The multiagency Buffalo Reef Task Force has made several advances in its efforts to learn more about the natural 2,200-acre Lake Superior reef and continues its collaborative work to protect this lake trout and lake whitefish spawning area.
Over the past roughly 100 years, historic copper mine tailings from the Wolverine and Mohawk mines – called stamp sands – were deposited at a milling 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 south down the shoreline from Gay, roughly 5 miles, inundating natural sand beach areas and threatening to cover spawning habitat and recruitment areas important to Lake Superior whitefish and lake trout associated with Buffalo Reef at Grand Traverse Bay.|
The north-south dividing line for the stamp sands migration is the mouth of the Traverse River at Grand Traverse Bay. Over the past few years, crews have worked to excavate and move stamp sands back from Lake Superior to limit transport farther south.
Powerful fall and winter storms have historically aided movement of the sands, further threatening the reef.
“The Michigan Department of Environment, Great Lakes, and Energy recently hired a contractor to keep the harbor near Buffalo Reef clear during fall and winter storm events,” said task force member Stephanie Swart, Lake Superior coordinator for EGLE. “The first movement of stamp sands took place in mid-November. Last year, this work was funded by the Keweenaw Bay Indian Community. The current contract will remain in place through the end of February 2022.”
One storm this autumn disrupted some of the lake trout egg studies on the reef and has washed plastic egg-trap cylinders to shore where residents and beachcombers are finding them.
|“These cylinders are a component of egg traps put on Buffalo Reef by biologists from the Great Lakes Indian Fish and Wildlife Commission and the U.S. Geological Survey,” said Mike Lowe, a fisheries biologist with the USGS. “The egg traps were placed on the eastern hump of Buffalo Reef during the last week of October with the purpose of collecting fertilized eggs from spawning lake trout.|
“Unfortunately, a major storm in the following days destroyed most of the egg traps and released the cylinders in the water. Biologists have been walking the beaches north and south of the harbor entrance during subsequent research trips and have collected some of the cylinders.”
Anyone finding one of the cylinders is asked to contact Bill Mattes, Great Lakes section leader for GLIFWC, at 715-682-6619, ext. 2120 or at firstname.lastname@example.org.
Advancing research goals
Meanwhile, Lowe is leading research on various aspects of the reef and stamp sands problem as the Buffalo Reef Task Force continues its work to create the Long-Term Adaptive Management Plan for the reef, which should be available for public review in late spring 2022.
Among the ongoing reef and stamp sand studies, researchers are working to determine exactly where lake trout and lake whitefish spawn and whether those areas are affected by stamp sands.
|To do this, scientists are using acoustic telemetry to identify where both species are spawning relative to migrating stamp sands and forecast changes in the extent of both under various alternatives. Since summer 2019, 100 acoustic telemetry tags have been attached to fish, with 118 acoustic telemetry receivers deployed to record their movements.|
Spawning-condition fish have been collected each year. Acoustic telemetry has narrowed the search for the most likely spawning areas. Egg traps have confirmed the presence of fertilized lake trout embryos on the reef.
Researchers are also working to find out whether the early life stage of either fish species is potentially affected by stamp sands. Laboratory experiments are being conducted on early stages of lake trout and lake whitefish with varying concentrations of stamp sands.
Each day, fertilization and hatching success are monitored. Once the embryos have hatched, researchers are assessing their relative condition, swimming capacity and ability to capture prey. Test results have shown lake trout fertilization success is impaired and lake whitefish hatching success is compromised. In addition, lake whitefish larvae may lack energetic capacity for sustained swimming.
“The key takeaway is that adult fish are still spawning at Buffalo Reef,” Mattes said.
|Researchers are also comparing juvenile lake whitefish abundance, age, growth and nursery habitat components across multiple 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 what the current distribution of stamp sands is on the reef. This is a critical component to understanding the fish production potential of Buffalo Reef.
The reef and the stamp sands areas were mapped in August 2021 using multibeam echosounders and a towed camera system. Visual and laboratory analysis of the percentage of stamp sands is being studied.
“Imaging software will be able to discriminate between stamp and native sands,” Peter Esselman, a fisheries biologist with the USGS, said. “The differences can be distinguished visually with native sands being small, rounded and mostly light-colored, compared with stamp sands which are large, angular and dark.”
Mapping the percentage of stamp sand with images and physical samples is planned for 2022. Another project seeks to quantify the water and sediment chemistry found between reef boulders where lake trout and lake whitefish are, and are not, spawning. Samples will be collected with a heavy-duty pump and autonomous water sampling equipment.
|Finally, work is ongoing to determine Buffalo Reef’s contribution to current fisheries, and how has that changed since the initial impact of stamp sands to the reef in the late 1980s.|
To find this out, researchers are studying otoliths, which are bodies containing calcium found in the inner ear of fish that incorporate elements from the surrounding water chemistry the fish are living in. The scientists are working to discover an “elemental fingerprint” in otoliths that can be used to identify fish produced at Buffalo Reef.
Juvenile lake whitefish study is in process, and the lake trout otolith study will take place next year. The data recovered can be compared with 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 wider Lake Superior fishery.
For comparison, lake trout were collected from Keweenaw Bay, the Huron Islands and off Isle Royale, with additional samples to be collected in 2022 from Michigan, Wisconsin and Minnesota. Similar studies will also be performed on lake whitefish.
An associated project begun this year and continuing until 2024 will tag and track 200 lake trout and 200 whitefish. Two receivers will be placed on each of 28 historical and known spawning reefs to determine their relative importance to lake trout and lake whitefish fisheries.
“We know adult fish are spawning at Buffalo Reef, but early life stages may be significantly impacted by stamp sands,” Swart said. “Work is being done to integrate mapping, crevice and biological studies. Habitat changes will be forecasted in response to a range of management alternatives.”
Beyond this extensive, ongoing research work, the task force will continue to provide technical assistance to its partners to identify and address additional data gaps.
The reef project, funded through the Great Lakes Restoration Initiative, is being executed in cooperation with the U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, Keweenaw Bay Indian Community, the Great Lakes Indian Fish and Wildlife Commission, the Michigan Department of Natural Resources and the Michigan Department of Environment, Great Lakes, and Energy.
For more information on Buffalo Reef or to sign-up for task force email updates, visit Michigan.gov/BuffaloReef.