Threatened fishes of the world: Plagopterus argentissimus Cope, 1854 (Cyprinidae)

From

Williams, J.E. 1995. Threatened fishes of the world: Plagopterus argentissimus Cope, 1874 (Cyprinidae). Environmental Biology of Fishes. 43: 400.

Conservation status

Endangered (IUCN red list, U.S. Endangered Species Act).

Identification

The woundfin, comprising a monotypic genus, is the most silvery of American cyprinids. D 8-10f A 9-11, V 7, A virtually scaleless, streamlined, torpedo-shaped fish with expansive, falcate fins (max. 100 mm SL). Dorsal fin with anterior-most 2 fin rays modified into elongated, solidified spinose rays, the second fitting into a grove on the first. First few pectoral and pelvic rays also spine-like.

Distribution

Tributaries of the lower Colorado River in western U.S.A. Recent records only from Virgin River downstream of La Verkin, Utah. Miller & Hubbs (1960) listed collections from the 1890's that suggest a broader distribution, including the Salt, Verde, and Gila rivers, and probably the mainstem Colorado River near Yuma, Arizona.

Abundance

Historically, the woundfin was probably the most abundant fish in the Virgin River. Even as recent as 1973 to 1975 surveys, the woundfin was the most common native species, comprising 5,000 of 10,822 native fish collected (Cross 1978). As the normative red shiner, Cyprinella lutrensis, invaded the Virgin River and moved upstream from the 1960's to the present, the range and abundance of woundfin have become increasingly curtailed.

Habitat and Ecology

Woundfin most commonly occur in shallow, moderately-flowing habitats over shifting sand substrates (Cross 1978). They also occur in faster-water habitats (riffles) and less-commonly in deeper pools. Historic riverine habitats of the woundfin are found in arid regions where seasonal and daily flows and water temperatures fluctuate greatly.

Reproduction

Woundfin spawning in the Virgin River begins in April to May and continues through August. Cross (1978) collected young-of-the-year in the Virgin River from early June to mid-August from shallow habitats lateral to the main current.

Threats

The unfortunate history of water management in the Virgin River and its impact on the woundfin is well-described by Deacon (1988). Numerous water diversion projects have been built for agricultural and energy development. The completion of Quail Creek Reservoir in 1985 substantially decreased the abundance and distribution of the woundfin in following years. Changes to flow patterns also facilitated movement of red shiners upstream in the Virgin River. This normative fish largely has replaced the woundfin and has introduced the Asian tapeworm, which now parasitizes many of the remaining woundfin (Heckmann et al 1986).

Conservation Action

Since 1971, numerous studies have been undertaken to determine the ecological requirements of the woundfin. Several transplants have been made in Arizona, including Sycamore Creek, Paria River, and Hassayampa River. No individuals are known to persist at any of the introduction sites although woundfin remained at the Hassayampa site for several years before flooding extirpated that population. Woundfin have been propagated at the Dexter National Fish Hatchery as a possible prelude to further introductions. Efforts to control normative species in the Virgin River largely have been unsuccessful.

Conservation Recommendations

Flow regimes that encourage recovery of the native Virgin River fishes and discourage normative fishes need to be reestablished. A comprehensive program to control the red shiner is needed. Transplant efforts should be reinitiated if the remarkable woundfin is to be saved.

Remarks

Modifications to the Virgin River have negatively impacted the entire native biota. The Virgin roundtail chub, Gila robusta seminuda, is listed as endangered by the U.S. Endangered Species Act, and the Virgin spinedace, Lepidomeda m. mollispinis, is becoming increasingly rare.

References

Cross, J.N. 1978. Contributions to the biology of the woundfin, Plagopterus argentissimus (Pisces: Cyprinidae), an endangered species. Great Basin Naturalist. 38:463-468.

Deacon, J.E. 1988. The endangered woundfin and water management in the Virgin River, Utah, Arizona, and Nevada. Fisheries (Bethesda). 13(l):18-24.

Heckmann, R.A., J.E. Deacon & P.D. Greger. 1986. Parasites of the woundfin minnow, Plagopterus argentissimus, and other endemic fishes from the Virgin River, Utah. Great Basin Naturalist. 46:662-676.

Miller, R.R. & C.L. Hubbs. 1960. The spiny-rayed cyprinid fishes (Plagopterini) of the Colorado River system. Miscellaneous Publications of the Museum Zoology, University of Michigan. 115:1-39.

Preparator

Jack E. Williams, Division of Wildlife and Fisheries, Bureau of Land Management, Department of the Interior, Washington, D.C. 20240 U.S.A.

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