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Analysis of Walleye Growth, Movement and Habitat Quality in Lake Erie, 1990-2001

Analysis of Walleye Growth, Movement and Habitat Quality in Lake Erie, 1990-2001. 1 Wang, H.-Y., 1 Rutherford, E.S., 2 Haas, R.C., and 3 Schwab, D. J. Funded by Great Lake Fisheries Commission. Lake Erie Committee Annual Meeting 3/25/2003. Lake Erie Bathymetry Map. Objectives

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Analysis of Walleye Growth, Movement and Habitat Quality in Lake Erie, 1990-2001

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  1. Analysis of Walleye Growth, Movement and Habitat Quality in Lake Erie, 1990-2001 1Wang, H.-Y., 1Rutherford, E.S., 2Haas, R.C., and 3Schwab, D. J. Funded by Great Lake Fisheries Commission Lake Erie Committee Annual Meeting 3/25/2003

  2. Lake Erie Bathymetry Map

  3. Objectives To explore walleye growth, movement and habitat quality in Lake Erie using tagging data, bio-data, catch rate data analyses, and bioenergetics modeling. Hypothesis Walleye migrate to areas of high growth rate potential (GRP) and grow faster there.

  4. Tag Recovery Location Map (1990-2001) Boundary of basins (Ludsin, S.A. et al, 2001)

  5. Walleye Biological Data From Ontario MNR Surveys, 1987-2001.

  6. Commercial CPUE Patterns (1999) in ON Waters

  7. Sport CPUE Patterns (1999) in U.S. Waters

  8. NOAA CoastWatch Data: Lake Erie Water Surface Temperatures, August 1992-2001 1992 1997 1993 1998 1994 1999 1995 2000 1996 2001

  9. Forage Fish Density Index U.S. Agency Trawl Surveys OMNR Gillnet Surveys

  10. Methods • Movement • - Map and model spatial pattern of commercial and sport CPUE by month and year. • - Analyze tagging data by stock, and explore distribution of recapture locations. • Growth • - Estimate growth rate and length at 50% mature from bio-data. • - Walleye Bioenergetic Growth Model.

  11. Commercial CPUE patterns (1999) indicate that walleye migrate to EB in June, and migrate back to WB in September

  12. Ordinary Kriging of Commercial CPUE in May-Nov, 1999

  13. Most (78%) Recaptured Walleye were from 5 Tagging Sites in WB and 1 Site in EB

  14. Large Walleye Tagged in WB were recaptured in CB and EB; EB-tagged Walleye Don’t Migrate

  15. Walleye Recaptured in CB and EB Were Larger, Regardless Where They Were Tagged

  16. Growth Rates of Age-2 and Older Walleye Appear Fastest in Eastern and Central Basin

  17. WB Walleyes Mature at larger size than in EB. Females Mature at larger size than Males.

  18. Walleye Bioenergetic Growth Model • Estimate growth based on lake temperatures and prey densities. • Assume Higher growth rate indicates better habitat quality

  19. Walleye Growth Model Framework • Growth = Consumption - Losses (Losses = Respiration, Egestion, Excretion) • Consumption is a function of temperature, walleye weight and prey fish density

  20. Gillnet CPUE Indicates Spatial Overlap is High Between Walleye and Clupeid Forage

  21. Walleye Growth Model Predictions Correlate with Walleye Movement patterns, but not with Commercial CPUE data.

  22. Results • Walleye in the EB and CB appear to grow better and mature at smaller sizes than in the WB. • Mostly large, female walleye migrate from WB to EB. Why??? Perhaps to increase fitness, i.e. increase female growth and fecundity.

  23. Future Work • Refine Walleye Growth Model using CPUE data on depth and temperature where walleye forage. • Examine effects of decadal (1990-2001) changes in walleye density on walleye growth and movement.

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