07/09/2026
You Can Help Protect the Apostle Islands Reefs
Did you know Lake Superior has reefs? Unlike coral reefs, these are shallow rocky areas that provide critical spawning habitat for native fish, like whitefish and lake trout. The reefs, or shoals, in the Apostle Islands are home to important whitefish and lake trout spawning habitats in Western Lake Superior.
But these reefs are now threatened. Invasive zebra mussels have begun appearing on shoals around the islands. These mussels over‑filter the water, stripping out the tiny organisms that native fish juveniles depend on for food. In Lake Michigan, similar invasions have contributed to a 95% decline in the whitefish harvest.
How you can help:
These invasive mussels often travel by boat, as tiny hitchhikers clinging to hulls, anchors, bilges, and ballast tanks. Before leaving the harbor and visiting the islands, you can make a huge difference by taking a few simple steps:
• Wash your boat thoroughly
• Drain your bilge and ballast tanks
• Clean, drain, and dry all equipment before launching
These small actions stop invasive species from spreading and protect the waters we all care about.
Image: Divers working at Oak Island shoal, credit: Toben Lafrancois