STATE OF CHINOOK SALMON IN LAKE HURON

in1999 BY:

Jim Johnson, Michigan Department of Natural Resources

Lloyd Mohr, Ontario Ministry of Natural Resources

Greg Wright, Chippewa Ottawa Fishery Resource

Authority

CHINOOK STOCKING TRENDS LAKE HURON, ALL AGENCIES

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2

CREEL CENSUS BEGINS20% reductionin stocking

ESTIMATED CHINOOK HARVEST (KG), GEORGIAN BAY & MAIN BASIN L. HURON

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1991 1992 1993 1994 1995 1996 1997 1998 1999

Yie

ld (k

g)

Comm. USEscap USM Basin USM. Basin CAGeorgian B

1

MEANS, 1991-99:935,600 KG

2,062,625 LB147,330 STONE

935,601 kg average

Salmonine objective is 2.4 million kg

CHINOOK CATCH AND CATCH RATES, INDEX PORTS, MAIN BASIN LAKE HURON

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

86 87 88 89 90 91 92 93 94 95 96 97 98 990

2

4

6

8

10

12

Total catch Catch rateCATCH/100 HRNO. HARVESTED

1

Chinook Salmon Catch Rates on LakeMichigan Compared to Lake Huron

Charlevoix Fisheries StationCHSMIHU

0.0

2.0

4.0

6.0

8.0

10.0

12.0

868788929394959697989900

No

. pe

r 10

0 A

ng

ler H

rs.MichiganHuron

TRENDS IN RECREATIONAL EFFORT, INDEX PORTS, MAIN BASIN LAKE HURON

0200,000400,000600,000800,000

1,000,0001,200,0001,400,0001,600,0001,800,0002,000,000

86 87 88 89 90 91 92 93 94 95 96 97 98 99

Hours

1

Mean = 1.65 million hours

Mean = 1.12 million hours

Why the rise in Lake Huron chinook catch rates?

The answer probably includes:

•Increase in pen culture•Increase in vulnerability

OPEN-WATER RETURNS/100,000 STOCKED,

0

20

40

60

80

100

120

140

Pen Conventional

Age-1Age-2Age-3Age-4

YEAR CLASS: 1993Released from pen vs. conventional

•Chi-square significant between pen & conventional

6

Total = 293.1

Total = 154.7

OPEN-WATER RETURNS/100,000STOCKED

0

20

40

60

80

100

120

140

160

Pen Conventional

Age-1Age-2Age-3Age-4

YEAR CLASS: 1994Pen reared & trucked to lake vs. conventional

Chi-square significantbetween pen & conventional

6

Total = 332.6

Total = 98.3

MEAN WEIGHTS (KG) OF CHINOOK HARVESTED, MICHIGAN RECREATIONAL

CATCH, MAIN BASIN LAKE HURON

4.04.24.44.64.85.05.25.45.65.86.0

Mea

n w

t (kg

)

1

REGRESSION OF CPUE WITH MEAN WEIGHT, CHINOOK RECREATIONAL

CATCH, MICHIGAN MAIN BASIN LAKE HURON

1

R2 = 0.5582

3.0

5.0

7.0

9.0

11.0

13.0

5.5 5.2 5.8 5.2 5.6 4.9

Recreational CPUE

Mea

n W

eigh

t (kg

)

Vulnerability a function of size (prey density)?

Number consumed/fish

Wt. (gm) consumed/fish

Number consumed/fish

Wt. (gm) consumed/fish

Smelt 0.17 0.86 1.07 3.21Alewives 0.69 9.58 1.07 4.61Total/Stomach 1.2 11.79 2.65 7.82

N = 103; 55.5% Void N = 84; 51.2% Void1997 & 1998 Combined 1999

PREY CONSUMPTION, CHINOOK SALMON, LAKE HURON

Spawning escapement trends

Chinook Salmon Weights (Kg), AuSable River, 1973-1999

1

3

5

7

9

11

Wei

ght (

Kg)

Age 1

Age 3

Mean - 8.83*

Mean = 5.40*

*Significant (p < 0.001) decline in growth at age 3

AGE DISTRIBUTIONS, 1973-1981 COMPARED TO 1996-1998, LAKE HURON

12

59

28

0.3

11

29

47

13

0

10

20

30

40

50

60

1970s 1990s

1234P

ER

CE

NT

W = 3.8E-08L2.792

R2 = 0.921

W = 1.1E-07x2.668

R2 = 0.94

0

2

4

6

8

10

12

14

16

200 400 600 800 1000 1200Length (mm)

Wei

ght

(Kg)

WEIGHT-LENGTH REGRESSIONSAuSable River, 1973-1981 compared with 1996-1999 Escapement Catch

from AuSable and Swan

1970’s:

1990’s:

Condition (Ktl) of Chinook, AuSable R. & Swan R. Escapement, 1970’s compared with 1990’s

1970’s 1990’s

0.9

1.0

1.1

1.2

0

2

4

6

8

10

12

Kg

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

Chinook salmon mean weight (kg) at age 3 from Strawberry Creek wier, Lake Michigan and Swan &

AuSable rivers, Lake Huron

Lake MichiganHuron (vertebrae)

BKD Period

Comparision of BKD positive fish sampled at spawning weirs from Lakes Michigan and

Huron (using QELISA), 1993-99

0

10

20

30

40

50

60

70

80

1993 1994 1995 1996 1997 1998 1999

Percent (+)

Lake MichiganLake Huron

BKD random sampling from MDNR fish hatcheries using DFAT on kidney smears 1995-99.

Number of TotalPositive Number

Year Samples Tested Percent

1995 1 780 0.13%1996 3 540 0.56%1997 0 823 0.00%1998 1 539 0.19%1999 0 654 0.00%

Species include: Chinook and coho salmon, rainbow trout, steelhead

Data provided by John Hnath, MDNR

MANAGEMENT IMPLICATIONS

GAPS IN KNOWLEDGE

•Recruitment, especially from wild;•Consumption and conversion efficiency rates; especially in winter;•Site-specific post-stocking survival;•Consequences of prey limitation:

-on recruitment rates;-disease (BKD);-nutrition (EMS).

FUTURE DIRECTIONS

•Maintain 20% reduction in stocking;•Continue site-specific marking

& collections;•Continue fall biological sampling; •Start reproduction study (new):

-mark all stocked chinooks;•Encourage funding for archival depth

& temperature tagging.

REPRODUCTION STUDY-LAKE HURON TECH. COMM.-

Objective: Determine rates of recruitment, especially from wild

•Experimental design (Done in June ‘00)•Mark all chinook stocked 2000-2003•Head-hunt during summer 2002-2006 •Fall escapement surveys 2003-2006