The Waccamaw silverside (''Menidia extensa'') is a rare species of fish in the family Atherinopsidae. It is a federally listed threatened species of the United States.

Description

This is a small (growing to about 2.5 inches), slim, almost transparent fish with a silvery stripe along each side. Its body is laterally compressed, the eyes are large, and the jaw is sharply angled upward. This fish spawns from April through June, but spawning reaches its peak when water temperatures are between 68 and 72 Fahrenheit. Fully developed larvae form small isolated schools by early May. No parental care of the young has been noted. The silversides reach sexual maturity by the following spring, spawn, and then shortly thereafter most of the adults die off. A few may survive a second winter.

Range and population level

Known only from

Lake Waccamaw Lake Waccamaw is a fresh water lake located in Columbus County, North Carolina, Columbus County in North Carolina. It is the largest of the natural Carolina Bay lakes. Although bay trees (''Magnolia virginiana L.'', ''Gordonia lasianthus Elli ...

and the upper

Waccamaw River The Waccamaw River is a river, approximately 140 miles (225 km) long, in southeastern North Carolina and eastern South Carolina in the United States. It drains an area of approximately 1,110 square miles (2886 km2) in the coastal pla ...

Columbus County, North Carolina Columbus County is a county located in the U.S. state of North Carolina. Its county seat is Whiteville. At the 2020 census, the population was 50,623. History Early history The area comprising Columbus County was originally inhabited by the ...

, 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 North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

and is administered by the North Carolina Department of Natural Resources and Community Development's Division of Parks and Recreation. The species' population is estimated to be in the millions.

Habitat

Lake Waccamaw is a natural lake with an approximate surface area of and an average depth of . 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 calcareous 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.

Biology

This species is normally found in large schools close to the surface in open water where the substrate is dark and sandy. The population is able to tolerate heavy predation and they are frequently observed skipping over the water surface, a behavior which is apparently related to predator avoidance.

References

Waccamaw silverside Endemic fish of the United States Natural history of North Carolina Fish described in 1946 Endemic fauna of North Carolina {{Atheriniformes-stub