Lees Ferry Trout Fishery 

and Trends Updat

May 2005

Glen Canyon Dam Adapt

Management Program

Technical Work Group
Updates: Status and T

•

Electrofishing catch rates by size 

1991-2004

• Condition Factor (Kn) 1991-200•

Discussion of possible flow, foo

effects
Lees Ferry Electrofishing

Catch per minute

SIZE: 1 <152

Year-Month

J

SEP 20

DEC 1999 MAY 1999 APR 1998 AUG 1997 AUG 1996 DEC 1995 JUL 1994 SEP 1993 NOV 1992 FEB 1992 FEB 1991

95% CI Catch/Minute

6543210

-1

O

MA
Lees Ferry Electrofishing

Catch per minute

SIZE: 2 152-304

Year-Month

SEP 

DEC 1999 MAY 1999 APR 1998 AUG 1997 AUG 1996 DEC 1995 JUL 1994 SEP 1993 NOV 1992 FEB 1992 FEB 1991

95% CI Catch/Minute

543210

-1
Lees Ferry Electrofishing

Catch per minute

SIZE: 3 305-405

Year-Month

SEP 20

DEC 1999 MAY 1999 APR 1998 AUG 1997 AUG 1996 DEC 1995 JUL 1994 SEP 1993 NOV 1992 FEB 1992 FEB 1991

95% CI Catch/Minute

6543210

-1
Condition Factor

N = 2106 2426 1680 3053 2441 5110 2991 3489 2639 3703 

Year

2

2000

1999

1998

1997

1996

1995

1994

1993

1992

1991

95% CI Kn Lees Ferry Equation

888684828078767472
Flows, Density, Growt

Condition

FLOWS

DENSITY

GROWTH AN

CONDITION

SAT

AN

FOODBASE
MEAN ANNUAL FL

Ye

ar

1997 1998 1999 2000 2001 2002 2003 

Mean Flow

22000200001800016000140001200010000

8000
Lees Ferry Electrofishing

Catch per minute

SIZE: 1 <152

Year-Month

J

SEP 20

DEC 1999 MAY 1999 APR 1998 AUG 1997 AUG 1996 DEC 1995 JUL 1994 SEP 1993 NOV 1992 FEB 1992 FEB 1991

95% CI Catch/Minute

6543210

-1

O

MA

High volume years
MEAN MONTHLY F

YR

M

O

JU

L 

JA

N 0

2

JU

L 01

JA

N 01

JU

L 0

0

JA

N 0

0

J

UL 99

JA

N 9

9

JU

L 9

8

JA

N 9

8

J

UL 97

JA

N 9

7

Mean Flow

300002000010000

0

Septe

LSSF
Lees Ferry Electrofishing

Catch per minute

SIZE: 1 <152

Year-Month

J

SEP 20

DEC 1999 MAY 1999 APR 1998 AUG 1997 AUG 1996 DEC 1995 JUL 1994 SEP 1993 NOV 1992 FEB 1992 FEB 1991

95% CI Catch/Minute

6543210

-1

O

MA

High volume years
Lees Ferry Electrofishing

Catch per minute

SIZE: 1 <152

Year-Month

J

SEP 20

DEC 1999 MAY 1999 APR 1998 AUG 1997 AUG 1996 DEC 1995 JUL 1994 SEP 1993 NOV 1992 FEB 1992 FEB 1991

95% CI Catch/Minute

6543210

-1

O

MA

High volume years

LSSF
Mean Daily Flow Ra

Year-Mont

h

J

AN 

J

AN 2002

J

AN 2001

J

AN 2000

J

AN 1999

J

AN 1998

J

AN 1997

Mean Daily Range

2000010000

0

September reference lines LSSF T
Lees Ferry Electrofishing

Catch per minute

SIZE: 1 <152

Year-Month

J

SEP 20

DEC 1999 MAY 1999 APR 1998 AUG 1997 AUG 1996 DEC 1995 JUL 1994 SEP 1993 NOV 1992 FEB 1992 FEB 1991

95% CI Catch/Minute

6543210

-1

MA

High volume years

LSSF 
MEAN MONTHLY F

YR

M

O

JU

L 

JA

N 0

2

JU

L 01

JA

N 01

JU

L 0

0

JA

N 0

0

J

UL 99

JA

N 9

9

JU

L 9

8

JA

N 9

8

J

UL 97

JA

N 9

7

Mean Flow

300002000010000

0

Septe

LSSF
Maximum daily flow by mo

January reference linesYear-Month

JAN 20

JAN 2001

JAN 2000

JAN 1999

JAN 1998

JAN 1997

Max Maximum daily flow

5000040000300002000010000

0
Minimum Daily Flows by Y

January Reference Lines

Year-Month

JAN 200

JAN 2001

JAN 2000

JAN 1999

JAN 1998

JAN 1997

Min Minimum daily flow

300002000010000

0
STAGE DISCHAR

RELATIONSHIP LEES 
Possible foodbase cha

•

Mudsnails?

•

Possible changes in species com

and community structure of inve(Gammarus

– chironomids?)

•

Wetted perimeter effects?

•

Possible changes in community 

aquatic plants