Dwindling sturgeon population focus of $119K Muskegon River study

By: Deborah Johnson Wood

Lake Sturgeon are the largest fish in the Great Lakes, with females at times reaching longer than six feet and living some 80 years. Their numbers have dwindled precariously over the last century, placing them on Michigan’s Threatened and Endangered Species List.

A new $119,000 study by Carl Ruetz of the GVSU Annis Water Resources Institute and Kregg Smith of the Michigan DNR focuses on the Muskegon River below Croton Dam to determine how many fish are left, their spawning habits and their habitats.

Before 1890, fisherman destroyed sturgeon for ripping their nets, and later overfished them for their caviar. Dams also block streams preventing access to spawning habitats. The fish, as a result of such intrusions, have struggled to sustain their population because of their slow reproduction rates: females don’t spawn until they’re in their twenties; males spawn at about 15 years.

The study tracks the numbers, sizes and genders of adults as they enter the Muskegon River to spawn, the number of larvae emerging from the gravel spawning beds and drifting downstream and, this fall, calls for implanting tracking devices in juvenile fish.

“There are lots of unknowns, like where their rearing habitat is,” Ruetz says. “It’s logical it’s a flat-water habitat that’s rich in food sources, but we don’t know where. The transmitters will help us find out what habitats they’re using and how long they stay in Muskegon Lake and in the river.”

The DNR’s Kregg Smith has studied sturgeon for a decade and brought in Ruetz this year to increase man-hours and talent. He says that in the early 1900s there were millions of pounds of sturgeon in the Great Lakes, but a count during the 2002 spawning season estimates only 50 to 60 fish are left.

Source: Carl Ruetz, Grand Valley State University Annis Water Resources Institute; Kregg Smith, Michigan Department of Natural Resources

Deborah Johnson Wood is the development news editor for Rapid Growth Media. She can be contacted at [email protected].