Marine Research in focus provides updates on marine research for coastal communities. This fact sheet was produced by Maine Sea Grant with

programing support provided by University of Maine Cooperative Extension.

Background Mercury is a highly toxic element that can impair brain development in children, and affect cognition, hearing, vision, and muscle coordination in adults. Many watersheds in the Northeast have relatively high mercury concentrations for the US, because the region is downwind of major pollution sources.

Mercury is especially active in aquatic environments, so people are exposed to mercury primarily through the consumption of fish. Shrimp, the most popular seafood in the United States, is often touted as a “low-mercury” seafood choice, although available information is not specific to Maine’s native shrimp species.

This study intended to answer two questions:

Are shrimp truly a low-mercury food? Does it matter where the shrimp come from?

April 2011 / Vol. 7

Healthy, Sustainable Seafood: A Study of Mercury in Shrimpby Sarah J. Nelson and Catherine Schmitt

MethodsWe purchased three types of frozen, headless shrimp from a Maine supermarket: Maine Northern shrimp (Pandalus borealis), Louisiana brown shrimp (Farfantepenaeus aztecus), and Thailand tiger shrimp (Penaeus monodon). After lab tests confirmed that shrimp had similar concentrations of mercury along the whole length of the edible part1 of their bodies, a section of shrimp meat was analyzed in the University of Maine’s Sawyer Environmental Chemistry Research Laboratory to determine total mercury concentration in each individual shrimp.

Why Study Shrimp?Shrimp is the number one type of seafood consumed in the United

States – over 1.2 billion pounds in 2009 (Fisheries Statistics Division

2010). While shrimp is promoted as a “low-mercury” seafood choice,

few2 studies have looked at mercury in commercially available shrimp.

The current safety level is based on only 24 samples from the 1990s3,

and the species is only identified for a few of those samples4, even

though several different species of

shrimp are available to consumers.

Most shrimp consumed in the

US is imported from farms in

Asia, but Maine has its own wild

shrimp fishery, for Pandalus

borealis or Northern shrimp. This

is a small but sustainable fishery

that employs fishermen in the

winter months. Maine shrimp

are typically available fresh from

December through April and

frozen year-round.

1. Some people do cook and/or consume shrimp whole with the shell, however we analyzed them headless and without shells, as most consumers prepare them.

2. One study found that shrimp do accumulate mercury rapidly when they are in a high mercury environment (Palmer and Presley 1993); another study in New Jersey (which did not say which species/origin shrimp they used) found low-mercury in shrimp and noted that bigger shrimp tended to have less mercury (Burger et al. 2005). We are not aware of any studies that determined mercury in commercially available Maine wild-caught shrimp.

3. http://www.fda.gov/Food/FoodSafety/Product-SpecificInformation/Seafood/FoodbornePathogensContaminants/Methylmercury/ucm115644.htm

4. http://www.fda.gov/Food/FoodSafety/Product-SpecificInformation/Seafood/FoodbornePathogensContaminants/Methylmercury/ucm191007.htm

FDA DataThe Maine Center for Disease Control and Prevention and the Environmental Protection Agency set limits on the level of mercury in fish that is considered safe to eat. Maine’s guideline is stricter, to protect sensitive populations like children and pregnant women. The average mercury concentration in shrimp in this study (21 ppb) is 10 times lower than Maine’s fish tissue action level of 200 ppb. Even the one shrimp with the highest mercury concentration (66 ppb) still had three times less mercury than Maine’s action level. By comparison, EPA recently found that approximately half of the freshwater fish sampled from 76,559 lakes across the US had mercury concentrations that exceeded the EPA’s recommended safety level of 300 ppb (US EPA 2009).

This StudyAll samples were very low in mercury, in agreement with the existing FDA data. Mercury in shrimp for all samples taken together (“All shrimp” bar) averaged 21 ppb, ww (parts per billion, wet weight). The range of values in our study was 4 – 66 ppb, ww. Although there were statistically significant differences among the three types of shrimp we studied, these differences are not meaningful for human consumption because the levels of mercury are so low. The differences among the types of shrimp raise interesting research questions, such as, Does shrimp size matter? What is the difference between farm raised and wild shrimp?

