Downtown Dinosaurs: Lake sturgeon rehabilitation in the Saginaw River system

By Jason Gostiaux, Fisheries Biologist, Southern Lake Huron Management Unit

Dinosaurs live in the Saginaw River. You can’t see a Tyrannosaurus Rex if you take a ride aboard the Princess Wenonah. You can’t hop in a Jeep Wrangler and see a herd of Brachiosaurus feeding on trees at Crow Island State Game Area. The dinosaurs in the Saginaw River are Lake Sturgeon, and they have been around for 150 million years, but their numbers drastically declined in the 1900s. Recent efforts are trying to reverse that trend.

Lake Sturgeon are considered living fossils, which means they look like organisms that existed millions of years ago. Other living fossils you may be familiar with are horseshoe crabs, cockroaches, and crocodiles. Lake Sturgeon play a key role in ecosystem function by linking lakes to rivers. Adult Lake Sturgeon are generalists and feed on a variety of prey items in a lake, including invertebrates and fish. They uptake energy and migrate into rivers to spawn, releasing energy into the river in the form of waste, eggs, and milt.

Lake Sturgeon were once abundant in Saginaw Bay and would migrate up tributaries to spawn during spring. Today, Lake Sturgeon are listed as a threatened species under the State of Michigan’s Endangered Species Act. To restore Lake Sturgeon populations in Michigan, the DNR has developed a Lake Sturgeon Rehabilitation Strategy, which includes specific goals for the Saginaw River Basin.

Dr. Jeffrey Jolley, Southern Lake Huron Management Unit (SLHMU) manager, is part of the DNR’s Lake Sturgeon Committee and explained, “The primary goal for Lake Sturgeon rehabilitation in the Saginaw River system is to produce a self-sustaining population that could provide sportfishing opportunities in Saginaw Bay.”

Stocking Lake Sturgeon into the Tittabawassee, Shiawassee, Flint, and Cass Rivers, four tributaries of the Saginaw River, is the management tool that started being implemented in 2018 to accomplish this goal.

Around Memorial Day, the US Fish and Wildlife Service (USFWS) has a team capturing adult Lake Sturgeon in the St. Clair River using baited setlines. They use a total of 8 lines with 50 hooks per line and place them along the bottom of the river. Jorden McKenna, USFWS biologist, said, “This work accomplishes two goals: complete a population assessment and utilize adults to support stocking fish into other systems.”

Dr. Jason Fischer is another USFWS biologist in the Detroit office. Fischer explained, “The St. Clair-Detroit River Lake Sturgeon population is one of the largest in the Great Lakes and a good candidate for supporting reintroduction programs.”

The USFWS crew fertilizes eggs on-site, releases the adults back to the river, and the eggs are transported to the Genoa National Fish Hatchery in Wisconsin. Fertilized eggs are incubated for 7-10 days and larval fish start feeding about 21 days after fertilization. Orey Eckes, acting hatchery manager at Genoa, said he starts feeding young Lake Sturgeon with brine shrimp, then switches to frozen bloodworms, and finally krill once they are 4-5 inches long. Lake Sturgeon at the Genoa Hatchery are stocked into the four Saginaw River tributaries during September when they are 7-8 inches long.

Lake Sturgeon from the Black River in the northern Lower Peninsula are also used for stocking efforts in the Saginaw River watershed. Doug Larson, Research Assistant at Michigan State University, operates the Black River Sturgeon Facility in Cheboygan County. You can take a 3-D tour of the facility at www.glsturgeon.com/about-us/360-hatchery-tour. Larson said he has “the coolest job in the world,” and it’s hard to argue. During the spring spawning season, Larson leads a team to snorkel the Black River and capture adult Lake Sturgeon for an adult population assessment. Larson’s crew is also responsible for collecting larval Lake Sturgeon drifting freely downriver after they hatch. The larval Lake Sturgeon are raised in the facility and typically released during August when they are around six inches.

Meaghan Gass, Michigan Sea Grant Extension Educator, and Mike Kelly, Great Lakes Director of The Conservation Fund, work with the Chippewa Nature Center, Friends of the Shiawassee, Flint River Watershed Coalition, Genesee County Parks, and the City of Frankenmuth to annually coordinate two release events at the Tittabawassee, Shiawassee, Flint, and Cass Rivers. Each release event allows children to individually release juvenile Lake Sturgeon into the river by hand.

Kelly reflected on the stocking events, saying that, “Putting a dinosaur in your hand and sending it on its way makes the release events exciting for folks. They are interested and invested because one of those fish in the river came out of their bare hands.”

Gass emphasized that, “The success of the restoration program is built on community support to successfully host stocking events across the watershed.”

To date, around 50 community release celebrations have stocked almost 8,000 Lake Sturgeon into the Saginaw River watershed.

The Lake Sturgeon stocking program has different goals from other stocking strategies around the state. Our goal is restoration, whereas others are supplementing populations for angler harvest, like salmon and trout. Rather than stocking tens of thousands of fish, the annual stocking goal is 1,000 Lake Sturgeon, divided between two different strains and spread across the four river systems.

Fischer said, “Lake Sturgeon are a long-lived species that spawn infrequently and we are more likely to see success with fewer fish over a longer period than higher numbers and fewer years.” He explained that, “Spreading the stocking events over several years gives the population a better chance to match with preferred environmental conditions.”

Raising and stocking Lake Sturgeon is only part of the story. Studying survival and movement helps evaluate the short- and long-term success of the program. Max Majinska earned a Master of Science in fisheries and wildlife at Michigan State University, studying stocked age-0 Lake Sturgeon in the Saginaw River watershed. Majinska and others performed 320 surgeries to implant acoustic telemetry tags into Lake Sturgeon before they were stocked into the four rivers from 2022 to 2023.

