Rehabilitating the Moon River Walleye

Biologists continue to monitor the waters of Eastern Georgian Bay’s Moon River near Parry Sound to see what effect more than 1,000 tonnes of rock will have on local walleye populations. The goal is to increase populations of this and other river-spawning fish species.


Close up of an adult walleye
Close up of an adult walleye - Photo: Matt Garvin/MNR

In the fall of 2008, 1,100 metric tonnes of rock were brought in to create 1,500 square metres of new spawning and nursery habitat. Contractors placed 35 clusters of large boulders topped with cobble rock on the south shore below the Moon River falls and added granite rubble to the north shore. This enlarged the known historic walleye spawning and egg incubation areas already there nearly 30 times; biologists also hope to provide new spawning habitat for lake sturgeon, a threatened fish species in Ontario which still spawns, in small numbers, in the Moon River.


Water levels in the Moon River fluctuate drastically from mid-April to late May, when walleye and sturgeon spawn. When the water flows fast and high, spawning adult walleye have to struggle upstream and incubating walleye eggs are dislodged. When water levels drop, the eggs are left high and dry.


The new layer of rocks and rubble is designed to ensure the Moon River provides suitable spawning and nursery habitat for walleye and other fish species over a wider variety of water depth and flow conditions


Visit for more information about the work being done to rehabilitate the Moon River walleye.


Click here to view a map of the project area


About the Moon River Walleye:

• In the first half of the 20th century, the Moon River had an international reputation for its magnificent walleye fishery and trophy-sized fish.
• The Moon river walleye population began declining in the late 1960s. By the 1990s, the river’s previous population of 30,000 walleye had dwindled to a few thousand fish.
• Many factors contributed to the decline of the Moon River’s walleye populations, but in the lead was lack of water flow in spawning areas due to upstream hydro power generating practices. Recent efforts to enlarge spawning habitat on the Moon River are designed to lessen this impact.
• Throughout the 1980s, and to the present day, the Ministry of Natural Resources and its partners have worked tirelessly to improve spawning and nursery habitat below the Moon River falls where it empties into eastern Georgian Bay.
• The Eastern Georgian Bay Stewardship Council is planning similar rehabilitation projects at Eastern Georgian Bay’s Musquash and Magnetawan rivers in the future.

Project Partners:

  • Eastern Georgian Bay Stewardship Council
  • Georgian Bay Biosphere Reserve
  • Georgian Bay Land Trust
  • Great Lakes Conservancy
  • Ontario Power Generation – Evergreen Energy
  • Sans Souci, Copperhead and Woods Bay community associations
  • W.S. Morgan Construction, Red Rock Barging and Reiger Contracting


For more information, contact:

  • Eric McIntyre, Coordinator, Eastern Georgian Bay Stewardship Council, Ministry of Natural Resources, Parry Sound (705) 733-4218
  • David Gonder, Management Biologist, Upper Great Lakes Management Unit – Lake Huron, Ministry of Natural Resources, Owen Sound (519) 371-5596
  • Andy McKee, Lake Huron COA Basin Coordinator, Upper Great Lakes Management Unit – Lake Huron, Ministry of Natural Resources, Owen Sound (519) 371-5449


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