Shortnose Sucker

Chasmistes brevirostris

Description

The shortnose sucker, Chasmistes brevirostris, can grow as long as 25 in (64 cm) at maturity. It is distinguished from other members of the genus Chasmistes by its terminal, oblique mouth, which has no (or only vestigal) papillae on the lips.

Behavior

In the spring, the shortnose sucker moves from its lake habitat to stream headwaters to spawn. Suckers are adapted to feed by suction, siphoning and filtering food from lake bottoms. The species is long-lived; several fish have been netted that were over 40 years old. Most shortnose suckers reach sexual maturity at age six or seven. The shortnose sucker was a food fish for the Klamath Indians for thousands of years.

Habitat

The shortnose sucker is lake-dwelling and prefers the freshwater reservoirs of mountainous, southeastern Oregon. It requires free-flowing streams for spawning. Shoreline river and lake habitats with vegetative structure are known to be important during larval and juvenile rearing.

Distribution

The shortnose sucker was once found throughout the Klamath Basin of south-central Oregon and north-central California. A shortnose sucker population in Lake of the Woods, Oregon, was lost during a program to eradicate carp and perch in 1952. A population in the Clear Lake Reservoir shows distinct evidence of interbreeding with the Klamath largescale sucker, creating a genetically impure hybrid. Specimens collected from Copco Reservoir in 1962, 1978, and 1979 were found to have hybridized with the Klamath smallscale sucker.

The current distribution of the shortnose sucker includes Upper Klamath Lake and its tributaries, Klamath River downstream to Iron Gate Reservoir, Clear Lake Reservoir and its tributaries, Gerber Reservoir and its tributaries, the Lost River, and Tule Lake. Gerber Reservoir represents the only habitat with a shortnose sucker population that does not also host the equally endangered Lost River sucker. In the Upper Klamath Lake water-shed, shortnose sucker spawning runs are primarily limited to the Sprague and Williamson Rivers, although spawning runs may also occur in the Wood River and in Crooked Creek. Shortnose sucker spawning has been documented in the Clear Lake watershed.

Drastic population declines in the 1980s caused the species to be placed on the state's protected species list and to be listed as Endangered by the FWS, along with the Lost River sucker (Deltistes luxatus ), another rare Klamath Basin fish. Populations for both sucker species have declined by some 95% due to sport-fishing, water quality degradation, algae-induced fish-kills, and the combined effects of river damming, instream flow diversions, draining of marshes, dredging of Upper Klamath lake, and other water manipulations.

The dramatic decline of the mid-1980s was documented beginning in 1984, when a survey estimated the number of spawning shortnose suckers swimming out of Upper Klamath Lake at 2,650 individuals. Surveys in 1985 and 1986 found significantly fewer fish. The catch of shortnose suckers declined 34% between the 1984 and 1985 spawning runs. In 1986, the spawning run declined 74% compared to 1985. No significant recruitment of young into the population has been documented in the last two decades.

Threats

Through the 1970s, runs of suckers moving from Upper Klamath Lake to spawning areas in the Williamson and Sprague Rivers were great enough to support a popular sport fishery. Sharp declines were noted in 1984-1986 and the sport fishery was closed in 1987.

The primary cause of this decline was the overall reshaping of the Klamath Basin through dams, water diversion, dredging, and the elimination of marshes. Once, the Upper Klamath Basin had over 350,000 acres (141,641 hectares) of wetlands, with extensive riparian corridors, and functional floodplains that handled storm runoff, dampened sharp peaks in the hydrograph, reduced erosion forces, removed organic and inorganic nutrients, and improved water quality. Currently, less than 75,000 acres (30,352 hectares) of wetlands remain in the Basin, and the loss of these wetlands has had large scale detrimental effects to the quality and quantity of suitable sucker habitat.

Although reservoirs provide suitable habitat for the shortnose sucker, the dams block the fish's spawning runs. Surviving suckers are almost all older fish. There has been no significant addition of young to the population since the Sprague River Dam was constructed at Chiloquin, Oregon, in 1970, cutting off 85% of the spawning range.

Fish ladders, installed at the Sprague River Dam, have been little or no help. Although the shortnose sucker is a strong swimmer, it cannot leap the rungs of the ladders. Damming has also facilitated hybridization with other sucker species in the dam's tailwaters. Non-native fishes have also contributed to shortnose sucker decline through hybridization and competition.

Conservation and Recovery

The Klamath Indian Tribe and local biologists alerted the Oregon Fish and Wildlife Commission to the critical situation of both the shortnose sucker and the Lost River sucker. If these species are to be recovered, these groups and the Fish and Wild-life Service must continue to cooperate in efforts to restore a breeding range for these endangered fish. The National Wildlife Refuge System (FWS) released the Sucker Critical Habitat Proposal in 1996 to preserve and restore the Klamath Basin habitat critical to both shortnose and Lost River suckers.

Contact

U.S. Fish and Wildlife Service
Division of Endangered Species
911 N.E. 11th Ave.
Portland, Oregon 97232
http://pacific.fws.gov/

References

Coots, M. 1965. "Occurrences of the Lost River Sucker, Deltistes luxatus (Cope), and Shortnose Sucker, Chasmistes brevirostris (Cope) in Northern California." California Fish and Game 51:68-73.

Miller, R. R., and G. R. Smith. 1981. "Distribution and Evolution of Chasmistes (Pisces: Catostomidae) in Western North America." Occasional Papers of the Museum of Zoology, University of Michigan 696:1-46.

Moyle, P. B. 1978. Inland Fishes of California. University of California Press, Berkeley.

U.S. Fish and Wildlife Service. 1988. "Determination of Endangered Status for the Lost River Sucker and Shortnose Sucker." Federal Register 53(137): 27130-27133.

U.S. Fish and Wildlife Service. 1993. "Recovery Plan for the Lost River Sucker and Shortnose Sucker." U.S. Fish and Wildlife Service, Portland.

White, R. and K. Stubbs, 1996. "The Sucker Critical Habitat Proposal." U.S. Fish and Wildlife Service, Portland.