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Published byBertram Caldwell Modified over 8 years ago
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Return Timing For Adult Winter Steelhead Based on Age Hal Michael Washington Department of Fish and Wildlife michahhm@dfw.wa.gov 360-902-2659
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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?
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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
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AGES OBSERVED FOR FIRST RETURN SW Age 12345 FW Age 1 XXX 2 XXX 3 XXXX 4 XX
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REPEAT SPAWNING OBSERVED.?+S+.?+S+S+.?+S+S+S+ ? Represents years in saltwater before first return
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FRESHWATER AGE Hoh days0 15 24 age 1age 2age 3 Snow Creek days0 7 11 age 1age 2age 3 White River days0 1 10 age 2age 1age 3
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FIRST RETURN FROM SALTWATER Hoh 02 days7 days 3 years1 year2 years Snow Creek 07 days11 days 1 year2 years3 years White River 014 days36 days 1 year2 years3 years
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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
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IMPLICATIONS OF VARIABLE RETURN TIME Runsize = 1000 Total mortality= 10% all fish arriving after closure survive to spawn close last day March Escapement900 esc post close734 Actual mortality rate38%
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