of fish stocking on angler’s fishing experience, the target species, and fish communities?” –Statewide Conservation and Preservation Plan

  3. Problem Description Social Context • The walleye is the most sought-after fish in Minnesota • The MNDNR uses various management techniques to ensure lakes produce enough walleyes to keep up with angler demand • Most popular technique…STOCKING • Immense political and social pressure to stock fish in a given lake

  4. Problem DescriptionPolicy Goals • Outlined in Walleye Stocking Guidelines for Minnesota Fisheries Managers (1996) • Provide a fishery where abundance and reproduction are limited • Introductory stocking • Maintenance stocking • Supplemental stocking Photograph by Michael Barrett

  5. Problem DescriptionComplimentary Policies • Habitat Protection/Restoration • Special Regulations

  6. Problem DescriptionParticipants • MNDNR – Section of Fisheries • Walleye Anglers • Walleye Angling Impacted Businesses • Private Fish Hatcheries

  7. “Without stocking, there’d hardly be any walleye fishing in Minnesota south of I-94 or in the Twin Cities Metro Region” - Jack Skrypek, DNR Fisheries Chief

  8. Why is this a problem??? • We are spending millions of dollars a year on a program that offers mixed results • We are mixing genetic pools and threatening genetic strains that developed over thousands of years • Stocking does not always lead to the establishment of strong year classes

  9. Evaluation Criteria • Economic Efficiency • Biological Impacts/Ecological Integrity • Effectiveness

  10. Economic Efficiency • Not practical for this analysis to try and determine the economic efficiency of every lake • Study found that stocking walleye fingerlings at 0.31 lb/littoral acre/year was the most economically efficient (largest gains in walleye CPE accompanied with lowest stocking costs) • Most common stocking density used by MNDNR fisheries managers is 0.50 lb/littoral acres/year Anderson and Jacobson (2001)

  11. Economic Efficiency • “Increased fingerling stocking is economically inefficient. However, even when presented with that fact, many of our anglers and state legislators at various input meetings and venues continue to demand increased rates. They put a premium on “squeezing out” as much walleye abundance as possible, in spite of greatly increased cost.” • Peter Jacobson, Research Scientist, MNDNR

  12. Economic Efficiency • In 2004, MNDNR spent 2.7 million on stocking program • In 2004, an estimated 462,000 stocked walleyes were harvested • 2,700,000/462,000 = $5.84 per walleye Anderson and Jacobson (2001)

  13. Biological Impacts/Ecological Integrity • Genetic Effects • Limited published data on genetic effects of walleye stocking • MNDNR does make sure that certain strains are only stocked in designated regions of the state • Widely accepted that there are adverse effects, yet there is no genetic monitoring program in place

  14. Biological Impacts/Ecological Integrity • Impacts on other species • Large amounts of juvenile walleyes can account for high percentage mortality of prey species - Lyons and Magnuson (1987) • Strong relationship between walleye stocking and decline in yellow perch populations - Special Publication 150, MNDNR

  15. Effectiveness • Study of 3 West-central lakes in MN • Angling success and walleye yields were lower 3 to 5 years after the high density stockings than in earlier years • An average of 1.8% of the stocked walleye were returned to the creel • Estimated cost per stocked walleye was $16.35!! Parsons et al (1994)

  16. Effectiveness • Estimated that 70% of walleye fingerlings stocked in East Okoboji Lake, Iowa, died within three weeks of stocking in 1992 • Larscheid (1995) • Natural reproduction and fry stocking are more likely to lead to the development of strong year classes than fingerling stocking • Parsons and Pereira (2001)

  17. Alternatives • No-Action • Keep stocking on “trial & evaluation” method • Develop a comprehensive long-range plan • Better goal setting, improve monitoring • Spend more on habitat improvement and stricter regulations • Reduce bio impacts, easier to monitor • Increase cooperation with private hatcheries • Less expensive, greater genetic diversity

  18. Recommendations • Inform the public that increased stocking is not cost-effective • Need more data to support the claim that there are adverse genetic effects • Increase walleye fry stocking (less expensive and more likely to develop strong year classes) • Invest in improving walleye spawning habitat

  19. Questions?

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