1. Lake Erie Hypoxia: History and Management Response Stuart A. Ludsin NOAA Great Lakes Environmental Research Laboratory Ann Arbor, MI Roger L. Knight Ohio Department of Natural Resources Division of Wildlife Sandusky, OH

2. Presentation Outline Lake Erie hypoxia Lake Erie’s fisheries Hypoxia effects on fisheries Ongoing research

3. Ian.umces.edu/symbols Lake Erie Facts OH MI ON  Small Volume = 484 km 3  Shallow Depth = 19 m  Warm > 200 Frost Free Days  Productive All Trophic Levels

4. Warm epilimnion West Central East Cool Source: Murray Charlton, NWRI Cool hypolimnion (hypoxic during summer) Periodic hypoxia Temperature Productivity HighLow Annual hypoxia Depth (m) 0 20 40 60

5. Max. Hypoxic (< 2 mg/l) Area = 10,000 km 2

6. Source: Paul Horvatin, US EPA-GLNPO Central Lake Erie Hypoxia

7. Lake Erie Hypoxia Hypoxia is “natural” –Lake Erie – present 100s to 1000s of yrs ago –Due to central basin bathymetry Nutrient (phosphorus, P) inputs also important –1950s-1970s:  point-source loading,  hypoxia –1980s-1990s:  point-source loading,  hypoxia –2000-present:  non-point source loading,  hypoxia

8. Presentation Outline Lake Erie hypoxia Lake Erie’s fisheries Hypoxia effects on fisheries Ongoing research

9. Numerous recreational & commercial fisheries –Billion-dollar per year fishery (during mid-1980s) Lake Erie’s Fisheries Walleye Yellow Perch Walleye (www.buckeyeangler.com) Yellow perch (©Shedd Aquarium)

10. Zooplankton Benthic Macroinverts. Walleye (www.buckeyeangler.com) Planktivorous Fish Benthivorous Fish Emerald shiner (www.cnr.vt.edu) Rainbow smelt (nas.er.usgs.gov) Yellow perch (©Shedd Aquarium) White perch (www.cnr.vt.edu) Central Lake Erie Food Web Benthivorous Fish Piscivorous Fish Lake whitefish (www.gov.mb.ca) Burbot (www.gov.mb.ca)

11. Presentation Outline Lake Erie hypoxia Lake Erie’s fisheries Hypoxia effects on fisheries Ongoing research

12. Lake Erie Fish Community Hypoxia Effects on Fisheries –1950s-1970s:  hypoxia,  lake whitefish & burbot (Leach & Nepszy 1976)  thermal & foraging habitat  vulnerability to commercial fishing (aggregation effect) –1980s-1990s:  hypoxia,  lake whitefish, burbot, smallmouth bass & silver chubs (Ludsin et al. 2001) –A word of caution is needed Leach & Nepszy (1976)…speculation only Ludsin et al. (2001)…based on time-series correlations –confounding factors: harvest, climate, exotic species – Until 2005, no mechanistic hypoxia-fisheries work

13. Reduced Phosphorus Inputs (A Management Dilemma) Oxygen & minor fisheries + Walleye & yellow perch - Ludsin et al. (2001)

14. Presentation Outline Lake Erie hypoxia Lake Erie’s fisheries Hypoxia effects on fisheries Ongoing research

15. International Field Years on Lake Erie (IFYLE) Program (www.IFYLE.org) - Stuart Ludsin & Stephen Brandt, project co-leaders - 45 PIs, 18 institutions - Field years: 2005, 2007, 2008-2009 - 130 ship days, >2,000 people-days at “sea” in 2005

16. IFYLE Program Primary Research Goal – –Understand ecological consequences of hypoxia Trophic interactions, growth, condition, recruitment Ultimate Research Goal –Help agencies understand if they should care about hypoxia when managing fisheries IFYLE data will be presented here –Höök, Vanderploeg, Lavrentyev

17. Forecasting the Causes, Consequences, and Potential Solutions for Hypoxia in Lake Erie Project Leader: Don Scavia NOAA-ECOFORE Program funding, 2006-2011 19 PIs, 8 institutions - Primarily NOAA-GLERL & U of Michigan scientists Modeling effort  means to integrate & synthesize IFYLE data Provide understanding, predictive capabilities, and recommendations to benefit management

18. Thanks for your attention

19. Hexagenia spp. Lake whitefish & burbot Oligo-Meso-Eu-Hyper- Trophic state Production or Fishery Yield Benthos Benthic Fish Planktivorous Fish Modified from Caddy (1990) Hypoxia Effects on Fisheries 1950s-1970s(Leach & Nepszy 1976) 2000 1950s-1970s (Ludsin et al. 2001)

20. Alteration of nutrient inputs –Hypoxia likely playing some role Relative abundance Percids (yellow perch) Oligotrophy (low nutrients) Eutrophy (high nutrients) Cyprinids (common carp) Coregonids (lake whitefish) Leach et al. (1972) Ludsin et al. (2001) Hypoxia Effects on Fisheries Pre-1950 1955-1970 1970s 1990-2000 1977-1987 1970s