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Will this be the year lake sturgeon spawn in the Milwaukee River?

Paul A. Smith, Milwaukee Journal Sentinel
·3 min read
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A sign explaining the protected status of lake sturgeon is placed along the Milwaukee River in Kletzsch Park.
A sign explaining the protected status of lake sturgeon is placed along the Milwaukee River in Kletzsch Park.

Advocates of Milwaukee River sturgeon restoration are asking: Will 2024 be the year sturgeon spawning will be observed in the river?

It's too early to say, according to Aaron Schilller, fisheries biologist with the Department of Natural Resources.

Schiller said two sturgeon were detected in early March swimming in the Milwaukee. The data are obtained with a cross-stream sensor system that detects fish implanted with passive integrated transponders, or PIT tags.

The high-tech equipment was installed in 2021 in the river south of Locust Avenue primarily to detect and record migrations of sturgeon as part of the native species' restoration project in the river. But it works on any PIT-tagged fish.

Another sensor was added to the river this year in the Kletzsch Park fish passage.

But since early March the river's water has cooled and no other sturgeon have been detected, Schiller said.

Sturgeon prefer water temperatures of 50 degrees Fahrenheit or higher to begin spawning, according to the DNR. On Tuesday the Milwaukee River water was 37 degrees.

Friday's snow will melt in the coming days and help increase river flows but it could take weeks for the water temperature to increase high enough for sturgeon spawning.

Even more important, of course, is whether adult sturgeon - and especially adult female sturgeon - will be present in the river this year.

Since 2006 sturgeon have been reared in a portable hatchery at Riveredge Nature Center in Newburg and stocked into the Milwaukee River or harbor.

It's part of "Return the Sturgeon," a joint effort of the DNR, U.S. Fish and Wildlife Service and Riveredge.

The goal is to restore the lake sturgeon population in the Milwaukee. The species is native to Lake Michigan and historically made spawning migrations up the Milwaukee and other tributaries. However, dams, pollution and overfishing combined to wipe out the local sturgeon population by the late 1800s.

Several dam removals in recent decades have opened up miles of river to migrating fish. And the water, while in need of further improvement, is arguably cleaner than it's been in 150 years.

Through 2022, the local work stocked the Milwaukee with 23,726 young sturgeon, according to DNR records; the project's target is to release about 1,000 a year.

Cheryl Masterson, DNR fisheries supervisor in Milwaukee, holds a lake sturgeon caught April 2, 2015 during an electro-shocking survey of the Milwaukee River. The fish was released.
Cheryl Masterson, DNR fisheries supervisor in Milwaukee, holds a lake sturgeon caught April 2, 2015 during an electro-shocking survey of the Milwaukee River. The fish was released.

Each stocked fish is implanted with a PIT tag similar to microchips used to identify cats and dogs, and receives a right ventral fin clip.

Since male lake sturgeon mature at about 15 years of age and females at about 20, DNR fisheries staff and others are watching closely for the first signs of sturgeon spawning behavior on the Milwaukee.

Adult sturgeon have been observed in the Milwaukee for the last several years, including a "milestone" fish netted April 7, 2021 by a DNR crew.

The 50-inch-long sturgeon had a right ventral fin clip and PIT tag that traced it to the 2007 year class of fish raised at Riveredge.

It was the first sturgeon from the stocking program documented to return to the river as an adult.

In 2022 the DNR documented 24 PIT-tagged sturgeon swimming up the Milwaukee, Schiller said.

And in 2023, 23 individual sturgeon were detected. It's assumed the fish were adults but unless the DNR can capture the fish it's not possible so say with certainty.

Interestingly, five of the sturgeon migrated up the Milwaukee in both 2022 and 2023, Schiller said.

And one of the sturgeon has been detected in 2022, spring of 2023, fall of 2023 and in 2024.

So sturgeon are returning to the river in modest numbers. But none of the adult sturgeon handled by the DNR in the Milwaukee in recent years was a female.

So the sturgeon spawning watch will continue this year. Anglers and others should know sturgeon in the Milwaukee River are protected and no fishing is allowed for the fish. Any sturgeon caught incidentally must be immediately released.

If anyone witnesses a sturgeon being harvested or harassed on the river, they are urged to call the DNR conservation warden tip-line at (800) 847-9367.

This article originally appeared on Milwaukee Journal Sentinel: Will this be the year lake sturgeon spawn in the Milwaukee River?