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Yellow Lampmussel consultation workbook

Information on the Yellow Lampmussel

Yellow Lampmussel

The yellow lampmussel, Lampsilis cariosa, is a freshwater bivalve mollusc. It is oval-shaped and has a glossy surface that varies in color from bright yellow to reddish brown with several fine radiating lines.  The interior of the shell is coloured white to pink, and there are several strong hinge teeth.  Although the yellow lampmussel has been recorded as large as 110mm in length, it is typically smaller than 75 mm.

In Canada, yellow lampmussel is only known to occur above the dam on the Sydney River in Cape Breton, Nova Scotia,and below the Mactaquac dam in the lower Saint John River, New Brunswick, which includes 5 of its large tributaries, and several large lakes.  Evidence suggests that the St. John River system yellow lampmussel population is the larger of the two.

The yellow lampmussel is found in areas with sand and gravel bottoms in fast flowing, riffle areas of large, low gradient rivers, and the shallow waters (less than 6m) of lakes in areas with sandy bottom and low aquatic plant cover.  

The yellow lampmussel requires a host fish (commonly white or yellow perch) for the parasitic portion of its larval development.  Although the actual spawning time is not known, it is assumed from similar species that release of these larvae to their hosts happens from spring to early autumn. The parasitic larvae remain on the host fish for roughly 43 to 80 days, and then drop to settle on the substrate below.  Within 5 years, yellow lampmussels reach sexual maturity.

Muskrats are the only known predator of this filter feeder, and they seem to prey only on adults.

COSEWIC assessment

COSEWIC provides the following rationale for designating the yellow lampmussel as special concern:

Populations quite large and apparently stable in Canada but found only in Sydney River, Nova Scotia and Saint John River watershed, New Brunswick. Threats are currently very limited but there are long-term concerns related to the potential for introduction of zebra mussels into the Saint John River, and maintaining habitat quality of the sole population in the Sydney River.

Threats to Yellow Lampmussel

The breach of the dam on the Sydney River would result in loss of habitat due to both a reduction in shoreline and an influx of salt water upstream of the dam. Siltation and pollution from suburban and recreational activities could also cause habitat damage.  Yellow lampmussel populations could also suffer if areas of Sydney River were treated with molluscicides to control “swimmer’s itch”.

There appear to be few threats to the lower Saint John River population although encroaching riparian development in some areas is a concern.  Low summer water levels may cause habitat loss due to elevated temperatures and increased saltwater intrusion.  The potential introduction and spread of zebra mussels in the Saint John River is another threat to the yellow lampmussel.

Protecting Yellow Lampmussel

The Federal Fisheries Act, intended to protect fish harvested for human consumption and their habitat, protects yellow lampmussel habitat and disturbance to the mussels themselves.

Under the Maritime Provinces Fishery Regulations, it is illegal to collect or harvest yellow lampmussels without a license.  No licenses have ever been issued to harvest yellow lampmussels in Nova Scotia or New Brunswick.

Potential Impacts on Stakeholders

Once listed in the Species at Risk Act, activities that affect the yellow lampmussel or its habitat may receive more scrutiny. A Management Plan will be developed and there is a range of management measures that may be implemented to conserve the yellow lampmussel. These measures may lead to a variety of impacts on stakeholders. The following list is not exhaustive. Please use this consultation as an opportunity to list omissions.

Aboriginal peoples

Management strategies that affect the activities of aboriginal people taking place in areas inhabited by yellow lampmussel may be considered.

Land owners

Development restrictions and other planning and management measures may be imposed for areas where yellow lamp mussels are found.

Recreational users

Restrictions and management measures may be imposed to prevent the introduction and spread of zebra mussels.  Restrictions on the use of molluscicides to improve swimming areas may be implemented.

Research activity

Those wishing to carry out research on the yellow lampmussel or in areas of their habitat may be required to comply with stricter guidelines.  This may limit the types and/or durations of research permitted on yellow lampmussel and may lengthen the preparation time required for planning research projects.


COSEWIC 2004. COSEWIC status report on the Yellow Lampmussel, Lampsilis cariosacommittee on the Status of endangered Wildlife in Canada. Ottawa. Vi + 44 pp