Michigan Sea Grant project enhances habitat for native lake sturgeon

A map of the Detroit River shows the location of three man-made sturgeon spawning reefs.

A map of the 32-mile Detroit River shows the location of three sturgeon spawning reefs constructed in the northern section of the river near Belle Isle.

A crane places broken limestone in the Detroit River during construction of spawning reefs.

Scientists oversee placement of broken limestone in the Detroit River during construction of the spawning reefs. Contractors used GPS to pinpoint placement of the materials in water 21 to 25 feet deep. Photo credit: Michigan Sea Grant

Project researchers prepare to release a 45-pound lake sturgeon caught at the Detroit River spawning reefs

Project researchers hold a 45-pound lake sturgeon caught at the Detroit River spawning reefs in May 2006. The scientists released the fish after implanting a transmitter to track its movements. Photo credit: U.S. Geological Survey

A life-size model of a lake sturgeon attracts travelers at Detroit Metropolitan Airport

A life-size model of a lake sturgeon attracts travelers at Detroit Metropolitan Airport, where millions pass through annually. Michigan Sea Grant developed the educational display to highlight the history and ecology of lake sturgeon and habitat restoration efforts in the Detroit River. A similar display was featured at the New Detroit Science Center for six months in 2006, attracting an estimated 500,000 visitors. Photo credit: Michigan Sea Grant

Most people know the Detroit River as a major commercial waterway connecting the upper and lower Great Lakes. But this 32-mile connecting channel has another distinction: until the late 1800s, the Detroit River was an important spawning ground for lake sturgeon. Its fast moving waters attracted thousands of the large, primitive fish every spring.

In the following decades, the number of lake sturgeon plummeted due to pollution, over-harvesting and loss of spawning habitat. The current population in Michigan is estimated to be about one percent of its former abundance. With support from NOAA and other sponsors, Michigan Sea Grant and partners are taking a multi-faceted approach to restore lake sturgeon in the waters of the Detroit River.

Led by Michigan Sea Grant Assistant Director Jennifer Read, the collaborative research, monitoring and education project began in 2004 with construction of three lake sturgeon spawning reefs in the northern section of the Detroit River. The reefs are made of broken limestone, fieldstone and coal cinders, respectively; the materials are similar to the natural spawning habitat preferred by lake sturgeon. This habitat gradually disappeared from the Detroit River, explains Read, as shipping channels were dredged and sediment increased from the surrounding landscape.

“It’s ironic that lake sturgeon have survived and thrived since prehistoric times, and now their recovery is limited because human activities have degraded their spawning habitat,” says Read. “We caused the problem; therefore we need to solve it.” A threatened species in the State of Michigan, lake sturgeon (Acipenser fulvescens) can grow more than six feet long and live more than 50 years. Despite this longevity, female lake sturgeon do not reproduce until about age 20 and then spawn only once every four years, making suitable spawning habitat essential.

As part of the NOAA project, Read works closely with biologists at U.S. Geological Survey (USGS) and the U.S. Fish and Wildlife Service (USFWS), who monitored the reefs in spring and fall for the past two years. Among their findings, project scientists confirmed the presence of a five-foot male lake sturgeon in spawning-ready condition at the reefs in May 2006. They released the 45-pound fish after implanting a transmitter to track its movements. Adding to the optimism, biologists from the USFWS caught and released four juvenile lake sturgeon in November 2006, 15 miles downstream from the spawning reefs. The rare capture of juveniles indicates lake sturgeon are most likely spawning at another location in the river.

Read says the presence of these lake sturgeon bodes well for the future of the population in the Detroit River. “We know sturgeon are here,” says Read. “If they’re successful spawning at the reefs, we can restore a thriving wild population in the heart of this bustling urban area.”

To highlight the habitat research, Michigan Sea Grant developed two educational displays featuring life-size models of lake sturgeon, as well as print materials and web pages for K-12 and general audiences that highlight the history and ecology of this unusual fish.

For more information about the sturgeon spawning habitat project, contact Dr. Jennifer Read, (734) 936-3622, jenread@umich.edu