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US Fish & Wildlife Service FieldNotes

Artificial reefs a success in the Huron-Erie Corridor!

Region 3, July 2, 2013
Fish biologist James Boase pulls in a gill net on the Detroit River.
Fish biologist James Boase pulls in a gill net on the Detroit River. - Photo Credit: n/a

A large scale habitat restoration effort is currently underway in the Huron-Erie Corridor in an effort to delist the St. Clair and Detroit River Areas of Concern. One of the Beneficial Use Impairments being addressed is the Loss of Fish and Wildlife Habitat. Dredging within the corridor to facilitate commercial ship traffic has led to a drastic loss of rocky habitat. This rocky habitat is of great importance to many native species within the Great Lakes, particularly for spawning.

 

Artificial spawning reefs are being constructed in the Detroit and St. Clair Rivers to increase the amount of suitable spawning habitat available to native fish species. Reefs have already been constructed near Belle Isle (2004) and Fighting Island (2008) in the Detroit River and in the Middle Channel (2012) of the St. Clair River. Several more reefs are scheduled for construction in the fall of 2013 near Fort Wayne on the Detroit River and near Algonac and Harts Light on the St. Clair River. These reefs are constructed of loosely piled rock about two feet thick and are one to two acres in size. The species of particular concern include lake sturgeon, northern madtom, walleye, and lake whitefish, which are threatened and/or economically important fish species that utilize rocky substrate for spawning.

Monitoring efforts evaluating the current restoration sites have shown the constructed reefs to be a success. Prior to construction of artificial reefs near Belle Isle, only 2 fish species were captured at this site. Following construction, 20 species were captured with 14 of these being native species in spawning-ready condition or recently hatched from eggs. At the reefs constructed near Fighting Island, the U.S. Geological Survey documented lake sturgeon spawning in 2009, 2010, and 2012 and collected lake sturgeon larvae, indicating the first evidence of successful lake sturgeon reproduction in the Detroit River. Reefs constructed in the Middle Channel of the St. Clair River have also been a success, with lake sturgeon spawning being documented each of the last two years.

This spring and summer, U.S. Fish and Wildlife Service fish biologists from the Alpena Fish and Wildlife Conservation Office – Waterford Substation conducted gill net surveys at current and proposed reef sites on the Detroit and St. Clair Rivers. Sampling was conducted over 13 weeks with 74 nets being set. A total of 16 species were captured over the sampling period. Data collected from gill net surveys will be compared prior to and after reef construction to evaluate the fish community response to these restoration efforts.

Monitoring these spawning reefs is important to the continued conservation of both aquatic species and aquatic habitat. The adult fish community sampling being conducted by the Alpena FWCO is just one aspect of the biological response being evaluated by project partners and a long-term monitoring program is currently being developed to assess system wide changes in these rivers. For more information on these projects please visit the Huron-Erie Corridor Initiative website at: http://www.huron-erie.org/

Contact Info: Andrew Briggs, 2488721979, andrew_briggs@fws.gov