Species At Risk


(Obovaria olivaria)




The Hickorynut is a freshwater mussel with a shell that is usually less than 75 millimetres long. It has a small, nearly oval hinged shell, ranging from green to yellowish brown, and becoming dark brown in old individuals. Thin greenish rays are often present in young mussels.

Action we are taking:


The Hickorynut is found within the Great Lakes – St. Lawrence basin and the Mississippi River basin. In Canada, the Hickorynut is found in sporadic locations within the Great Lakes and St. Lawrence basin, from Lake Huron to Quebec City. In Ontario, it is found in the Mississagi River and the Ottawa River.


Hickorynuts live on the sandy beds in large, wide, deep rivers – usually more than two or three metres deep – with a moderate to strong current. Mussels filter water to find food, such as bacteria and algae. Mussel larvae must attach to a fish, called a host, where they consume nutrients from the fish body until they transform into juvenile mussels and then drop off. In Canada, the fish host of the Hickorynut is the Lake Sturgeon. Presence of the fish host is one of the key features determining whether a body of water can support a healthy Hickorynut population.


Many of the large-river habitats of the Hickorynut have been damaged by Zebra Mussel infestations, dams, or pollution caused by some industrial and agricultural activities.

As Hickorynuts appear to need Lake Sturgeon present to complete their life cycle, threats to sturgeon, including habitat loss due to water quality, water manipulation, and barriers to migration, also pose a threat to the Hickorynut’s survival.


The Hickorynut and its habitat are protected under Ontario’s Endangered Species Act.

What You Can Do to Help the Hickorynut

  • The Ministry of Natural Resources tracks species at risk such as the Hickorynut. You can use a handy online form to report your sightings to the Natural Heritage Information Centre. Photographs with specific locations or mapping coordinates are always helpful. nhic.mnr.gov.on.ca
  • Report any illegal activity related to plants and wildlife to 1-877-TIPS-MNR (847-7667).
  • Private land owners have a very important role to play in species at risk recovery. You may be eligible for stewardship programs that support the protection and recovery of species at risk and their habitats.
  • Invasive species seriously threaten many of Ontario’s species at risk. To learn what you can do to help reduce the threat of invasive species, visit: ontario.ca/invasivespecies; www.invadingspecies.com; www.ontarioinvasiveplants.ca; and, www.invasivespecies.gc.ca.
  • Volunteer with your local nature club or provincial park to participate in surveys or stewardship work focused on species at risk.

Did you know?

Hickorynut shells were considered valuable for the pearl button industry in the early 20th century, and were harvested for these purposes in the United States.

Did you know?

Hickorynuts live from seven to 14 years. A mussel's age can be estimated by counting the rings that form on its shell each winter when growth slows or stops – similar to the rings on a tree.

Did you know?

Like many mussels, the Hickorynut has a specialized larval stage that is parasitic on fish. Larvae hitch a ride on the fish, living in cysts on the fish’s skin until they grow and drop off as adults. The fish are not harmed by their mussel hitchhikers.

The Endangered Species Act

Contact your local ministry office

Often the best source of local information on species at risk is your nearest ministry office. Call with your questions or concerns.