Assessed June 2010 by COSSARO as Threatened

Part 1: COSSARO candidate species at risk evaluation form – June 2010

Wavy-rayed Lampmussel (Lampsilis fasciola)

Current Designations:

NRANK Canada – N1
COSEWIC – Endangered; April 1999; re-evaluated and confirmed October 1999; re-examined and designated Special Concern April 2010.
SARA – Endangered. (Schedule 1; June 2003)
General Status Canada – At Risk (1) (Canadian Endangered Species Conservation Council 2006)
ESA 2007 – Endangered
SRANKS1 (NatureServe 2010)
General Status Ontario – At Risk (1) (Canadian Endangered Species Conservation Council 2006)

Distribution and status outside Ontario:

The species’ range includes the Ohio and Mississippi river systems as far south as the Tennessee River drainage. It is found in the Great Lakes drainage in tributaries of Lake Michigan, lower Lake Huron, Lake St. Clair, and Lake Erie (NatureServe 2010; COSEWIC 2010). The species is listed as S1 in NY, GA, and NC; S1S2 in AL; and S2 in IL, MI, and WV.

Eligibility criteria

Native status

Yes. The species was known historically from the Maitland, Sydenham, Thames, Detroit and Grand Rivers, the western basin of Lake Erie, and from Lake St. Clair (COSEWIC 2010).

Taxonomic distinctness

Yes. The species is well recognized; no subspecies have been identified.

Designatable units

Canadian populations are in the same COSEWIC Freshwater Biogeographic Zone (Great Lakes—Upper St. Lawrence) therefore they do not warrant assessment as separate DUs. However, recent analysis of genetic relatedness (Zanatta et al. 2007) suggests that the populations in each Ontario drainage should be treated as separate management units.

Priority-setting criteria

Recent arrival




Primary criteria (rarity and declines)

  1. Global Rank
    Not in any category. (G5)
  2. Global Decline
    Not in any category. Declines are noted only at the edge of the range in Canada (NatureServe 2010).
  3. Northeastern North America Ranks
    THR. S1, S2, SH, or SX in 5 of 10 jurisdictions (50%), including ON.
  4. Northeastern North America Decline
    Not in any category. Declines are only noted at the edge of the range in Canada (NatureServe 2010).
  5. Ontario Occurrences
    THR. A total of 25 Element Occurrences is listed by NHIC; however only 18 E (verified extant), 4 H (historical), and 3 X (extirpated). The status report identifies 12 locations defined on the basis of the predominant threat and the configuration of sub- watersheds: Ausable River watershed (1); Grand River watershed (3); Maitland River watershed (3), Thames River watershed (4); and Lake St. Clair (1).
  6. Ontario Decline
    SC. There are 18 extant occurrences, and NHIC information suggests that the species is absent from 7 of 25 (28%) of documented Ontario sites. The current status report suggests that Lampsilis fasciola is likely extirpated from the Sydenham River (COSEWIC 2010: 6). However, surveys conducted since the previous COSEWIC assessment confirmed the existence of a large population in the Grand River and smaller, reproducing populations in the Ausable River and St. Clair delta. In addition, large, reproducing populations were identified in the Maitland River (previously unknown) and Thames River (previously thought remnant). Many populations are showing signs of improvement, population estimates have risen, area of occupancy has increased 2-3 fold, and relative abundances have increased (COSEWIC 2010).
  7. Ontario’s Conservation Responsibility
    Not in any category. Global range of the species is thought to be from 200,000 to 2,500,000 km2 (NatureServe 2010). Estimated extent of occurrence (MCP) was estimated as 14,153 km2 in Ontario (COSEWIC 2010); therefore < 10% of the global range is in Ontario.

Secondary criteria (threats and vulnerability)

