Understanding the impacts of legacy copper mining activities on Lake Trout and Whitefish spawning habitats along the eastern side of the Keweenaw Peninsula.

SSKWP

August 2019 - June 2022

Legacy copper mining activities around Lake Superior resulted in the disposal of hundreds of millions of tonnes of stamp sand (i.e., remnants of the mechanical breakdown of ores) along shoreline habitats. Among the most conspicuous deposits, the Grand Traverse Bay shoreline along the Keweenaw Peninsula’s eastern shore received 22.7 million metric tonnes (Mt) of stamp sand material between 1902 and 1932. Since that time, an estimated 11.5 Mt of stamp sands have migrated southwards into Grand Traverse Bay and covered approximately 35% of Buffalo Reef, which is recognized as critically important spawning and nursery habitat for lake trout Salvelinus namaycush and lake whitefish Coregonus cluepaformis populations that support valuable tribal commercial and subsistence fisheries and state recreational fisheries in this region. By 2025, stamp sand is expected to inundate >60% of the 2200-acre reef. As a result, the Buffalo Reef Task Force, which consists of tribal, federal, and state agencies, is currently considering several alternatives for containing stamp sand erosion and restoring valuable reef habitat. However, both the extent to which and the mechanisms of how stamp sands affect lake trout and lake whitefish spawning remain unclear.

• To define spawning habitat and understand how stamp sands effects spawning site selection for both species, two fine-scale positioning acoustic telemetry arrays (Vemco VPS) will be used to locate where lake trout and whitefish are spawning on 1) a reef impacted by migrating stamp sands (i.e., Buffalo Reef; 47 receivers) and 2) a reef that has not been impacted by stamp sands (i.e., Traverse Island reef; 45 receivers).
• Three receiver curtains will be used to monitor post-spawning dispersal patterns of tagged individuals from Buffalo Reef and Traverse Island Reef. Each curtain will consist of 6-7 VR2AR (acoustic release) receivers set at 1.5 km spacing, extend from 20 m to 80 m water depth, and will be located at (from north to south) Betsy Jetty, Traverse Point, and Huron River Reef, which are all known spawning reefs.

• Results will provide decision makers information about the susceptibility of lake trout and lake whitefish spawning stocks to stamp sands, data necessary to evaluate the efficacy of various mitigation efforts (near term), and critical information to inform the development of a recommended restoration solution for Buffalo Reef (e.g., rebuild, stop sands from moving, remove sands, or other options).

• Michael Lowe (United States Geological Survey) - mlowe@usgs.gov
• Thomas Binder (Michigan State University)
• Andrew Muir (Great Lakes Fishery Commission)

• United States Geological Survey - Hammond Bay Biological Station
• GLIFWC
• Michigan Department of Natural Resources
• Michigan State University
• Great Lakes Fisheries Commission