DNR probes why 27 lake sturgeon got trapped

By ISABELLA FIGUEROA NOGUEIRA

Capital News Service

LANSING – The Department of Natural Resources is embarking on a three-year project to understand why nearly 30 threatened lake sturgeon became trapped last summer near the Ontonagon River in the Upper Peninsula.

The DNR is reviewing historical river flow and water temperature data to better understand the conditions surrounding the incident to hopefully prevent it from happening again. 

“We are still evaluating what operational changes need to take place,” said Cory Kovacs, the DNR’s Lake Superior Basin management unit supervisor.

The trapped fish were rescued after hikers reported three stranded lake sturgeon in an isolated pool downstream from the Victoria Dam. Officials discovered there were actually 27 fish trapped and conducted three rescue missions with the Keweenaw Bay Indian Community and Upper Peninsula Power Co.

Now the three organizations plan to work together on surveys to determine whether sturgeon continue to become stranded in the channel. If the problem recurs, the partners may consider changes to the dam’s operations, which could require an amendment to its federal license.

The agency wants to determine whether spring flows attracted sturgeon to the channel before the water was shut off, leaving them stranded.

The Victoria Dam is a hydroelectric facility operated by UPPCO. Under its federal operating license, water is diverted from the West Branch of the Ontonagon River through a channel that generates electricity before returning to the river downstream. The original river channel can have little or no flow during parts of the year.

Kovacs said the dam’s operations followed its federal license. Under the license, the company maintains specified flows during the spring before gradually reducing and eventually shutting off flow in the channel.

In 2026, heavy winter snowfall was followed by a prolonged dry period, Kovacs said. The dam’s gates were shut June 6, about 10 days earlier than the usual June 15 date, after the reservoir reached the level specified in its operating license. UPPCO requested a variance from the DNR, which approved the early shutdown.

The fish remained isolated until the rescue effort began in late August.

Kovacs said sturgeon may have entered the channel during the spring spawning season, when they seek suitable conditions to reproduce. But he said it remains unclear why they were in that stretch of river and whether water flows contributed to their becoming trapped.

“Projects like hydroelectric dams have environmental impacts,” said Dave Caroffino, the DNR’s Lake Superior Basin coordinator, in the agency’s announcement. “We have to work collaboratively with partners like Keweenaw Bay Indian Community and UPPCO, as well as the public, to prevent and mitigate negative effects.”

The hikers reported the fish through the DNR’s Report All Poaching hotline. Fisheries technicians Kyle Urban and Jack Cole responded and found two sturgeon in an isolated pool. They moved them downstream to where the river had flowing water, carrying them by hand through a rocky riverbed.

Urban said in an email that the first transfer took about 35 to 40 minutes. With temperatures in the mid-80s, clear skies and no wind, the technicians moved the fish as quickly as possible while stopping to place them in pools of water so they could breathe.

The rugged terrain made the trip difficult. Large boulders slowed their progress, and the technicians had to consider their own safety while transporting the fish.

The team returned with additional DNR and tribal fisheries staff to search for the third sturgeon. Instead, they discovered more fish hidden in a sediment-clouded pool.

“When I was standing in the stream and it started really amounting, like, this is a big deal,” said Kovacs. “But that third fish turned into 25.”

Staff moved 10 more downstream during the second mission, but the team knew more fish remained. UPPCO released water into the channel within the allowances of its permit to improve conditions for the remaining fish while the partners planned another rescue.

For the final mission, the agencies brought additional personnel and equipment. Staff placed the sturgeon in backpacks lined with thick plastic bags and filled with about three gallons of water each. They then carried the fish over the boulders and through a wooded path before releasing them into flowing water downstream.

The new method reduced transport time to about eight or nine minutes per fish, Urban said.

The third mission brought the total number of rescued sturgeon to 27 and confirmed that none remained in the channel.

Lake sturgeon have been listed as a threatened species in Michigan since 1994. Restoration efforts in the Ontonagon River began with stocking in 1998, and the fish rescued in August represent part of that long-term investment.

The largest fish recovered measured 55 inches, according to the DNR. It estimated that none of the rescued fish was older than 28 years.

Kovacs said losing the fish would have been a substantial setback because lake sturgeon take many years to reach maturity. Some do not mature until their teens or around age 20.

The rescue also gave biologists an opportunity to collect information they might not have obtained through routine monitoring. Staff gathered measurements, including the fish’s length and girth, and recorded identification information from implanted passive integrated transponder tags.

Those tags allow researchers to identify individual fish and determine when and where they were stocked. By combining information held by the DNR, tribe and federal partners, biologists say they hope to learn more about their ages, growth and survival rates across different stocking groups.

The information could help determine which restoration methods have been most successful and guide future stocking efforts.

Kovacs said the fish likely would have faced increasingly difficult conditions if they had remained in the isolated pools. The shallow water could have frozen to the bottom during winter, and the concentration of fish in a small area raised concerns about food availability.

The rescue also highlighted the importance of public reporting in protecting threatened species.

Without the hikers’ report, the DNR might not have discovered the stranded fish, Kovacs said. He encouraged people to report unusual wildlife or environmental conditions so experts can investigate.

“It’s worth the phone call, worth the emails, worth the text message,” he said.

Isabella Figueroa Nogueira writes for Great Lakes Echo.