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Return Timing For Adult Winter Steelhead Based on Age

Return Timing For Adult Winter Steelhead Based on Age. Hal Michael Washington Department of Fish and Wildlife michahhm@dfw.wa.gov 360-902-2659. QUESTIONS FOR DISCUSSION. If a steelhead run is best described as “temporally mixed” how do you model this?

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Return Timing For Adult Winter Steelhead Based on Age

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  1. Return Timing For Adult Winter Steelhead Based on Age Hal Michael Washington Department of Fish and Wildlife michahhm@dfw.wa.gov 360-902-2659

  2. QUESTIONS FOR DISCUSSION • If a steelhead run is best described as “temporally mixed” how do you model this? • If a steelhead run is best described as “temporally mixed” how do you manage this?

  3. STREAMS EVALUATED • Hoh River commercial fishery, Nov-March 2004-05, n=454 • Snow Creek upstream trap 1977-2006, n=1014 • Buckley Trap, White River 1998-2006, n=1236

  4. AGES OBSERVED FOR FIRST RETURN SW Age 1 2 3 4 5 FW Age 1 X X X 2 X X X 3 X X XX 4 X X

  5. REPEAT SPAWNING OBSERVED • .?+S+ • .?+S+S+ • .?+S+S+S+ • ? Represents years in saltwater before first return

  6. FRESHWATER AGE Hoh days 0 15 24 age 1 age 2 age 3 Snow Creek days 0 7 11 age 1 age 2 age 3 White River days 0 1 10 age 2 age 1 age 3

  7. FIRST RETURN FROM SALTWATER • Hoh 0 2 days 7 days 3 years 1 year 2 years • Snow Creek 0 7 days 11 days 1 year 2 years 3 years • White River 0 14 days 36 days 1 year 2 years 3 years

  8. FIRST TIME vs. REPEAT SPAWNERS • Hoh (n=376, 78) first timers 6 days earlier • Snow (n=203, 21) first timers same day • White (n=1205, 22) first timers 4 days later

  9. IMPLICATIONS OF VARIABLE RETURN TIME • Runsize = 1000 • Total mortality= 10% • all fish arriving after closure survive to spawn • close last day March • Escapement 900 • esc post close 734 • Actual mortality rate 38%

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