Utterbackiana implicata - (Say, 1829)
Alewife Floater
Synonym(s): Anodonta implicata Say, 1829
Taxonomic Status: Accepted
Related ITIS Name(s): Anodonta implicata Say, 1829 (TSN 79941)
French Common Names: anodonte du gaspareau
Unique Identifier: ELEMENT_GLOBAL.2.108462
Element Code: IMBIV04080
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Mussels
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Bivalvia Unionoida Unionidae Utterbackiana
Genus Size: B - Very small genus (2-5 species)
Check this box to expand all report sections:
Concept Reference
Concept Reference: Turgeon, D.D., J.F. Quinn, Jr., A.E. Bogan, E.V. Coan, F.G. Hochberg, W.G. Lyons, P.M. Mikkelsen, R.J. Neves, C.F.E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F.G. Thompson, M. Vecchione, and J.D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland: 526 pp.
Concept Reference Code: B98TUR01EHUS
Name Used in Concept Reference: Anodonta implicata
Taxonomic Comments: Graf and Cummings (2007) and Cummings and Graf (2010) place Anodonta implicata in Utterbackia (Williams et al. 2017).

Recently, Zanatta et al. (2007) supported the monophyly of both Pyganodon and Utterbackia using mutation coding of allozyme data, but also resolved the Eurasian Anodonta cygnea to Pyganodon, Utterbackia, and North American Anodonta; indicating futher phylogenetic analysis of the Anodontinae is required including both North American and Eurasian species. There has been some suggestion the name Anodonta atra (Rafinesque, 1820) has priority over Anodonta implicata based on two characters from the description of A. atra. However, A. atra was described without illustration and with limited descriptive characters attributable to other Anodonta and Pyganodon species. With such limited information, there is insufficient evidence to justify replacing the name at this time.
Conservation Status

NatureServe Status

Global Status: G5
Global Status Last Reviewed: 01Aug2017
Global Status Last Changed: 25Nov1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: This wide ranging Atlantic slope species is considered relatively common and secure throughout most of its range, but is limited to only the coastal areas of the North Atlantic Slope from North Carolina to Maine with disjunct populations in North Carolina.
Nation: United States
National Status: N5 (16Jul1998)
Nation: Canada
National Status: N5 (01Aug2017)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Connecticut (SU), Delaware (S1), District of Columbia (SNR), Maine (SNR), Maryland (S3), Massachusetts (S4), New Hampshire (S3?), New Jersey (S4), New York (S1S2), North Carolina (S2), Pennsylvania (S3), Rhode Island (SNR), Vermont (S1), Virginia (S3?)
Canada New Brunswick (S5), Nova Scotia (S4S5), Quebec (S1)

Other Statuses

IUCN Red List Category: LC - Least concern
American Fisheries Society Status: Currently Stable (01Jan1993)

NatureServe Global Conservation Status Factors

Range Extent: 200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Range Extent Comments: This is a coastal plains species distributed from Nova Scotia to eastern Quebec and south to Virginia (Burch, 1975; Clarke, 1981; Nedeau et al., 2000) with disjunct populations in the Pee Dee (Bogan and Alderman, 2004) and Chowan (Bogan, 2002) basins in North Carolina.

Number of Occurrences: > 300
Number of Occurrences Comments: In Maine, it is found in nearly all the coastal watersheds and as far inland as its anadromous fish hosts once traveled (absent from Aroostook, Franklin, Oxford, Piscataquis, York Cos.) (Nedeau et al., 2000). In Rhode Island, it can be found in various coastal rivers and ponds (Raithel and Hartenstein, 2006). In Vermont, it is found in the Connecticut River below Bellows Falls in southern Vermont (Fichtel and Smith, 1995) to Massachusetts (Kart et al., 2005). In the Delaware River basin, it has been recorded in the Middle Delaware- Mongaup- Broadhead drainage in New York to bordering Pennsylvania (Strayer and Ralley, 1991). In Maryland, it is known from the Upper Potomac River, Elk River, Chester River, and Choptank River drainages (Bogan and Proch, 1995); and Lower Susquehanna. (Ashton, 2009). Johnson (1970) cites the southern range limit as the Potomac River, Virginia. In the Carolinas, it is found in the Pee Dee River basin in North Carolina and is expected in South Carolina (Bogan and Alderman, 2004). In North Carolina, it is known from the Chowan River (Alderman and Alderman, 2009- collected 2001), Roanoke and Pee Dee River systems (Bogan, 2002) in Anson, Bertie, Chowan, Gates, Halifax, Hertford, Northampton, Richmond, and Washington Cos. (LeGrand et al., 2006). In Canada, it has historically been found in Quebec in lac des Deux-Montagnes, the Saint-Charles River close to Quebec City, and on the southern bank of St.-Lawrence between Saint-Vallier and Montmagny; in several large rivers in New Brunswick where it is widespread and abundant (Athearn, 1961; Davis, 1999), common in Nova Scotia throughout the central, northern, and eastern counties (Athearn and Clarke, 1962; Metcalfe-Smith and Cudmore-Vokey, 2004). Clarke and Rick (1964) include occurrences in Cape Breton Co., Nova Scotia.

