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Waccamaw silverside

Menidia extensa

While population size is difficult to determine, this species continues to be commonly found in schools near the surface throughout Lake Waccamaw. It remains vulnerable to threats to water quality and habitat degradation from human-made land-use activities, drought, physical constraints of its habitat, and natural and introduced predators.

Appearance

The Waccamaw silverside, also known as skipjack or glass minnow, is a small (growing to about 2.5 inches), slim, almost transparent fish with a silver lateral stripe along each side. Its body is laterally compressed, the eyes are large, and the jaw is sharply angled upward. There are two widely separated dorsal fins; the first has thin spines. It may often be seen jumping out of the water.

An outstretched hand with six small fishes with bright, iridescent sides
Waccamaw silversides. Photo by NCWRC.

Habitat

Lake Waccamaw is a natural lake with an approximate surface area of 8,934 acres and an average depth of 7.5 feet. Although it is fed by acidic swamp streams, the lake has a virtually neutral composition. This neutral condition, unusual among North Carolina’s coastal plain lakes, is believed to be caused by the buffering effect of the chalky Waccamaw Limestone formation, which underlies the lake and is exposed on the north shore. The Waccamaw silverside inhabits open water throughout the lake, where schools are commonly found near the surface over shallow, dark-bottomed areas.

Diet

This fish is a surface-feeder and travels in schools. Food sources include zooplankton, particularly microcrustaceans. Silversides forage in areas of shallow, high quality clear, open water over clean, dark sand substrate with no vegetation.

Current range

Known only in Lake Waccamaw and the upper Waccamaw River in Columbus County, North Carolina, the silverside is found in the upper Waccamaw River only during periods of high water and is not a permanent resident. Lake Waccamaw (not to be confused with the town of Lake Waccamaw) is the property of the state of North Carolina and is administered by the North Carolina Department of Environment and Natural Resources’s Division of Parks and Recreation. Lake Waccamaw, is the third largest natural lake in North Carolina (after Lake Mattamuskeet and Lake Phelps). The lake is shallow for its size, with a maximum depth of 11 feet and an average depth of five feet. The Waccamaw silverside population is estimated to be in the millions.

Conservation challenges

Runoff and siltation from nearby logging practices, land use changes such as stream channelization and bridge/road construction, and watershed development are the top threats to the Waccamaw silverside. Water quality issues (including increased temperature and nutrient enrichment) from pesticide/herbicide use and wastewater discharges are also prevalent threats. Because the Waccamaw silverside has an annual life cycle, it is susceptible to rapid extinction given reproductive failure for even a single year. Additionally, the recent invasion of the lake by the brook silverside, is of concern, as well as the potential adverse effects from hydrilla in the Lake. While this species is prey for larger fish, no signs of over-predation or disease have been observed in this species.

Recovery plan

Download the 1993 recovery plan.

Partnerships, research and projects

The Service works with other organizations to protect and maintain a self-sustaining population of Waccamaw silverside in Lake Waccamaw and to protect its habitat from present and foreseeable threats.

A natural area preserve at the northern portion of Lake Waccamaw is beneficial for water quality and ensures protection of the species.

The Service works with appropriate federal and state agencies to identify actions that could negatively affect the species and incorporate protective measures into such actions

  • Permits for wetland alterations (Section 404 of the Clean Water Act) have the potential to adversely impact wetlands, headwaters, and streams that flow into Lake Waccamaw and wetlands along the lakeshore.

How you can help

  • Learn about the Waccamaw silverside’s needs and threats, including hydrilla and other invasive species.
  • Support and participate in research and voluntary conservation activities at Lake Waccamaw.

Subject matter experts

Designated critical habitat

Check out a map of critical habitat for the Waccamaw silverside in Southern North Carolina just West of Wilmington.

Federal Register notices

The following Federal Register documents were automatically gathered by searching the Federal Register Official API with this species’ scientific name ordered by relevance. You can conduct your own search on the Federal Register website.

  • We're sorry but an error occurred. Visit the Federal Register to conduct your own search.

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