1. Background:
• Plug (red circles)
• Small amount of muscle tissue
• Below the dorsal fin using biopsy punch
• DEC filet (blue outlined area)
• Left side filet of muscle tissue
• Includes rib cage and skin (no scales)
Comparison of Fish Mercury Concentrations among Sample
Preparation Methods
Michael Persson1, Dr. Charles Driscoll2, Mario Montesdeoca2, Amy Shaw2 & Mariah Taylor2
1 State University of New York College of Environmental Science and Forestry; 2 Syracuse University
Introduction:
Three primary methods exist for sample preparation of fish muscle tissue for analysis of total mercury concentrations: 1) biopsy plug 2) standard left side filet and 3) New
York State Department of Environmental Conservation (DEC) left side filet including skin and bone. The benefits of utilizing the biopsy plug method include reduced time
processing and a potentially humane alternative. Literature has shown that biopsy plug and standard left side filet results are statistically similar (Dittman, 2007; Murphy,
2009). However, differences between these two methods and the DEC standard filet method have not been established. A comparison study between biopsy plug and DEC
filet methods was completed to evaluate potential differences in mercury concentrations using EPA method 7473 (thermal decomposition, amalgamation and atomic
absorption spectrophotometry).
This study was inclusive of thirteen lakes, seven species, and 241 individual fish from New York State waters. Results indicated that plugs from each fish sample had
higher mean concentrations of mercury compared to the DEC filets. A correction factor was developed using least squares regression to compare between data sets and
regression calculated concentrations were compared with measured values verifying a correction factor could be broadly applied. These results provide the framework for
being able to compare fish mercury concentrations regardless of preparation method used. The influences of fish size, species and lake-specific fish length-mercury
relationships should be evaluated in future research to support results observed in this study. This information will support future mercury research and is essential to
interpreting temporal fish mercury trends and setting advisories regarding human consumption of fish.
Methods:
• Take filet and plug samples from the same fish
(1 & 2)
• Bagging and labeling (3)
• Freeze dried muscle tissue (4)
• Homogenized sample using a freeze miller (5)
• Obtained mercury concentrations (µg/g) plug
and DEC filet data (6)
Significance of Research:
• Less time spent processing
• 30 – 45 sec per plug
• 3 – 10 mins per DEC filet
• Maximize freezer space
• Plugs: minimal
• Whole fish: large amount
• No cost of liquid nitrogen and energy for homogenization
• Humane alternative
Acknowledgments:
• This research was made possible through a NYSERDA grant and Syracuse University
• Thank you to the NYS DEC, Eric Paul, and everyone else involved with the sampling efforts
References:
Dittman, J. (2007). Comparison of Fish Tissue Sampling Procedure for Yellow Perch (Perca flavescens).
Murphy, M. (May 17, 2009). Onondaga Lake Research: Plug vs. Filet Comparison.
-2.6
-2.1
-1.6
-1.1
-0.6
-0.1
0.4
-3 -2 -1 0 1 2 3
Plugln(Hgwetweightinµg/g)
Filet ln(Hg wet weight in µg/g)
All YP
All RB
All CP
All LT
All LM
All SM
All WY
1 to 1
Fig 1. All plugs & filets in log-space
n=241
y = 0.0012x + 0.1043
R² = 0.2272
y = 0.0014x + 0.1065
R² = 0.2476
y = 0.0014x + 0.1105
R² = 0.2272
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0 200 400 600 800
[THgwetweight](µg/g)
Length (mm)
Linear (DEC Filet)
Linear (Plug)
Linear (Predicted DEC Filet)
Fig 2. All fish sample lengths (mm) vs.
[THg wet weight] (µg/g)
y = 0.0003x + 0.341
R² = 0.1873
y = 0.0003x + 0.3985
R² = 0.1847
y = 0.0003x + 0.3814
R² = 0.1873
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0 1000 2000 3000 4000
[THgwetweight](µg/g)
Weight (g)
Linear (DEC Filet)
Linear (Plug)
Linear (Predicted DEC Filet)
Fig 3. All fish sample masses (g) vs.
[THg wet weight] (µg/g)
1. BIOPUNCH
2. Plug sample (red circles) & DEC
filet sample (blue outlined area)
3. Bagging
and labeling
4. Freeze drying
5. Homogenizing
6. Analysis
Results:
• Mercury concentrations vary across species, with the lowest being
yellow perch & highest being smallmouth bass (Fig. 1)
• Plug trend concentrations are higher compared to the measured
DEC filet regression, but within close proximity to the predicted
DEC filet regression (Fig. 2 & 3)
• The average RPD of the predicted DEC filets and the measured
DEC filets was 10.7%, and the average RPD of the predicted DEC
filets and the measured plugs was 7.5% (Fig 2 & 3)
Future Research:
• Apply empirical corrections to archived data sets
• Investigate correlations for lakes with varying chemical properties and other target species
Conclusion:
• Low DEC filet sample concentrations may lead to inaccurate fish consumption advisories
• Utilizing plugs better represents the filet being consumed as well as promotes tagging and
recapture to better monitor mercury accumulation in an individual