Population Size: >1,000,000 individuals

Number of Occurrences with Good Viability/Integrity: Some to many (13-125)
Viability/Integrity Comments: Damariscotta Lake in Lincoln Co., Maine, has an exceptional population because it supports one of the best alewife runs in the state (Nedeau et al., 2000).

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: Raithel and Hartenstein (2006) speculated on some recent range expansion in Rhode Island and Smith (1985) speculated on the same for Massachusetts and Connecticut based on restoration of clupeid fish in the Connecticut River system. This species was likely extirpated from a number of rivers in southern Maine that historically lost their alewife runs due to dam construction (Nedeau et al., 2000). In Canada, it is declining in Quebec but stable in eastern provinces (Metcalfe-Smith and Cudmore-Vokey, 2004).

Long-term Trend: Decline of <30% to increase of 25%

Intrinsic Vulnerability: Moderately vulnerable to not intrinsically vulnerable.
Intrinsic Vulnerability Comments: Not intrinsically vulnerable, although susceptible to anadromous host fish distribution.

Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.
Environmental Specificity Comments: Confined to coastal plains ponds.

Other NatureServe Conservation Status Information

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) This is a coastal plains species distributed from Nova Scotia to eastern Quebec and south to Virginia (Burch, 1975; Clarke, 1981; Nedeau et al., 2000) with disjunct populations in the Pee Dee (Bogan and Alderman, 2004) and Chowan (Bogan, 2002) basins in North Carolina.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States CT, DC, DE, MA, MD, ME, NC, NH, NJ, NY, PA, RI, VA, VT
Canada NB, NS, QC

Range Map
No map available.

U.S. Distribution by County Help
State County Name (FIPS Code)
DE Kent (10001), New Castle (10003), Sussex (10005)
NC Anson (37007), Bertie (37015), Chowan (37041)*, Gates (37073), Halifax (37083), Hertford (37091), Montgomery (37123), Northampton (37131), Richmond (37153), Sampson (37163), Stanly (37167), Washington (37187)
NY Albany (36001), Columbia (36021), Delaware (36025), Dutchess (36027), Orange (36071), Rensselaer (36083), Saratoga (36091)*, Sullivan (36105), Ulster (36111)
PA Bucks (42017)*, Luzerne (42079), Monroe (42089), Northampton (42095), Philadelphia (42101)*, Pike (42103), Wayne (42127)
VT Windham (50025), Windsor (50027)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Black-Ottauquechee (01080106)+, West (01080107)+, Middle Connecticut (01080201)+
02 Hudson-Hoosic (02020003)+, Mohawk (02020004)+*, Middle Hudson (02020006)+, Hudson-Wappinger (02020008)+, Upper Delaware (02040101)+, East Branch Delaware (02040102)+, Lackawaxen (02040103)+, Middle Delaware-Mongaup-Brodhead (02040104)+, Middle Delaware-Musconetcong (02040105)+, Crosswicks-Neshaminy (02040201)+*, Lower Delaware (02040202)+*, Brandywine-Christina (02040205)+, Broadkill-Smyrna (02040207)+, Chincoteague (02040303)+, Upper Susquehanna-Tunkhannock (02050106)+, Upper Susquehanna-Lackawanna (02050107)+, Western Lower Delmarva (02080109)+
03 Lower Roanoke (03010107)+, Ghowan (03010203)+, Meheriin (03010204)+, Albemarle (03010205)+*, Black (03030006)+, Upper Pee Dee (03040104)+, Lower Pee Dee (03040201)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Reproduction Comments: The alewife floater is a long-term brooder- eggs are fertilized in August and glochidia released the following spring. A known glochidial host is the alewife (Alosa pseudoharengus) which is a predominantly saltwater fish that in the spring migrates into freshwater to spawn (Clarke, 1981). Other documented host fish include white sucker (Catostomus commersoni), threespine stickleback (Gasterosteus aculeatus), pumpkinseed (Lepomis gibbosus), and white perch (Morone americana) (Davenport and Warmuth, 1965; Wiles, 1975).
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Riverine Habitat(s): CREEK, Low gradient, MEDIUM RIVER, Moderate gradient
Lacustrine Habitat(s): Shallow water
Special Habitat Factors: Benthic
Habitat Comments: This species is found in coastal streams and lakes in sand and gravel substrates (Clarke, 1981; Nedeau et al., 2000). It occurs in a wide variety of substrate types including silt, sand, and gravel; but is limited to coastal areas due to the nature of its host fish.
Economic Attributes Not yet assessed
Management Summary Not yet assessed
Population/Occurrence Delineation
Group Name: Freshwater Mussels

