The rock reef restoration project is the culmination of years of work to restore historical fish spawning habitat within inner Saginaw Bay. The goal of this project is not simply to create additional spawning habitat for native fish species, but rather to help facilitate a resilient and diverse fish population. Evaluation of this demonstration project can also inform future reef restoration throughout the Great Lakes.
This rock reef restoration project is the culmination of years of work to restore historical fish spawning habitat within inner Saginaw Bay. The first major step in this habitat restoration effort concluded in 2016 with the completion of a multi-year assessment of several potential reef restoration sites. Funded by the U.S. Fish and Wildlife Service, the project helped resource managers determine the feasibility of restoring rock reef habitat within Saginaw Bay.
The results of the assessment found that conditions in the inner bay are suitable for restoration, with the Coreyon and Saginaw River Mouth Reefs identified as priority restoration sites (Figure 1). Federal, state, and local partners are now preparing to construct and restore reef habitat at these two sites.
Historically, rock reefs formed in the Great Lakes as glacial deposits and provided important spawning habitat for many native fish species. This project will mimic these naturally-formed reefs by placing approximately 5,000 cubic yards of rock material at each restoration site. The rocks will range in size from 4 to 8 inches in diameter and will be placed on the lakebed by barge and crane (Figure 2). This will create a 1-acre pile of rocks rising 2 to 4 feet from the lake bottom (Figure 3). The height of the rock pile may vary to prevent navigational hazards.
When complete, this project will restore a 1-acre rock reef at both the Coreyon and Saginaw River Mouth sites (2 acres total). These restored reefs will create important spawning and juvenile habitat for many native fish, including species that spawn in spring (Walleye, Smallmouth Bass, Suckers) or fall (Lake Whitefish, Cisco, Lake Trout, Burbot). During spawning, the gaps formed between the rocks will create a sheltered environment protected from predators where fish eggs can incubate. As the eggs hatch, the warm and highly productive waters of the inner Bay will provide excellent nursery habitat and abundant food sources for larval and young fish, encouraging fast growth and increasing survival potential.
The goal of this reef restoration project is not simply to create additional spawning habitat, but rather to facilitate a resilient and diverse fish population. This project will also serve as a demonstration project which can be evaluated to inform future reef restoration throughout the Great Lakes.
Funding for this project was provided through a $980,000 U.S. Environmental Protection Agency, Great Lakes Restoration Initiative (GLRI) grant and a $25,000 Saginaw Bay Watershed Initiative Network grant. Restoration of the Coreyon and Saginaw River Mouth Reefs is anticipated to occur during the 2019 construction season and be completed by the fall of 2019.