Systematic Review of Trends in Fish Tissue Mercury Concentrations

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1 Systemati Review of Trends in Fish Tissue Merury Conentrations Tom Grieb 1, Roxanne Karimi 2, Niholas Fisher 2, Leonard Levin 3 (1) Tetra Teh, In., Lafayette, CA, USA; (2) State University of New York, Stony Brook, NY, USA; (3) Eletri Power Researh Institute, Palo Alto, CA, USA INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 2017

2 Synthesis of Existing Summaries of Trends Review of Published Literature Evaluate ability of the fish tissue monitoring programs to assess the responses to emission redutions Identify fators that should be onsidered in the interpretation of the reported trends Evaluate the data olletion efforts and the statistial methods with the goal of making reommendations for effiient monitoring strategies moving forward Identifiation of New Data to Support the Analysis of Trends in Fish Tissue Hg Conentrations Reommendations for Future Work and Collaborations 2

Review of Published Literature 200 Papers Compiled and Reviewed Google Sholar Database, 1972 2016 Referenes from Seafood Merury Database Cited By Searhes Siene Diret Searh of Key Journals

3 Review of Published Literature 200 Papers Compiled and Reviewed Google Sholar Database, Referenes from Seafood Merury Database Cited By Searhes Siene Diret Searh of Key Journals Referene Database Created Citation, Year of Publiation Speies Water Body Type Trend Diretion Sample Size Geographi Area Statistial Methods Key Findings Number of Referenes by Publiation Year 3

4 Literature Review Summary Most of the literature addresses freshwater fisheries Majority of data from North Ameria Primary data soures: field sampling programs to support the development of fish onsumption advisories and ompliane with water quality standards 4

5 Fous on U.S. and Canadian Freshwater Study Trends 46 Published Studies Data Reords: ~ 10 6 fish samples 5

6 Studies Reviewed Ranked by Duration of Data Reord Inreasing Length of Data Reord

7 Merury Point-Soure Emissions and Conentration Trends in Wet Deposition Hg Trends, MDN Wet Deposition 1 : (19 sites) 53% Sign. - Trends 0% Sign. + Trends (71 sites) 13% Sign. - Trends 17% Sign. + Trends (81 sites) 6% Sign. - Trends 30% Sign. + Trends Shift to more positive, fewer negative trends in Hg wet deposition 1 Weiss-Penzias et al.,

Summary of Observed Fish Tissue Merury Conentration Trends Proportion of dereasing trends exeeds inreasing trends by a fator of two Greatest

8 Summary of Observed Fish Tissue Merury Conentration Trends Proportion of dereasing trends exeeds inreasing trends by a fator of two Greatest delines in fish tissue onentrations were observed over the past few deades and are related to redued anthropogeni merury emissions in North Ameria 8

9 Annual Perent Change (APC) in Fish Tissue Hg Conentration Negative Trends 87 reported or alulated APC values Average APC = % redution in 10 years Positive Trends 32 reported or alulated values Average APC = % inrease in 10 years 9

Reversals in Fish Tissue Merury Conentration Trends Small portion of the trend studies reported the existene of reent leveling off in the rate of Hg tissue onentration dereases or inreases in tissue

10 Reversals in Fish Tissue Merury Conentration Trends Small portion of the trend studies reported the existene of reent leveling off in the rate of Hg tissue onentration dereases or inreases in tissue onentrations Time Periods (Dereasing Trends) (Inreasing Trends) Multiple speies inluded in eah study, all speies responding alike in 2 of 8 studies Minnesota Statewide Lakes Data for Northern Pike and Walleye, Monson,

11 Fators Reported to Affet Trend Reversals in Fish Tissue Conentrations Inreased Hg deposition from the global pool Global anthropogeni emissions inreased ~ 19% ( ) Climate hange effets Inreasing water temperature resulting in metaboli hanges and higher uptake rates of methylmerury Inreased rainfall and runoff leading to inreased hydrologi export of organi matter arrying Hg(II) Loal hanges Food web strutural shifts indued by invasive speies, reating new or expanding role for sediments as a net ontaminant soure Linear Temporal Trend Walleye (Monson, et al., 2010) 11

12 Time Trend Data Charateristis Within-lake variability is high, oeffiients of variation > 0.60 Variable sample sizes Multiple tissue types (whole body, skin-on, skin-off fillets) Differenes in sex, reprodutive status One-time samples or samples olleted at unequal intervals Hg onentrations osillated upward and downward at approximately the same frequeny, a wax and wane pattern Differenes in statistial analyses performed, data pooling Azim et al., Data from fish onsumption advisories, Ontario Ministry of the Environment. 12