Majinska said results from his project showed the stocked fish typically live in the tributaries for 1-2 months before migrating to the Saginaw River or Saginaw Bay. In addition, Majinska incorporated predation tags in his study. These tags emitted a different code if they were consumed by a predator.

“Across both years, 63 fish were released with predation tags, 52 of those were detected, and only 9 transmitters emitted a predation signal. We do see incidental catches of Lake Sturgeon in the Saginaw River system, so fish are surviving,” Majinska explained.

It was rare to see a picture of Lake Sturgeon in the Saginaw River before stocking efforts began. Since 2018, many photos have popped up on social media from anglers targeting other species and accidentally catching Lake Sturgeon. As a reminder, targeting Lake Sturgeon is illegal in the four tributaries, Saginaw River, and Saginaw Bay.

Dr. Scott Colborne is an assistant professor based out of the Quantitative Fisheries Center within the Department of Fish and Wildlife at Michigan State University. Dr. Colborn co-advised Majinska with Dr. Chris Cahill after the untimely passing of Dr. Chris Vandergoot. Colborne emphasized that Lake Sturgeon rehabilitation in the Saginaw River Watershed is a long-term investment, “But, that does not mean we will not see positive trends along the way.”

We talked about the incidental
captures by anglers fishing the Saginaw River and Colborne said, “We need to appreciate those positive signs and use that to fuel interest.”

Majinska’s graduate project at MSU relied on acoustic telemetry tags detected by receivers located around the Saginaw River, connecting tributaries, and Saginaw Bay. This telemetry receiver network is part of the Great Lakes Acoustic Telemetry Observation System (GLATOS). Dr. Tom Binder is the current director of GLATOS. According to Binder, “The single most important thing GLATOS has is the detection database.”

Telemetry receivers from other projects are deployed around the Great Lakes Basin and give researchers the ability to track their fish outside of their immediate project area.

The Michigan DNR is also harnessing the GLATOS network to study habitat use of juvenile and sub-adult Lake Sturgeon in the Saginaw River Basin. Last year, the SLHMU out of Bay City began tagging Lake Sturgeon in the Saginaw River and Saginaw Bay. Unlike telemetry tags used to study newly stocked Lake Sturgeon that only “pinged” for a few months, tags for this project have a battery life of around ten years. The goal is to tag 20 Lake Sturgeon and so far, two were tagged in the Saginaw River by “The Ping Queen,” April Morey, SLHMU biologist, and two were tagged in Saginaw Bay with help from Alpena Fisheries Research Station staff. Morey has experience tagging walleye and brown trout in Saginaw Bay for other projects, but said, “There was more pressure tagging Lake Sturgeon when you are aware of the time and money to get that fish in the water.”

In addition to some fish receiving telemetry tags, each Lake Sturgeon stocked into the Saginaw River basin is implanted with a passive integrated transponder (PIT) tag. These tags are about the size of a grain of rice and don’t emit pings like the telemetry tags. Instead, they act like a bar code and provide a unique serial number for each fish. When Lake Sturgeon are captured by agency staff in the future, they can be scanned for the PIT tag number and traced back to a specific stocking year, strain, and river.

While this information helps managers monitor the success of the stocking program, these unique PIT tag numbers are also utilized for the “Adopt-A-Sturgeon” program. The adoption program allows interested citizens or businesses to sponsor a Lake Sturgeon and receive updates if that specific Lake Sturgeon is captured in future surveys. You can adopt a Lake Sturgeon at www.saginawbaysturgeon.org/adopt.

The Lake Sturgeon rehabilitation project in the Saginaw River system is in the eighth year of a 25-year commitment. The past, present, and future success of this program relies on funding and partnerships.

John Riley, an environmental quality specialist with the Department of Environment, Great Lakes, and Energy, is a trustee representative for the Dow Natural Resource Damage Assessment and Restoration (NRDA) along with representatives from the US Fish and Wildlife Service, Bureau of Indian Affairs, Saginaw Chippewa Indian Tribe, Michigan Attorney General’s Office, and Michigan DNR. The trustees utilize money from the Dow NRDA to fund projects that restore ecological function back to baseline conditions before the release of hazardous substances.

Riley said, “The trustees recognize the importance of Lake Sturgeon recovery and the long-term benefits of restoring their populations. Funding the DNR’s telemetry project is a worthwhile investment to better understand the life cycle of long-lived animals. We better understand where they are going and what they are doing if we are serious about rehabilitating their populations to sustainable levels.”

Unlike Jurassic Park, Lake Sturgeon are not being stocked in the Saginaw River system to create an amusement park on Ojibway Island or as a special exhibit for the Saginaw Children’s Zoo. This effort is to restore a native fish population. Just think, a child could release a Lake Sturgeon, become a fisheries biologist, and capture it again in their own fisheries survey on the Saginaw River. As Dr. Ian Malcolm’s character said, “Life finds a way.”

If you are interested in learning more about the Lake Sturgeon program in the Saginaw River Basin, please visit www.saginawbaysturgeon.org. Here you can learn more about the life history of Lake Sturgeon, as well as join the mailing list for upcoming release events, and watch a 23-minute documentary titled “Dinosaur Fish,” which provides more details about the Lake Sturgeon Rehabilitation Strategy for the Saginaw River Basin.

This article was developed in memory of Dr. Chris Vandergoot. “Goot” was one of my mentors and was well-connected with several people quoted in this article. He was excited about the early success of the Lake Sturgeon program, and I hope to write a future article documenting Lake Sturgeon successfully spawning in the Saginaw River Basin for the first time in decades.