1. Snake River Trout Population Dynamics Jon Ewert, Colorado Division of Parks and Wildlife All photos by Bob Berwyn Andrew Todd, US Geological Survey

2. C O L O R A D O Denver Continental Divide MAP AREA 108°104° Upper Snake River Deer Creek Peru Creek Snake River North Fork Snake River N 01 SCALE (miles)   Arapahoe Basin Ski Area Keystone Ski Area To Silverthorne 2 Chihuahua Gulch Fish Absent Fish Present LEGEND

3. “Tram Bridge” station

5. Brook trout capture, Tram Bridge station

8. Rainbow trout overwinter survival Year # RBT marked # RBT recaptured Min. survival estimate 200846n/a 200935511% 2010726% 201121114% 20125000 % 20133512%

9. Rainbow trout body condition: 2009 sample # of fish captured Body condition Unmarked fish 3083 Marked fish5 71 (p = 0.02)

10. “Hole 7” Station

11. Hole 7 Station vs. Tram Bridge: Brook Trout Population Estimates Tram BridgeHole 7 Yearfish per mile Avg. body condition fish per mile Avg. body condition 201217681 30277 20139280 27987

12. Snake River Above Peru Creek Increases in metals concentrations beyond toxicity thresholds may render currently marginal fish habitat uninhabitable

13. Thanks!... questions?