Overview of project
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. It is estimated that more than 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 species, such as lake trout, lake whitefish, walleye, and smallmouth bass, use rocky reefs for spawning and foraging. Rock piles have interstitial spaces in which prey can be found, and which also provide refuge for fish eggs and fry. This purpose of this project is to create new reefs to mitigate the damage to natural reefs, with a goal of enhancing reproductive success of lake trout and lake whitefish. The reefs will also provide valuable foraging areas for walleye and bass.
Work is being conducted in four phases:
(1) evaluation of current condition of the natural and impacted reefs; measureing of lake trout spawning and abundance of eggs and fry (completed in 2009)
(2) map areas to determine best placement of artificial reefs that will attract spawning lake trout and provide a safe refuge for eggs and larval fish (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 (begun in 2011).
Monitoring the abundance of adult lake trout and lake whitefish, eggs, and fry has been conducted since 2009, and will continue on the natural and artificial reefs until at least 2014.