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on some evidence of historical or current presence of single or multiple specimens, including live specimens or recently dead shells (i.e., soft tissue still attached and/or nacre still glossy and iridescent without signs of external weathering or staining), at a given location with potentially recurring existence. Weathered shells constitute a historic occurrence. Evidence is derived from reliable published observation or collection data; unpublished, though documented (i.e. government or agency reports, web sites, etc.) observation or collection data; or museum specimen information.
Mapping Guidance: Based on the separation distances outlined herein, for freshwater mussels in STANDING WATER (or backwater areas of flowing water such as oxbows and sloughs), all standing water bodies with either (1) greater than 2 km linear distance of unsuitable habitat between (i.e. lotic connections), or (2) more than 10 km of apparently unoccupied though suitable habitat (including lentic shoreline, linear distance across water bodies, and lentic water bodies with proper lotic connections), are considered separate element occurrences. Only the largest standing water bodies (with 20 km linear shoreline or greater) may have greater than one element occurrence within each. Multiple collection or observation locations in one lake, for example, would only constitute multiple occurrences in the largest lakes, and only then if there was some likelihood that unsurveyed areas between collections did not contain the element.

For freshwater mussels in FLOWING WATER conditions, occurrences are separated by a distance of more than 2 stream km of unsuitable habitat, or a distance of more than 10 stream km of apparently unoccupied though suitable habitat. Standing water between occurrences is considered suitable habitat when calculating separation distance for flowing water mussel species unless dispersal barriers (see Separation Barriers) are in place.

Several mussel species in North America occur in both standing and flowing water (see Specs Notes). Calculation of separation distance and determination of separation barriers for these taxa should take into account the environment in which the element was collected. Juvenile mussels do not follow this pattern and juveniles are typically missed by most standard sampling methods (Hastie and Cosgrove, 2002; Neves and Widlak, 1987), therefore juvenile movement is not considered when calculating separation distance.

