New UToledo Study Tracks Juvenile Sturgeon from Ohio’s First-Ever Reintroduction Effort

New UToledo Study Tracks Juvenile Sturgeon from Ohio's First-Ever Reintroduction Effort

A new telemetry study published in the Canadian Journal of Fisheries and Aquatic Sciences finds that the method used to raise juvenile lake sturgeon before stocking has little bearing on how the fish behave after release - an important finding for ongoing efforts to restore the species to the Maumee River and other Ohio rivers.

Lake sturgeon were once abundant throughout the Great Lakes but were nearly wiped out by overfishing, pollution and habitat loss. A collaborative reintroduction program - led by the Ohio Department of Natural Resources, the U.S. Fish and Wildlife Service, the U.S. Geological Survey, The University of Toledo, Michigan State University and the Toledo Zoo - began annually stocking baby sturgeon in the Maumee River in 2018. The long-term goal is to establish 1,500 naturally spawning adults in the river.

The program used two approaches to raise young fish: a traditional hatchery at Genoa National Fish Hatchery in Wisconsin, and a "streamside" facility at the Toledo Zoo that used Maumee River water. The streamside method was designed to expose fish to local water chemistry during a critical early window, potentially improving imprinting - the process by which fish learn to recognize and return to their home river to spawn or lay their eggs as adults.

For the new study, researchers tracked the movements of 120 acoustically tagged sturgeon across three release years (2018, 2019, and 2021) using a network of underwater receivers. They found that regardless of how the fish were raised, most left the Maumee River for Lake Erie within three to 47 days of release, then spent the bulk of their first year in the western basin of the lake, primarily hugging the south shore.

Key findings

• 74 of 94 detected sturgeon (79%) moved from the Maumee River into Lake Erie after release.

• Sturgeon spent an average of 3-47 days in the river, then 54-207 days in Lake Erie.

• No statistically meaningful differences in river residency, distance traveled or habitat area were found between the two rearing groups.

• Most fish traveled along the south shore of the western basin toward the Lake Erie islands region.

• Time will tell if rearing strategy affects the number of lake sturgeon returning to the Maumee River to spawn.

"While we found no difference between rearing strategies at this age, the real test of our work will come when these fish are old enough to spawn," said co-author Dr. William Hintz, an associate professor of ecology based at UToledo's Lake Erie Center in Oregon, Ohio. "Because sturgeon take a decade or more to mature to reproductive age, we won't know for years whether the sturgeon return to the Maumee River to spawn and rearing strategy matters as sturgeon age, but we will continue to focus on that long-term goal."

As they continue to stock the river and track the juvenile fish as they grow, the research team suggests several steps to strengthen the program going forward, including adding stocking sites further upstream, using Maumee River source water in hatchery rearing if straying - that is, leaving the Maumee River to colonize another ecosystem as adults - becomes a problem, and expanding the acoustic receiver network to better track the fish as they mature.

The study was funded by the USGS Science Support Program and the Great Lakes Fishery Commission via Great Lakes Restoration Initiative appropriations.

Researchers at UToledo's Lake Erie Center on the shores of western Lake Erie study algal blooms, invasive species, salt pollution and other freshwater ecosystem topics for insights applicable throughout the Great Lakes and worldwide. The Lake Erie Center also offers hands-on research opportunities to students ranging from first-semester undergraduates to doctoral students.

Along with Hintz, the latest study's co-authors included lead author Jorden McKenna, who graduated from UToledo with a master's degree in ecology and organismal biology in 2023 and now works as a biologist with the U.S. Fish and Wildlife Service.