Sturgeon Spawning Habitat Project Background

Lake Sturgeon (Acipenser fulvescens) were once abundant throughout the waters of the Great Lakes, especially in the rivers connecting Lake Huron to Lake Erie including the Detroit River. Now, however, the US Fish and Wildlife Service identify them as a species of special concern. The American Fisheries Society considers them a threatened North American species. And the Nature Conservancy lists them as globally rare. They are listed as either threatened or endangered by 19 of 20 states in their original range in North America and estimated to be at about one percent of their former abundance in Michigan. 

Historic lake sturgeon populations in the Huron—Erie Corridor supported a fishery that produced four million pounds of sturgeon in 1880 and a catch of more than 4,000 fish in 1889. More recently, Detroit River anglers report taking 21 sturgeon, primarily immature adults in 1998 and 1999. Between April 2000 and June 2001, researchers captured 70 sturgeon in the Detroit River and implanted 20 with ultrasonic transmitters. The tagged fish remained primarily in a “home area” in the lower river, except during the 2001 spawning season when they moved upstream to deposit eggs on a man-made coal cinder “reef” near Zug Island.

It appears that Detroit River lake sturgeon may be recruited to Lake Erie. In 2001, a fish tagged in the Detroit River was recovered in the Ohio waters of Lake Erie and an additional 100 juvenile fish, with a unique genetic composition, have been caught in western Lake Erie. This evidence supports the hypothesis that recruitment of lake sturgeon in Lake Erie is taking place from an unknown source, possibly the Detroit River. The other closest known population, in the St. Clair River, does not appear to mix with the Detroit River population or move through the river. More than 850 lake sturgeon have been caught and tagged in the St. Clair River and 20 have been implanted with ultrasonic sensors.  Although these tagged fish move into Lake St. Clair, none have been detected in the Detroit River. Together this evidence suggests that a rehabilitated Detroit River lake sturgeon population will benefit western Lake Erie as well.

A lack of suitable spawning habitat appears to be limiting lake sturgeon reproduction, and therefore population restoration, in the Detroit River. Other limitations, such as space, food and contaminants are not known to affect lake sturgeon spawning success in the Detroit River. All fish caught to date were in good or excellent condition and growing rapidly. However, a recent survey showed that 12 reputed spawning sites were not suitable either due to siltation or a lack of appropriate substrate.

Fortunately, all necessary limnological conditions for sturgeon spawning exist near Belle Isle in the Detroit River. Construction of sturgeon spawning reefs in areas of high current velocity near Belle Isle, using materials that encourage successful spawning in the St. Lawrence and Fox, Wolf and Winnebago Rivers, should enable sturgeon to reproduce and begin the recovery of a Detroit River population and the support of a western Lake Erie fishery. All design criteria and materials needed for construction of self-cleaning, sturgeon spawning reefs have been determined.

One known and one of four suspected lake sturgeon spawning sites in the Detroit River are anthropogenic.  One is composed of coal cinders in 30 feet of water and the other is large limestone rip-rap in 4-8 feet of water near a reputed historic spawning site. A lack of spawning habitat was shown to limit sturgeon recovery and reproduction in the Wolf River in Wisconsin.

This project will be integrally related to ongoing activities in the Detroit River and Huron—Erie Corridor. Data from lake sturgeon captured and released at the project site on Belle Isle will augment data on the Detroit River sturgeon population. Spawning success at the project site will provide quantitative estimates for comparison with such data collected at two active coal-cinder sturgeon spawning sites in the St. Clair River and Detroit River by Jerry Nichols (US Fish and Wildlife Service), Greg Kennedy and Bruce Manny of the U.S. Geological Survey. Data on the degree to which eggs are deposited on the three test spawning substrates will aid Bruce Manny in his work evaluating the extent of suitable spawning habitat present in the Detroit River.

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