2018-07-12 / Outdoors

State warning includes fish caught in Leelanau Co. waters

By Jen Murphy
of the Enterprise staff

Fish caught in Leelanau County are basically safe to eat — but be wary of certain species.

And don’t eat too much.

That’s the gist of the “Eat Safe Fish Guide” recently released by the Michigan Department of Health and Human Services.

The 2018 ESF Guide, based on research conducted by the Department of Natural Resources and the Department of Environmental Quality, warns against consumption of walleye over 22 inches, brown trout, whitefish, lake trout and carp of any size from Lake Michigan as well as lake trout over 32 inches from north Lake Leelanau.

The guide does have one “Best Choice” for fish from Leelanau County lakes: bullhead.

Glen Lake Association fish biologist Rob Karner said the reports change over time.

“They tend to focus on heavy metals, particularly mercury,” he said.

Karner explained that certain chemicals build up in fish over time and magnify at higher levels of the food chain.

He provided an example of zooplankton consumed by zebra mussels. Mercury contained in each of the tiny organisms are concentrated into a single zebra mussel.

A round goby, according to a study conducted by the University of Minnesota, can consume over 70 zebra mussels in one day. In an average four-year lifespan of the goby, that’s well over 100,000 zebra mussels.

Further up the food chain, any predator fish is eventually consuming a concentrated amount of unwanted heavy metal that could end up on someone’s dinner plate.

“The mercury gets more and more concentrated,” Karner said. “Fish accumulate the metals in their bodies. They are stored in fish in places like belly fat, skin and subcutaneous connective tissue.”

And predatory fish at the top of the aquatic food chain like salmon, trout and whitefish — all considered tasty — eventually accumulate the highest level of toxins.

That’s why DNR fisheries biologist Heather Hettinger and her team provide data for the guide each year.

“We are told how many of each species to collect,” she said. “We are updating, to the best of our abilities, and collecting data for the report.”

Fortunately, over the past decade or so, Hettinger said she has observed a decrease in the overall levels of mercury in fish samples.

“We have seen a shift historically. Twenty or thirty years ago, mercury was mover prevalent. As our manufacturing practices have changed, our mercury levels have decreased,” she said.

But mercury isn’t the only “bad guy” in the mix. The MDHHS report also raises warning flags for fish testing positive for dioxins and PCBs.

Like mercury, both of chemicals have significant impacts on human and environmental health. They are generated during the manufacturing of a variety of products, including herbicides.

As production of these items fluctuates, levels of the chemicals found in fish will fluctuate.

“Compounds will vary because of industry generating atmospheric pollutants has become idle or stagnant,” Karner said. “As deregulation continues, we may see more mercury (or other pollutants).”

Hettinger said the Eat Safe Fish Guide is a “living document” that changes from year to year. She encourages people to consult the report annually so they are informed about which fish to eat and how much to eat.

“It’s about quantity,” she said. “We really like for people to eat fish. It’s a healthier choice. But if you catch a larger fish, it probably belongs on the wall and not in your frying pan.”

The complete ESF Guide can be found online at michigan.gov.

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