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

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Revision as of 16:48, 26 April 2017
NatalOrigins.jpg
  • There is a low probability for an individual fish to move large distances.
  • Abundance is a key factor: the more fish upstream in the Lees Ferry reach = more fish will move downstream
  • Recruitment in the reach below the LCR can be accounted for solely by immigrants from upstream sources (little to no local recruitment at the LCR)
  • 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
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