Mercury in Fish: What Grand Rapids, Michigan Families Need to Know

Mercury is a naturally occurring element found in air, water, and food. In West Michigan, including the Grand Rapids area, mercury can build up in certain types of fish caught in the Great Lakes and inland lakes and rivers. Understanding how to choose low‑mercury fish is especially important for pregnant women, people planning pregnancy, and families with young children.

How Most People in Grand Rapids Are Exposed to Mercury

Most people are exposed to mercury through the food they eat, especially fish and seafood. The form of mercury found in fish is methylmercury, which is more toxic than other forms. It binds to proteins in the body, including those in muscle tissue.

Common points to remember:

  • Methylmercury builds up in fish over time.
  • Food processing, cleaning, and normal cooking do not significantly reduce mercury levels in fish.
  • Mercury levels vary by fish species, size, age, and where the fish live and feed.

In the Grand Rapids area, people may eat:

  • Store‑bought or restaurant fish (ocean or farmed fish)
  • Locally caught fish from:
    • Lake Michigan
    • Grand River
    • Thornapple River
    • Reeds Lake and other Kent County inland lakes

For locally caught fish, it’s important to follow Michigan Department of Health and Human Services (MDHHS) fish consumption advisories.

Why Unborn Babies Are at the Greatest Risk

Babies developing in the uterus are especially sensitive to mercury’s effects on the brain and nervous system. When a pregnant person eats fish high in mercury:

  • Mercury can enter the bloodstream.
  • It crosses the placenta.
  • It can affect the baby’s developing brain and nerves.

Possible effects (often not seen until later in childhood) can include:

  • Delays in reaching milestones such as walking and talking
  • Problems with memory
  • Language and learning difficulties
  • Shorter attention span

Because of this, pregnant women, women planning to become pregnant within 6 months, and families with young children in Grand Rapids should be especially careful about the types and amounts of fish they eat.

Forms of Mercury and Why Fish Are a Concern

Mercury in the environment exists in three main forms:

  • Elemental (metallic) mercury
  • Inorganic mercury compounds
  • Organic mercury compounds, mainly methylmercury – the most dangerous form for people

Methylmercury in fish usually comes from mercury in water and sediment that is converted by microorganisms into the organic form. Fish absorb methylmercury:

  • Through their gills as they swim
  • Through their digestive tract when they eat

Over time, mercury builds up in fish tissue. Levels differ between species due to:

  • Type of fish (predator vs. non‑predator)
  • Size and age
  • Habitat (Great Lakes vs. inland lakes/rivers vs. ocean)
  • Diet

Fish at the Top of the Food Chain Have More Mercury

Predatory fish (those that eat other fish) tend to be larger and live longer. Because of this, they accumulate higher levels of mercury.

Higher‑mercury fish (limit or avoid, especially in pregnancy and for young children):

  • Shark
  • Swordfish, marlin, and other large billfish
  • Some large tuna species (e.g., bigeye, some fresh/frozen steaks)
  • Certain large Great Lakes predator fish (consult Michigan advisories for specific species like walleye, northern pike, and some trout/salmon sizes)

Lower‑mercury fish (generally safer choices when eaten in recommended amounts):

  • Canned light tuna
  • Salmon (fresh, frozen, or canned)
  • Pollock
  • Cod
  • Tilapia
  • Whitefish
  • Most shellfish (shrimp, crab, lobster, oysters, clams)
  • Many smaller panfish from local lakes (follow MDHHS guidance)

Fish, Mercury, and Health in West Michigan

Health Benefits of Eating Fish

Fish is an important part of a healthy diet and can be especially helpful for people in Grand Rapids who are at higher risk of:

  • Heart disease and stroke
  • High cholesterol
  • Obesity and type 2 diabetes

Some benefits of eating fish:

  • High in protein
  • Low in saturated fat
  • High in healthy unsaturated fats, including omega‑3 fatty acids that support heart and brain health

For most healthy adults and older children (age 6 and up) in Grand Rapids, fish sold in U.S. grocery stores and restaurants is not a health risk when eaten as part of a normal, varied diet and when high‑mercury species are limited.

General Guidance for Healthy Adults and Older Children

For healthy adults who are not pregnant and children 6 years and older:

  • Fish with high mercury levels should not be eaten more than once a week.
  • A standard adult serving is about 150 g (5 oz) of cooked fish.
  • For children, a serving is smaller (about 75 g / 2.5 oz for young children).

Mercury and Pregnancy: Why Extra Caution Matters

When a pregnant person regularly eats fish high in mercury:

  • Mercury levels in the blood can rise.
  • Mercury can cross the placenta and reach the baby.
  • Effects on the baby’s brain and nervous system may not be obvious at birth but may appear later as developmental or learning problems.

International research in places like New Zealand, the Faroe Islands, and the Seychelles has shown that high intake of mercury‑containing fish during pregnancy can affect child development. This research has led to worldwide recommendations to:

  • Limit fish with known high mercury levels
  • Choose low‑mercury fish more often, especially during pregnancy and early childhood

U.S. guidelines have been updated several times to reflect this research. Michigan has also issued specific consumption advisories for fish caught in:

  • Lake Michigan
  • Inland lakes and rivers
  • Areas with known contamination (including some stretches of the Grand River and other West Michigan waterways)

How Much Fish Is Safe? Serving Guidance

Below is simplified guidance for fish consumption, adapted for Grand Rapids residents. Always cross‑check with the latest FDA/EPA and Michigan Department of Health and Human Services (MDHHS) advisories, especially for locally caught fish.

