Mercury in walleye, northern pike keeps rising, MPCA finds

  • Article by: MARY LYNN SMITH , Star Tribune
  • Updated: February 18, 2009 - 8:29 AM

The concentration of mercury in walleye and northern pike has shown an unexpected long-term rise in lakes throughout Minnesota, and scientists believe the problem has global causes and consequences.

A Minnesota Pollution Control Agency study released Tuesday after being published last week in the journal Environmental Science & Technology showed an unexpected rise in mercury concentrations in fish collected from 845 Minnesota lakes. The finding, from an analysis of records kept over 25 years, is a concern because methylmercury, the form of mercury that contaminates fish, is toxic to humans and wildlife.

The new finding, however, won't affect current fish-consumption guidelines from the Minnesota Department of Natural Resources. Those guidelines are based on current data about mercury levels in fish, while the MPCA study showing the rise in those levels is a historic look at the data.

Under the Minnesota Deptartment of Health guidelines, men and women not planning to get pregnant can safely eat one meal a week of Minnesota-caught walleye and northern pike. Pregnant women, those who may become pregnant and children younger than 15 should eat only one meal a month of walleye shorter than 20 inches and northern pike shorter than 30 inches from most Minnesota lakes. It's recommended they don't eat fish larger than that.

A change in direction

At one time, methylmercury concentrations in fish were decreasing in Minnesota. Those levels in northern pike and walleye fell 37 percent from 1982 to 1992, after the state began limiting the use of mercury, said Sam Brungardt, MPCA spokesman.

But then mercury levels in fish began to fluctuate. From 1996 to 2006, mercury concentrations in northerns and walleye rose by 15 percent, he said.

MPCA scientist Bruce Monson, who conducted the analysis, said the source of the mercury probably isn't local because the trend is statewide. Scientists also have found an increase in mercury concentrations in coho and chinook salmon from Lake Ontario from 1999 through 2003.

The cause is probably either increased global mercury emissions by sources outside the United States, such as China or India, or factors associated with climate change, or both, Monson said. Global mercury emissions increased between 1990 and 1995, largely because of an increase in electricity produced by coal-fired power plants in Asia.

Mercury deposited from the air is converted to methylmercury by bacteria that live in the sediments of wetlands and lakes. It then accumulates in the aquatic food chain, with predator fish such as northerns having the highest concentrations.

Compounding that problems is climate change, which creates major variations in rainfall, sometimes drying up wetlands and causing more mercury to be converted to methylmercury.

Seeking a solution

Monson said he and others are working with scientists from the other Great Lakes states and provinces in an effort to look at trends throughout the region.

"Increased mercury pollution of fish underscores the need for nations worldwide to reduce mercury emissions to the greatest extent possible and address the problems brought on by climate change," said MPCA Assistant Commissioner David Thornton.

Earlier this week, the United States endorsed negotiations for a new global treaty to control mercury pollution. The Bush administration had opposed legally binding measures to control mercury.

With mercury concentrations rising in Minnesota fish, residents here should advocate for a worldwide solution, MPCA's Brungardt said.

Mary Lynn Smith • 612-673-4788

  • get related content delivered to your inbox

  • manage my email subscriptions

Click here to send us your hunting or fishing photos – and to see what others are showing off from around the region.

