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Return Timing For Adult Winter Steelhead Based on Age

This study by Hal Michael analyzes the timing of winter steelhead returns based on age, exploring their behavior and implications for fisheries management. The research evaluates streams like the Hoh River, Snow Creek, and White River, observing first return ages and repeat spawning patterns. Results show variations in freshwater and saltwater migration timing, as well as differences between first-time and repeat spawners. The study discusses the impact of variable return times on runsize, mortality rates, and escapement goals, providing insights for effective conservation strategies.

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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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