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
  lengthmercury 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)

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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
Mercury Concentrations1998-2003

• 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

16
Few Good Time Series in 30-year Data Set
LengthHg 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)

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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)

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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

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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

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

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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

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Laboratory Analyses

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

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Lengthmercury Relationships

• For many fish species, mercury is higher in
  larger individuals
• Control for lengthmercury 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

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size limits
Largemouth Bass
27
size limits
Channel Catfish
28
size limits
White Catfish
29
size limits
Redear Sunfish
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• Overall
• Impact
• Colors represent relative mercury contamination
• Symbol shapes represent species with highest
  average concentration
• Size limits applied, and minimum sample size 1
  fish

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• 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

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Relative Impact by Species
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• 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

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Lengthmercury 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)

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Sacramento and tributaries
Lengthmercury 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
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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)

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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

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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
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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
• Lengthmercury regression (p lt 0.05)
• Regressed residuals on year
• Mix of composite and individual data
• not the ideal data set

49
Feather River at Nicolaus

• Lengthmercury significant
• p lt 0.0001
• No significant time trend
• p 0.823
• Individuals and composites

50
Sacramento River at RM44

• Lengthmercury significant
• p lt 0.0001
• No significant time trend
• p 0.929
• Individuals and composites

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Progress toward Goals

• Goal 1 Characterize mercury concentrations in
  fish
• Mercury contamination of sport fish was
  significant
• Concentrations varied by species and over space
• Maximum concentrations were most often in the
  orange category

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Progress toward Goals

• Goal 1 Characterize mercury concentrations in
  fish
• Ranking of species by relative mercury
• Largemouth bass
• Channel catfish
• White catfish
• Redear sunfish
• Organic contaminants not analyzed

Highest mercury Lowest mercury
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Progress toward Goals

• Goal 2 Characterize spatial and temporal
  patterns
• Mercury higher in the Sacramento and San Joaquin
  Rivers lower in the Delta
• Wetland areas had mid-level mercury did not
  stand out from other sites
• No evidence of long-term time trends few data
• Significant inter-annual variation 2005 lower
  than 2000

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Data Available To Date
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Sacramento and tributaries
Lengthmercury in channel catfish by site
Delta
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Sacramento and tributaries
Lengthmercury in white catfish by site
Delta
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