13 Statistial Tehniques Applied in Trend Analyses Two-Sample Time Comparison t-test or non-parametri equivalent Subjetive determination in breakpoint Regression Simple Linear, ANCOVA Mixed effets linear models 2-segment linear pieewise regression Polynomial regression models Other Approahes: Hierarhial Models, Bayesian Analysis, Dynami Linear Models Foreasting or detetion of model shifts Ability to inlude prior Information 13

14 Probability of Detetion Statistial Considerations Moving Forward Effet of sample size and sampling duration on ability to detet trends Opportunities exist to use existing data to design and implement effiient long term fish monitoring programs to detet trends and to relate fish tissue measurements to the measurement of other influening fators Statistial Power Analysis for Linear Regression Models Example, 20 samples per year for years to be assured of deteting 2% APC; CV s: 0.5, 0.6,

15 Assessment of Trends in Marine Fish The primary soure of Hg exposure in the human diet is from the ommerial fish market; marine and estuarine speies omprise > 90% of the fish in the ommerial ath MeHg onentrations in ommonly onsumed marine fish speies exeed the U.S. EPA human health riterion of 0.3 ppm in most marine systems studied Approximately 90% of Hg entering the oean is deposited from the atmosphere to the sea surfae Sine 1990 Hg emissions from Europe and North Ameria have dereased while total anthropogeni Hg emissions have inreased 17-19%, largely due to the inrease of Hg emissions from Asia Hg onentrations in the North Paifi intermediate waters have inreased at a rate of 3%/year between 1995 and

16 Reported Trends in Hg Tissue Conentrations in Marine Fish 39 marine studies identified in the literature searh. Fish tissue measurements in ~ 14,000 individual or omposite fish, ompared with > 10 6 in FW published papers Proportion of dereasing trends exeeds inreasing trends by a fator of two Overall, there are very few systemati studies of trends in marine fish speies 16

Seleted Marine Studies Measurements in 1,292 samples of wild-aught bluefin tuna in North Atlanti show fish tissue onentrations delined 19% over an 8-year period (Lee et al.

17 Seleted Marine Studies Measurements in 1,292 samples of wild-aught bluefin tuna in North Atlanti show fish tissue onentrations delined 19% over an 8-year period (Lee et al., 2016) Derease in fish-tissue onentrations parallels the redution in anthropogeni emission rates in NA. Measurements in Yellowfin tuna, , aught in the North Paifi show an inrease in fish tissue Hg onentrations (Drevnik and Brooks, 2015 and 2017) Limited sampling and variability in Hg onentrations introdue unertainty and affet the overall understanding of fish tissue trends. 17

18 Findings The importane of fish onsumption as a pathway of merury exposure and the establishment of fish onsumption advisories to protet human health have led to large fish tissue monitoring programs worldwide The largest omponent of the trend literature is for North Amerian freshwater speies important in rereational fisheries A signifiant overall dereasing trend in fish tissue Hg onentrations in North Amerian lakes is evident over the period of reord ( ), and the trend is onsistent with Hg emission redutions and wet depositional trends aross the U.S. and Canada 18

19 Findings (ontinued) More reently, a leveling off in the rate of Hg tissue onentration dereases or inreases in tissue onentrations. Key fators affeting the reent trends: Inreased Hg deposition from the global pool Climate hange effets Food web strutural shifts Opportunities exist to use existing data to design and to implement effiient long-term fish monitoring programs to detet trends and to relate fish tissue merury measurements to the measurement of other influening fators There is a need for systemati and onsistent monitoring as well as inreased aess to olleted data in order to monitor trends in fish tissue onentrations in a hanging environment. 19

20 Systemati Review of Trends in Fish Tissue Merury Conentrations Assessment of Trends in Fish Tissue Merury Conentrations Tehnial Report Tehnial Report, May

Southwest Fisheries Science Center National Marine Fisheries Service 8604 La Jolla Shores Dr. La Jolla, California 92037

Southwest Fisheries Science Center National Marine Fisheries Service 8604 La Jolla Shores Dr. La Jolla, California 92037 233 Abstrat We estimated the total number of pantropial spotted dolphin (Stenella attenuata) mothers killed without their alves ( alf defiit ) in all tuna purse-seine sets from 1973 90 and 1996 2000 in