Separation Barriers: Separation barriers within standing water bodies are based solely on separation distance (see Separation Distance-suitable, below). Separation barriers between standing water bodies and within flowing water systems include lack of lotic connections, natural barriers such as upland habitat, absence of appropriate species specific fish hosts, water depth greater than 10 meters (Cvancara, 1972; Moyle and Bacon, 1969) or anthropogenic barriers to water flow such as dams or other impoundments and high waterfalls.
Separation Distance for Unsuitable Habitat: 2 km
Separation Distance for Suitable Habitat: 10 km
Alternate Separation Procedure: None
Separation Justification: Adult freshwater mussels are largely sedentary spending their entire lives very near to the place where they first successfully settled (Coker et al., 1921; Watters, 1992). Strayer (1999) demonstrated in field trials that mussels in streams occur chiefly in flow refuges, or relatively stable areas that displayed little movement of particles during flood events. Flow refuges conceivably allow relatively immobile mussels to remain in the same general location throughout their entire lives. Movement occurs with the impetus of some stimulus (nearby water disturbance, physical removal from the water such as during collection, exposure conditions during low water, seasonal temperature change or associated diurnal cycles) and during spawning. Movement is confined to either vertical movement burrowing deeper into sediments though rarely completely beneath the surface, or horizontal movement in a distinct path often away from the area of stimulus. Vertical movement is generally seasonal with rapid descent into the sediment in autumn and gradual reappearance at the surface during spring (Amyot and Downing, 1991; 1997). Horizontal movement is generally on the order of a few meters at most and is associated with day length and during times of spawning (Amyot and Downing, 1997). Such locomotion plays little, if any, part in the distribution of freshwater mussels as these limited movements are not dispersal mechanisms. Dispersal patterns are largely speculative but have been attributed to stream size and surface geology (Strayer, 1983; Strayer and Ralley, 1993; van der Schalie, 1938), utilization of flow refuges during flood stages (Strayer, 1999), and patterns of host fish distribution during spawning periods (Haag and Warren, 1998; Watters, 1992). Lee and DeAngelis (1997) modeled the dispersal of freshwater into unoccupied habitats as a traveling wave front with a velocity ranging from 0.87 to 2.47 km/year (depending on mussel life span) with increase in glochidial attachment rate to fish having no effect on wave velocity.

Nearly all mussels require a host or hosts during the parasitic larval portion of their life cycle. Hosts are usually fish, but a few exceptional species utilize amphibians as hosts (Van Snik Gray et al., 2002; Howard, 1915) or may metamorphose without a host (Allen, 1924; Barfield et al., 1998; Lefevre and Curtis, 1911; 1912). Haag and Warren (1998) found that densities of host generalist mussels (using a variety of hosts from many different families) and displaying host specialists (using a small number of hosts usually in the same family but mussel females have behavioral modifications to attract hosts to the gravid female) were independent of the densities of their hosts. Densities of non-displaying host specialist mussels (using a small number of hosts usually in the same family but without host-attracting behavior) were correlated positively with densities of their hosts. Upstream dispersal of host fish for non-displaying host specialist mussels could, theoretically, transport mussel larvae (glochidia) over long distances through unsuitable habitat, but it is unlikely that this occurs very often. D. Strayer (personal communication) suggested a distance of at least 10 km, but a greater distance between occurrences may be necessary to constitute genetic separation of populations. As such, separation distance is based on a set, though arbitrary, distance between two known points of occurrence.

Date: 18Oct2004
Author: Cordeiro, J.
Notes: Contact Jay Cordeiro (jay_cordeiro@natureserve.org) for a complete list of freshwater mussel taxa sorted by flow regime.
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 19Sep2011
NatureServe Conservation Status Factors Author: Cordeiro, J.
Element Ecology & Life History Edition Date: 23Dec2011
Element Ecology & Life History Author(s): Cordeiro, J.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

  • Alderman, J.M. and J.D. Alderman. 2009. Chowan River freshwater mussel survey. Report prepared for Citizens Against OLF by Alderman Environmental Services, Pittsboro, North Carolina. 56 pp.

  • Bauer, G. 1988. Threats to the freshwater pearl mussel Margaritifera margaritifera. Biological Conservation 45:239-253.

  • Becker, A.J., R. Gauza, and J.A. Smith. 2006. A summary of Freshwater Mussel data collected by the Maryland Biological Stream Survey 1995-2006. MD DNR-MBSS, Annapolis. 28 pp.

  • Bogan, A.E. and J.M. Alderman. 2004. Workbook and key to the freshwater bivalves of South Carolina. North Carolina Museum of Natural Sciences: Raleigh, North Carolina. 64 pp.

  • Burch, J.B. 1975. Freshwater unionacean clams (mollusca: pelecypoda) of North America. Malcological Publications. Hamburg, Michigan. 204 pp.

  • 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.

  • Cummings, K. S., and D. L. Graf. 2010. Mollusca: Bivalvia. Pages 309-384 in: J. H. Thorp and A. P. Covich, editors. Ecology and Classification of North American Freshwater Invertebrates. 3rd ed. Elsevier, Amsterdam, The Netherlands.

  • Davenport, D. and M. Warmuth 1965. Notes on the relationship between freshwater mussel Anodonta implicata Say and the alewife Pomolobus pseudoharengus (Wilson). Limnology and Oceanography, Supplement, 10: R74-R78.

