A freshwater limestone reef that once harbored a vibrant community of lake trout and other Great Lakes fish now sits degraded, pierced by century-old dock posts and damaged by invasive species.
The Nature Conservancy is restoring this reef and others in northern Lake Michigan that are critical spawning grounds for native fish. And they are doing it, in part, with help from the Dole Family Foundation.
“Our family has been coming to the Grand Traverse Bay area each summer for more than 50 years,” said Betsy Dole. “Fishing is among our favorite activities. It’s exciting to think that The Nature Conservancy’s work will restore healthy reefs where young fish can grow and thrive and, perhaps, come back to spawn someday.”
Without these essential limestone reefs, lake trout, lake whitefish and lake herring have nowhere safe to spawn. That leaves their eggs vulnerable to the relentless action of the waves, as well as to invasive species like rusty crayfish and round gobies.
To address these issues, Conservancy scientists are developing and testing techniques for reducing the number of invasive species on the reefs. This year, scientists set about 150 traps, which allow them to collect data on the number of crayfish and gobies caught and measure the egg-laying success of native fish to determine whether trapping invasives is improving spawning.
“If we can drive the number of invasive species down in this particular habitat, we could really benefit the native fish,” said Matt Herbert, an aquatic ecologist for the Conservancy.
Another part of the approach focuses on habitat rehabilitation – adding limestone rocks to degraded reefs, such as the one damaged by dock posts, in hopes of creating better spawning grounds for native fish.
Lake trout, herring and whitefish historically played a big role in Michigan’s fisheries, but invasive species, past overfishing and habitat degradation from coastal development have reduced populations significantly. The Conservancy hopes that rescuing these reefs will boost native fish populations for commercial fishermen and families like the Doles, who just love to fish.