A Walleye Recovery Plan For Saginaw Bay Fisheries Division May, 2003

Historic Walleye Harvest from Saginaw Bay

MDNR Investment in Walleye Recovery

Research Conclusions Fish community out of balanceFish community out of balance Walleye recruitment limitedWalleye recruitment limited Management action required to develop sustainable fisheryManagement action required to develop sustainable fishery

Recreational Value Saginaw Bay’s fishery accounts for 58% of all the fishing pressure in the Michigan waters of Lake HuronSaginaw Bay’s fishery accounts for 58% of all the fishing pressure in the Michigan waters of Lake Huron Economic Value The Saginaw Bay sport fishery generates $18 million/year in economic activityThe Saginaw Bay sport fishery generates $18 million/year in economic activity Future Value Opportunity to provide future legacy for recovered fisheryOpportunity to provide future legacy for recovered fishery

Saginaw Bay Sport Fishery Yield Year Yield (lb) 0 200, , , ,000 1,000,000 1,200, Mean Historic Yield ( )

Predator / prey balance in Saginaw BayPredator / prey balance in Saginaw Bay Walleye population at carrying capacityWalleye population at carrying capacity Walleye population sustained by natural reproductionWalleye population sustained by natural reproduction Recovery Goals

Proposed 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 recoveryProvides ecosystem recovery Platform for collaboration and investmentPlatform for collaboration and investment

Recovery Plan Strategy 1. Riparian/land use management 2. Habitat Management Stream Habitat Bay Habitat 3. Stocking

Recovery Criteria Self sustaining walleye population capable of supporting an annual yield of 1 million lbsSelf sustaining walleye population capable of supporting an annual yield of 1 million lbs Walleye population density with growth rates of 110% of state averageWalleye population density with growth rates of 110% of state average Hatchery to wild fish ratios consistently at or below 50:50Hatchery to wild fish ratios consistently at or below 50:50

Expected Outcomes of Walleye Recovery in Saginaw Bay Improved walleye fisheryImproved walleye fishery Increased yellow perch growth rateIncreased yellow perch growth rate Eventual elimination of dependence on stockingEventual elimination of dependence on stocking Other native species recoveryOther native species recovery Restoration of ecosystem integrity/resiliencyRestoration of ecosystem integrity/resiliency

Walleye Fingerling Stocking in Saginaw Bay Since 1978

Age-0 Walleye Trawl CPUE Saginaw Bay & Percent Hatchery Fish Contribution 0% 61 % 24% 18% 8% 85% 96% 85% 81% Trawl mean CPUE (no./10min tow) Year

Trawl CPUE of age-0 Yellow Perch

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

High Catch Rates of Walleye in Saginaw Bay!

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? Questions