June Sucker

Chasmistes liorus

Description

Named for its peak spawning time, the June sucker is a small fish, attaining a mature length of only about 1.25 in (3 cm). It has often been confused with the Utah sucker but can be readily distinguished by its underhanging mouth, relatively smooth, divided lips, a broad skull, and greater numbers of gill rakers.

The species as it exists today, differs slightly from specimens collected in the 1800s. It is hypothesized that the June and Utah suckers interbred during a prolonged drought in the 1930s when their populations were seriously stressed. The name Chasmistes liorus liorus was assigned to specimens collected in the 1800s, and C. l. mictus to those collected after 1939. To avoid confusion, the June sucker is now being classified as a full species—C. liorus. It has retained its distinct characteristics and is not actively interbreeding with any other species today.

Behavior

In spite of its former abundance, biological data for this bottom-feeding species is mostly wanting. The adult June sucker ascends the Provo River during the second or third week of June and completes spawning within five to eight days.

Habitat

The June sucker thrives in the shallow, saline waters of Utah Lake, Utah, a 94,000-acre (38,000-hectare) remnant of ancient Lake Bonneville. The lake's average depth is 10 ft (3 m) and maximum depth only about 14 ft (4 m). Its turbid waters are slightly saline. The June sucker spawns in the Provo River, the largest tributary of the lake, with limited activity in the Spanish Fork River.

Distribution

The species historically occupied the Spanish Fork River and possibly other tributaries of Utah Lake. Millions of June suckers were reported in Utah Lake in the late 1800s and composed an important part of the commercial fish harvest. During the early 1930s, hundreds of tons of suckers were lost when the lake was nearly drained because the water was needed for irrigation. In 1951, the June sucker was considered the second most abundant species in Utah Lake; by 1959 it was considered fourth in abundance; by 1970 it ranked seventh.

The June sucker is restricted to Utah Lake and the lower portion of the Provo River (Utah County). Spawning is restricted because the fish can travel only about 5 mi (8 km) upstream to where a diversion barrier blocks further movement.

Though less than a decade ago, fewer than 1,000 adult June suckers were known to survive (and of those, none were younger than 15 years of age), recent recovery efforts have dramatically increased the population numbers. A cooperative propagation effort by the Bureau of Reclamation, Central Utah Water Conservancy District, Provo water users, Utah Division of Wildlife Resources and the U.S. Fish and Wildlife Service, has resulted in the production of 6,000 fry. The Utah Correction Institute has been converted to a June sucker rearing facility and more than 400 fish are being raised there with excellent results.

Threats

The species decline is believed to result from several events, including significant alterations in the species' lake and river habitat. Dams and water diversions constructed on the rivers flowing into Utah Lake have reduced water flows, altered flow regimes within the river, and dramatically increased fluctuations in the level of the lake. Increased pollution and nutrient inflow, caused by urban development surrounding Utah Lake, have degraded water quality within the lake and destroyed shoreline vegetation. In addition, over 20 non-native fishes have been introduced into Utah Lake, including white bass, largemouth bass, walleye, black bullhead, channel catfish, and carp that compete with the June sucker for food and prey upon juvenile June suckers. The combination of these factors has apparently reduced the survival of young fish to the point that most fish found today, other than the newly introduced fry, are between 20 and 43 years old.

The Central Utah Water Conservancy District, the Provo River Water Users Association, and several other groups questioned the efficacy of listing the June sucker as Endangered. These groups feared that listing would interfere with the Central Utah Project, an ongoing, federally funded, construction project designed to supply more water for irrigation and human use. The Governor of Utah supported the listing. Subsequently, the Fish and Wildlife Service (FWS) determined that existing plans to dike Goshen and Provo bays and to create further upstream reservoirs would result in habitat losses.

Conservation and Recovery

The state of Utah is currently implementing sections of a June Sucker Management Plan to ensure the survival of the species and attempt to overcome the impacts of predation. The Bonneville Chapter of the American Fisheries Society has been involved in the recovery effort, and the Utah Correction Institute has been converted to a June sucker rearing facility, where more than 400 fish are being raised.

In 1995, a draft Recovery Plan was announced by the FWS, with the goal of increasing reproduction and survival of young June suckers to increase population numbers and ensure the species' survival. Recovery actions recommended to facilitate recovery of the species include identification of habitat requirements, coordination of efforts to restore required water flows and other appropriate habitat conditions, and identification and amelioration of the effects of predation by non-native fish species.

Contact

U.S. Fish and Wildlife Service
Division of Endangered Species
Denver Federal Center
P.O. Box 25486
Denver, Colorado 80225
http://www.r6.fws.gov/

References

Bureau of Reclamation. 1979. "Central Utah Project, Bonneville Unit, Municipal and Industrial System, Final Environmental Statement, Volume I." Bureau of Reclamation, Salt Lake City.

Radant, R. D. 1983. "Fisheries Impact Analysis of Utah Lake Diking Plan, Irrigation and Drainage System, Bonneville Unit, Central Utah Project." Utah Division of Wildlife Resources with the Bureau of Reclamation, Salt Lake City.

Radant, R. D., and T. J. Hickman. 1984. "Status of the June Sucker." In Proceedings of the Desert Fishes Council 15th Annual Symposium. Bishop, California.