A big catch for Riveredge

A fish captured in the Milwaukee River last week turned out to be a really big catch.

At more than 50 inches long, the sturgeon was not only physically big, it was huge in significance to efforts to reintroduce this ancient species to the Milwaukee River, bolster its numbers in the Great Lakes and, in particular, to Riveredge Nature Center’s role in these efforts. 

“This is really, really big,” Mary Holleback, the senior naturalist at the Town of Saukville center, said of the importance of the fish.

Since 2006, when Riveredge joined the Return the Sturgeon project, it has reared more than 17,000 sturgeon from eggs in water pumped from the Milwaukee River to its streamside facility, then released them in the river.

The theory was that fish raised this way would imprint on the river, and after their maiden voyage downstream and years spent in Lake Michigan they would follow their instincts back to the river when they reached spawning age — 15 years old for males and 25 for females — to reproduce. 

That was theory until Wednesday, April 7, when Wisconsin Department of Natural Resources employees documented for the first time the return of an adult sturgeon from Riveredge to its native waters. Its fin clip and passive integrated transponder identified it as a member of the Riveredge sturgeon Class of 2007.

“This is the first time a fish from this project did what it was supposed to do, and right on time,” Holleback said, noting the male sturgeon was 15 years old.

“We’re really excited about this because for years we’ve been doing this on faith,” she said. “We knew all along this was supposed to happen. Now we know it does happen.”

Although the sturgeon made the trip upstream, it appears his journey was in vain.

“This guy probably didn’t find a female, so it’s kind of a waste of his time,” Holleback said. “But when you consider that sturgeon live to between 80 and 120 years old, he’s still young and hopefully didn’t get discouraged and will be back.”

Also caught in the Milwaukee River last week were a 47-inch sturgeon released from the Wild Rose State Fish Hatchery in 2005 and one that was more than 60 inches long that had no tag, which suggests it was hatched in the wild or lost its tag.

The presence of sturgeon in the river is good news for the Return the Sturgeon project, a partnership between Riveredge, the DNR and U.S. Fish and Wildlife Service intended to bolster the number of the state’s oldest and largest fish species in the Great Lakes and reintroduce it to the Milwaukee River.

By the turn of the 20th century, the population of sturgeon, prized for the caviar made from its eggs, in the Great Lakes had been decimated by overfishing, Holleback said. 

“These fish were killed for their eggs, then thrown on the shores,” she said. “Like everything else, fishermen at one time thought the number of sturgeon was limitless.”

The species, which has managed to survive for 200 million years and is now one of the most studied fish, is making a slow comeback, but its population in the Great Lakes is still only estimated to be 1% of what it once was.

Sturgeon are native to the Milwaukee River, but were wiped out there in the 1800s by pollution, habitat destruction and the construction of barriers such as dams that blocked their spawning runs upstream.

The Ozaukee County Milwaukee River Restoration Project has played an important role in the Return the Sturgeon project by removing dams and other barriers along the river and its tributaries, Holleback said. 

“When we started this project, there were no fewer than nine dams between Riveredge and the (Milwaukee) harbor. Now there is only one,” she said. “The restoration has really been instrumental to the sturgeon project.”