  • Graf, D.L. and K.S. Cummings. 2007. Review of the systematics and global diversity of freshwater mussel species (Bivalvia: Unionoida). Journal of Molluscan Studies, 73: 291-314.

  • Hastie, L.C., P.J. Cosgrove, N. Ellis, and M.J. Gaywood. 2003. The threat of climate change to freshwater pearl mussel populations. Ambio 32(1):40-46.

  • Howard, A.D. 1915. Some exceptional cases of breeding among the Unionidae. The Nautilus 29:4-11.

  • 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.

  • Kart, J., R. Regan, S.R. Darling, C. Alexander, K. Cox, M. Ferguson, S. Parren, K. Royar, B. Popp (eds.). 2005. Vermont's Wildlife Action Plan. Vermont Fish & Wildlife Department. Waterbury, Vermont. Available: http://www.vtfishandwildlife.com

  • LeGrand, H.E., Jr., S.P. Hall, S.E. McRae, and J.T. Finnegan. 2006. Natural Heritage Program List of the Rare Animal Species of North Carolina. North Carolina Natural Heritage Program, Raleigh, North Carolina. 104 pp.

  • Lefevre, G. and W.T. Curtis. 1912. Studies on the reproduction and artificial propogation of fresh-water mussels. Bulletin of the Bureau of Fisheries 30:102-201.

  • Lellis, W.A. 2001. Freshwater mussel survey of the Upper Delaware Scenic and Recreational River: Qualitative Survey 2000. Report to the National Park Service. New York Natural Heritage Program, Albany, NY.

  • Letson, E. J. 1905. Checklist of the Mollusca of New York. Bulletin. No. 88. New York State Museum, Albany, NY.


  • Michaelson, D.L. and R.J. Neves. 1995. Life history and habitat of the endangered dwarf wedgemussel Alasmodonta heterodon (Bivalvia: Unionidae). Journal of the North American Benthological Society, 14(2): 324-340.

  • Moyle, P. and J. Bacon. 1969. Distribution and abundance of molluscs in a fresh water environment. Journal of the Minnesota Academy of Science 35(2/3):82-85.

  • New York State Department of Environmental Conservation, Division of Fish, Wildlife, and Marine Resources. 2006. New York State Comprehensive Wildlife Conservation Strategy. Albany, NY: New York State Department of Environmental Conservation.

  • Nickens, T. 1994. Printout of all computerized District of Columbia mollusk specimens at the U.S. National Museum. Printout of 22 December. 4 pp.




  • Smith, D.G. 1985. Recent range expansion of the freshwater mussel Anodonta implicata and its relationship to clupeid fish restoration in the Connecticut River system. Freshwater Invertebrate Biology, 4: 105-108.

  • Spoo, A. 2008. The Pearly Mussels of Pennsylvania. Coachwhip Publications: Landisville, Pennsylvania. 210 pp.

  • Strayer, D. 1983. The effects of surface geology and stream size on freshwater mussel (Bivalvia, Unionidae) distribution in southeastern Michigan, U.S.A. Freshwater Biology 13:253-264.

  • Strayer, D.L. 1999a. Use of flow refuges by unionid mussels in rivers. Journal of the North American Benthological Society 18(4):468-476.

  • Strayer, D.L. 1999b. Effects of alien species on freshwater mollusks in North America. Journal of the North American Benthological Society 18(1): 74-98.

  • Strayer, D.L. and J. Ralley. 1991. The freshwater mussels (Bivalvia: Unionoidea) of the upper Delaware River drainage. American Malacological Bulletin 9(1):21-25.

  • Strayer, D.L. and J. Ralley. 1993. Microhabitat use by an assemblage of stream-dwelling unionaceans (Bivalvia) including two rare species of Alasmidonta. Journal of the North American Benthological Society 12(3):247-258.

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

  • 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 D.R. Smith. 2003. A guide to sampling freshwater mussel populations. American Fisheries Society Monograph 8. American Fisheries Society, Bethesda, Maryland. 103 pp.

  • Strayer, David L. and J. Ralley 1991. The freshwater mussels (Bivalva: Unionidae) of the upper Delaware River drainage. American Malacological Bulletin 9 (1): 21-25.

