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Central Michigan University helps restore reef for fish in Grand Traverse Bay

The Nature Conservancy, Michigan Department of Natural Resources and CMU work together to increase native fish population

Contact: Curt Smith


Adapted from a news release by The Nature Conservancy​​

A mountain of seemingly ordinary limestone rocks made an extraordinary splash for conservation this past weekend.

Approximately 450 tons of specially selected rocks were lowered into Grand Traverse Bay near Elk Rapids Aug. 29, rebuilding a reef that is essential to the survival of native fish. A team of scientists from Central Michigan University, The Nature Conservancy and Michigan Department of Natural Resources worked together to make it happen.

"The restoration of the reef has been a longtime goal of the project team," CMU biology professor Tracy Galarowicz said. "It is exciting to be part of the project and to have the opportunity to study the effects of the restoration on our native fish."

Galarowicz, one of the lead researchers on the project, said restoring the reef is part of the process to restore the population to a level where fish can sustain their own population without stocking by humans.

"We wanted to mimic the healthy reefs as closely as possible to encourage the fish to spawn there," Galarowicz explained. "We used rocks from a local quarry to match the size, shape, and composition of the cobbles in the healthy reefs. We arranged them so the rehabilitated site is the same size and shape of the other reefs. When it comes to habitat, quality matters over quantity."

Matt Herbert, an aquatic ecologist for The Nature Conservancy, says this particular reef system is unique.

"This reef system is the only place in Lake Michigan where three of our important native fish species — lake herring, lake whitefish and lake trout — are all known to spawn," Herbert said.

While two of the reefs in the system are in good condition, the third was damaged by a dock built more than 100 years ago. Rehabilitating the reef will provide the nooks and crannies native fish need to lay their eggs and keep them safe until they mature, which will hopefully increase population numbers, especially of lake herring. Historically the largest commercial catch in the Great Lakes, lake herring also played a key role in sustaining populations of apex predators – a predator that has no natural predator within its ecosystem – like lake trout.

But overfishing, degraded habitat and aquatic invasive species caused their numbers to plummet. Today, only a few remnant populations remain. This restoration project represents an opportunity to change that.

"We have seen a positive trend in lake herring populations in the last few years," Herbert said. "The food web has changed, and the conditions are conducive to their recovery. We just want to give them that extra boost they need to make a comeback."

Producing native fish

Results of this project could be dramatic.

"A healthy Great Lakes reef can produce hundreds of thousands of native fish," said Randy Claramunt, fisheries research biologist for the Michigan Department of Natural Resources. "For four years, we have been working together toward this goal. Each partner brought their strengths to the table, and it is wonderful to see this next step of the plan come to fruition."

Now that the rocks are in the water, the team will monitor the site to see how many eggs are deposited during the fall spawning season, how many of those eggs survive and how many adults return to spawn at the reef each year.

"Ultimately, when adults come back to use the reef, that means the population is growing, and that's what we want to see," Herbert said.

"If we can get lake herring back to abundance in Lake Michigan and across the Great Lakes, the benefit would be two-fold: They would not only provide a fishery themselves, but they also would help boost populations of other fish like lake trout."

EricCalabro.jpgCMU graduate student Eric Calabro also is working closely on the project, studying the effects of the restoration on the ecosystem.

"Eric has been collecting data on the physical characteristics of the reef as well as documenting the invasive species that are residing on the reef," Galarowicz said. "He also will collect this data throughout the fall and winter after the restoration to document the changes in habitat and invasive species." 

About The Nature Conservancy

The Nature Conservancy is the leading conservation organization working to protect the most ecologically important lands and waters around the world for nature and people. To date, the Conservancy and its 1 million members have been responsible for the protection of more than 120 million acres worldwide, including 360,000 acres in Michigan. The Nature Conservancy is working to make the Great Lakes watershed among the most effectively managed ecosystems on Earth. For more information and watch a video visit http://nature.org/gtbay


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