1. 1 National Descriptive Model of Mercury in Fish Tissue Stephen P. Wente Mounds View, MN U.S. Department of the Interior U.S. Geological Survey

2. NIEHS 2 Sampling for Mercury in Fish Spatial variation Spatial variation Temporal variation Temporal variation Fish consumption advisories Fish consumption advisories

3. NIEHS 3 Problem 1: Cost of Information Species Size Class 1 Size Class 2 Size Class 3 A?SampledSampled B?Sampled? CSampled?? D??Sampled E???

4. NIEHS 4 Possible Sample Designs Collect fish samples with consistent characteristics Collect fish samples with consistent characteristics –Species confined to definite ranges –Cannot compare to existing data Use existing data Use existing data –Must use model to make samples comparable –Variations in quality of existing studies

5. NIEHS 5 Problem 2: Difficult Comparisons Sampling Events Species1234567 AXXXX BXXXX CXXXX DXXX EXXX

6. NIEHS 6 Fish Mercury (Hg) Model Details Regression method (Covariance model) Regression method (Covariance model) Accounts for: Accounts for: –Less than detection limit values –Species (Hg increases with trophic position) –Tissues sampled (skin-off fillet > skin-on > whole fish) –Fish length (larger fish are higher in Hg) Calibrated to national dataset (N=45,605) Calibrated to national dataset (N=45,605)

7. NIEHS 7 Simple yet Realistic Description Log-log Space Arithmetic Space High Low

8. NIEHS 8 Consumption Advisory Bluegill Largemouth bass Carp No Consumption Limited Unlimited Species Size Class 1 Size Class 2 Size Class 3 A??? B?Sampled? CSampled?? D??Sampled E???

9. NIEHS 9 Standardize Sample Type Estimate concentration of a standard sample type (e.g. 14 inch skin-off largemouth bass fillets) for all sampling events (specific site and time) Sampling Events Species1234567 AXXX BXXXXX CXXXX DXXXX

10. NIEHS 10 Modeled ‘Spatial’ Variation (14 inch Largemouth Bass Skin-off Fillets) Raw Data

11. NIEHS 11 Standard Fish Hg Concentration (mg/Kg) Date Northwestern US Fish Hg Trends: NCBP Data 196519901965199019651990 (NCBP = National Contaminant Biomonitoring Program)

12. NIEHS 12 Analytical Cost Reduction Species5 Size classes 3 Sites50 Years5 Replicates4 Cost/Sample$100 $1,500,000 Covariance$100,000 *Sample types is number of species × size classes × tissue types Time Sites Sample types*

13. NIEHS 13 TimeCost Fish-Hg Concentration Fish-Hg Standard Fish-Hg Response Cost Function Uncertainty Model Reduces Compliance Costs by Reducing Uncertainty $1$1$1$1 $1$1$1$1 $1$1$1$1 $2$2$2$2 $3$3$3$3 $1$1$1$1 $2$2$2$2

14. 14 Project Website (emmma.usgs.gov) “Continuously updated” data & analysis Raw Data Temporal Trends Consumption Advisories No Consumption Limited Consumption Unlimited Consumption

15. NIEHS 15 Benefits of National Model Consistent nationwide interpretation of many independent monitoring efforts Consistent nationwide interpretation of many independent monitoring efforts More comprehensive fish consumption advisories More comprehensive fish consumption advisories Better description of spatial and temporal trends Better description of spatial and temporal trends Reduced analytical and compliance costs Reduced analytical and compliance costs Contact: Steve Wente (spwente@usgs.gov)