Translocation of humpback chub (G

above Chute Falls, Little Colorad

Pamela Sponholtz, Dennis Stone

Arizona Fish and Wildlife Conservation 

Glen Knowles

Ecological Services
• December 2002 Biological Opinion “to increase 

survival from floods, reduce predation...”

• Up to 300 fish

• November 2004 Biological Opinion “increase 

survival from high mortality area to good nursery area”

• Up to 600 fish

Chute Falls Project
HBC distribution

•Physical Barrier: Chute Falls

Robinson (1996)

•Chemical Barrier: CO2 levels

Mattes (1993); Strength (1997)

•Do migrate but are pushed downstream via floods and/or rising CO2 concentrations

•Lack of imprinting
Capture Site




Objectives

• 1) Determine if transplanted humpback c

survive and remain above Chute Falls

• 2) Determine if humpback chub will grow 

Chute Falls 

• 3) Determine if any transplanted YOY hu

chub will recruit to adulthood above Chu

• 4) Determine if a humpback chub spawn

population will develop above Chute Fal

• 5) Develop population estimates for fish 

Falls

Translocations

• August 2003, 2004, 2005• Collect 50-100mm HBC near 

confluence

• Implanted with visible elastomer tags• Released 1148 HBC above Chute 

Falls
The 2003-05 findings were insi

• Translocated humpback chub were 

growing extremely fast 

• Many were becoming reproductive 

adults

• Many “unknown origin” chub were 

caught by fall 2005! 

• Could have been previously 

translocated, progeny thereof, and/or upriver migrants

350 m

at 
Growth Comparison

Translocation and Monitoring T

TR03 FA03SP04TR04FA04SP05TR05

0

50

100150200250300350

Translocated 2003Translocated 2004Translocated 2005

Mean Total Length (mm)
2003 2004 

Growth rate (mm/month +/- SE)

02468

101214

Lower 14km LCR

Growth Rates for Translocat
2006-2007 Captures

• Numerous adult humpback chub that were f

gametes 

• Three non-translocated YOY progeny• Four adult humpback chub moved above Ch

originally been captured, tagged, and releasFalls

• Fish above Chute Falls, appear to be movin
Chute Falls

3 YOY Hum

Recapture trip (June 26-July 2, 

13.57 13.77 13.89 14.02 14.10 14.19 14.54 14.76 15.61 15.90 16.19 16.5

100

80604020

0

YO
2003-05 translocations of 1,150 

YOY humpback chub

May 2000 June 2006 June 2007

Total unique humpback chub 

350300250200150100

50

0

Humpback chub are migrating d

Translocations
2006 2007

Abundance Estimate (SE)

0

100200300400500600700800

Lower Atom to Chute Falls

Above Chute Falls

Population Estimates
Benefits of Chute Falls 

• Increased abundance of 

HBC

• 2yr old fish >200mm• Reduced mortality of YOY 

chubs

• Increased historical range 

by 4km

• Better understanding of life 

history
2001 2002 2003 2004 2005 

Abundance Estimate (+/- SE)

500

10001500200025003000

Lower LCR Population Estimates fo
Benefits of Chute Falls 

• Increased abundance of HBC• 2yr old fish >200mm• Reduced mortality of YOY chubs• Increased historical range by 4k• Better understanding of life histo
Why we propose transloc

2008 and 2009

• Conservation Measure for 2008 BO • Increase survivorship of small fish..offset lo

mainstem

• Chute Falls fish have slightly less genetic d

Willow Beach fish

• Fewer fish above Chute Falls, geomorphol

numbers moving upstream

• Draft Genetics Management Plan Recomm

» Provide for an influx of fish to span a ge» Establish a reasonable approximation of » Normal size, age distribution and gene f» Additional 300 YOY should be moved in 
Total Length (mm)

Number of Unique Humpback Chub 102030

40

Below Chute (Marking trip) Above Chute (Marking 

Below Chute (Recap trip) Above Chute (Recap 

100 200 300 400

10203040

100 200 

2007
The Future

• Maintain Chute Falls population until:

• Mainstem reproduction increases and replac

contribution

• Other tributaries and translocations are comp• Spawning and rearing occurs in other parts o

outside of the LCR

• Continuing monitoring above Lower Ato

• In conjunction with monitoring that occurs in 

LCR 

• Until number of fish above falls is no longer i

recovery and conservation perspective