0 600 900 1200 1500 1800 3000 3300

ShrimpClam

Salmon (fresh/frozen)Haddock

CrabFreshwater trout

Freshwater perchCanned light tuna

LobsterBass (saltwater, striped, black)

HalibutCanned albacore tuna

Sword�sh

300

Average

Maximum

0 100 200 300

MaineGulf of Mexico

Thai

All shrimp

Total mercury, ppb ww

Total mercury, ppb ww

Mercury in commercially-available shrimp

Mercury in commonly-eaten seafood (FDA data)

Maine mercury guideline

Maine mercury

guideline

EPA mercury guideline

EPA mercury

guideline

Average and maximum mercury concentrations in shrimp and other seafood

ReferencesBurger J., A.H. Stern, M. Gochfeld. 2005. Mercury in commercial fish: optimizing individual choices to reduce risk. Environmental Health Perspectives 113:266-271.

Fisheries Statistics Division. 2010. Fisheries of the United States 2009. Silver Spring, MD: National Marine Fisheries Service. http://www.st.nmfs.noaa.gov/st1/fus/fus09/index.html

Palmer, S.J., B.J. Presley. 1993. Mercury bioaccumulation by shrimp (Penaeus aztecus) transplanted to Lavaca Bay, Texas. Marine Pollution Bulletin 26:564-566.

US EPA. 2009. The National Study of Chemical Residues in Lake Fish Tissue, EPA-823-R-09-006. Washington, DC: US Environmental Protection Agency Office of Water.

0 600 900 1200 1500 1800 3000 3300

ShrimpClam

Salmon (fresh/frozen)Haddock

CrabFreshwater trout

Freshwater perchCanned light tuna

LobsterBass (saltwater, striped, black)

HalibutCanned albacore tuna

Sword�sh

300

Average

Maximum

0 100 200 300

MaineGulf of Mexico

Thai

All shrimp

Total mercury, ppb ww

Total mercury, ppb ww

Mercury in commercially-available shrimp

Mercury in commonly-eaten seafood (FDA data)

Maine mercury guideline

Maine mercury

guideline

EPA mercury guideline

EPA mercury

guideline

Maine Sea Grant supports marine science research and outreach activities. Based at the University of Maine, our coastwide program works in partnership with marine industries, scientists, government agencies, private organizations, and a wide range of marine resource users. For more information on the activities of the Maine Sea Grant College Program at the University of Maine, please call 207.581.1435 or visit our website at www.seagrant.umaine.edu.

Edited by Catherine Schmitt, Maine Sea Grant; Design by Kathlyn Tenga-González, Maine Sea Grant. Photos—Cover, shrimp: NOAA; seafood: Kathlyn Tenga-González. Page 2: Ken La Valley.

In complying with the letter and spirit of applicable laws and pursuing its own goals of diversity, the University of Maine shall not discriminate on the grounds of race, color, religion, sex, sexual orientation, including transgender status or gender expression, national origin, citizenship status, age, disability, or veteran’s status in employment, education, and all other areas of the University System. The University provides reasonable accommodations to qualified individuals with disabilities upon request. Questions and complaints about discrimination in any area of the University should be directed to the Director of Equal Opportunity, the University of Maine, 5754 North Stevens Hall, Room 101, Orono, ME 04469-5754, telephone (207) 581-1226, TTY (207) 581-9484.

MSG-E-10-16NA06OAR4170108

Funding provided by:

ConclusionBalancing safety, nutritional value, affordability, and environmental concerns when making food decisions is challenging for many Maine families. This study provided more data to support the assertion that people who are concerned about mercury should feel comfortable eating shrimp, including Maine shrimp. Shrimp are a low-fat, healthy protein source, and Maine shrimp are a local, affordable, and sustainably managed seafood choice.

