a multi-agency effort to address declines in yellow perch abundance in lake michigan
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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
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