Fish Returning to Restored Habitat in Great Lakes Faster than Expected

When NOAA started building rock reefs in Michigan’s St. Clair River, they were hoping that the restored habitat would help bring fish to the area. What they didn’t expect were such immediate results—they’ve already seen sturgeon swimming by the reef. And now researchers have found eggs: evidence the sturgeon are spawning on the reef.

In the early 1900s, the rivers connecting Lake Huron and Lake Erie were straightened, widened, and deepened to create shipping channels for large freighters. Dredging and disposal of excavated material in the river damaged fish spawning sites, which led to declines in lake sturgeon populations. Dams along major tributaries blocked fish access, cutting off that spawning route as well. To compensate for the loss of habitat, NOAA and its partners built a reef across the middle channel of the river. 

Even before construction ended in June, researchers saw sturgeon swimming around the reef—much earlier than expected. And eggs collected from the site have hatched viable sturgeon.

“It’s special because this would not have happened without the restoration project, without restoring spawning habitat in the river,” said Terry Heatlie, habitat restoration specialist with NOAA’s Restoration Center.

Valuable commercial and sport fish such as walleye, lake whitefish, and perch are also expected to use the reefs for spawning. The restoration has potential to benefit waters upstream and downstream of the construction. The overarching goal is to help remove the St. Clair River from the list of environmentally degraded areas within the Great Lakes basin called “Areas of Concern.”