Maine Safe Eating GuidelinesAccording to the Maine Department of Environmental Protection, mercury levels in Maine fish, loons, and eagles are among the highest in North America. This has led the Maine Center for Disease Control and Prevention to issue a statewide advisory recommending that pregnant women, women of childbearing age, and young children limit their fish consumption based on the type of fish they consume. The advisories have been in place since 1994 and remain in effect today because mercury levels in fish have not decreased. Currently 49 states, including Maine, have fish consumption advisories due to mercury contamination. http://www.maine.gov/dep/mercury/

The Maine Safe Eating Guidelines set fish consumption limits to protect everyone. http://www.maine.gov/dhhs/eohp/fish

Clams and Scallops

Light Canned Tuna

Flounder and Sole

Haddock, Hake,Cod and Pollock

Lobster Imitation Crab and Lobster

Fish low in mercury and high in Omega 3 fish oils Fish low in mercury

Don’t Eat These Fish!If you are pregnant, nursing, may get pregnant or a child under 8

Fresh Salmon Atlantic MackerelSmelt

ShrimpCanned Salmon Sardines Mussels

Swordfish • Shark • King Mackerel • Tilefish

Everyone else can eat 2 meals a month of these 4 fish

Healthy Fish for Pregnant Women and Families

Questions? Call the Maine CDC toll free in Maine: 1-866-292-3474

Eat 2 Meals a Week of Different Fish

High Mercury Fish to Limit or Avoid

Advice for Pregnant and Nursing Women,Women Who May Get Pregnant, and Children Under Age 8

Fish to Avoid: Pregnant and nursing women, women who may getpregnant, and children under age 8 should NOT eat these 4 fish.They’re too high in mercury:

• Swordfish• Shark• King Mackerel• Tilefish

These fish are high in mercury because they eat other fish or live a long time. Mercury can damage a brain starting to form or grow. That’s why babies in the womb, nursing babies, and young childrenare at most risk.

Fish to Limit: Pregnant and nursing women and children under age8 may safely eat one meal per week of one of these fish. Chooseother fish listed on page 3 for the 2nd fish meal that week.

• Tuna steak• White canned tuna (see page 9)• Halibut steak

Advice for Everyone ElseFish to Limit: Other adults and children over age 8 may safely eat up to 2 meals per month of swordfish, shark, king mackerel, andtilefish. These fish are high in mercury because they eat other fish orlive a long time. Too much mercury lowers the heart healthy benefits ofOmega 3 fish oils.

Limits on Fish You Catch: See eating limits for sport caughtfish (fish from Maine rivers, lakes, ocean) on page 11.

4

Don’t Buy Smelly Fish! Buy Fresh Fish

• Buy fish in places you trust. Ask when the fish you plan to buycame in. If it’s more than a day or two old, choose another kind.

• Check that fish has been properly iced or kept in a refrigerator. Ask to smell it. It should smell fresh and mild, not strong or “fishy.”

• Ask for recipes.

Buy Frozen Fish

• Frozen seafood is just as healthy as fresh. Just make sure the packagesare sealed tight, not torn or crushed on the edges. Also don’t buypackages covered in frost or ice crystals. This could mean the fish hasbeen stored a long time or thawed and refrozen.

• If you see the letters FAS, they mean Frozen At Sea. When you buy FAS fish, it may still be frozen or it may be thawed.It’s safe to buy either way.

Store Fish Safely

• Best to cook and eat, or freeze, fresh fish (and thawed FAS fish)within 2 days of purchase. You can safely keep fresh fish that youbuy or catch in the freezer for up to 3 months. Mark the date onthe package!

• Fish that you buy frozen should go right into your freezer whenyou get home. Don’t let it thaw until ready to cook. It can stay in the freezer for up to 3 months.

• If fish smells strong or feels slimy, throw it out. Don’t cook it or eat it.

