Historical Status and Current Trends

Early records indicate that Lost River suckers were once widespread and abundant in the upper Klamath Basin of Oregon and California. This area historically contained over 350,000 acres of wetlands and floodplains. These wetlands protected sucker habitat by controlling erosion, recycling organic and inorganic nutrients, and maintaining water quality. Because suckers were historically very abundant, they were a major food source for Native Americans and local settlers in the late 1800s. Canneries were established along the Lost River to process suckers into oil, dried fish, and other products. However, agricultural development and associated water and land use changes in the basin have contributed to the significant loss of wetland habitat and a significant decline in sucker populations. Although overharvesting and pollution may have played a role in the species decline, it is believed that the combined effects of the construction of dams, the draining or dredging of lakes, and other alterations of natural stream flow have reduced the reproductive success of Lost River suckers by as much as 95 percent through the degradation of suitable breeding habitat. At the time the Lost River sucker was listed as endangered, it was noted that there had been no significant addition of young into the population in 18 years.

Currently, the Lost River sucker occupies only a fraction of its former range and is restricted to a few areas in the Upper Klamath Basin, such as the drainages of Upper Klamath Lake, Tule Lake, and Clear Lake. Poor water quality, reduced suitable habitat for all sizes and ages, and the impacts of non-native fishes continue to threaten remaining Lost River sucker populations.

Description and Life History

Locally known as mullet, the Lost River sucker is a large, long-lived sucker that can reach 43 years of age. It has unique triangular-shaped gill structures which are used to strain a diet of detritus (decomposing organic matter), zooplankton (tiny floating aquatic animals), algae, and aquatic insects from the water. Lost River suckers typically begin to reproduce at nine years, when they first participate in spawning migration. Adult suckers migrate from the quiet waters of lakes into fast moving streams from March through May in order to spawn. They may also spawn in lakeshore springs from February to mid-April when the water temperature is a constant 15 C (60 F). Thousands of eggs (from 44,000 for smaller fish to 218,000 for larger suckers) are typically laid near the stream bottom in areas where gravel or cobble is available. Once the eggs hatch, the larval fish begin their migration back to calmer waters. They generally migrate at night and stay in shallow, shoreline areas and in aquatic vegetation during the day. Upon their return to the lake, larvae may be preyed upon by largemouth bass, yellow perch, or other non-native predatory fish, and larger juveniles may compete for food with non-native fishes such as fathead minnows, yellow perch, and others.

Habitat

The Lost River sucker dwells in the deeper water of lakes and spawns in springs or tributary streams upstream of the home lake. Areas with gravel or close-set stone ("cobble") bottoms at springs or in moderate to fast-flowing springs are preferred for spawning. In addition, the spawning streams have a fairly shallow shoreline with abundant aquatic vegetation; these areas provide a safe haven for the young larvae during their journey back downstream to their home lakes or the deep, quiet waters of rivers.

Reasons for Decline

Although a number of factors have contributed to the decline of the Lost River sucker, habitat degradation is considered the primary cause. Streams, rivers, and lakes have been modified by channelization and dams. Grazing in the riparian zone has eliminated streambank vegetation, and has added nutrients and sediment to river systems. Eggs and larvae, for example, suffocate when the water is cloudy, or dry out or get eaten by other fish when they are not protected by aquatic vegetation. Loss of streambank vegetation due to overgrazing, logging activities, agricultural practices, and road construction has also led to increases in stream temperatures, high levels of nutrients (which encourages the buildup of excess algae and bacteria), and serious erosion and sedimentation problems in streams. Such water quality problems have reduced the availability of suitable Lost River sucker habitat and have resulted in major fish mortality. Entire age classes of young suckers are routinely lost due to poor water quality conditions. As a result, few young suckers survive to sexual maturity, and therefore, do not increase the population size. Other factors affecting the decline of the Lost River sucker include previous overharvesting, chemical pollution from pesticides, herbicides, and forestry practices, and predation and competition from native and non-native fishes such as largemouth bass, blue chub, yellow perch, fathead minnows, and rainbow trout.

Conservation Measures

Conservation efforts for the Lost River sucker focus on the re-establishment of a more naturally functioning ecosystem in the Klamath Basin. Fencing portions of streams to reduce cattle-caused erosion, replanting streambanks with native vegetation, improving forestry and agricultural practices, and assuring adequate water levels in reservoirs will contribute to the recovery of this species. Through coordination of the actions of land use agencies and private landowners, further degradation of sucker habitat can be avoided and steps can be taken to improve current conditions. By minimizing the impacts of future modifications to spawning habitat and restoring waters to a more natural state, recovery of Lost River sucker populations is possible in the Klamath Basin.

References and Links

U.S. Fish and Wildlife Service. 1988. Determination of Endangered Status for the Shortnose Sucker and Lost River Sucker. FR 53:27130-27134.

U.S. Fish and Wildlife Service. 1993. Shortnose Sucker (Chasinistes brevirostris) and Lost River (Deltistes luxatus) Sucker Recovery Plan. Portland, Oregon 108pp.