Monitoring Humpback Chub

Aggregations in the Mainstem

1991‐2015

Kirk Young

David Van Haverbeke

Mike Dodrill

William Persons
Objectives

• Obtain relative abundances (CPUEs) of humpback 

(HBC) at aggregation sites and compare to former 

• Provide HBC length frequencies and other informa

• Investigate utility of PIT antennas, seining, and e‐fi

In addition:

• Only study that focusses on HBC throughout the m

• Helps to monitor other recovery actions (transloca• Information for recovery purposes.
Aggregation

“a consistent and disjunct group of fish with 

significant exchange of individuals with otheaggregations, as indicated by recapture of PI

juveniles and adults and movement of radio‐

adults” (Valdez and Ryel 1995).
Map courtesy of Tom Gushue, GCMR

52

3,482

57

98

13

5

Valdez and Ryel 1995Population estimates 30M

LCR

BAC

SHI

MGG

HAV

PUM

STE
Methods

• Period 1 (1991‐1993) ‐ Mostly trammel nettin

West, Valdez and Ryel 1995).

• Period 2 (2002‐2006) ‐ Trammel netting AND 

hoop netting (SWCA, Ackerman 2008).

• Period 3 – (2010‐2014) Trammel netting and 

hoop netting (USGS and USFWS, Persons et a

review).

• 2015 – Continued baited hoop netting, minim

trammel netting, added investigation of seini

remote antennas, and e‐fishing.
Hoopnet CPUE by 3 Periods and 2

Provisional: 
Hoopnet CPUE by 3 Periods and 2

Provisional: 
HBC Aggregation Hoop & Trammel CPU

combined by year (excluding LCR aggrega
HBC & FMS Aggregation CPUE combined by yea

Hoop & Trammel (excluding LCR aggregation)
HBC, FMS & RBT Aggregation CPUE combined by y

Hoop & Trammel (excluding LCR aggregation)
Observations from CPUE

• Hoopnet CPUEs for HBC generally incre

the aggregations post‐ 2009 timeframe

• The significant increase of 2015 CPUE fo

aggregation suggests unusually strong e

from LCR (i.e., may be related to 2015 l

abundance).

• Significant increase in 2015 CPUE at Pu

Provisional: Do not use or cite
Seining
Provisional: Do not use or cite

Spatial Look at Seining Results
2015 length frequencies of HBC by size 

Hoop netting (red) and seining (blue
Large adult HBC from 34 mile (L

Redwall dripping springs area

Photo by D. Van 
Provisional: Do not use or cite

30M

LCR

BAC

SHI

STE

MGG

HAV
Observations from 2015

Hoop Net & Seining

• Large group of adult HBC ≥200 mm near 34 m

300, CI = 109‐491, estimated from 2014 close

recapture).

• Many HBC in the LCR aggregation – possible e

from LCR.

• Very few age‐0/juvenile HBC seen until below 

(~80 miles downriver) suggesting: 1) not via L

export, and 2) spawning in or below Havasu.

• Age‐0/juvenile HBC also seen again well belo

Diamond Creek – suggesting local mainstem

spawning in western Grand Canyon. 
Submersible antennas
ANTENNA

• Marsh & Associates Ante

• 1.0m x0.6 m rectangular 

(multi ‐ sizes available)

• 7.4 v Li‐ion Removable B

• 38‐60 cm detection• 10+ days battery life 

• < ~10 m depth• $2,400 each
September 2015 Antennas (7) 

Combined with hoop net data, Recaptures: 

Captures

& Detections of Unique Recaps Only (PITTAG_RECAP

= Y

Species Antenna Only Hoopnet Only Both 

n

% of total

n

% of total

n

% of total

BNT

2 100.0

0 0.00

0 0.0

CRP

2 66.7

1 33.3

0 0.0

FMS 219 42.5 255 49.5 41 8.0 

FRH

0 0.0

1 100.0

0 0.0

HBC 274 57.9 173 36.6 26 5.5 

RBT

9 100.0

0 0.0

0 0.0

UNK 42 100.0

0 0.0

0 0.0 

Total 548 52.4 430 41.1 67 6.4 

Provisional: Do not use or cite
2015 Agg Trip Catches by Gear

Gear

Species Hoop Seine E‐fishing Antenna 

Bluehead SuckerBrown TroutChannel CatfishCommon CarpFathead MinnowFlannelmouth SuckerHumpback Chub

Plains KillifishRainbow TroutRed ShinerSpeckled DaceUnidentified SuckerUnknown species

5

1

0

7

2

1991

353

0

23

0

257

0

0

74

1

1

4

183

1642

210

6

22

33

1304

23

0

50004

97

3010

148

00

0 2 0 1 0 

259 

299 

0 5 0 0 0 

49 

Totals 2639 3503 258 615 

Provisional: Do not use or cite
Future directions

• Continue hoop netting, seining, and remote anten

Minimize or eliminate trammel nets.

• Eliminate e‐fishing. Very few chub captured (only 3

logistically complex, safety factor.

• If abundance estimates are desired, an absolute m

of 2‐trips/year would be needed for open robust m

(more likely 3 trips or more, as in Westwater/Black

Canyon).

• Interest in release and tracking of sonic tagged adu

western Grand Canyon (spawning sites, movemen

Provisional: Do not use or cite
Thank You

Photo by D. Van Hav
Provisional: Do not use or c
September 2015 Antennas (7)

Combined with hoop net data total capture (ant. detecdetections and new PIT tags): 

Species

Hoop Net Only Antenna Only Both 

Captures

% of Total Contacts

% of Total Cap/Contact

% of T

BHS

5 100%

0 0%

0 0%

BNT

1 33%

2 67%

0 0%

CRP

5 83%

1 17%

0 0%

FMS 1799 90% 209 10% 50 2% 

FRH

5 100%

0 0%

0 0%

HBC 323 54% 273 46% 26 4% 

RBT

0 0%

5 100%

0 0%

UNK

0 0% 49 100%

0 0% 

TOTAL 2138 80% 539 20% 76 3% 

Provisional: Do not use or cite