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DescriptionThe yellow lampmussel is a large (up to 4½-inch)

freshwater mussel that superficially resembles a marineclam. Its shell is oval-shaped and distinctly yellow, occasion-ally with faint green rays. The nacre, or pearly lining of theinside of the shell, is usually white or bluish-white. Thisspecies can be confused with the tidewater mucket, which isof similar shape and coloration but usually has a bronzetinge in adult specimens. The structure and placement ofthe hinge teeth, plus color of the nacre, help to distinguishthese two species. (For more detailed information onidentification, see MDIFW’s book, The Freshwater Musselsof Maine.)

Range and HabitatThe yellow lampmussel is found in Atlantic coastal

drainages from Georgia to Nova Scotia. In Maine it iscurrently known only from the Penobscot, St. George, andlower Kennebec River watersheds. This species typicallyprefers medium to large rivers, but in Maine is often foundin lakes and ponds, and will tolerate impounded sections ofrivers. It occurs in a variety of bottom types, including silt,sand, gravel, and cobble.

Life History andEcology

Freshwater mussels havea curious way of reproduc-ing that depends on thepresence of fish. Theyellow lampmussel breedsin late summer, whenmales release sperm intothe water and females filterit out of the water withtheir gills. Once the eggsare fertilized, femalesbrood the growing larvae,called glochidia, in a

modified portion of their gills called a marsupium.The following summer, each larvae-bearing female

releases thousands of mature glochidia. At this stage,glochidia require fish hosts to change into the subadultform of a mussel. They can only survive for a short time ontheir own and must quickly encounter a suitable host fish.To aid the glochidia in finding a host, larvae-bearing femaleyellow lampmussels use a fleshy modification of theirmantle (flap-like tissue lining the shell) that is shaped like asmall minnow to attract fish. When a fish bites the lure,glochidia are released. They then attach to the fish’s gills(without apparent harm to the fish) for a period of weeksor months before transforming into tiny mussels anddropping off to settle in the bottom. Each mussel speciesrequires one or more specific fish species to serve assuitable hosts. Currently, known fish hosts for the yellowlampmussel are yellow and white perch.

Freshwater mussels grow rapidly during their first 4-6years of life, before they become reproductively mature.Longevity of the yellow lampmussel is likely 15 years ormore. Mussels continually filter vast quantities of water andconsume bacteria, algae, and plant and animal debris. Theyburrow into the bottom and anchor themselves with amuscular foot. They have a limited ability to move slowlyaround the lake or river bottom to find the best sites forfeeding and reproducing. Mussels are an important fooditem for some aquatic mammals, especially otters, musk-rats, and raccoons, as evidenced by piles of shells(middens) often seen along shorelines.

ThreatsFreshwater mussels are the most endangered group of

animals in North America. Of the nearly 300 species nativeto North America, approximately 75 percent are state orfederally listed as endangered, threatened, possiblywarranting listing status, or already extinct. Their popula-tion declines are the result of more than a century ofindustrialization and development of our waterways,causing alteration and loss of habitat and degradation ofwater quality.

YellowLampmussel

(Lampsilis cariosa)

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Range in Maine Known locations

• For more information: MDIFW Endangered Species Program • 207-941-4466 • www.mefishwildlife.com •

The yellow lampmussel has declined throughout itsrange and has been extirpated from many rivers in theNortheast. Habitat degradation and pollution have elimi-nated some populations. Unlike many species of mussels,however, the yellow lampmussel is able to survive inimpoundments.

Another serious threat to native mussels is the exoticzebra mussel, which was accidentally introduced to theGreat Lakes and is spreading across North America. Itcarpets the bottom of lakes and rivers, and out-competesnative mussels for space and food. Although it has not beenfound in Maine, the zebra mussel could represent a majorthreat to yellow lampmussel populations if introduced here.

Conservation and ManagementPopulation declines have been documented for the

yellow lampmussel throughout much of its range, prompt-ing many states to add it to their lists of endangered andthreatened species. It also is a former candidate for federallisting. In 1997, the species was listed as threatened inMaine. It is known from only three watersheds in the state,and is usually found in low numbers at most sites.

Conservation of mussels requires identification andprotection of their habitats, and suitable populations of theirfish hosts. MDIFW completed a seven-year survey of thestate’s freshwater mussels in the 1990s. Populations ofyellow lampmussels are well documented, and informationis being provided to towns, land trusts, and lake andwatershed associations. In 2001, research was initiated atthe University of Maine to document the fish host(s),population size and structure, and genetic uniqueness ofpopulations. Monitoring is needed to assess populationtrends, and additional life history studies are needed tolearn more about the species’ habitat requirements,reproduction, and interaction with fish host populations.

Maine may have some of the largest remaining popula-tions of yellow lampmussels in the East, and will play animportant role in the species’ conservation. Protection ofclean, unaltered watersheds and associated forested riparianareas is necessary for the long-term existence of thisspecies. The yellow lampmussel shares much of its habitatin Maine with the tidewater mucket (threatened), shortnosesturgeon (federally threatened), Atlantic salmon (federallyendangered), and other rare species like the brook floater(mussel), wood turtle, and New England bluet damselfly.Adhering to state wetland and Shoreland Zoning laws andwater quality Best Management Practices contributesgreatly to maintaining the quality of aquatic habitats for thisspecies. Shoreland zoning and LURC zoning standardsprovide protection of habitat up to 250 feet from largerrivers. Some forest companies voluntarily extend theconservation of intact, forested riparian zones to 330-600feet for larger rivers.

Recommendations:✔ Prior to land development or forest harvesting nearwaterways providing habitat for threatened and endangeredspecies, consult with a biologist from MDIFW to assist withplanning.

✔ Municipalities should strive to maintain areas adjacentto waterways providing habitat for rare mussels in a low-density, rural setting and identify these areas in comprehen-sive plans. Consider protecting waterways and a 250-footupland buffer as Resource Protection Districts.✔ Use voluntary agreements, conservation easements,conservation tax abatements and incentives, and acquisitionto protect important habitat for threatened and endangeredspecies.✔ Follow Shoreland Zoning and LURC standards.✔ To preserve water quality and river functions, maintaincontiguous, forested riparian habitats at least 250 feet fromwaterways providing habitat for threatened and endangeredspecies.✔ Avoid placing roads, houses, yards, and other develop-ments within 250 feet of waterways providing habitat forthreatened and endangered species.✔ When projects are proposed within 250 feet of water-ways providing habitat for endangered or threatenedspecies, adhere to forestry Best Management Practices(handbook available from the Maine Forest Service, SHS#22, Augusta, ME 04333) and Maine Erosion andSediment Control Recommendations (available from theMaine Department of Environmental Protection, SHS #17,Augusta, ME 04333).✔ Avoid road crossings or use of heavy equipment instreams or rivers.✔ Avoid stream alteration projects (water withdrawals,dredging, rip-rap, channelization, pipeline crossings, dams)that would alter flow or remove natural stream featuressuch as riffles and pools.✔ Avoid the use of broad-spectrum pesticides within ¼mile of waterways providing habitat for threatened andendangered species.✔ To maintain or improve water quality, conduct thor-ough reviews of dam and wastewater discharge proposals.Avoid land uses that would contribute to non-point sourcesof pollution.✔ It is illegal to introduce fish species. Such introductionscould alter aquatic invertebrate communities and affect hostfish populations.