Yellow Lampmussel

Lampsilis cariosa (Say, 1817)


Bivalvia (Bivalves)
Unionidae (Unionid Mussels)
State Protection
Not Listed
Not listed or protected by New York State.
Federal Protection
Not Listed
State Conservation Status Rank
Imperiled or Vulnerable in New York - Very vulnerable, or vulnerable, to disappearing from New York, due to rarity or other factors; typically 6 to 80 populations or locations in New York, few individuals, restricted range, few remaining acres (or miles of stream), and/or recent and widespread declines. More information is needed to assign either S2 or S3.
Global Conservation Status Rank
Vulnerable globally, or Apparently Secure - At moderate risk of extinction, with relatively few populations or locations in the world, few individuals, and/or restricted range; or uncommon but not rare globally; may be rare in some parts of its range; possibly some cause for long-term concern due to declines or other factors. More information is needed to assign either G3 or G4.


Did you know?

The particular fish species which serves as the host for the parasitic glochidia (larvae) is unknown (Stryaer and Jirka 1997).

State Ranking Justification

This species has declined over most of its range, nevertheless it is still relatively common and reproducing in the Susquehanna River basin, lower Schoharie Creek, and in tributaries of the St. Lawrence River. Most of the Hudson River records are historical (Strayer and Jirka 1997), and the great majority of the records in the state are of marginal population viability.

Short-term Trends

Between 1955 to 1997 L. cariosa expanded its range primarily in the lower reaches of the Susquehana River basin (Strayer and Fetterman 1997). The last mussel report from the Hudson River was a shell found in 1985 (New York Natural Heritage 2020). In some areas the apparent range expansion may be misleading because some stream reaches were not surveyed prior to more recent survey efforts and many reports were not based on statewide or regional survey (Mahar and Landry 2013). Yellow Lampmussel has declined in most of the river basins in the state (Strayer and Fetterman 1997). Only a handful of the known populations in New York are viable.

Conservation and Management


The single most important cause of the decline of freshwater mussels during the last century is the destruction of their habitat by siltation, dredging, channelization, impoundments, and pollution. A healthy fish assemblage is critical to viable mussel populations, and dams have resulted in heavy losses of mussels, mainly due to elimination of host fish species. Erosion due to deforestation, poor agricultural practices and the destruction of riparian zones, causes an increase in siltation and shifting substrates that can smother mussels. Domestic sewage, effluents from paper mills, tanneries, chemical industries and steel mills, acid mine runoff, heavy metals, and pesticides have all been implicated in the destruction of native mussel fauna (Strayer et al. 2004).

Conservation Strategies and Management Practices

When feasible, the removal of impoundments in order to restore rivers to their natural flow would be beneficial since these structures negatively effect required host fish species as well as the mussels themselves.

Research Needs

There is still much to learn about this species, especially determination of the host fish species. Details about habitat requirements (current speed, water depth, substrate grain size, substrate stability, water temperature, and water quality factors) also need further study. However, Strayer et al. (1994) found that the distribution of Unionids was not related to these typical physical habitat qualities, but instead was related to long term stability of the substrate (i.e., flow refuges) and other large-scale habitat variables such as riparian zone vegetation (i.e., grassy vs. forested). Both large and smaller scale forces promoting the patchy occurrence of Unionid mussel beds is an active area of research (Strayer et al. 2004).



This is a species of small to large rivers, especially on sandy substrates in riffles (Strayer and Jirka 1997).

Associated Ecological Communities

  • Confined river (guide)
    The aquatic community of relatively large, fast flowing sections of streams with a moderate to gentle gradient.
  • Riverside sand/gravel bar (guide)
    A meadow community that occurs on sand and gravel bars deposited within, or adjacent to, a river channel. The community may be very sparsely vegetated, depending on the rates of deposition and erosion of the sand or gravel.
  • Tidal river (guide)
    The aquatic community of a river under the influence of daily lunar tides. We restrict this community to the continuously flooded portions of the river where plants do not grow out of the water. A deepwater zone has depths averaging more than 2 m (6 ft) at low tide. Salinities at any one place in the river may fluctuate as the tides flow in and out.
  • Unconfined river (guide)
    The aquatic community of large, quiet, base level sections of streams with a very low gradient.

Associated Species

  • Elktoe (Alasmidonta marginata)
  • Triangle Floater (Alasmidonta undulata)
  • Eastern Elliptio (Elliptio complanata)
  • Eastern Lampmussel (Lampsilis radiata)
  • Creeper (Strophitus undulatus)


New York State Distribution

In New York, Yellow Lampmussel occurs in 25 waterbodies. There are many records from the Susquehanna and Hudson River basins. Although the species is not known from the Champlain basin, it is widespread in the St. Lawrence River watershed. The highest densities are from areas of the Chenango, Raquette, and Susquehanna rivers. Mussels have not been found in the Hudson River for decades. Many of the historical records from central New York are questionable because of confusion with the Pocketbook (L. ovata) (Strayer and Jirka 1997).

Global Distribution

This species has a wide geographic range in Atlantic drainages, from Nova Scotia to Georgia, as well as in the St. Lawrence River system westward to Ontario. On the Atlantic Slope, it occurs east of the Appalachian Mountains from the Sydney River, Nova Scotia, to the Ogeechee River, Georgia (South Carolina, North Carolina, Virginia, West Virginia, Maryland, Delaware, Pennsylvania, New Jersey, New York, Connecticut (extirpated), Massachusetts, Maine, New Brunswick). Recently, the species' range has contracted in most of the southern states and populations are in decline and disappearing nearly everywhere. In Canada, it is currently known from only two localities: Cape Breton Island, Nova Scotia, and Fredericton, New Brunswick.

