Invasive Brown Trout Population Assessment and Suppression Feasibility Pilot Study Phase 1

Salmonid Research, Monitoring, and Evaluation (RM&E)

Project IDHOOPA-2013-2
Recovery DomainsN CA - S Oregon
Start Date09/01/2014
End Date09/30/2015
Last Edited05/08/2024
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This project involved the collection of brown trout through a variety of methods including electrofishing, angling, and capture at fish sampling weirs to provide information on trout population size, distribution, age and diet. The majority of captured brown trout had stomach contents, scales, and tissue samples taken to assess age and diet. Scales collected during these efforts as well as scales provided by CDFW were prepped for aging. Future analysis of data from this collection will be used to build a bioenergetics model to help illuminate the magnitude of the problem and capture success rates informed suppression feasibility. This project was conducted in close coordination with NOAA, CDFW, and Humboldt State University.

Project Benefit    

Brown Trout are predators of and compete with ESA listed SONCC, contributing to their imperiled state. In order to quantify the impact that Brown Trout are imposing on Coho salmon, Hoopa Valley Tribal Fisheries Department (HVTFD) began to enumerate the population of brown trout within the Trinity River, assess brown trout diet, age and habitat utilization, and develop recommendations for suppressing brown trout population to levels that do not significantly impede ESA and tribal trust species recovery. The findings of this study will provide justification for any changes in management actions concerning Brown Trout on the Trinity River. All Brown Trout captured will be used for research and/or humanely euthanized (permit dependent) as part of an initial suppression effort. The projects goals, objectives, activities and methods are listed below. Brown Trout populations have increased significantly in the upper Trinity River, confounding efforts to restore anadromous fish (Chinook salmon, Coho salmon, steelhead trout, Pacific lamprey) to pre-Dam levels as envisioned in the Trinity Record of Decision.


Metric Completed Originally
Research and Monitoring
  Stream Miles Monitored 42.00 42.00

Funding Details

Report Total:$68,400

Project Map


Trinity River    

  • Worksite Identifier: Trinity River
  • Start Date: 09/30/2014
  • End Date: 09/30/2015
Area Description

No Area Description data was found for this worksite.

Location Information

  • Basin: Klamath (180102)
  • Subbasin:
  • Watershed:
  • Subwatershed:
  • State: California
  • Recovery Domain: N CA - S Oregon
  • Latitude: 41.22242346175928
  • Longitude: -123.70788574218358


    No ESU data was found for this worksite.




  • E.0 Salmonid Research, Monitoring, and Evaluation (RM&E)Y (Y/N)
    •      . . E.0.a RM&E Funding 68,400.00
    •      . . E.0.b
      Complement habitat restoration project
      Trinity River Restoration Program
    •      . . E.0.c
      Project identified in a plan or watershed assessment.
      SONCC Coho Restoration Plan
    •      . . E.0.d.1 Number of Cooperating Organizations 9
    •      . . E.0.d.2
      Name Of Cooperating Organizations.
      Yurok Tribe, US Forest Service, NOAA Fisheries, Bureau of Reclamation, Trinity County, Hoopa Tribe, US Fish and Wildlife Service, California Department of Fish and Wildlife, California Department of Water Resources
    •      . . E.0.e.1 Number of reports prepared 0
    •      . . E.0.e.2
      Name Of Report
      Will report at end of multi year study in 2017
    •      . . E.1 MonitoringY (Y/N)
      •      . . . . E.1.a Monitoring funding 68,400.00
      •      . . . . E.1.b.1 Stream Miles Monitored 42.00
      •      . . . . E.1.b.2 Acres of Watershed Area Monitored 18,560,000.0
      •      . . . . E.1.b.3 Square miles of water monitored29000 (Square miles)
      •      . . . . E.1.c.18 Predator/competitor monitoringY (Y/N)
        •      . . . . . . E.1.c.18.a # miles (to nearest 0.01 mile) of stream or streambank monitored 42.00
        •      . . . . . . E.1.c.18.c # acres (to nearest 0.1 acre) monitored 18,560,000.0
        •      . . . . E.1.d
          Name Of Comprehensive Monitoring Strategy/Program