Trends in the Recruitme

Abundance of the Little Colo

Population of Humpback 

Lew Coggins

Grand Canyon Monitoring and Resea

and

Carl Walters

University of British Columb
Presentation Outlin

•

Stock Assessment/Population Dyn

Primer

•

Partial History of HBC Research in 

Canyon

•

Program Supertag
Definitions

• Stock Assessment

– Stock assessment involves the use of va

and mathematical calculations to estimacurrent abundance and productivity of a population. The ultimate goal of stock aconstruct quantitative predictions about fish populations to alternative managem

• Population Dynamics 

– Population dynamics is the study and m

representation of how and why a popula
Definitions

• Cohort or Year Class

– Animals resulting from reproduction du

year.

– Principle: Once established, cohorts can 

in number.

• Recruitment (Recruits)

– All animals entering a particular size or 

population.

– For program supertag, recruits are defin

• Recruitment Anomalies

– Deviations from an average recruitment– Ri = Ro * Recanomi

• Brood Year

– Year in which a particular cohort was sp
Stock Assessment Elem

•

Clear definition of the stock

–

Geographic boundaries, movement, spawning anlocations, etc.

•

Abundance and demography

–

Catch per uni

t effort indices

–

Mark-recapture population estimati

o

n

•

Recruitment and recruitment variability

–

Spawner-recruit relationships

–

Spawner abundance, fecundity, maturity, spawn

information, early life mortality.

•

Mortality

–

Early-life, juvenile, adult

•

Effect of management actions on recruitme

–

Allows projections
Assessing Abundanc

•

Catch per unit effort (CPUE) index

–––

C is catch, q is catchability coefficient, E 

abundance, U is CPUE

–

Problem is that q is not always constant

•

q can be a function of time, abundance, envi

–

Basing management decisions solely on 

(or lack of trend) can be dangerous

C

= qEN

qN

E

C

U

=

=
Assessing Abundanc

•

Estimating Abundance via Mark

–

Closed population models

•

Estimate abundance but not mortality 

recruitment.

•

Chapman-Peterson, Schnabel, Progra

–

Open population models

•

Estimate abundance, mortality, or rec

•

Jolly-Seber, Cormack-Jolly-Seber, H

Method
Presentation Outlin

•

Stock Assessment/Population Dyn

Primer

•

Partial History of HBC Research in 

Canyon

•

Program Supertag
HBC Research in Grand 

• 1944 Species Description (Miller 194• 1944-80 Various researchers documenti

occurrence and distribution (StRathbun 1967-69; Holden and 1975; Suttkus and Clemmer 19Minckley and Blinn 1976; Min1975,1977, 1979; Carothers et 

• 1980-82 LCR Investigations (Kaeding & 

1983)

• 1984-87 GCES Phase I (Maddux et al. 1• 1987-90 LCR Investigations (Minckley1

Kubly 1990)

• 1990-95 Phase II (BioWest, USFWS, A• 1995-01 Transitional/Monitoring (AGF

SWCA, ASU, Hualapai)
HBC Research in Grand 

Grand Canyon, Arizona

X

X

XX

X

X

X
HBC Abundance Estimation Gran

2001 May LCR >150 mm 2000 USFW

2000 Oct. LCR >135 mm 1600 Coggin

1992 May LCR >150 mm 4508 Dougla

1989 May LC

R Confluence >150 mm 10120 Minckl

1992 May LC

R Confluence >150 mm 1320 Dougla

1990 May LCR >150 mm 11985 Minckl

1990 May LC

R Confluence >150 mm 6492 Minckl

1989 May LCR >140 mm 25000 Kubly 

1989 May LCR >150 mm 18253 Minckl

1988 May LC

R Confluence >140 mm 2900 Kubly 

1988 May LC

R Confluence >120 mm 7060 Minckl

1987 May LC

R Confluence >140 mm 1800 Kubly (

1987 May LC

R Confluence >120 mm 5783 Minckl

1982 May LCR >200 mm 7500 Kaedin

Year Month Location Size Estimate Source
HBC Abundance Estimation Gran

ValdPopu

Pumpkin Spring >200 mm

5

Aggregation

1991-93 All

ValdPopu

Ha

v

asu Inflo

w >200 mm 10

Aggregation

1991-93 All

ValdPopu

Shinumo Inflow >200 mm 55Aggregation

1991-93 All

ValdPopu

1991-93 All LCRI Aggregation >200 mm 3000-4000

ValdPopu

30-Mile >200 mm 55Aggregation

1991-93 All

ValdPopu

1993

? MGG Aggregation >200 mm 68-155

ValdPopu

1991-93 All LCRI Aggregation >200 mm 3200

Year Month Location Size Estimate Sour
Presentation Outlin

•

Stock Assessment/Population Dyn

Primer

•

Partial History of HBC Research in 

Canyon

•

Program Supertag
Background

Grand Canyon, Arizona
Motivation

• Little Colorado River Humpback Chu

– After 20+ years of study, we did n

clear understanding about the statuof the population

– Need to reanalyze existing data to 

it was possible to reconstruct popu
Background
Background
Background
Background
Background
30MI 

