U.S. Department of the Interior

U.S. Geological Survey

Is rainbow trout control necessary, 

and if so what is the most 

cost-effective approach?

Lucas S. Bair, U.S. Geological Survey

Charles B. Yackulic, U.S. Geological Survey

Michael R. Springborn, University of California at Davis 

Mathew N. Reimer, University of Alaska at Anchorage

Craig A. Bond, RAND Corporation

U. S. Department of Interior

U.S. Geological Survey
Project 13.3: Applied Decision Methods

• Develop a bioeconomic model to identify the 

cost-effective management strategy for 

rainbow trout that achieves humpback chub 

population goals.

2

http://www.coloradoriverrecovery.org/general-information/the-fish/humpback-chub.html
Presentation Outline

• Importance of cost-effectiveness analysis

• Bioeconomic model with population and 

management components 

• Ongoing and future workplan research

3
Cost-effectiveness Analysis

• Comparing the costs of alternative means to 

achieve goals set through a political or public 

process (Sagoff 2009)

• Example: Determine an operation at GCD that 

limits impact to hydropower while meeting 

recovery and long-term sustainability of 

downstream resources (Reclamation, 1996).

4

Sagoff, M. 2009. Regulatory review and cost-benefit analysis. Philosophy & Public Policy Quarterly. 29(3/4):21-26.

U.S. Department of the Interior. 1996. Operation of Glen Canyon Dam, Record of Decision. Upper Colorado 

Region, Salt Lake City, Utah.
Presentation Outline

• Importance of cost-effectiveness analysis

• Bioeconomic model with population and 

management components 

• Ongoing and future workplan research

5
Population Component

Juvenile Chub 

Monitoring Reach

Juvenile Chub 

Monitoring Reach

6

Preliminary data, do not cite
Humpback Chub (Gila cypha)

Adapted from: Yackulic, C. B., M.D., Yard, J. Korman, and D.R. Van Haverbeke. 2014. A quantitative life history of endangered humpback 

chub that spawn in the Little Colorado River: variation in movement, growth, and survival. Ecology and Evolution 4(7): 1006-1018.

Juvenile Chub 

Monitoring Reach

7
Juvenile Humpback Chub Survival

Target survival with cold

mainstem temperatures

Target survival with warm 

mainstem temperatures

Trout Abundance in Juvenile Chub Monitoring Reach

Annual Percent Juvenile Chub Survival

8

Preliminary data, do not cite
Management Component

• Mechanical removal

– Remove rainbow trout in the vicinity of JCM reach

– Limit of one trip per month and six trips per year

• Minimize costs 

– Number of trips

– Period of analysis 

9

Preliminary data, do not cite
Bioeconomic Model

• Simulate population component over 20 year 

period with: 

– Random rainbow trout recruitment at Lees Ferry

– Fixed policy strategy where removals are triggered 

by rainbow trout numbers in the juvenile 

humpback chub monitoring reach

10

Preliminary data, do not cite
Removal Options

1,000 2,000

1

0

5

4

3

2

6

Annual Removals

Frequency 

Expected Annual Trout in Juvenile Chub Monitoring Reach

11

Preliminary data, do not cite

5% 10% 15% 20%
Bioeconomic Model

• Simulate population dynamics model over 20 

year period with 

– Random rainbow trout recruitment at Lees Ferry

– Fixed policy strategy where removals are triggered 

by rainbow trout numbers in the juvenile 

humpback chub monitoring reach

– Rerun 1,000 times and identify the probability of 

meeting target survival and expected costs

12

Preliminary data, do not cite
Removal Options

500 1,500

1

0

5

4

3

2

6

Annual Removals

Frequency

Expected Annual Trout in Juvenile Chub Monitoring Reach

13

Preliminary data, do not cite

5% 10% 15% 20%
Expected target survival 

with warm mainstem 

temperatures

Expected juvenile 

humpback chub survival 

function 

Annual Percent Juvenile Chub Survival

Trout in Juvenile Chub Monitoring Reach 14

Preliminary data, do not cite
Expected least cost removal strategy that 

meets juvenile humpback chub survival 

target 95 percent of the time.

Annual Removals

Observed Trout in Juvenile Chub Monitoring Reach 15

Preliminary data, do not cite
Expected target survival 

High target survival

Annual Percent Juvenile Chub Survival Target

Low target survival

July Juvenile Chub Recruitment in the LCR

16

Preliminary data, do not cite
Expected target survival 

High target survival

Low target survival

Annual Removals

Observed Trout in Juvenile Chub Monitoring Reach 17

Preliminary data, do not cite
Uncertainty in the Chub-Trout 

Relationship 

Annual Percent Juvenile Chub Survival

Trout in Juvenile Chub Monitoring Reach 18

Preliminary data, do not cite
Annual Juvenile Chub Survival

Trout in Juvenile Chub Monitoring Reach 19

Preliminary data, do not cite

High impact 

on survival

Expected impact on 

survival
High 

target 

survival

Low 

target 

survival

Expected 

target 

survival

Annual Removals

Observed Trout in Juvenile Chub Monitoring Reach 20

Preliminary data, do not cite
Annual Juvenile Chub Survival

Trout in Juvenile Chub Monitoring Reach 21

Preliminary data, do not cite

High impact on 

survival

Expected impact on 

survival

Low impact 

on survival
Presentation Outline

• Importance of cost-effectiveness analysis

• Bioeconomic model with population and 

management components 

• Ongoing and future workplan research

22
Ongoing Workplan Research

• Humpback chub population parameter 

uncertainty

– Identify the importance of parameter uncertainty 

in prioritization of monitoring and research.

• Trout management flows

– Incorporate additional management options and 

associated costs, such as trout management flows 

at GCD, to improve humpback chub survival.

23
Humpback Chub Uncertainty

Adapted from: Yackulic, C. B., M.D., Yard, J. Korman, and D.R. Van Haverbeke. 2014. A quantitative life history of endangered humpback 

chub that spawn in the Little Colorado River: variation in movement, growth, and survival. Ecology and Evolution 4(7): 1006-1018. 24

Preliminary data, do not cite
Parameter Uncertainty

Predictive 

model

Optimal 

policy

Low High

25
Trout Management Flows

Adapted from: Glen Canyon Dam Long-Term Experimental and Management Plan December 2015 Draft 

Environmental Impact Statement http://ltempeis.anl.gov/documents/draft-eis/vol1/Chapter_2-Alternatives.pdf

Example implementation of a two-cycle TMF in June and July with resumption of 

normal fluctuations between cycles and afterward

26
• Rainbow trout management triggers

Future Workplan Research

27
Conclusions

• If trout removals are necessary, they are costeffective when implemented under moderate 

trout numbers, not too high, not too low

• A bioeconomic approach is useful for 

prioritizing research and evaluating 

experiments (e.g., TMFs) or other 

management actions (e.g., removal triggers) 

28