|Listed||October 13, 1970|
|Description||Silvery minnow with a flat head and sharp, dorsal spine.|
|Habitat||Shallow water near riffles.|
|Reproduction||Spawns in May.|
|Threats||Dam construction, water diversion.|
The silvery blue woundfin, Plagopterus argentissimus, which grows to a length of about 3 in (7.5 cm), has a flattened head, giving it a torpedo shape. Its sharp dorsal spine is responsible for its name. It is scaleless, except for small plates of bone in the leathery skin, and has barbels (sensors) on its lips like a catfish.
The woundfin is a member of the unique tribe, Plagopterini, which is endemic to the lower basin of the Colorado River and its ancestral tributary, the White River. This tribe has only three genera, two of which consist of a single species.
The woundfin's reproductive cycle is probably triggered by increasing temperature, lengthening daylight, and declining spring runoff in late May. Spawning females leave pools to join groups of males in swifter flowing water over cobble or gravel beds. After spawning, the females return to pools.
Woundfins are omnivorous and eat algae, detritus, seeds, insects, and larvae.
Adult and juvenile woundfin inhabit runs and quiet waters adjacent to riffles with sand and sand/gravel substrates. Adults are generally found in habitats with water depths between 6 in and 1.4 ft (15 and 43 cm) and with velocities between 0.8 and 1.6 ft/second (24 and 49 cm/second). Juveniles select areas with slower and deeper water, while fry are found in backwaters and stream margins which are often associated with growths of filamentous algae. Spawning areas have a swifter flow and sand or mud substrates.
Based on early records, the original range of the woundfin extended from near the junction of the Salt and Verde Rivers at Tempe, Arizona, to the mouth of the Gila River at Yuma, Arizona. Woundfin were also found in the mainstem Colorado River from Yuma upstream to the Virgin River in Nevada, Arizona, and Utah and into La Verkin Creek, a tributary of the Virgin River in Utah. However, there is reason to believe that the woundfin occurred further upstream in the Verde, Salt, and Gila Rivers in Arizona.
Except for the mainstem of the Virgin River, woundfin were extirpated from most of their historical range. Woundfin presently range from Pah Tempe Springs (also called La Verkin Springs) on the mainstem of the Virgin River and the lower portion of La Verkin Creek in Utah, downstream to Lake Mead. A single specimen was taken from the middle Muddy (Moapa) River, Clark County, Nevada, in the late 1960s and since that time no additional specimens have been collected. Population numbers remain unclear.
The woundfin declined when the flow of the Virgin River was altered by dams, reservoirs, canals, and other diversion structures. Many spawning streams have been depleted by the diversion of water for irrigation and municipal uses. Remaining populations are threatened by the introduction of non-native fish, notably the red shiner (Notropis lutrensis ), which has completely replaced the woundfin in some areas. In 1988, Fish and Wildlife Service regional personnel, in cooperation with the Utah Division of Wildlife Resources and the Washington County Water Conservancy District, eliminated red shiners from a 21-mi (34-km) portion of the upper Virgin River.
Conservation and Recovery
During the 1970s the state of Arizona attempted to transplant the woundfin to a number of rivers and creeks. These initial transplants, however, appear to have been unsuccessful. The Endangered Species Act allows "experimental populations" to be established through transplantation, and plans for reintroducing the woundfin into its original range and other suitable habitat are now being developed.
In 1995, the FWS proposed the designation of 94.8 mi (151.7 km) of critical habitat for the woundfin (approximately 13.5% of its historical range); the same proposal also recommended the designation of critical habitat for two rare fishes that share its habitat, the endangered Virgin River chub Gila semi-nuda and the threatened Virgin spinedace (Lepidomeda mollispinis mollispinis ). The majority of the land to be designated as critical habitat is under Federal or private ownership. The proposed critical habitat designation incorporates portions of the mainstem Virgin River and its tributaries, including the 100-year floodplain.
U.S. Fish and Wildlife Service
Division of Endangered Species and Habitat Conservation
2105 Osuna Road N.E.
Albuquerque, New Mexico 87113-1001
Telephone: (505) 346-2525
E-mail: [email protected]
U.S. Fish and Wildlife Service
Upper Colorado River Endangered Fish Recovery
Denver Federal Center
P.O Box 25486
Lake Plaza North
134 Union Boulevard
Denver, Colorado 80228-1807
Telephone: (303) 236-2985
Fax: (303) 236-5262
Deacon, J. E., and W. L. Minckley. 1973. "A Review of Information on the Woundfin, Plagopterus argentissimus Cope (Pisces: Cyprinidae): Progress Report on Population Dispersion and Community Structure of Fishes of the Virgin River System." U.S. Fish and Wildlife Service, Salt Lake City.
U.S. Fish and Wildlife Service. 1985. "Recovery Plan for Woundfin, Plagopterus argentissimus Cope." U.S. Fish and Wildlife Service, Albuquerque.