U.S. Department of the Interior

U.S. Geological Survey

Colorado River fish monitoring in Grand 

Canyon, Arizona: 2002-2012 humpback 

chub, Gila cypha, aggregations.

William R. Persons1 and 

David R. VanHaverbeke2

1U.S.G.S. Grand Canyon Monitoring and Research 

Center

2 U.S. Fish and Wildlife Service
Aggregation: 

“a consistent and disjunct group of 

fish with no significant exchange of 

individuals with other aggregations, 

as indicated by recapture of PITtagged juveniles and adults and 

movement of radio-tagged adults”

(Valdez and Ryel, 1995). 
Aggregation Abundance 95% C.I.

30-Mile 52 24-136

Little Colorado River Inflow 3,482 2,682-4,281

Lava Chuar to Hance -

Bright Angel Creek Inflow -

Shinumo Creek Inflow 57 31-149

Stephen Aisle -

Middle Granite Gorge 98 74-153

Havasu Creek Inflow 13 5 - 70

Pumpkin Spring 5 4-16

1993 Aggregations
52

3,482

57

98 13

5

Aggregations 1993
METHODS (1): Generate pooled capture 

probabilities estimates

Data from 2002-2012 consecutive years (2002-2004 Ackerman 2008).

Years Marks Captures Recaptures p1 mark 

rate

p2 recap 

rate

2002 - 2003 31 46 3 0.065 0.097

2003 - 2004 46 29 2 0.069 0.043

2010 - 2011 168 141 8 0.057 0.048

2011 - 2012 141 99 5 0.051 0.035

Pooled 386 315 18 0.057 0.047
METHODS (2): Generate abundance 

estimates

Abundance = Catch / p

16 / 0.0507 = 280

16 / 0.0407 = 343

Average = (280 + 343)/2 = 312
Catches of humpback chub 2002-2012.
Abundance estimates 1993-2012.
52

3,482

57

98 13

5

Aggregations 1993
2012 Aggregations

565

545 526

10,000

58

117
Location of tagging and recapture, 

humpback chub 1989-2012.

Location recaptured

Location 

tagged

Number 

Marked 30M LCR LCR 

reach LCH BAC SHI STE MGG HAV PUM Total FIDELITY

30M 61 36 2 2 - - - - - - - 40 59%

LCR 38,502 3 33,841 2,720 73 3 4 2 4 3 - 36,656 88% 

LCR reach 4,698 1 1,934 1,870 16 1 1 - 1 2 - 3,826 40%

LCH 271 - 47 22 10 - - - - - - 79 4% 

BAC 22 - 1 - - - - - - - - 1 -

SHI 1,001 - - - - - 71 1 2 - - 74 7% 

STE 76 - 1 1 - - - 1 2 - - 5 1% 

MGG 314 - - 1 - - 1 1 87 1 - 92 28% 

HAV 617 - 4 - - - - - - 14 - 18 2% 

PUM 27 - - - - - - - - - 2 2 7% 

Total 45,589 40 35,831 4,616 99 5 77 5 96 23 2 40,799 
Location of tagging and recapture, 

humpback chub 1989-2012.

Location recaptured

Location 

tagged

Number 

Marked 30M LCR LCR 

reach LCH BAC SHI STE MGG HAV PUM Total FIDELITY

30M 61 36 2 2 - - - - - - - 40 59%

LCR 38,502 3 33,841 2,720 73 3 4 2 4 3 - 36,656 88% 

LCR reach 4,698 1 1,934 1,870 16 1 1 - 1 2 - 3,826 40%

LCH 271 - 47 22 10 - - - - - - 79 4% 

BAC 22 - 1 - - - - - - - - 1 -

SHI 1,001 - - - - - 71 1 2 - - 74 7% 

STE 76 - 1 1 - - - 1 2 - - 5 1% 

MGG 314 - - 1 - - 1 1 87 1 - 92 28% 

HAV 617 - 4 - - - - - - 14 - 18 2% 

PUM 27 - - - - - - - - - 2 2 7% 

Total 45,589 40 35,831 4,616 99 5 77 5 96 23 2 40,799 
Increasing abundance:

 Warmer than normal water during 2004, 2005, 

2011

 Translocations 

 Shinumo Creek 

 902 fish 2009-2011

 Havasu Creek

 543 fish 2011-12

 Mechanical trout removal at LCR confluence 

2003-2006, 2009

 Good production from Little Colorado River
Future Directions:

 Increase sampling effort at areas outside of 

discrete aggregations during 2013-14.

 Humpback chub natal origins project 2013-14.

 Otolith microchemistry, ultrasound.