Mercury in Central Valley Sport Fish

1. Mercury in Central Valley Sport Fish Letitia Grenier, Aroon Melwani, Jennifer Hunt, Shira Bezalel, and Jay Davis (SFEI) Gary Ichikawa and Billy Jakl (CDFG) Wes Heim and Autumn Bonnema (MLML) Margy Gassel (OEHHA)

2. Overview of Presentation • Review of historical and recent mercury bioaccumulation data from California • Goals of sport fish sampling • Results from 2005 sampling • Mercury concentrations in sport fish • Spatial and temporal trends in mercury in fish • Non-technical summary of main findings

3. Review of Historic and Recent Data • Fish Mercury Project (FMP), funded by the California Bay-Delta Authority • Surface Water Ambient Monitoring Program (SWAMP), funded by the California State Water Resources Control Board

4. Past, Present, and Future of Mercury in California • The programs combined provide a multi-tiered approach to understanding Hg contamination • Historic review of sport fish mercury data • Extensive fish sampling over the next three years • Development of a long-term strategy for monitoring mercury and other pollutants in aquatic biota

5. Historical Data Review - Methods • Compilation of all available data from statewide and regional sport fish monitoring efforts • Mercury, PCBs, and legacy pesticides (chlordane, DDT, dieldrin) • QA of incoming data sets • e.g., lab QA, fish length, compositing scheme • Standardized data base

6. Monitoring Programs Included • Statewide • Toxic Substances Monitoring Program • State Mussel Watch Program • Coastal Fish Contamination Program • Regional • Regional Monitoring Program for Water Quality (SF Bay) • Sacramento River Watershed Program • Many others

7. Historical Data Review Sampling Locations 1969 – 2003 Colored symbols represent different studies or programs Sampling is uneven across the state

8. Assessing Mercury Impact • Apply size limits for each species to control for length:mercury relationship • Minimum sample size = 1 observation/site • Calculate median of Hg concentration in muscle tissue (wet weight) • Median chosen because many non-detects • Select the species at each site with highest mercury • Interpret concentrations using human health thresholds from OEHHA

9. These Analyses are not Consumption Advisories • This data set is one of many OEHHA will draw on to develop advisories • Different process for data analysis (single contaminant, sample size requirements, geographic areas) • These analyses are a preliminary look at • Relative impairment • Spatial, temporal, and species patterns

10. Guidance Tissue Levels for Hg • Thresholds developed by OEHHA for consumption advisories (ppm, wet weight)

11. Mercury Impact on Fish Contamination1998-2003 High Low Highest mercury concentration, based on median concentration for each species, is shown at each site.

12. The pattern of mercury impact parallels the pattern of net pollutant impact Hg Hg PCBs DDTs chlordanes dieldrin

13. X Consumption advisories based at least partly on mercury

14. Spatial Distribution of Advisories • Areas without advisories are not necessarily places with uncontaminated fish • Areas without advisories are often lacking the data to develop them • Providing data for advisory development is one of the main purposes of FMP sport fish sampling

15. Species with highest median Hg at each site are shown Spatial variation in watershed Overall spatial correlation with Hg and gold mining Worst hot spots are associated with mines Unexpected low Hg in Central Delta Mercury Concentrations1998-2003

16. Few Good Time Series in 30-year Data Set Length:Hg residuals • Little evidence of long-term time trends • Largely NS trends • White catfish decline at Sacramento River site poorly understood Year

17. Acknowledgements for Historical Data • California State Water Resources Control Board • CBDA • Researchers contributing data • OEHHA staff, Michelle Wood (Region 5 Water Board)

18. Sport Fish Sampling Goals • Characterize mercury concentrations in fish – Goal 1, Objective 3 (SFEI, MLML, CDFG) • Assess the health risks of consuming contaminated fish (OEHHA) • Communicate these risks to appropriate target audiences based on environmental justice principles (EHIB) • Characterize spatial and temporal trends in mercury in fishery resources – Goal 2, Objective 1 (UCD, SFEI, MLML, CDFG) • Determine how habitat restoration and mercury clean-up actions affect methylmercury accumulation in the food web (UCD, SFEI, MLML, CDFG)

19. FMP Sport Fish Sampling, 2005 • 2124 individual fish • 24 species • 70 sport fishing locations • Coordinated sampling • Central Valley Regional Water Quality Control Board • Sacramento River Watershed Project

20. Sampling Location Types • Advisory sites • Majority of sites • Data from these sites and all the other site types, including SCVWD and SRWP, will be used to develop consumption advisories and communicate risk to stakeholders (Goal 1) • Popular fishing areas and hatcheries for salmon and trout • Index and intensive sites • Temporal and regional trends in sport fish mercury contamination • Effects of restoration and remediation actions on regional scale • Link sport fish mercury to biosentinel data • Restoration sites • Local effects of restoration