Serving Sizes

  • Adults (including pregnant women): 1 serving = about 150 g (5 oz) cooked fish
    (≈ 2 frozen crumbed fish portions)
  • Children up to 6 years: 1 serving = about 75 g (2.5 oz) cooked fish
    (≈ 3 fish fingers)

Pregnant Women and Women Planning Pregnancy (Within 6 Months)

Aim for 2–3 servings of low‑mercury fish per week for your health and your baby’s development.

Safer choices (2–3 servings/week):

  • Salmon (including Lake Michigan salmon within MDHHS guidelines)
  • Canned light tuna (limit albacore/white tuna)
  • Pollock, cod, tilapia
  • Shrimp, crab, lobster
  • Whitefish, perch, smaller panfish (check MDHHS advisories for local catches)

Limit higher‑mercury fish:

  • Orange roughy or catfish:
    • Up to 1 serving per week, and no other fish that week
  • Shark or large billfish (swordfish, broadbill, marlin):
    • Up to 1 serving per fortnight (every 2 weeks), and no other fish that fortnight

For locally caught fish (Grand River, Lake Michigan, inland lakes), follow MDHHS “Eat Safe Fish” guidelines, which may be more restrictive for certain species and sizes.

Children Up to 6 Years Old

Children are more sensitive to mercury. Use smaller serving sizes (about 75 g / 2.5 oz).

  • Low‑mercury fish:
    • 2–3 servings per week
  • Orange roughy or catfish:
    • 1 serving per week, and no other fish that week
  • Shark or billfish:
    • 1 serving per fortnight, and no other fish that fortnight

General Population (Everyone Else, Age 6+ and Not Pregnant)

  • Any low‑mercury fish and seafood (other than shark or billfish):
    • 2–3 servings per week
  • Shark or billfish:
    • Up to 1 serving per week, and no other fish that week

If You Ate High‑Mercury Fish in Grand Rapids

Women should not panic if they have had an occasional meal of fish that may be high in mercury.

Important points:

  • Mercury becomes a concern when high‑mercury fish are eaten regularly over many months.
  • The body gradually clears mercury over time.
  • A one‑time or rare exposure is unlikely to cause harm.
  • Methylmercury from fish eaten during pregnancy appears to pose the greatest risk while the baby is still in the womb.
  • Once the baby is born, mercury levels in breastmilk are generally too low to pose a risk when the mother follows current fish consumption guidelines.

If you are pregnant or planning pregnancy and are concerned about mercury exposure:

  • Talk to your primary care provider, OB/GYN, or midwife at:
    • Spectrum Health (Corewell Health) in Grand Rapids
    • Trinity Health Grand Rapids
    • Metro Health – University of Michigan Health
    • Mercy Health and affiliated clinics

They can order a blood test for mercury if needed and help you adjust your diet safely.

Mercury, Breastfeeding, and Grand Rapids Families

Breastfeeding has many proven health benefits for both mother and baby. Current evidence shows:

  • Mercury levels in breastmilk are usually much lower than levels that could harm an infant.
  • Following fish consumption guidelines during pregnancy and breastfeeding helps keep levels safe.
  • In almost all cases, breastfeeding should continue, even if the mother eats fish, as long as she follows recommended limits.

If you have questions, you can also speak with:

  • A dietitian at a Grand Rapids hospital system (Spectrum Health, Trinity Health, Metro Health, Mercy Health)
  • A lactation consultant through your birth hospital or local clinics

Local Considerations for Grand Rapids and West Michigan

Seasonal and Local Fishing

Grand Rapids residents often fish in:

  • Lake Michigan (especially for salmon, trout, and whitefish)
  • Grand River and its tributaries
  • Kent County inland lakes and ponds

Cold Michigan winters and ice fishing can increase reliance on locally caught fish as a food source. Because some Michigan waters have higher mercury and other contaminants (like PCBs or PFAS), always:

  • Check the MDHHS Eat Safe Fish Guide for:
    • Lake Michigan
    • Grand River
    • Kent County inland lakes
  • Follow local advisories posted by the Kent County Health Department and Grand Rapids Public Health when available.

Where to Get Help in Grand Rapids, Michigan

If you have questions about mercury in fish, safe fish choices, or your family’s diet, you can contact:

  • Your primary care provider or pediatrician
    (Spectrum Health/Corewell Health, Trinity Health Grand Rapids, Metro Health, Mercy Health, or local clinics)
  • Kent County Health Department
    For local fish advisories and public health information
  • Grand Rapids Public Health resources
    For community nutrition and maternal–child health programs
  • Registered dietitians at:
    • Spectrum Health/Corewell Health
    • Trinity Health Grand Rapids
    • Metro Health – University of Michigan Health
  • Michigan Department of Health and Human Services (MDHHS)
    For statewide Eat Safe Fish guidelines and Great Lakes advisories

Key Points for Grand Rapids Residents

  • Unborn babies are at the greatest risk from mercury exposure in fish.
  • Mercury is common in the environment and exists in several forms; methylmercury in fish is the most concerning for human health.
  • Most fish sold in U.S. stores and restaurants is safe when eaten in recommended amounts and when high‑mercury species are limited.
  • Pregnant women, women planning pregnancy, and young children should follow specific fish consumption guidelines and be extra cautious with high‑mercury fish.
  • After birth, breastmilk mercury levels are typically low and not considered a risk when fish guidelines are followed.
  • The body does clear mercury over time, so problems usually occur only with frequent, long‑term intake of high‑mercury fish.
  • In Grand Rapids and West Michigan, always check Michigan’s Eat Safe Fish advisories for Lake Michigan, the Grand River, and local lakes before eating locally caught fish.

By choosing low‑mercury fish and following local guidance, Grand Rapids families can enjoy the health benefits of fish while protecting themselves and their children from mercury exposure.