ADVERTISEMENT

New England 2/1/15 5:30 PM
Seattle
Milwaukee 6:00 PM
Orlando
New York 6:00 PM
Indiana
Denver 7:00 PM
Memphis
Chicago 9:30 PM
LA Lakers
Montreal 6:00 PM
NY Rangers
Winnipeg 6:00 PM
Philadelphia
Boston 6:00 PM
NY Islanders
Arizona 6:30 PM
Toronto
Dallas 6:30 PM
Ottawa
Detroit 6:30 PM
Tampa Bay
Columbus 6:30 PM
Florida
Nashville 7:00 PM
St. Louis
Minnesota 8:00 PM
Calgary
Buffalo 8:30 PM
Edmonton
Anaheim 9:00 PM
San Jose
DePaul 1:00 PM
Providence
Michigan State 5:00 PM
Rutgers
Boston Univ 6:00 PM
Army
Fla Atlantic 6:00 PM
Charlotte
Youngstown St 6:00 PM
Detroit
East Tenn St 6:00 PM
Furman
Saint Louis 6:00 PM
George Mason
USC Upstate 6:00 PM
Jacksonville
High Point 6:00 PM
Liberty
Central Conn St 6:00 PM
Long Island
Western Ky 6:00 PM
Louisiana Tech
Dayton 6:00 PM
Massachusetts
Chattanooga 6:00 PM
Mercer
Wofford 6:00 PM
UNC Greensboro
Maryland 6:00 PM
Ohio State
FIU 6:00 PM
Old Dominion
Fair-Dickinson 6:00 PM
Robert Morris
Mount St Marys 6:00 PM
St Francis-NY
Bryant 6:00 PM
St Francis-PA
Northern Ky 6:00 PM
Stetson
Coll of Charleston 6:00 PM
Towson
Western Carolina 6:00 PM
Va Military
Sacred Heart 6:00 PM
Wagner
Lipscomb 6:00 PM
Fla Gulf Coast
Kennesaw St 6:00 PM
North Florida
Appalachian St 6:30 PM
Ga Southern
Holy Cross 6:30 PM
Loyola-Maryland
Eastern Ill 6:30 PM
UT Martin
Jacksonville St 7:00 PM
Belmont
Connecticut 7:00 PM
Cincinnati
Rider 7:00 PM
Saint Peters
SIU Edwardsville 7:00 PM
SE Missouri St
Marshall 7:00 PM
Southern Miss
Tenn Tech 7:00 PM
Tennessee St
Middle Tennessee 7:00 PM
TX-San Antonio
Ill-Chicago 7:00 PM
Milwaukee
Weber State 7:00 PM
North Dakota
Denver 7:00 PM
North Dakota St
IUPU-Ft Wayne 7:00 PM
South Dakota
Louisiana 7:05 PM
South Alabama
Georgia State 7:15 PM
Texas-Arlington
Ark-Little Rock 7:30 PM
Arkansas State
ULM 7:30 PM
Troy
Portland 8:00 PM
Gonzaga
Kentucky 8:00 PM
Missouri
Eastern Ky 8:00 PM
Murray State
UAB 8:00 PM
Texas-El Paso
Idaho State 8:00 PM
Northern Colorado
UMKC 8:00 PM
Grand Canyon
Chicago State 8:05 PM
Utah Valley U
Colorado 8:30 PM
USC
Cal Poly 9:00 PM
UC Irvine
Hawaii 9:00 PM
CS-Northridge
Pepperdine 9:00 PM
Pacific
Santa Clara 9:00 PM
San Diego
Utah 9:00 PM
UCLA
UC Santa Barbara 9:00 PM
UC Davis
Montana 9:05 PM
Portland State
Montana State 9:05 PM
Sacramento St
Long Beach State 9:30 PM
Cal State Fullerton
Loyola Marymount 9:30 PM
St Marys-CA
San Francisco 10:00 PM
BYU
California 10:00 PM
Washington St
Louisiana 23 2nd Half 15:49
South Alabama 32
Saint Josephs 27 2nd Half
Saint Louis 20
Appalachian St 4:00 PM
Georgia Southern
Niagara 4:00 PM
Saint Peters
Old Dominion 5:00 PM
FIU
Southern Miss 5:00 PM
Marshall
Georgia State 5:00 PM
TX-Arlington
Ark-Little Rock 5:05 PM
Arkansas State
ULM 5:15 PM
Troy
Pittsburgh 5:30 PM
(17) Duke
(6) Tennessee 6:00 PM
(10) Kentucky
(24) Oklahoma 6:00 PM
(14) Texas
Nebraska Omaha 6:00 PM
IUPU-Ft Wayne
UC-Riverside 6:00 PM
CS-Northridge
Army 6:00 PM
Boston U
New Orleans 6:00 PM
Nicholls
Charlotte 6:00 PM
Florida Atlantic
Towson 6:00 PM
Delaware
Hofstra 6:00 PM
Northeastern
New Hampshire 6:00 PM
Maine
Albany 6:00 PM
Vermont
Hartford 6:00 PM
Stony Brook
UNC-Wilmington 6:00 PM
William & Mary
Clemson 6:00 PM
Wake Forest
Alabama 6:00 PM
(1) South Carolina
(23) Syracuse 6:00 PM
(8) Louisville
Missouri 6:00 PM
Florida
Iona 6:00 PM
Fairfield
Manhattan 6:00 PM
Marist
NC State 6:00 PM
Virginia
(4) Notre Dame 6:00 PM
Virginia Tech
(22) Rutgers 6:00 PM
Purdue
(5) Maryland 6:00 PM
Michigan
Milwaukee 6:00 PM
Cleveland State
Wright State 6:00 PM
Oakland
Jacksonville 6:00 PM
USC Upstate
North Florida 6:00 PM
Kennesaw St
Stetson 6:00 PM
Northern Ky
Loyola-Maryland 6:05 PM
Holy Cross
Lamar 6:30 PM
Sam Houston St
Fla Gulf Coast 6:30 PM
Lipscomb
Vanderbilt 7:00 PM
(18) Miss State
IUPUI 7:00 PM
Western Ill
Abilene Christian 7:00 PM
Houston Baptist
Incarnate Word 7:00 PM
TX A&M-CC
McNeese State 7:00 PM
SE Louisiana
Oral Roberts 7:00 PM
South Dakota St
Louisiana Tech 7:00 PM
Western Ky
TX-San Antonio 7:00 PM
Middle Tennessee
Texas-El Paso 7:00 PM
UAB
Auburn 7:00 PM
Arkansas
Grand Canyon 7:00 PM
UMKC
Illinois 7:00 PM
(15) Nebraska
(20) Iowa 7:00 PM
Northwestern
Utah Valley U 7:05 PM
Chicago State
Green Bay 7:05 PM
Valparaiso
Ole Miss 8:00 PM
LSU
Portland State 8:00 PM
Montana
Sacramento St 8:00 PM
Montana State
North Dakota 8:00 PM
Weber State
Ohio State 8:00 PM
Wisconsin
Northern Colorado 8:00 PM
Idaho State
BYU 9:00 PM
San Francisco
St Marys-CA 9:00 PM
Loyola Marymount
Pacific 9:00 PM
Pepperdine
Cal-Irvine 9:00 PM
UC Santa Barbara
San Diego 9:00 PM
Santa Clara
UC Davis 9:00 PM
Cal Poly
Long Beach St 10:59 PM
Hawaii
Connect with twitterConnect with facebookConnect with Google+Connect with PinterestConnect with PinterestConnect with RssfeedConnect with email newsletters

ADVERTISEMENT

ADVERTISEMENT

ADVERTISEMENT

ADVERTISEMENT

question of the day

Poll: Should the lake where the albino muskie was caught remain a mystery?

Weekly Question

ADVERTISEMENT

 
Close