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Michigan Department of Natural Resources Photo This 2019 aerial photo shows stamp sands piled up along the shore of Lake Superior, south of the community of Gay. The chimney in the image shows the location of the Mohawk Mill in Gay.
The multi-agency Buffalo Reef Working Group has made several advances in its efforts to learn more about the 2,200-acre Lake Superior natural reef and continues its collaborative work to protect this lake trout and lake spawning area. lake whitefish.
Over the past 100 years or so, historic copper tailings from the Wolverine and Mohawk mines – known as buffer sands – have been deposited at a grinding site along Lake Superior, located in the community of Gay in Keweenaw County.
Since that time, the stamp sands have been moved by winds and waves southward along the Gay Shoreline, about 5 miles, inundating beaches with natural sand and threatening to cover spawning habitat and areas. significant recruitment rates for Lake Superior whitefish and lake trout associated with Buffalo Reef at Grand Traverse Bay.
The north-south dividing line for the buffer sands migration is the mouth of the Traverse River at Grand Traverse Bay. Over the past few years, crews have worked to excavate and reclaim the sands of Lake Superior sifting to limit transportation further south.
Powerful autumn and winter storms have historically favored the movement of the sands, further threatening the reef.
“The Michigan Department of the Environment, Great Lakes and Energy recently hired a contractor to keep the harbor near Buffalo Reef clear during fall and winter storms.” said Stephanie Swart, Task Force Member, Lake Superior Coordinator for EGLE. “The first movement of buffer sands took place in mid-November. Last year this work was funded by the Indian community of Keweenaw Bay. The current contract will remain in place until the end of February 2022. “
Egg trap cylinders
A storm this fall disrupted some of the lake trout egg studies on the reef and washed cylinders of plastic egg traps to the shore where residents and beach fishermen find them.
“These cylinders are part of the egg traps set up on Buffalo Reef by biologists from the Great Lakes Indian Fish and Wildlife Commission and the US Geological Survey,” USGS fisheries biologist Mike Lowe said. “Egg traps were placed on the east hump of Buffalo Reef during the last week of October for the purpose of collecting fertilized eggs from the spawning lake trout.
“Unfortunately, a major storm in the following days destroyed most of the egg traps and released the cylinders into the water. Biologists scoured the beaches north and south of the harbor entrance on subsequent research trips and collected some of the cylinders. “
Anyone finding one of the cylinders is urged to contact Bill Mattes, Great Lakes Section Chief for GLIFWC, at 715-682-6619, ext. 2120 or at bmattes@glifwc.org.
Advance research objectives
Meanwhile, Lowe is researching various aspects of the reef and buffer sands problem as the Buffalo Reef Working Group continues its work to create the long-term adaptive management plan for the reef, which is expected to be available for public review in late spring 2022.
Among ongoing studies of reefs and buffer sands, researchers are working to determine exactly where lake trout and lake whitefish spawn and whether those areas are affected by buffer sands.
To do this, scientists use acoustic telemetry to identify where the two species breed in relation to migrating buffer sands and predict changes in the extent of both under various alternatives. Since summer 2019, 100 acoustic ranging beacons have been attached to fish, with 118 acoustic ranging receivers deployed to record their movements.
Spawning fish were collected every year. Acoustic telemetry restricted the search for the most likely spawning grounds. Egg traps confirmed the presence of fertilized lake trout embryos on the reef.
Researchers are also working to determine whether the early life stages of either species of fish are potentially affected by the sands in the buffer. Laboratory experiments are being carried out on the early stages of lake trout and lake whitefish with varying concentrations of buffer sands.
Every day, the success of fertilization and hatching is monitored. Once the embryos have hatched, researchers assess their relative condition, swimming ability, and ability to capture prey. Test results have shown that lake trout fertilization success is compromised and lake whitefish hatching success is compromised. In addition, lake whitefish larvae may lack the energy capacity for sustained swimming.
“The bottom line is that adult fish always spawn in Buffalo Reef,” Matt said.
Researchers are also comparing the abundance, age, growth, and components of juvenile lake whitefish nursery habitat in several spawning reefs in the region, including Grand Traverse Bay where the reef is located and Little Traverse Bay, both in Houghton County, Bette Grise and Great Sand Bay in Keweenaw County and Big Bay in Marquette County.
Efforts are also continuing to better understand the current distribution of buffer sands on the reef. This is an essential part of understanding the fish production potential of Buffalo Reef.
The reef and buffer sands areas were mapped in August 2021 using multibeam echosounders and a towed camera system. Visual and laboratory analysis of the percentage of buffer sands is under study.
“The imaging software will be able to distinguish between buffer and native sands”, Peter Esselman, a fisheries biologist at the USGS, said. “The differences can be distinguished visually, with native sands being small, rounded and predominantly light in color, compared to timbre sands which are large, angular, and dark. “
Mapping of the percentage of buffer sand with images and physical samples is scheduled for 2022. Another project aims to quantify the water and sediment chemistry found between rock reefs where lake trout and lake whitefish either spawn or not. Samples will be collected using a heavy-duty pump and self-contained water sampling equipment.
Finally, work is underway to determine Buffalo Reef’s contribution to current fisheries and how this has changed since the initial impact of buffer sands on the reef in the late 1980s.
To find out, researchers are studying otoliths, which are calcium-containing bodies found in the inner ear of fish that incorporate elements of the chemistry of the surrounding water in which the fish live. Scientists are working to discover a “Basic fingerprints” in otoliths that can be used to identify fish produced at Buffalo Reef.
A study on juvenile lake whitefish is underway and the otolith study on lake trout will take place next year. The data retrieved can be compared to archived adult fish otoliths to determine past and present contributions of the reef to fish production.
Genetic studies will also take place early next year to estimate the genetic contributions of Buffalo Reef lake trout recruits to the overall Lake Superior fishery.
For comparison, lake trout have been collected from Keweenaw Bay, the Huron Islands and off ÃŽle Royale, and additional samples will be collected in 2022 in Michigan, Wisconsin and Minnesota. Similar studies will also be carried out on lake whitefish.
A related project started this year and continuing until 2024 will mark and track 200 lake trout and 200 whitefish. Two receivers will be placed on each of the 28 historic and known spawning reefs to determine their relative importance to the lake trout and lake whitefish fishery.
“We know that adult fish spawn at Buffalo Reef, but the early stages of their life can be significantly affected by buffer sands,” said Swart. “Work is underway to integrate mapping, crevices and biological studies. Habitat changes will be predicted in response to a range of management alternatives.
Beyond this in-depth and ongoing research work, the working group will continue to provide technical assistance to its partners to identify and address additional data gaps.
The reef project, funded by the Great Lakes Restoration Initiative, is carried out in cooperation with the US Army Corps of Engineers, US Environmental Protection Agency, Keweenaw Bay Indian Community, Great Lakes Indian Fish and Wildlife Commission, Michigan Department of Natural Resources. and the Michigan Department of the Environment, Great Lakes and Energy.
For more information on Buffalo Reef or to sign up for Task Force email updates, visit Michigan.gov/BuffaloReef.
Check out previous presentations of DNR stories in our archives at Michigan.gov/DNRStories. To subscribe to upcoming Showcasing articles, sign up to receive free emails at Michigan.gov/DNR
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