State of the Fishery 

Lees Ferry 

(TWG Meeting April 2015)

Bill Stewart 
 NPS Comprehensive Fish Management 

 Low recruitment <20% for 3 consecutive ye Low population < 1 fish/min for 2 consecut

years

 Low angler catch rates <0.5 fish/hr for two 

consecutive years
0

12345678

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 20

Electrofishing History 

(preliminary data)
0

2468

10121416

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 

33%

16% 55%

15% 

3

80%

78%

65%

91%

36% 29% 62%

Recruitment History 

(preliminary data)
0

0.5

1

1.5

2

2.5

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

Angling History 

(preliminary data)
0.8

0.85

0.9

0.95

1

1.05

1.1

1.15

1.2

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2

Fish Condition History 

(preliminary data)
Dissolved Oxygen

TempConductivity

Preliminary Data
Current Status (angler catch rat

 Boat anglers

 24 year ave = 1.04 Oct - Dec 2014 = 1.82 Jan - March 2015 = 1.35

 Walk-in anglers

 4 year ave = 1.03 Oct - Dec 2014 = 1.08 Jan - March 2015 = 0.12

Preliminary data-do not cite
0.80

0.850.900.951.001.051.101.15

Rainbow trout relative condition (Kn) 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15

Year

1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 

0.70.80.91.01.11.21.31.4

sub-adult>=152 < 305 mm

adult304.99-404.99 mm

big>405.99 mm

Current status 

(spring fish condition)

12-16 inch fish•24 yr mean = 0.99 •2015 = 0.89

Preliminary data-do not cite

6-12 inch fish•24 yr mean = 1.01 •2015 = 0.88
Trip sample date

1/1/01 1/1/02 1/1/03 1/1/04 1/1/05 1/1/06 1/1/07 1/1/08 1/1/09 1/1/10 1/1/11 1/1/12 1/1/13 

CPUE 

(rainbow trout/minute)

02468

1012141618

SpringSummerAutumnWinter

Preliminary data-do not cite 

E-fishing
Summary of Current Status

 Spring e-fishing CPUE declining since 

but still above mid-2000 levels

 Spring fish condition lowest since 1991 Anger catch rates dropping, but still hi

boat anglers. Very low for walk-in ang
U.S. Department of the Interior

U.S. Geological Survey

Lees Ferry and Marble CanyoRainbow Trout UpdateTWG Meeting, April 2015Scott VanderKooiSouthwest Biological Science CenterGrand Canyon Monitoring and Research Center
Reach I

Apr12

Jul12

Sep12

Jan13

Apr13

Jul13

Sep13

Jan14

Apr14

Jul14

Sep14

Jan15

5

1015202530

Reach II

Apr12

Jul12

Sep12

Jan13

Apr13

Jul13

Sep13

Jan14

Apr14

Jul14

Sep14

Jan15

2468

10121416

Reach III

Apr12

Jul12

Sep12

Jan13

Apr13

Jul13

Sep13

Jan14

Apr14

Jul14

Sep14

Jan15

12345

Re

Apr12

Jul12

Sep12

Jan13

Apr13

0.40.60.81.01.21.41.61.8

Re

Apr12

Jul12

Sep12

Jan13

Apr13

0.20.40.60.8

Trip

Abundance ('000s per km)

Rainbow Trout Abundance Estimates By 

I – Glen Canyon/Lees FerryII – House RockIII – Buck FarmIVa – Upstream of LCRIVb – Downstream of LCR

(Preliminary Data from Korman and Yard 201

Considerab

abundance in 

Sept. 14 – J

Jan. 15 estim

of LCR below 
Rainbow Trout Abundance Estimates in Gle

Total Abundance ('000s)

Apr12

Jul12

Sep12

Oct12

Dec12

Jan13

Apr13

Jul13

Sep13

Oct13

Dec13

Jan14

Apr14

Jul14

Sep14

Oct14

Dec14

Jan15

0

200400600800

10001200

(Preliminary Data from Korman and Yard 201

Rainbow Trout abunda

Canyon has declined b

80% since early 20

abundance was the h

observed. Abundance lik

in 2015, approaching pa

goal of 100,000 trout a
Rainbow Trout Abundance Estimates in Gle

By Size Class

(Preliminary Data from Korman and Yard 201

Abundance by Size Class ('000s)

Apr12

Jul12

Sep12

Oct12

Dec12

Jan13

Apr13

Jul13

Sep13

Oct13

Dec13

Jan14

Apr14

Jul14

Sep14

Oct14

Dec14

Jan15

0

100200300400500600 100

150200250300

75-125 mm

125-175 mm175-225 mm225-275 mm

> 275 mm

Declines in overall R

abundance from sp

summer 2014 due to 

numbers of smaller fi

Declines since due to 

numbers of larger fis

2011 year class 

(mostly)
Rainbow Trout Early Life Stage St

Redd Counts

(Preliminary Data from Avery and Foster 20

Estimated # of redds

Number of redds 

most similar to 2

low redd counts d

result in low juven
Rainbow Trout Early Life Stage St

Age-0 Population Estimates

Year and Month of Survey

Thousands of Fish

(Preliminary Data from Avery, Foster, and Korman 20

2010

Low redd

counts

Relatively h

abundance in N

despite low redd 

due to compen

related to lo
Preliminary Findings:

 Rainbow Trout

 Decline in abundance at all Natal Origins s

reaches (Sept. 2014 – Jan. 2015)

 Low redd counts to date, similar to 2010 >80 % decline in abundance in Glen Canyo

spring 2012

 Initially due to declines in numbers of small fish

recent changes due to fewer large fish

 Initial observations from April trip

 Continued declines in catches in most reaches; 

change upstream, little change near LCR conflu

 Apparent shift in size/age structure, now domin

small/young fish

 Condition of smaller fish appears to be good, ne

review data to confirm
Quest
 NPS Comprehensive Fish Management P

 Low recruitment <20% for 3 consecutive years Low population < 1 fish/min for 2 consecutive  Low angler catch rates <0.5 fish/hr for two 

consecutive years

 Preliminary Lees Ferry Fish Plan goals an

objectives

 Maintain recruitment between 20-50% Angler catch rates > 1 fish/hr Angler catch rates for 20”+ fish 1/day Summer fish condition > 1.0 Increase EPT such that index is >0 Matintain DO levels >5 mg/L out of GCD
0

12345678

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 

<20%

<20%

<20%

<20%

<20%

>50%

>50%

>

>50%>50%

Electrofishing History 

(preliminary data)
0

0.5

1

1.5

2

2.5

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

Angling History 

(preliminary data)
0.8

0.85

0.9

0.95

1

1.05

1.1

1.15

1.2

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2

Fish Condition History 

(preliminary data)