Transport and Consumption of Fish

A ferry pulls into a dock
Voyageur II arrives from Grand Portage.

NPS / Katie Keller

Fish Consumption Advisories in National Park Waters

The Environmental Protection Agency, states, territories, and tribes provide advice on fish and shellfish caught in the waters in their jurisdiction to help people make informed decisions about eating fish. Advisories are recommendations to limit your consumption of, or avoid eating entirely, certain species of fish or shellfish from specific bodies of water due to chemical or biological contamination.

Fish is part of a healthy balanced diet, but eating wild fish and shellfish caught in park waters is not risk free. Parks are “islands”, but the much larger “ocean” that surrounds them affects the natural resources inside a park. Other aquatic toxins are the result of natural biological processes. Also, chemical contaminants that originate outside of park boundaries can come into parks.

Mercury is an example of a toxin originating outside a park that can find its way into a park. Mercury exists naturally in some rocks, including coal. When power plants burn coal, mercury can travel in the air long distances before falling to the ground, usually in low concentrations. Once on the ground, microorganisms can change this elemental mercury to methyl mercury. This type of mercury can build up in animal tissues, and it can increase in concentration to harmful levels. This high concentration can occur in large predatory fish - those often pursued and eaten by anglers. Studies have shown that fish in some National Park System waters have mercury levels that may be a concern to people who regularly eat a lot of fish.

Isle Royale National Park Fish Consumption Advisories

Transporting Fish to the Mainland

You are allowed only one day's catch in your possession. One day's limit may be transported via ferries or seaplane with a Michigan DNR permit while license holder remains in the park.

Fish Consumption Advisory

  • Contaminants discovered in the park ecosystem remind us that although Isle Royale is remote, it is part of a global system.

  • Ongoing research in six inland lakes (Sargent, Siskiwit, Eva, Shesheeb, Wagejo, and Angleworm) shows fish with mercury levels exceeding the State of Michigan fish consumption advisories.

  • More information can be found through the Michigan Department of Community Health.

To learn more about this topic, the National Park Service maintains information about Fish Consumption Advisories and Mercury and Toxins in Nature.


Last updated: March 26, 2021

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