5

Find the Facts Fast

Best Fish to Eat and Fish to Avoid• Family-Friendly Fish: Eat 2 Meals a Week of Different Fish. . . . . . Page 3

• High Mercury Fish to Limit or Avoid . . . . . . . . . . . . . . . . . . . . . . . . Page 4

How to Buy, Cook, Eat Fish Out• Don’t Buy Smelly Fish! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 5

• Pull-Out Poster: Healthy Seafood 2 Meals A Week . . . . . . . . . . Page 6

• Fish for Dinner: Cook In or Eat Out . . . . . . . . . . . . . . . . . . . . . . . . Page 8

Tuna, Fish Sticks, Salmon, and Fish You Catch• OK to Eat Tuna, Fish Sticks, Farm-Raised Fish . . . . . . . . . . . . . . . . Page 9

• Salmon: 3 Choices for Taste, Health, and Budget . . . . . . . . . . . . . Page 10

• Fish You Catch in Rivers, Lakes, or the Ocean . . . . . . . . . . . . . . . . Page 11

This brochure was produced with funding from the U.S.Environmental Protection Agency Cooperative Agreement#CR82628301-0

In accordance with Federal laws, the Maine Department ofHealth and Human Services does not discriminate on the basisof sex, age, color, national origin, or disability in admission oraccess to or treatment or employment in its programs andactivities. The Department’s Affirmative Action Coordinator hasbeen designated to coordinate our efforts to comply with andimplement these Federal laws and can be contacted for furtherinformation at: 221 State Street, Augusta, Maine 04333, (207)287-2567, or Hearing Impaired call 1-800-606-0215.

For more information:

General information: http://www.maine.gov/dhhs/eohp/fish/

Cooking fish: www.deliciousdecisions.org/cb/rec.html (under Main ingredients, check seafood, scroll to bottom and click submit)

Buying fish: www.ocean.udel.edu/mas/seafood/handling.html

For health information about mercury in fish or omega 3 oils, call Maine CDCtoll-free in Maine: 1-866-292-3474

Environmental and Occupational Health Program,Maine Center for Disease Control and Prevention, DHHS(formerly Bureau of Health}11 State House Station, Augusta, ME 04333TTY: (800)606-0215Produced December 2005

In collaboration with: AHEC Health Literacy Center, University of New England, Biddeford, MaineDesign: Campbell CreativeThanks to these community partners who helped decide and test content, language,and graphics: Franklin County Children’s Task Force, York County Alliance forHealthy Families, Knox County Parents as Teachers, Maine Nutrition Network

Gov. John Elias Baldacci

Healthy Fish for Pregnant Women and Families: Eat 2 Meals a Week of Different Fish

Best ChoicesSeafood High in Omega 3 Oils and Low in Mercury• Salmon – fresh and canned

Try budget friendly canned salmon. See recipe on page 10.

• Sardines and Herring

• Smelt

• Atlantic Mackerel

• Mussels

More Great ChoicesOther Seafood Low in Mercury, but Not as Highin Omega 3 Fish Oils• Light Canned Tuna

• Scallops and Clams

• Shrimp – fresh, frozen, canned, from Maine and away

• Flounder and Sole

• Haddock, Hake, Pollock, and Cod

• Imitation Crab or Lobster (This is made from various fish.)

• Lobster – but do not eat tomalley, the green stuff inside the body

Why are Omega 3 fish oils important? Omega 3 fish oils are “brainfood” for babies in the womb and babies who are nursing. These oils alsohelp protect adults from heart attack deaths. Fish is also a great source of protein, zinc and iron and is low in saturated fat.

Most farm raised fish are safe to eat. See page 9. For farm raised salmon,see page 10.

3

The Maine Family Fish Guide: Advice from theMaine Center for Disease Control and Prevention

Fish: 2 Meals a Week for Good Health

Buy Cook

Catch Eat Out

If you’re pregnant, this sign means caution

for pregnant women, children, and adults

Acknowledgements

Maine Sea Grant provided funding and support for this research. The Senator George J. Mitchell Center at the University of Maine provided support to S.J. Nelson for participation in this work. M. Lagerklint and C. Devoy at the Sawyer Environmental Chemistry Research Laboratory at the University of Maine analyzed samples. K. Johnson of Husson University and staff from the Maine Center for Disease Control and Prevention provided constructive comments and information about Maine’s human health guidelines.