A Multi-Agency Effort toAddress Declines in

Yellow Perch Abundancein Lake Michigan

David ClappMichigan Department of Natural Resources

andYellow Perch Task Group, Lake Michigan Technical Committee

Lake Michigan RecreationalYellow Perch Catch(Michigan Waters)

0

1

2

3

4

1985 1989 1993 1997

Year

Cat

ch (

# of

fis

h, m

illio

ns)

Walleye

Yellow perch

Whitefish

Trout/salmon

Is therea problem?

Age Distribution ofYellow Perch Catch

0

5

10

15

20

25

30

35

1985 1986 1987 1988 1989 1990 1991 1992

Year

Pe

rce

nt

of

catc

h

Age 6

Age 3

Yellow Perch SamplingFishery Independent versus Dependent Data

0

50

100

150

200

250

300

350

1985 1987 1989 1991 1993 1995 1997

Year

Cat

ch

0

500

1000

1500

2000

2500 Catch per unit effort

Creel Trawl

What steps have we taken to address perch declines?

Step #1 - Formation of YellowPerch Task Group (1994)

• Increased sampling coverage• Gear standardization

Yellow PerchTask Group

SamplingLocations

Summer Trawland SeineSurveys

• Catch per unit effort• Total length• Age• Abundance of other species

Gill Net Surveys

• Catch per unit effort• Total length and weight• Sex, Fecundity• Scales, Otoliths

Lake MichiganCreel Survey

Programs

(Photo courtesy of The Hunting and Fishing Library)

What steps have we taken to address perch declines?

Step #2 - Lakewide public meeting (Yellow Perch Conference - December, 1994 - Kenosha, Wisconsin)

• Protect spawning stock• Conduct research on declining recruitment• Enforce harvest regulations

Regulation changes

State Commercial(pounds)

Recreational(Daily bag)

Illinois 300,000…Suspended

No limit… 15

Indiana No limit…Suspended

No limit… 15

Michigan No commercialfishery

No limit… 35

Wisconsin 300,000…Suspended

50… 5

Step #3 - Conduct research on declining recruitment

Hypotheses• Egg stage:

Egg quality and/or egg mortality limits perch• Diet:

Inappropriate diet limits larval survival• Alewife / predation:

Alewife predation limits recruitment

What steps have we taken to address perch declines?

Early Life History (Egg Stage)

Were maternal effects important?

9 8 6 10 3 5 1 4 70

400

800

1200

1600

Surv

ival

(nu

mbe

r of

indi

vidu

als)

Female

Survival: 601 (1) - 1283 (8)

Provided by: Christopher J. HeyerChesapeake Biological Laboratory

A trade-off exists between yolk volume and larval size

• Large, old female perch = small yolk volume

= large larvae

Abundant food, many predators

• Small, young female perch = large yolk volume

= small larvae

Scarce food, few predators

Provided by: Christopher J. HeyerChesapeake Biological Laboratory

Were maternal effects important?

Food Resources (Diet)

Mean ZP Density in June (No./L)10 20 30 40 50

Lo

g (

YO

Y Y

P C

PU

E)

-2

0

2

4

6

96 97

98

88

89

90

Yellow Perch Survival versus Zooplankton Density

Data provided by John Dettmers, Illinois Natural History Survey)

Alewife

(Predation, Competition)

Yellow Perch Year Class Strength versus Alewife Abundance

0

200

400

600

800

1000

0 20 40 60 80 100

Alewife CPUE (Age 1+)

Yel

low

per

ch C

PU

E(A

ge 2

)

(Data provided by Steve Shroyer, Ball State University)

Other Predators

(Photo courtesy of The Hunting and Fishing Library)

Other Predators

YEP(#) = Function (“Cycles” * (x+y+z+…))

What steps have we taken to address perch declines?

Step #4 - Implementing Yellow Perch Research in Great Lakes Management

Yellow Perch AbundanceSaginaw Bay - Lake Huron

0

50

100

150

200

250

1930 1935 1940 1945 1950 1955

Year

Pro

du

ctio

n(p

erc

en

t o

f a

vera

ge)

YEP(#) = Function (“Cycles” * (a+b+c+d+…))

d

ba

c

RecreationalHarvest

CommercialHarvest

Implementing Perch Research

0

500

1000

1500

2000

2500

1890 1900 1910 1920 1930 1940 1950 1960Year

La

nd

ings

(th

ousa

nds

of

pou

nds)

Egg stage, diet, predators

0

500

1000

1500

2000

2500

1890 1900 1910 1920 1930 1940 1950 1960Year

La

ndin

gs

(th

ou

san

ds

of

po

un

ds)

Recreational and Commercial harvest

Implementing Perch Research