Time Trends of Methylmercury in Walleye in Northern Wisconsin:  A Hierarchical Bayesian Analysis

Madsen, Eric; Stern, Hal S.

doi:10.1021/es0700294

Cited by 19 publications

(20 citation statements)

References 25 publications

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“…Hg concentrations in northern pike and walleye from Minnesota declined by an average of 11% between 1990 and 2000, or~1% per year (MPCA 2007). Madsen and Stern (2007) found walleyes (skin-on and skin-off fillets) from northern Wisconsin decreased 0.6%/year over 1982-2005 using hierarchical Bayesian methods. In a study of common loons in northern Wisconsin, Fevold et al (2003) estimated that adult loon blood Hg levels decreased by 4.2% per year, while loon chick blood Hg decreased by 4.9% per year.…”

Section: Discussionmentioning

confidence: 99%

Temporal trends of mercury concentrations in Wisconsin walleye (Sander vitreus), 1982–2005

2007

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The Wisconsin Department of Natural Resources has monitored mercury (Hg) in several species of fish since the early 1970s primarily for fish consumption advisory purposes. We selected skin-on fillets of walleye (Sander vitreus) from inland lakes collected over the years 1982-2005 to assess temporal trends of Hg concentrations. While individual lakes are of interest, sample sizes, and unbalanced collections across fish lengths, seasons, or years prevent estimates of temporal trends of walleye Hg concentrations within most lakes. We evaluated temporal trends over all lakes using mixed effects models (3,024 records from 421 lakes). Relationships between Hg concentrations and a suite of lake chemistry, morphometry, and other variables were also explored. Hg concentrations generally increased with walleye length but the relationship varied among lakes. The best-fitting mixed effects models suggested that the overall rate of change in walleye Hg across all lakes in the dataset varied with latitude. Hg in walleye decreased 0.5% per year in northern lakes, increased 0.8% in southern lakes, and remained constant in middle latitude lakes over the period of 1982-2005. Season of collection was also an important predictor variable. Hg concentrations were highest in walleye captured in the spring and lowest in the fall. Other variables such as gender, lake area, and total alkalinity were also important predictors.

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Section: Discussionmentioning

confidence: 99%

Temporal trends of mercury concentrations in Wisconsin walleye (Sander vitreus), 1982–2005

2007

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“…For example, within-lake concentrations of mercury in these piscivorous fish decreased in 35% but increased in 60% of lakes. Concentrations of mercury in walleye in northern Wisconsin have also decreased by about 0.5% annually between 1982 and 2005, remained relative constant in the middle latitude lakes of the state, but have increased approximately 0.8% annually in southern Wisconsin (Madsen and Stern 2007;Rasmussen et al 2007). Bhavsar et al (2010) reported that, since 1990, mercury in walleye has declined in Lake Superior (0.18-0.20 lg g -1 wet weight per decade) and Lake Huron (0.05-0.07 lg g -1 wet weight per decade), remained unchanged in Lake Ontario, and has increased in Lake Erie (0.036 lg g -1 wet weight per decade).…”

Section: Estimated Mercury Concentration In Standard-size Fishmentioning

confidence: 99%

Ecological risk of methylmercury to piscivorous fish of the Great Lakes region

Sandheinrich

Bhavsar²,

Bodaly³

et al. 2011

Ecotoxicology

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Contamination of fish populations with methylmercury is common in the region of the Laurentian Great Lakes as a result of atmospheric deposition and methylation of inorganic mercury. Using fish mercury monitoring data from natural resource agencies and information on tissue concentrations injurious to fish, we conducted a screening-level risk assessment of mercury to sexually mature female walleye (Sander vitreus), northern pike (Esox lucius), smallmouth bass (Micropterus dolomieu), and largemouth bass (Micropterus salmoides) in the Great Lakes and in interior lakes, impoundments, and rivers of the Great Lakes region. The assessment included more than 43,000 measurements of mercury in fish from more than 2000 locations. Sexually mature female fish that exceeded threshold-effect tissue concentrations of 0.20 μg g(-1) wet weight in the whole body occurred at 8% (largemouth bass) to 43% (walleye) of sites. Fish at 3% to 18% of sites were at risk of injury and exceeded 0.30 μg g(-1) where an alteration in reproduction or survival is predicted to occur. Most fish at increased risk were from interior lakes and impoundments. In the Great Lakes, no sites had sexually mature fish that exceeded threshold-effect concentrations. Results of this screening-level assessment indicate that fish at a substantive number of locations within the Great Lakes region are potentially at risk from methylmercury contamination and would benefit from reduction in mercury concentrations.

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“…Trend analysis of walleye (Sander vitreus) in Wisconsin lakes between 1982 and 2005 has shown an annual percent change (APC) of 0.5 to 0.6% in northern Wisconsin and an upward trend of 0.8% APC in southern Wisconsin (Madsen and Stern 2007;Rasmussen et al 2007). Over the same period in Minnesota (1982Minnesota ( -2006, the overall trend in walleye and northern pike (Esox lucius) was the same as northern Wisconsin, but a better fitting piecewise linear regression model indicated a steeper decline of 4.7% per year from 1982 to 1992, followed by an increase of 1.4% per year for 1992-2006 (Monson 2009).…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal trends of mercury in walleye and largemouth bass from the Laurentian Great Lakes Region

et al. 2011

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The risk of mercury (Hg) exposure to humans and wildlife from fish consumption has driven extensive mercury analysis throughout the Great Lakes Region since the 1970s. This study compiled fish-Hg data from multiple sources in the region and assessed spatiotemporal trends of Hg concentrations in two representative top predator fish species. Walleye (Sander vitreus) and largemouth bass (Micropterus salmoides) were chosen for the trend analysis because they had more Hg records (63,872) than other fish species that had been sampled from waters throughout the region. Waterbody types were inland lakes (70%), the Great Lakes, impoundments, and rivers. The compiled datasets were analyzed with a mixed effects statistical model having random effects of station, year, and fish length; and fixed effects of year, tissue type, fish length, habitat, and season. The results showed a generally declining temporal trend in fish-Hg for the region (1970-2009), with spatial trends of increasing Hg concentration from south to north and from west to east across the region. Nonlinearity was evident in the general downward trends of Ontario walleye, with a shift to an upward trend beginning in the 1990s. Only ongoing monitoring can reveal if this upward shift is an oscillation in a long-term decline, a statistical anomaly, or a sustained declining temporal trend in regional fish-Hg concentrations.

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Time Trends of Methylmercury in Walleye in Northern Wisconsin: A Hierarchical Bayesian Analysis

Cited by 19 publications

References 25 publications

Temporal trends of mercury concentrations in Wisconsin walleye (Sander vitreus), 1982–2005

Temporal trends of mercury concentrations in Wisconsin walleye (Sander vitreus), 1982–2005

Ecological risk of methylmercury to piscivorous fish of the Great Lakes region

Spatiotemporal trends of mercury in walleye and largemouth bass from the Laurentian Great Lakes Region

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