21. Sampling Locations 2005 • Colors represent different types of sampling sites

22. Not All 2005 Available Yet • Species in this presentation • Largemouth Bass • White Catfish • Channel Catfish • Redear Sunfish • Other data coming from lab soon

23. Field Collection • Late July to mid December 2005 • California Department of Fish and Game • Electrofisher boat and fyke nets • Clean handling techniques • Length measurements

24. Laboratory Analyses • Total mercury • Fillet (muscle tissue) • Wet weight • Individual analyses (not composites) • Passed QA (van Buuren 2006) • Including lab inter-comparison study

25. Length:mercury Relationships • For many fish species, mercury is higher in larger individuals • Control for length:mercury relationship with size limits for all analyses other than ANCOVA • Choose size limits based on peak of frequency distribution • Narrow size limits according to EPA guidance • Smallest fish in a composite should be no less than 75% of the largest

26. size limits Largemouth Bass

27. size limits Channel Catfish

28. size limits White Catfish

29. size limits Redear Sunfish

30. Overall Impact • Colors represent relative mercury contamination • Symbol shapes represent species with highest average concentration • Size limits applied, and minimum sample size = 1 fish

31. Relative Impact by Species • Colors represent mercury concentrations • Quadrants represent species • Gray quadrants mean species not collected • Size limits applied, and minimum sample size = 1 fish

32. Relative Impact by Species

33. Largemouth Bass • Colors are mercury concentration categories • Height of bar represents mean concentration • Size limits applied, and minimum sample size = 1 fish

34. Channel Catfish • Colors represent range of mercury concentrations • Height of bar represents concentration • Size limits applied, and minimum sample size = 1 fish

35. White Catfish • Colors represent range of mercury concentrations • Height of bar represents concentration • Size limits applied, and minimum sample size = 1 fish

36. Redear Sunfish • Colors represent range of mercury concentrations • Height of bar represents concentration • Size limits applied, and minimum sample size = 1 fish

37. Spatial and Temporal Trends • Relative to restoration and remediation actions (none underway yet) • Addressed in the biosentinel report and presentations by Darell Slotton • All sites have been sampled only once • Can examine temporal and regional spatial trends using data at hand from all sites

38. Length:mercury varies by site • Tremblay (1995, 1998) ANCOVA method for bass and channel catfish • Allows different slopes between sites • Polynomial term allows non-linear relationship • Significant variation within species for intercept, slope, shape of fit (linear or curved)

39. Sacramento and tributaries Length:mercury in largemouth bass by site Delta

40. N Largemouth Bass Spatial Patterns • Mercury mean ± CI estimated for standard length of 350 mm • Using ANCOVA results • Sites from N to S on Y-axis S

41. Channel Catfish Spatial Patterns Few collected in Delta N S • Mercury mean ± CI estimated for standard length of 425 mm • Using ANCOVA results

42. White Catfish Spatial Patterns Most collected in Delta N S • Mercury mean ± CI • Size limits applied, minimum sample size was 5 fish

43. Redear Sunfish Spatial Patterns N • Similar overall spatial pattern • Mercury mean ± CI • Size limits applied, minimum sample size was 5 fish S

44. Spatial Patterns Summary • Lower mercury bioaccumulation in the Delta not well understood • Many hypotheses • E.g.: photodegredation of methylmercury • May occur more readily in the Delta • water velocity low • water clarity and residence time high • (Byington et al. 2005)

45. Mercury and Wetlands • Main wetland areas near Prospect Slough and Liberty Island • Prospect Slough (intensive) and Sacramento River at Rio Vista (index) sampling sites • Higher mercury than the rest of the Delta • Lower mercury than the rivers • Need more data

46. N Largemouth Bass Spatial Patterns • Mercury mean ± CI estimated for standard length of 350 mm • Using ANCOVA results • Sites from N to S on Y-axis S

47. 2000 vs. 2005 Largemouth Bass N L L H L L S • Mercury mean ± CI estimated for standard length of 350 mm • Using ANCOVA results

48. Long-term Time Trends • Two sites with sufficient data to examine time trends • Length:mercury regression (p < 0.05) • Regressed residuals on year • Mix of composite and individual data • not the ideal data set

49. Feather River at Nicolaus • Length:mercury significant • p < 0.0001 • No significant time trend • p = 0.823 • Individuals and composites

50. Sacramento River at RM44 • Length:mercury significant • p < 0.0001 • No significant time trend • p = 0.929 • Individuals and composites