Anticipated fish kill should not affect Saginaw Bay


ARENAC COUNTY — The Michigan Department of Natural Resources announced last week that due to heavy snow cover on waterways this year, fish kill may be a common occurrence in the spring, but the Saginaw Bay is not expected to see a massive fish kill event.

In a DNR press release, fish production manager Gary Whelan said a fish kill, referred to as “winterkill” after the season passes, occurs when fish do not receive enough dissolved oxygen. This typically occurs when the snow cover blocks the sunlight from aquatic plants, which in turn stop producing oxygen.

“Winterkill begins with distressed fish gasping for air at holes in the ice and often ends with large numbers of dead fish that bloat as the water warms in early spring,” Whelan said. “Dead fish and other aquatic life may appear fuzzy because of secondary infection by fungus, but the fungus was not the cause of death. The fish actually suffocated from a lack of dissolved oxygen from decaying plants and other dead aquatic animals under the ice.”

Chris Freiburger, a supervisor in the DNR’s habitat management division, told the Independent a fish kill is possible in the Saginaw Bay, but is not likely.

“Typically we’re going to experience fish kills on inland lakes,” he said. “Typically, they’re shallower or smaller lakes.”

Unlike many inland lakes, the bay is fed water from large rivers and usually has open water far off the shores, Freiburger said. Fish often gather at these areas where the water is being oxygenated, he said.

“If there’s a tributary, you’ll see a lot of fish concentrated around there, or near a hole trying to get the oxygen,” he said.

When there is heavy snow cover preventing aquatic plants from providing oxygen to fish and other aquatic animals, Freiburger said the oxygen that is in the water is used up by decomposing plants.

A fish kill is usually visible about one week after the ice melts away, Freiburger said. As the waves start moving again, dead fish wash up on the shore, sometimes partially decomposed, he said. There is not much a person can do to avoid the fish kill, Freiburger said.

“If the stench is so bad you can attempt to remove them,” he said. “If you want to, you can bury them.”

Whelan said fish kills do not affect the long-term health of a body of water when it comes to recreational fishing.

“These kills are localized and typically do not affect the overall health of the fish populations or fishing quality,” he said.


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