Freshwater Mussels of New Hampshire

There are 10 species of native freshwater mussels in the state of New Hampshire. Some species, such as the eastern Elliptio, are common and widespread in our rivers, ponds and lakes. Others, particularly the brook floater and dwarf wedgemussel, have reached population numbers so low that they are now considered endangered. Eastern pond mussels are currently a species of special concern and are restricted to a handful of ponds and lakes in southeastern NH.  Many of our other native mussels, even those not officially listed as conservation concern, are often considered good environmental indicators because they are sensitive to water quality and habitat degradation. Freshwater mussels may also be threatened by changes in fish species composition, dams that limit passage of diadromous fish species, and the potential spread of invasive non-native species like zebra mussels. Freshwater mussels spend their initial stage of life (called glochidia) attached to the gills, fins and scales of certain fishes. When the mussel drops off the fish as a juvenile, it lives the rest of its life as a suspension feeder on bacteria and organic matter, making it an important part of aquatic systems.  Mussels are fascinating and we encourage all interested to read some of the more detailed publications and resources.   

The New Hampshire Fish and Game Department encourages reports of mussel sightings through our Wildlife Sightings website to help keep track of our mussel populations. View the distribution maps included with each species account and help fill in the missing data gaps. You should never kill a mussel to identify it and mussels should only be removed from water long enough to take a photo (Note: Dwarf wedgemussels and brook floaters can not be legally handled without a permit).   Information and photographs are provided below to help accurately report your sightings:

NH Species:
Family Unionidae
Dwarf wedgemussel – State Endangered
Brook floater – State Endangered
Eastern pondmussel – State Special Concern
Eastern elliptio (Most common mussel in NH)
Triangle floater
Eastern floater
Alewife floater
Eastern lampmussel

Family Margaritiferidae
Eastern pearlshell

Non-native invasives:
Zebra mussels – not currently known from NH

Asian clam – currently known from several locations in the Merrimack River, Cobbett’s Pond (Windham), and Sunset Lake (Wash Pond).


Brook floater
Brook floater

pond mussel shell
Eastern Pondmussel

Eastern elliptio
Eastern Elliptio

Triangle floater
Triangle Floater

Eastern floater
Eastern Floater

Alewife floater
Alewife Floater


Eastern lampmussel
Eastern Lampmussel

Eastern pearlshell

Eastern Pearlshell


Lake habitat

Freshwater mussels occur in a variety of aquatic habitats in NH including lakes, ponds, wetlands, rivers, and streams. Photo by M. Marchand

mussels siphoning

Freshwater mussels filter water in through an inhalant aperture and expel water through an exhalant aperture (both visible in these mussels).  Mussels often are partially to mostly buried within substrate with only the posterior end of the mussel visible (the end where filtering occurs).  In this photo, a brook floater mussel and triangle floater mussel are actively filtering. Photo by E. Nedeau

muskrat predator

Muskrats are a common predator of freshwater mussels.  

shell midded from predator

A pile of mussel shells, called a midden, after they were consumed by a predator. Photo by E. Nedeau


Special thanks to Ethan Nedeau, Biodrawversity LLC for allowing NHFG use of photographs and illustrations on this website.

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NH Fish and Game Dept.
11 Hazen Drive
Concord, NH 03301

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