Measuring in at just eight inches long, the juvenile lake sturgeon caught by researchers from the Grand Rapids Public Museum in September 2022 hardly looked formidable. But the small fish could grow to a six-foot-long, 150-pound benthic powerhouse, moving along the bottom of rivers and lakes eating insects, snails, and even invasive zebra mussels.
That is what researchers from the museum are hoping for. They are working with the John Ball Zoo and Encompass Socio-ecological Consulting to conserve the elusive lake sturgeon. Once abundant in the Great Lakes basin, lake sturgeon was designated a threatened species in Michigan in 1994, prompting recovery efforts from multiple organizations.
The team has been conducting surveys for lake sturgeon in the Grand River – the longest river in Michigan – for five years. This year the U.S. Fish and Wildlife Service provided nearly $150,000 in grants to the team through the Great Lakes Fish and Wildlife Restoration Act grant program; using those funds, they were able to add graduate research to the project in partnership with Grand Valley State University.
Their discovery of juvenile sturgeon in the river confirmed its status as a potential spawning ground for lake sturgeon. During the 2023 research season the team documented 15 additional sturgeon in the Grand River.
“Having lake sturgeon there indicates that there’s clean, fresh water. It indicates that they’ve been able to survive out in Lake Michigan and come up to these large river systems to spawn,” said Stephanie Ogren, vice president of education at the museum.
The lake sturgeon is the oldest and largest native fish species in the Great Lakes, according to the National Wildlife Federation. They are also long-lived, with a lifespan of 55 to 120 years. They can grow to over six feet long and weigh nearly 200 pounds. They look impressive, covered in rows of diamond-shaped scutes instead of scales and with four barbels – sensory organs that help them locate prey – hanging from their long snouts.
Ogren explained that the fish also has a unique life cycle: they hatch in rivers where they spend the first months of their lives before swimming out into larger lakes like Lake Michigan. There, they grow and reach sexual maturity – for females, that’s between 20 and 25 years old; for males, 15 to 20 years – then they return to the rivers where they hatched, swimming upstream to spawn. Females release thousands of eggs that are fertilized by waiting males. After spawning, the adult sturgeon return to the lakes.
This life cycle can make conserving lake sturgeon challenging: the fish are vulnerable to changes in water levels and temperature as they move through different habitats, and climate change is expected to further exacerbate these changes, according to the National Wildlife Federation.
Lake sturgeon populations in the Great Lakes basin were decimated by the early 1900s from habitat degradation and overfishing, according to the Nature Conservancy. The sturgeon's bony, armor-like plates and tough barbels tore fishermen's nets and led to their designation as a nuisance. During this time, many dams were also built within sturgeon habitat, blocking migration to and from spawning grounds.
Ogren said that the research being conducted by the museum and its partners fills a gap in the lake sturgeon database.
“Really the Grand River is one of those last large river systems where good documentation of the juvenile population is still not complete. Getting this completed on the Grand River is really exciting. We’re really excited to start to build the genetic database so we can look at the genetics of this population,” Ogren said.
Over the next few years, the team hopes to employ hydroacoustic and sonar techniques to try to find more lake sturgeon and continue genetic sampling of the Grand River population. Ogren said the research is exciting.
“There’s just a lot of stuff we still don’t know about the world around us. I have students look out at the river and say ‘We don’t even know all the different population dynamics in this river, right here in this urban center,’ ... so there’s always something new and exciting to find nearby.”
