Spawner and Redd Characteristics of Wild- and Hatchery-Origin Upper Yakima River Spring Chinook
Snorkel Surveyor Crew
- David Childs
- Devona Ensmenger
- Marlene Farrell
- Tyler Forman
- Corene Luton
- Luke Peterson
- Keith Pitts
Objectives
- Compare hatchery and wild origin redds constructed between 2002 and 2006.
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- Analyze correlations between female body size and redd characteristics.
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- Analyze correlations between spawning density and redd characteristics.
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Surveys
- Female origin
- In-river - adipose fin presence/absence
- Redd locations identified and numbered
- Female body length
- In-river - visually estimated
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- Surveys over 8 km between Easton Dam and the Easton spring chinook Acclimation site
In-river Redd Surveys
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Redd characteristics
- Physical dimensions of redds (length, width)
- Water velocities and depths
- Habitat type (riffle, pool, glide)
- Substrate characteristics – visual estimate of the proportion of sand, gravel, cobble and boulders
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Selected variables used in MANOVA
- Bowl velocity
- Apex height
- Bowl length
- Absolute Bowl depth
- Bowl % sand (arc sin square root transformed)
- Distance to nearest redd
MANOVA Results
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Female Size
and
Spawning Density
vs
Redd Characteristics
Mean POHP Length (+ 1 sd)
Spawning Density
- We used these weekly redd counts as a measure of Spawning Density (SD) in the survey area.
- These values were assigned to a female’s redd based on the week she was first observed in constructing her redd.
- SD values were log transformed due to increasing variance with increasing SD.
Correlations between female FL or Spawning Density and redd variables.
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Conclusions:
- Little evidence that there are significant differences between Hatchery and Natural redds.
- There were significant differences between Years in redd measurement distributions.
- Because there was only weak correlations between redd characters and female body size it is unlikely that the size differences we have observed will have significant impacts on redd characteristics.
- Our analyses were under powered due to low sample sizes.
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