  1. Population Sustainability
    Not in any category. Populations in the Grand River, Maitland River, and Thames River are all apparently reproducing well. Much smaller populations in the Ausable River and Lake St. Clair delta appear to be reproducing.
  2. Lack of Regulatory Protection for Exploited Wild Populations
    Not in any category. Protection federally under SARA, and the Fisheries Act and under Ontario’s Endangered Species Act, 2007.
  3. Direct Threats
    SC. The main threats are: runoff of sediment, pesticides, fertilizers, and livestock manure associated with changes in agricultural practices since the 1970s; loss or riparian vegetation, damage to streambeds by livestock, and input of pollutants from sewage treatment plants and storm sewers. If zebra mussels became established in reservoirs upstream of areas occupied by Wavy-rayed Lampmussel, this could pose a significant threat.
  4. Specialized Life History or Habitat-use Characteristic
    THR. The species is mainly found in and around riffle areas of clear, hydrologically stable small- to medium-sized streams and rivers of various depths up to 1 m with clean substrates of gravel and sand stabilized with cobble and boulders. As filter feeders, all life stages are exposed to contaminants in water both associated with suspended particles and in sediments. The larval stage (glochidium) of the Wavy-rayed Lampmussel are obligate parasites on Smallmouth Bass (Micropterus dolomieu) and Largemouth Bass (M. salmoides). Based on laboratory experiments, other hosts include Mottled Sculpin (Cottus bairdii) and Brook Stickleback (Culaea inconstans). Potential hosts respond to a specialized lure used to attract suitable hosts and facilitate infestation of the fish with glochidia.

COSSARO criteria met (primary/secondary)

  • Endangered – [0/0]
  • Threatened – [2/1]
  • Special concern – [1/1]

Recommended Status: Threatened


This mussel was formerly widespread in southwestern Ontario where it now persists in only five river systems. They live in clear streams and are filter feeders. Their motile juvenile stage require fish hosts Smallmouth Bass (Micropterus dolomieu), Largemouth Bass (Micropterus salmoides), and perhaps also sculpins and sticklebacks. Some populations show evidence of recovery and there are large populations in three river systems. The area of occupancy has increased since the last status report. There is, however, a methodological problem used to estimate populations. Earlier surveys involved visual searches for the mussels and more recent ones also involved digging. Digging exposes younger animals and more animals so the apparent increase in population could be an artifact of sampling. Direct threats affecting streams and streambeds include contaminated runoff associated with agriculture and sedimentation Zebra Mussels are established downstream in some of these rivers and could pose a significant problem if they spread upstream. This species is Threatened in Ontario.

Information sources

Canadian Endangered Species Conservation Council (CESCC). 2006. Wild Species 2005: The General Status of Species in Canada. [link inactive]. (Accessed: May 18, 2010).

COSEWIC. 2010. COSEWIC 2-month interim updated status report on the Wavy-rayed Lampmussal (Lampsilis fasciola) in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa, Ontario. xiv + 67 p.

NatureServe. 2010. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available (Accessed: May 18, 2010).

Zanatta, D.T., S.J. Fraley, and R.W. Murphy. 2007. Population structure and mantle display polymorphisms in the wavy-rayed lampmussel, Lampsilis fasciola (Bivalvia: Unionidae). Canadian Journal of Zoology 85: 1169-1181.

Appendix 1

Northeastern North America rank, status and decline

CTNot present
DENot present
IANot present
LBNot present
MANot present
MBNot present
MDNot present
MENot present
MNNot present
NBNot present
NFNot present
NHNot present
NJNot present
NSNot present
PENot present
QCNot present
RINot present
VTNot present
WINot present

Occurs as a native species in 10 of 29 northeastern jurisdictions SRANK or equivalent information available for 10 of 10 jurisdictions = 100% S1, S2, SH, or SX in 5 of 10 = 50%

Part 2: Ontario evaluation using COSEWIC criteria

Regional (Ontario) COSEWIC criteria assessment

Criterion A – declining population

N/A; The number of mature individuals is not declining.

Criterion B – small distribution and decline or fluctuation

N/A; Extent of Occurrence = 14,153 km2, and Area of Occupancy = 764 km2 i.e., meets criterion for Threatened. However, the species occurs at > 10 locations, and there is no evidence of severe fragmentation, continuing decline in numbers, or evidence of extreme fluctuations. The status report suggests that continuing decline in quality of habitat is inferred (i.e., water quality), so b(iii) may be applicable.

Criterion C – small population size and decline

N/A; The total number of mature individuals in Ontario is estimated at > 2.7 million [Ausable R.: 33,600; Grand R.: 2.1 million; Maitland R.: 310,000; Thames R.: 325,000; Lake St. Clair delta: 3,300]

Criterion D – very small or restricted

N/A; Area of occupancy 764 km2 (or 426 km2 using 1 x 1 km grid). However, status report indicates Biological AO of 19.4 km2.

Criterion E – quantitative analysis

NA; None have been conducted.

Rescue effect

No. All Canadian populations are isolated from each other and from U.S. populations by large areas of unsuitable habitat. The two hosts, Largemouth and Smallmouth bass, are not capable of movements sufficient to connect these populations.