  • 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. and Kurt J. Jirka. 1997. The Pearly Mussels of New York State. New York State Museum Memoir 26.

  • Strayer, David L. and Lane C. Smith. 1996. Relationships between zebra mussels (Dreissena polymorpha) and Unionid clams during the early stages of the zebra mussel invasion of the Hudson River. Freshwater Biology 36: 771-779.

  • 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.

  • Turgeon, D.D., J.F. Quinn, Jr., A.E. Bogan, E.V. Coan, F.G. Hochberg, W.G. Lyons, P.M. Mikkelsen, R.J. Neves, C.F.E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F.G. Thompson, M. Vecchione, and J.D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland: 526 pp.

  • Van der Schalie, H. 1938a. The naiad fauna of the Huron River in southeastern Michigan. Miscellaneous Publication of the Museum of Zoology, University of Michigan 40:7-78.

  • Watters, G.T. 1992a. Unionids, fishes, and the species-area curve. Journal of Biogeography 19:481-490.

  • Wiles, M. 1975a. The glochidia of certain Unionidae (Mollusca) in Nova Scotia and their fish hosts. Canadian Journal of Zoology 53: 33-41.

  • Williams, J. D., A. E. Bogan, R. S. Butler, K. S. Cummings, J. T. Garner, J. L. Harris, N. A. Johnson, and G. T. Watters. 2017. A revised list of the freshwater mussels (Mollusca: Bivalvia: Unionida) of the United States and Canada. Freshwater Mollusk Biology and Conservation 20:33-58.

  • Williams, J.D., M.L. Warren, Jr., K.S. Cummings, J.L. Harris, and R.J. Neves. 1993b. Conservation status of freshwater mussels of the United States and Canada. Fisheries 18(9): 6-22.

  • Williams, James D.; A.E. Bogan, R.S. Butler, K.S.Cummings, J.T. Garner, J.L. Harris, N.A. Johnson, and G.T. Watters. 2017. A Revised List of the Freshwater Mussels (Mollusca: Bivalvia: Unionida) of the United States and Canada

  • Zanatta, D.T., A. Ngo, and J. Lindell. 2007a. Reassessment of the phylogenetic relationships among Anodonta, Pyganodon, and Utterbackia (Bivalvia: Unionoida) using mutation coding of allozyme data. Proceedings of the Academy of Natural Sciences of Philadelphia 156: 211-216.

References for Watershed Distribution Map
  • Ashton, M. 2009. Recent mussel surveys in the Susquehanna River, below Conowingo Dam, Maryland. Ellipsaria 11(3):12.

  • Athearn, H.D. 1961. Additions to the New Brunswick checklist. Sterkiana 4:33-34.

  • Athearn, H.D. 1963. Some new records of naiades from eastern North America. Sterkiana 9:39.

  • Athearn, H.D. and A.H. Clarke, Jr. 1962. The freshwater mussels of Nova Scotia. National Museum of Canada Bulletin 183:11-41.

  • Bogan, A.E. 2002. Workbook and key to the freshwater bivalves of North Carolina. North Carolina Museum of Natural Sciences: Raleigh, North Carolina. 101 pp.

  • Bogan, A.E. and T. Proch. 1995. Manual of the freshwater bivalves of Maryland. Prepared for a workshop held at Versar, Inc., Columbia, Maryland, 9 March 1995. 68 pp.

  • Clarke, A.H. and A.M. Rick. 1963 [1964]. Supplementary records of Unionacea from Nova Scotia with a discussion of the identity of Anodonta fragilis Lamarck. National Museum of Canada Bulletin, Biological Science Series, 199(72): 15-27.

  • Cordeiro, J. 2003c. Freshwater Mussels of the New York Metropolitan Region and New Jersey. A Guide to Their Identification, Biology and Conservation. American Museum of Natural History, New York. Available online: http://cbc.amnh.org/mussel/.

  • Davis, D.S. 1999. Reports of museum visits and field collections related to studies of the distribution of the freshwater mussels Lampsilis cariosa (Say, 1817) and Leptodea ochracea (Say, 1817), Mollusca, Unionidae in New Brunswick and Nova Scotia in 1999. Unpublished, 23 pp.

