A Multi-Agency Effort to Address Declines in Yellow Perch Abundance in Lake Michigan

1. A Multi-Agency Effort toAddress Declines inYellow Perch Abundancein Lake Michigan David ClappMichigan Department of Natural ResourcesandYellow Perch Task Group, Lake Michigan Technical Committee

2. Lake Michigan RecreationalYellow Perch Catch(Michigan Waters)

3. Is there a problem?

5. Age Distribution ofYellow Perch Catch Age 6 Age 3

6. Yellow Perch SamplingFishery Independent versus Dependent Data

7. What steps have we taken to address perch declines? • Step #1 - Formation of Yellow • Perch Task Group (1994) • Increased sampling coverage • Gear standardization

8. Yellow Perch Task Group Sampling Locations

9. Summer Trawland SeineSurveys • Catch per unit effort • Total length • Age • Abundance of other species

10. Gill Net Surveys • Catch per unit effort • Total length and weight • Sex, Fecundity • Scales, Otoliths

11. Lake Michigan Creel Survey Programs (Photo courtesy of The Hunting and Fishing Library)

12. What steps have we taken to address perch declines? • Step #2 - Lakewide public meeting (Yellow Perch Conference - December, 1994 - Kenosha, Wisconsin) • Protect spawning stock • Conduct research on declining • recruitment • Enforce harvest regulations

13. Regulation changes

14. What steps have we taken to address perch declines? • Step #3 - Conduct research on declining recruitment • Hypotheses • Egg stage: • Egg quality and/or egg mortality limits perch • Diet: • Inappropriate diet limits larval survival • Alewife / predation: • Alewife predation limits recruitment

15. Early Life History (Egg Stage)

16. Survival: 601 (1) - 1283 (8) Survival (number of individuals) 9 8 6 10 3 5 1 4 7 Female Were maternal effects important? Provided by: Christopher J. Heyer Chesapeake Biological Laboratory

17. Were maternal effects important? A trade-off exists between yolk volume and larval size • Large, old female perch = small yolk volume = large larvae Abundant food, many predators • Small, young female perch = large yolk volume = small larvae Scarce food, few predators Provided by: Christopher J. Heyer Chesapeake Biological Laboratory

18. Food Resources (Diet)

19. Yellow Perch Survival versus Zooplankton Density 6 88 89 4 90 Log (YOY YP CPUE) 2 98 0 97 96 -2 10 20 30 40 50 Mean ZP Density in June (No./L) Data provided by John Dettmers, Illinois Natural History Survey)

20. Alewife (Predation, Competition)

21. Yellow Perch Year Class Strength versus Alewife Abundance (Data provided by Steve Shroyer, Ball State University)

22. Other Predators (Photo courtesy of The Hunting and Fishing Library)

23. Other Predators

24. What steps have we taken to address perch declines? Step #4 - Implementing Yellow Perch Research in Great Lakes Management YEP(#) = Function (“Cycles” * (x+y+z+…))

25. Yellow Perch AbundanceSaginaw Bay - Lake Huron

26. YEP(#) = Function (“Cycles” * (a+b+c+d+…)) b a d c

27. Recreational Harvest Commercial Harvest

28. Implementing Perch Research Egg stage, diet, predators

29. Implementing Perch Research Recreational and Commercial harvest