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Photo Courtesy of Utah Division of Wildlife Resources
Woundfin
Plagopterus argentissimus
NatureServe conservation status
Global (G-rank): G1
State (S-rank): S1
External links
General information
The historic range of the woundfin, Plagopterus argentissimus, included the lower Colorado and Gila River drainages of Utah, Arizona, and Nevada. Unfortunately, flow regulation, dewatering, and the introductions of nonnative fishes have negatively impacted the woundfin, and the species is now restricted to the Virgin River system. Because of the reduction in woundfin numbers and distribution, the species is Federally listed as endangered.
The woundfin is a small (about two inches in length) minnow usually found in the main channel of swift, turbid, warm streams over sand substrate. Woundfin diets are quite varied, consisting of insects, insect larvae, other invertebrates, algae, and detritus. The species spawns during the spring in swift shallow water over gravel substrate. Eggs are fertilized in the water and then fall to the bottom; no parental care is given to the eggs or young.
Species range
This species occurs in Utah only in the Virgin River system in Washington County.
Migration
Appears to undertake relatively long migrations within present habitat (Lee et al. 1980).
Habitat
Lee et al. (1980) stated: "Occupies main channel of seasonally swift highly turbid, and extremely warm streams, with sandy, constantly shifting bottoms." The Virgin River fishes recovery plan (U. S. Fish and Wildlife Service 1994) summarized habitat findings: "Woundfin adults and juveniles are most often collected from runs and quiet waters adjacent to riffles. Juveniles use habitats which are generally slower and deeper than those characteristic of adults. Woundfin larvae are collected in backwaters or slow-velocity habitat along stream margins, often associated with dense growths of filamentous algae."
Food habits
Apparently feeds on aquatic insects, detritus and algae. Near Mesquite, Nevada, fed primarily on ceratopogonid larvae in February, mayflies in June, chironomids and ceratopogonids in December; near Beaver Dam Wash, fed primarily on chironomid larvae and organic debris in February, TAMARIX seeds, simuliid larvae, organic debris, and mayflies in June, chironomid larvae, organic debris, and SPIROGYRA in September, and ceratopongonids, simuliid pupae, chironomid larvae, and organic debris in December (Greger and Deacon 1988).
Ecology
Life span: apparently seldom, if ever, more than 4 years. Found in association with GILA ROBUSTA SEMINUDA.
Reproductive characteristics
Reproductive cycle probably is triggered by increasing temperature and declining spring runoff (Matthews and Moseley 1990). Spawning begins in April-May and continues into August (Cross 1978). In captivity, most spawn the second spring after hatching; most survive two reproductive seasons (see Minckley and Deacon 1991).
Threats or limiting factors
Threats to this species in Utah include flow alterations (e.g., dewatering for agricultural, commercial, and residential development), pollution (from sewage and agricultural run-off), introduced predators (game fishes and turtles), introduced parasites (see Heckman et al. 1987), and introduced competitors (bait fishes) (Deacon 1988).
References
- Biotics Database. 2005. Utah Division of Wildlife Resources, NatureServe, and the network of Natural Heritage Programs and Conservation Data Centers.
- Sigler, W. F. and J. W. Sigler. 1996. Fishes of Utah[:] a natural history. University of Utah Press. Salt Lake City. 375 pp.