  • Fichtel, C. and D.G. Smith. 1995. The freshwater mussels of Vermont. Nongame and Natural Heritage Program, Vermont Fish and Wildlife Department. Technical Report 18. 54 pp.

  • Metcalfe-Smith, J.L. and B. Cudmore-Vokey. 2004. National general status assessment of freshwater mussels (Unionacea). National Water Research Institute / NWRI Contribution No. 04-027. Environment Canada, March 2004. Paginated separately.

  • Nedeau, E.J. and J. Victoria. 2003. A Field Guide to the Freshwater Mussels of Connecticut. Connecticut Department of Environmental Protection, Hartford, Connecticut. 31 pp.

  • Nedeau, E.J., M.A. McCollough, and B.I. Swartz. 2000. The Freshwater Mussels of Maine. Maine Department of Inland Fisheries and Wildlife, Augusta, Maine. 118 pp.

  • Raithel, C.J. and R.H. Hartenstein. 2006. The status of freshwater mussels in Rhode Island. Northeastern Naturalist 13(1):103-116.

  • Sabine, D.L., S. Makepeace, and D.F. McAlpine. 2004. The yellow lampmussel (Lampsilis cariosa) in New Brunswick: a population of significant conservation value. Northeastern Naturalist, 11(4): 407-420.

  • Smith, D.G. 2000a. Keys to the Freshwater Macroinvertebrates of Southern New England. Douglas G. Smith: Sunderland, Massachusetts. 243 pp.

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Note: All species and ecological community data presented in NatureServe Explorer at http://explorer.natureserve.org were updated to be current with NatureServe's central databases as of March 2019.
Note: This report was printed on

Trademark Notice: "NatureServe", NatureServe Explorer, The NatureServe logo, and all other names of NatureServe programs referenced herein are trademarks of NatureServe. Any other product or company names mentioned herein are the trademarks of their respective owners.

Copyright Notice: Copyright © 2019 NatureServe, 2511 Richmond (Jefferson Davis) Highway, Suite 930, Arlington, VA 22202, U.S.A. All Rights Reserved. Each document delivered from this server or web site may contain other proprietary notices and copyright information relating to that document. The following citation should be used in any published materials which reference the web site.

Citation for data on website including State Distribution, Watershed, and Reptile Range maps:
NatureServe. 2019. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org. (Accessed:

Citation for Bird Range Maps of North America:
Ridgely, R.S., T.F. Allnutt, T. Brooks, D.K. McNicol, D.W. Mehlman, B.E. Young, and J.R. Zook. 2003. Digital Distribution Maps of the Birds of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Bird Range Maps of North America:
"Data provided by NatureServe in collaboration with Robert Ridgely, James Zook, The Nature Conservancy - Migratory Bird Program, Conservation International - CABS, World Wildlife Fund - US, and Environment Canada - WILDSPACE."

Citation for Mammal Range Maps of North America:
Patterson, B.D., G. Ceballos, W. Sechrest, M.F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B.E. Young. 2003. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Mammal Range Maps of North America:
"Data provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE."

Citation for Amphibian Range Maps of the Western Hemisphere:
IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Acknowledgement Statement for Amphibian Range Maps of the Western Hemisphere:
"Data developed as part of the Global Amphibian Assessment and provided by IUCN-World Conservation Union, Conservation International and NatureServe."

NOTE: Full metadata for the Bird Range Maps of North America is available at:

Full metadata for the Mammal Range Maps of North America is available at:

Restrictions on Use: Permission to use, copy and distribute documents delivered from this server is hereby granted under the following conditions:
  1. The above copyright notice must appear in all copies;
  2. Any use of the documents available from this server must be for informational purposes only and in no instance for commercial purposes;
  3. Some data may be downloaded to files and altered in format for analytical purposes, however the data should still be referenced using the citation above;
  4. No graphics available from this server can be used, copied or distributed separate from the accompanying text. Any rights not expressly granted herein are reserved by NatureServe. Nothing contained herein shall be construed as conferring by implication, estoppel, or otherwise any license or right under any trademark of NatureServe. No trademark owned by NatureServe may be used in advertising or promotion pertaining to the distribution of documents delivered from this server without specific advance permission from NatureServe. Except as expressly provided above, nothing contained herein shall be construed as conferring any license or right under any NatureServe copyright.
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