LCR LCRIN UGG BAC SHM SHMIN STEPH-CMGG KAN KANIN HAV HAVIN BLOHAV 

Stock Definition

Tag-Recapture Matrix 

-Pit Tag Data from 1989-2000

Tag Location Total Tagged 30MI LCR LCRIN UGG BAC SHM SHMIN STEPH-CONQ MGG KAN K

30MI 34 16 1 0 0 0 0 0 0 0 0 LCR 11779 1 12032 766 3 0 0 0 0 0 0 LCRIN 1158 0 883 257 0 0 0 0 1 1 0 UGG 43 0 2 0 2 0 0 0 0 1 0 BAC 2 0 0 0 0 0 0 0 0 0 0 SHM 18 0 0 0 0 0 2 1 0 0 0 SHMIN 47 0 0 0 0 0 0 15 0 0 0 STEPH-CONQ 32 0 0 0 0 0 0 0 3 1 0 MGG 181 0 0 0 0 0 0 1 1 75 0 KAN 1 0 0 0 0 0 0 0 0 0 0 KANIN 5 0 0 0 0 0 0 0 0 0 0 HAV 42 0 1 0 0 0 0 0 0 1 0 HAVIN 4 0 0 0 0 0 0 0 0 0 0 BLOHAV 8 0 0 0 0 0 0 0 0 0 0 Total 13354 17 12919 1023 5 0 2 17 5 79 0 RED is Downstream MovementYELLOW is Upstream MovementGrey is "no movement"

Recapture Location
Methods–Supertag Model Deve

Hilborn’s Method (1990)

Population 

dynam

ics 

model

Statistical

compariso

Observation

model

(e.g. Mark-Rate) 
Methods–Supertag Model Deve

Ro

Recruitment

Anom

aly

Year 12345

1.919 1989 18540 4080 1567 754 410 21.278 1990 35571 4080 1567 754 410 2

2.435 1991 23695 7831 1567 754 410 2

0.167 1992 45147 5215 3007 754 410 2

0.594 1993 3098 9938 2003 1447 410 20.364 1994 11006 682 3816 964 787 2

0.216 1995 6740 2422 262 1837 524 40.853 1996 4002 1484 930 126 998 30.648 1997 15820 882 570 448 68 5

1.000 1998 12012 3508 339 274 243 

1.000 1999 18540 2690 1347 163 149 

2000 18540 4202 1033 648 89 

Ag

e

0

0 . 10 .

2

0 .

3

0 .

4

0 .

5

0 .

6

0 . 70 .

8

0 .

9

0

5 1 0 1 5 2 0 

A g

e

Proportion

A nnual D eat h F r a c t io n

A nnual S u r v iv a l F r a c t io n
Methods – Data Typ

• Length Frequency and Catch Rate (C

– Did not use due to inconsistencies in sam

protocols

• Mark-Recapture (PIT Tags)

– 1989 – 2000 mark-recapture data from t

Colorado River and mainstem Colorado to 68).

– 12,937 fish marked, 13,948 recaptures (

multiple recaptures)
Results – Recruitment T

Supertag Estimates of Age-1 HBC Recruitmen

0

100002000030000400005000060000

1989 1990 1991 1992 1993 1994 

Brood Year

Abundance
Results – Recruitment T

AGE-1 HBC Recruitm

Supertag versus C

0

100002000030000400005000060000700008000090000

1986

1987

1988

1989

1990

1991

1992

1993

Broo

Abundance

• Spring/Summer hoopnet 

CPUE indices of AGE-1 in the Little Colorado River

• AGFD data is longest and 

most consistent sampling protocols over time (lower 1200 meters)

• USFWS data primarily 

from two locations in the Little Colorado River(3 km and 11 km)

• Catch-rate scaled to 

abundance by calculating catchability coefficient
Supe

rta

g E

stimate

s of A

g

e-1 H

C

PUE o

f Unma

r

k

0

100002000030000400005000060000700008000090000

1987

1988

1989

1990

1991

1992

1993

B

rood Y

e

Abundance

SuUn

Results –

Recruitment T

•

Annual hoopnet 

CPUE of unmarked AGE-2 fish in the Little Colorado River

•

Humpback chub 

reach tagging size (150 mm) at Age-2.

