Difference between revisions of "Natal Origins Project (NO)"

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*There is a low probability for an individual fish to move large distances.
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*There is a low probability for an individual rainbow trout to move large distances.
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*Abundance is a key factor: the more fish upstream in the Lees Ferry reach = more fish will move downstream
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*Abundance is a key factor: the more rainbow trout upstream in the Lees Ferry reach = more trout will move downstream to the LCR reach
 
*Recruitment in the reach below the LCR can be accounted for solely by immigrants from upstream sources  
 
*Recruitment in the reach below the LCR can be accounted for solely by immigrants from upstream sources  
 
*Food limitation lead to the collapse in the trout population, and by extension also likely happened in the downstream reaches.
 
*Food limitation lead to the collapse in the trout population, and by extension also likely happened in the downstream reaches.

Revision as of 08:13, 27 April 2017
NatalOrigins.jpg
  • There is a low probability for an individual rainbow trout to move large distances.
  • Abundance is a key factor: the more rainbow trout upstream in the Lees Ferry reach = more trout will move downstream to the LCR reach
  • Recruitment in the reach below the LCR can be accounted for solely by immigrants from upstream sources
  • Food limitation lead to the collapse in the trout population, and by extension also likely happened in the downstream reaches.
  • Inflow hydrology and reservoir limnology likely govern the quality and quantity of nutrients supplied to the downstream river segments.
  • Nutrient limitation is hypothesized as being the “BIG HAMMER” to the riverine ecosystem, which needs to be evaluated in greater detail in future research.
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Updates

ReachAbundances.jpg
[1]


EmigrationLargeRecruitmentEvents.jpg
Episodic movement occurs under periods of high recruitment (lots of little trout looking for a place to live)

[2]


EmigrationEnvironmentalStressor.jpg
Episodic movement occurs under periods of environmental stress (poor conditions) [3]


NOconclusions.jpg
[4]

Links and Information

Background

Initial investigations found:

  • Efficacy of Mechanical Removal is dependent on immigration levels
  • RBT abundance was high and variable, partially offset by trout immigration
  • BNT were more predaceous than RBT
  • RBT were more numerous than BNT
  • Predation risk is a function of both density & predatory behavior

Information Needs:

  • What controls trout abundance?
  • Where were RBT migrants originating from?
  • What controls trout abundance?
  • Where were RBT migrants originating from?
  • How many sub-adult HBC move into the mainstem?
  • How variable was subadult HBC survival?
  • Was there a relationship between HBC survival & RBT abundance?

Outcomes:

  • Develop alternative sampling methods for determining trout and chub abundance and vital rates
  • Natal Origin Project: Movement and Trout dynamics
  • NSE/JCM Projects: Juvenile HBC survival and other regulating factors

Presentations and Papers

2017

2016

2015

2014

2013

Other Stuff

NatalOriginsSamplingDesign (1).jpg

Local recruitment in Marble Canyon down to the LCR There does appear to be some local trout recruitment in Marble Canyon down to the LCR but the numbers of fish at in the reach below the LCR can be accounted for solely by immigrants from upstream sources. [5] [6]


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