A Walleye Recovery Plan For A Walleye Recovery Plan For Saginaw BaySaginaw Bay

Fisheries DivisionMay, 2003

Historic Walleye Harvest from Historic Walleye Harvest from Saginaw BaySaginaw Bay

0

200

400

600

800

1000

1880 1901 1922 1932 1945 1962

Year

Com

mer

cial

Har

vest

(met

ric to

ns)

MDNR Investment in Walleye MDNR Investment in Walleye RecoveryRecovery

Research Research ConclusionsConclusions

• Fish community out of Fish community out of balancebalance

• Walleye recruitment limitedWalleye recruitment limited

• Management action Management action required to develop required to develop sustainable fisherysustainable fishery

Recreational ValueRecreational Value

• Saginaw Bay’s fishery accounts for 58% of all Saginaw Bay’s fishery accounts for 58% of all the fishing pressure in the Michigan waters of the fishing pressure in the Michigan waters of Lake HuronLake Huron

Economic ValueEconomic Value• The Saginaw Bay sport fishery The Saginaw Bay sport fishery

generates $18 million/year in generates $18 million/year in economic activityeconomic activity

Future ValueFuture Value

• Opportunity to provide future Opportunity to provide future legacy for recovered fisherylegacy for recovered fishery

Saginaw Bay Sport Fishery Saginaw Bay Sport Fishery YieldYield

YearYear

Yie

ld (

lb)

Yie

ld (

lb)

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1983 19861987 19881989 199119921993 19941995 19961997 19981999 20002001

Mean Historic Yield (1912-1940)Mean Historic Yield (1912-1940)

• Predator / prey balance in Saginaw BayPredator / prey balance in Saginaw Bay

• Walleye population at carrying capacityWalleye population at carrying capacity

• Walleye population sustained by Walleye population sustained by

natural reproductionnatural reproduction

Recovery GoalsRecovery Goals

Proposed Recovery PlanProposed Recovery Plan

• Suite of strategiesSuite of strategies

• Addresses limiting factorsAddresses limiting factors

• Defines recovery decision pointsDefines recovery decision points

• Includes research needsIncludes research needs

• Provides ecosystem recovery Provides ecosystem recovery

• Platform for collaboration and Platform for collaboration and

investmentinvestment

Recovery Plan StrategyRecovery Plan Strategy

1. Riparian/land use 1. Riparian/land use managementmanagement

2. Habitat Management2. Habitat Management

Stream HabitatStream Habitat

Bay HabitatBay Habitat

3. Stocking3. Stocking

Recovery CriteriaRecovery Criteria

• Self sustaining walleye Self sustaining walleye population capable of population capable of supporting an annual supporting an annual yield of 1 million lbsyield of 1 million lbs

• Walleye population Walleye population density with growth density with growth rates of 110% of state rates of 110% of state averageaverage

• Hatchery to wild fish Hatchery to wild fish ratios consistently at or ratios consistently at or below 50:50below 50:50

Expected Outcomes of Walleye Expected Outcomes of Walleye Recovery in Saginaw BayRecovery in Saginaw Bay

• Improved walleye fisheryImproved walleye fishery• Increased yellow perch growth rateIncreased yellow perch growth rate• Eventual elimination of dependence Eventual elimination of dependence

on stockingon stocking• Other native species recoveryOther native species recovery• Restoration of ecosystem Restoration of ecosystem

integrity/resiliency integrity/resiliency

Walleye Fingerling Stocking in Saginaw Bay Since 1978

0

500

1000

1500

2000

2500

Nu

mb

er (

tho

usa

nd

s)

78 80 82 84 86 88 90 92 94 96 98 OO O2 O4 O6

Year

Age-0 Walleye Trawl CPUE Saginaw Bay& Percent Hatchery Fish Contribution

0%61%

24%

18%

8%

85%96%

85%

81%

81%

0

5

10

15

20

25

30

35

40

45

Tra

wl

me

an

CP

UE

(n

o./

10

min

to

w)

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006

Year

Trawl CPUE of age-0 Yellow Perch

0

500

1000

1500

2000

2500

Tra

wl

mea

n C

PU

E (

no

./10

min

to

w)

1970 1974 1978 1982 1986 1990 1994 1998 2002

Year

Walleye Diet from Fall Samples 1989 – 2006Percent-Abundance of Food Item by Type

0

10

20

30

40

50

60

70

80

90

Alewife Gizzard shad Rainbow smelt Spottail shiners Yellow perch

Walleye Emerald shiners white perch Round Goby

High Catch Rates of Walleye in Saginaw Bay!

0.000.020.040.060.080.100.120.140.160.180.200.220.24

1983 1987 1989 1992 1994 1996 1998 2000 2002 2004 2006

Year

Wa l

l ey e

pe r

hr .

•Niche space for lake herring?Niche space for lake herring?•Yellow perch bottleneck?Yellow perch bottleneck?•What is the energy flow in the Bay?What is the energy flow in the Bay?•What is the impact of invasive species?What is the impact of invasive species?•Top down versus bottom up productivity?Top down versus bottom up productivity?•Climate change?Climate change?•What might we manage realistically?What might we manage realistically?

QuestionsQuestions