•

Suggests 1993 

cohort suffered increased mortality as compared to the 1991 cohort
Results – Abundance T

Estimated Abundance of Humpback Chub > 150** m

0

100020003000400050006000700080009000

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

Supertag

Douglas and Marsh Mbh (1996)

Douglas and Marsh Mo (1996)

USFWS 2001

Kaeding and Zimmerman (1982)

Average 89-91

Ro

Average 92-97

Fit USFWS

** Kaeding & Zimmerman estimate for HBC 
Presentation Outlin

•

Stock Assessment/Population Dy

Primer

•

Partial History of HBC Research in 

Canyon

•

Program Supertag

–

Background and Motivation

–

Development and methods

–

Results Humpback Chub

–

Results Flannelmouth Sucker

–

Conclusions
Background
MODELED FMS RECRUITM

(LCR SECTION)

0

500

10001500200025003000

1990 1991 1992 1993 1994 1995 1996 

B

rood YE

A

R

RECRUITMENT 
MODEL RECRUITMENT AND CPUE OF 

(ASU LCR HOOP NET DATA AND AGFD LOWER 1200M H

0

0.0010.0020.0030.0040.0050.006

1990 1991 1992

1993

1994

1995

1996

1997

B

rood Y

e

a

r

CPUE Age 1 FMS
LCR ESTIMATION OF FMS POP

>150 mm

(Douglas and Marsh 1998)

10001500200025003000350040004500

1990 1991 1992 1993 1994 1995 1996 1997 

YEAR

POPULATION ESTIMATE

D

M
Conclusions – HBC Population 

• Data sources suggest that post-1993 re

lower than pre-1992 recruitment.

• A Few Hypotheses :

– Predation or Competition

• Mainstem Colorado• Little Colorado River
Conclusions – HBC Population D

Estimated Humpback Chub Recruitment versus Rainbow T

0

5000

100001500020000250003000035000400004500050000

1989

1990

1991

1992

1993

1994

1995

1996

1997

Brood Year

Humpback Chub Recruitmen
Conclusions – HBC Population D

Estimated Humpback Chub Recruitment versus Brown T

0

5000

100001500020000250003000035000400004500050000

1989

1990

1991

1992

1993

1994

1995

1996

1997

Year

Humpback Chub Recruitmen
Conclusions – HBC Population 

• Data sources suggest that post-1993 re

lower than pre-1992 recruitment.

• A Few Hypotheses:

– Predation or Competition

• Mainstem Colorado• Little Colorado River



Conclusions – HBC Population 

• Data sources suggest that post-1993 re

lower than pre-1992 recruitment.

• A Few Hypotheses:

– Predation or Competition

• Mainstem Colorado• Little Colorado River

– Hydrology

• Dam Operations (Research & interim Flows 

EIS ROD)
Conclusions – HBC Population D

Supertag Estimates of Age-1 HBC Recruitment by 

versus Mainstem Flow

0

100002000030000400005000060000

1/1/1975

1/1/1977

1/1/1979

1/1/1981

1/1/1983

1/1/1985

1/1/1987

1/1/1989

1/1/1991

1/1/1993

1/1/1995

1/1/1997

Date

Abundance
Conclusions – HBC Population 

• Data sources suggest that post-1993 re

lower than pre-1992 recruitment.

• A Few Hypotheses:

– Predation or Competition

• Mainstem Colorado• Little Colorado River

– Hydrology

• Dam Operations (Research & interim Flows 

EIS ROD)

• Little Colorado River Hydrology (1992 poor 
Conclusions – HBC Population D

Supertag Estimates of Age-1 HBC Recruitment by Broo

versus LCR Flow

0

100002000030000400005000060000

Jan-88

Jan-89

Jan-90

Jan-91

Jan-92

Jan-93

Jan-94

Jan-95

Jan-96

Jan-97

Jan-98

Brood Year

Abundance
Conclusions – HBC Population 

• Data sources suggest that post-1993 re

lower than pre-1992 recruitment.

• A Few Hypotheses:

– Predation or Competition

• Mainstem Colorado• Little Colorado River

– Hydrology

• Dam Operations (Interim flows August 199• Little Colorado River Hydrology (1992 poor 

– Parasitism

• Asian Tapeworm

– Is this just natural variability?
Conclusions – HBC Population D

Humpback chub

0

0.05

0.1

0.15

0.2

0.25

0 5 10 

Age (yr.)

Proportion of fish
Conclusions – HBC Population 

• Data sources suggest that post-1993 re

lower than pre-1992 recruitment.

• A Few Hypotheses:

– Predation or Competition

• Mainstem Colorado• Little Colorado River

– Hydrology

• Dam Operations (Interim flows August 199• Little Colorado River Hydrology (1992 poor 

– Parasitism

• Asian Tapeworm

– Is this just natural variability?– Others and interactions