Best Places to See

  • Susquehanna River

Identification Comments

General Description

The shell is subovate, with an evenly rounded margin, of variable size and thickness. The beak sculpture is weakly double-looped, but often it will be obliterated. The periostracum is usually glossy, with a distinctive clear yellow color, often without rays. If rays are present, they are well defined and restricted to the posterior slope and ridge. The pseudocardinal and lateral hinge teeth are both well developed, but variable in shape and strength. The pseudocardinals are strong and triangular, but sometimes delicate and lamellar, especially in young animals or in specimens from northern New York. The nacre is white and the sexes are dimorphic with males more elongate than females (Strayer and Jirka 1997).

Identifying Characteristics

This species can be identified by its clear yellow periostracum on which color rays are absent or are confined to the posterior of the shell (Strayer and Jirka 1997).

Best Life Stage for Proper Identification



Adults of this species are sessile with only limited movement in the substrate. Passive downstream movement may occur when they are displaced from the substrate during floods. More major dispersal occurs while glochidia (larvae) are encysted on their as yet, unknown host(s). Being ectothermic, activity levels of mussels are presumably greatly reduced during colder months of the year.


Adult mussels are filter feeders. Algae, detritus and bacteria are all important food sources. Mussels in turn are eaten by muskrats, raccoons, fish, and birds. The glochidial (larval) host fish species has not yet been determined (Strayer and Jirka 1997).

Best Time to See

Little is known about the activity periods of Unionid mussels but they are presumed to be greatly reduced during cold times of the year. Freshwater mussels are most often easiest to locate during late summer when water levels are lowest. This species is a long-term breeder but the limits of its breeding season are unknown (Clarke 1981).

  • Present
  • Active
  • Larvae present and active

The time of year you would expect to find Yellow Lampmussel present, active, and larvae present and active in New York.

Similar Species

  • Tidewater Mucket (Atlanticoncha ochracea)
    Leptodea has color rays widely distributed on the shell as opposed to being restricted to the posterior as in L. cariosa.
  • Pocketbook (Lampsilis ovata)
    L. ovata has color rays widely distributed on the shell as opposed to being restricted to the posterior as in L. cariosa.

Yellow Lampmussel Images


Yellow Lampmussel
Lampsilis cariosa (Say, 1817)

  • Kingdom Animalia
    • Phylum Mollusca (Mollusks)
      • Class Bivalvia (Bivalves)
        • Order Unionoida (Freshwater Mussels)
          • Family Unionidae (Unionid Mussels)

Additional Resources


Alderman, John A. 1990. Lampsilis cariosa (Say, 1817) Yellow Lampmussel. pages 97-100. [in] A Report on the conservation status of North Carolina's freshwater and terrestrial molluscan fauna. Scientific Council on Freshwater and Terrestrial Mollusks. Raleigh, NC. 283 pages.

Burch, J.B. 1975a. Freshwater unionacean clams (Mollusca: Pelecypoda) of North America. Malacological Publications: Hamburg, Michigan. 204 pp.

Clarke, A.H. 1981a. The freshwater mollusks of Canada. National Museum of Natural Sciences, National Museums of Canada, D. W. Friesen and Sons, Ltd.: Ottawa, Canada. 446 pp.

Johnson, R.I. 1970a. The systematics and zoogeography of the Unionidae (Mollusca: Bivalvia) of the southern Atlantic slope region. Bulletin of the Museum of Comparative Zoology, Harvard University 140(6): 263-449.

Marshall, W.B. 1895. Geographical distribution of New York Unionidae. Annual Report. New York State Museum. 48: 47-99.

New York Natural Heritage Program. 2024. New York Natural Heritage Program Databases. Albany, NY.

New York State Department of Environmental Conservation. 2020. ArcGIS layer package on mussel records in New York State.

Ortmann, A.E. 1919. Monograph of the naiades of Pennsylvania. Part III. Systematic account of the genera and species. Memoirs of the Carnegie Museum 8(1):1-385.

Strayer, David L. 1987. Ecology and zoogeography of the freshwater mollusks of the Hudson River basin. Malacological Review 20:1-68.

Strayer, David L. 1995. Some collections of freshwater mussels from Schoharie Creek, Tonawanda Creek, and the Allegheny basin in New York in 1994. Unpublished report. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY.

Strayer, David L. and A.R. Fetterman. 1999. Changes in distribution of freshwater mussels (Unionidae) in the upper Susquehanna River basin, 1955-1965 to 1996-1997. American Midland Naturalist 142:328-339.

Strayer, David L. and K.J. Jirka. 1997. The Pearly Mussels (Bivalva: Unionoidea) of New York State. New York State Museum Memoir 26. The New York State Education Department.

Strayer, David L., D.C. Hunter, L.C. Smith, and C.K. Borg. 1994. Distribution, abundance, and roles of freshwater clams (Bivalva, Unionidae) in the freshwater tidal Hudson River. Freshwater Biology 31:239-248.

Strayer, David L., J.A. Dowling, W.R. Haag, T.L. King, J.B. Layzer, T.J. Newton and S.J. Nichols. 2004. Changing perspectives on Pearly Mussels, North America's most Imperiled Animals. BioScience 54:429-439.


About This Guide

This guide was authored by: Jeffrey D. Corser

Information for this guide was last updated on: May 7, 2014

Please cite this page as:
New York Natural Heritage Program. 2024. Online Conservation Guide for Lampsilis cariosa. Available from: Accessed July 19, 2024.