Finding Freshwater Mussels | U.S. Fish & Wildlife Service

Searching for these cryptic creatures

Mar 4, 2025

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Two people snorkel and three people wade with viewbuckets in a small, shallow river. — Staff from Erwin National Fish Hatchery, Asheville Ecological Services Field Office, Tennessee Ecological Services Field Office, UT Knoxville, and the Tennessee Valley Authority survey the Emory River, searching for the imperiled Alabama Lampmussel.

The Emory River slowly makes its way downstream, flowing through the eastern Tennessee landscape. Hidden under its surface lies some of nature's more cryptic creatures: freshwater mussels. Freshwater mussels are a highly imperiled fauna group, with the amazing ability to filter and clean water. The mussels typically stay buried below the substrate, with just their siphon being visible.

A freshwater mussel siphon is barely visible on the sandy substrate of a creek. — Freshwater mussels can be very hard to spot when they are buried in the substrate. The siphon of an Alabama Lampmussel can be seen peaking out of the river floor inside the red box.

Mussel biologists, also known as malacologists, will slowly search the stream, looking carefully for the siphons. Oftentimes, biologists will snorkel in the river, trying to spot the siphons. Other times biologists will use a specialized tool known as a view-bucket to look at the river bottom to find the mussels.

A man attached a PIT tag to a freshwater mussel — Jason Mays attaches a PIT tag to a freshwater mussel.

Sometimes biologists will PIT tag mussels to make them easier to find during future visits to the site. PIT tags, which stands for Passive Integrated Transponder, are similar to the microchips that are used to identify cats and dogs, except when tagging mussels the tag is glued on to the outside of the shell. PIT tags can be used to identify and keep track of specific individuals, or to locate the mussels that are hidden under the surface of the substrate. The PIT tags remain dormant until they are close to the receiver. The receiver can be used to locate the mussels, similar to a metal detector, or to identify the individuals after they have been found.

A freshwater mussels sits in a stream with a chunk of plaster containing a PIT tag on its shell. — A PIT tagged Alabama Lampmussel sits near the shore, waiting to be placed back in the substrate.

Knowing these different techniques for locating freshwater mussels can be extremely helpful for biologists. Visual surveys and PIT tags are useful tools when monitoring and managing freshwater mussel populations, and can help managers make informed decisions about the status of these populations.