In the 1950s, cement kiln dust (CKD, a by-product of cement production) was stockpiled along the shore of Thunder Bay near Alpena, MI. Precipitation, wind, and wave action eroded the loose CKD material and led to discharge of slurries into Thunder Bay. An estimated 80 acres of shoreline and submerged habitat were impacted. In 2002, the CKD pile was capped and a revetment wall was built to prevent further erosion of material into the lake. Unfortunately, damage had already occurred to valuable fish habitat. In particular, spawning reef substrate had been lost due to covering and filling of the natural reefs. The loss of spawning habitat may be contributing to the lack of substantial progress toward restoration of self-sustaining lake trout populations.
Many popular game fish and commercially fished species, such as lake trout, lake whitefish, walleye, and smallmouth bass, use rocky reefs for spawning and foraging. Interstitial spaces in rock piles contain prey organisms and provide refuge for fish eggs and fry. This purpose of this project is to create new reefs with open interstitial spaces to mitigate the damage to natural reefs. The goal of the project is to enhance reproductive success of lake trout and lake whitefish. The reefs also provide valuable foraging areas for walleye and bass.
Work was conducted in four phases:
(1) evaluate current condition of the natural and impacted reefs; measure abundance of lake trout spawners, eggs, and fry (completed 2009)
(2) determine best placement of artificial reefs to attract spawning lake trout and provide a refuge for eggs and fry (completed 2009)
(3) construct and place artificial reefs (completed in two stages: 8 small reefs in 2010, 25 large reefs in 2011)
(4) assess spawning and production of juvenile fish on the natural and artificial reefs (completed in 2015).
The results of this project have been published in a scientific paper, available here, that describes the assessment of lake trout spawners, eggs, and fry on the new reefs from 2010-2015. A second paper that describes the stability of the reefs and their colonization by other fishes, invertebrates, and algae, is in development and will be posted on this site when it is published.
This project is led by the Michigan Department of Environmental Quality, Remediation Division, with funding from the Clean Michigan Initiative Fund; the project was made possible by grants from the Great Lakes Fish and Wildlife Restoration Act, the Estuary Restoration Act (NOAA Estuary Habitat Restoration Program in conjunction with the U. S. Army Corps of Engineers), and donations from Lafarge - Alpena Plant.
Janice Adams, MDEQ