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Shortnose sucker

Shortnose sucker.  Photo credit: Ron Larson/USFWS

Scientific name: Chasmistes brevirostris 

Status:Endangered

Critical Habitat: Designated

Listing Activity: The shortnose sucker was federally listed as endangered in 1988 and critical habitat was designated December 11, 2012. A recovery plan was published in 1993 and was revised in 2013.  A species status assessment and a new five-year status review was conducted and finalized in 2019.

  • Historical Status and Current Trends

    Early records indicate that shortnose suckers were once widespread and abundant in the upper Klamath Basin of Oregon and California. Currently, greatly reduced numbers of shortnose sucker occupy few waterbodies in the upper Klamath Basin: Upper Klamath Lake, Tule Lake Sump 1A, Gerber Reservoir, Lake Ewauna, and Clear Lake Reservoir. The species apparently recruited a substantial number of juveniles to the adult population in Upper Klamath Lake during the late 1990’s, but since 2001, the abundance of this population has decreased by nearly 85 percent (Hewitt et al 2018). Long-term monitoring indicates that most adults in the Upper Klamath Lake hatched in 1991, well beyond the average expected life span of 12 years. The remaining populations appear to be somewhat more stable, but possess relatively low abundance and/or high levels of hybridization with the Klamath largescale sucker (Catostomus snyderi; Hayes and Hewitt 2012; GERBER Report; Downing 2016, Markle 2006).

    Description and Life History

    Their large heads with oblique, terminal mouths with thin but fleshy, deeply-notched lower lips distinguish Shortnose suckers. They are dark on their back and sides and silvery or white on the belly. The shortnose sucker can live up to 33 years, but the average life span is closer to 12. Adults are usually less than 50 centimeters (20 inches) in length. The diet consists of detritus (decomposing organic matter), zooplankton (tiny floating aquatic animals), algae, and aquatic insects. Shortnose suckers reach sexual maturity around four to six years. Each female can produce between approximately 20,000 to 70,000 eggs annually (Perkins et al. 2000).

    Habitat

    Adult shortnose sucker inhabit deeper water of lakes and reservoirs, and spawn tributary rivers of their home lake.  Adults migrate from the lakes into rivers beginning in March through May in order to spawn.  Spawners broadcast and fertilize eggs over gravel or cobble bottoms. Once the larvae hatch, they quickly move downstream to inhabit shoreline and wetlands areas around lakes. Shoreline vegetation in both lake and river habitats is important for the rearing of larval and juvenile suckers.

    Reasons for Decline

    Although a number of factors have contributed to the decline of the shortnose sucker, habitat degradation is the primary cause. The upper Klamath Basin historically contained over 350,000 acres of wetlands, which provided essential rearing habitats and promoted healthy water quality. Water and land use changes associated with agricultural development contributed to substantial wetland loss. The resulting reduction and degradation of shortnose sucker habitat triggered significant population decline. Although over-harvesting may have played a role in the species’ decline, construction of dams, the draining or dredging of lakes, and other alterations to natural hydrology are the primary sources of reduced population viability. Poor water quality and reduced and degraded habitat continue to threaten remaining shortnose sucker populations. Channelization and dams have modified the hydrology and structure of streams, rivers, and lakes. Grazing in the riparian zone eliminated streambank vegetation, and promoted nutrient mobilization and sediment into river systems. Loss of streambank vegetation due to overgrazing, logging activities, agricultural practices, and road construction led to amplified levels of nutrients (which cause excessive blue-green algae). The blue-green algae produce severely impaired water quality conditions. Such water quality problems have resulted in major fish mortality. These conditions have caused nearly complete mortality of every year class since at least 1991. As a result, very few young suckers survive to sexual maturity, and therefore, do not increase or even sustain the population size. Other potential factors affecting shortnose sucker include previous over-harvesting, predation and competition from native and non-native fishes, and hybridization with other sucker species.

    Conservation Measures

    Assisted rearing to augment sucker populations in Upper Klamath Lake began in 2015. The primary target of the effort are shortnose sucker because of the drastic population declines, but an inability to discriminate live larvae and juveniles means that all Klamath sucker species are collected and reared. The first release of reared suckers into Upper Klamath Lake occurred in the spring of 2018, but the proportion of released individuals that will eventually join the spawning population remains unknown. This program will expand to supplement populations with 40,000 individuals annually.

    Conservation efforts for the shortnose sucker focus on the re-establishment of a more naturally functioning ecosystem in the Klamath Basin, particularly reducing phosphorus inputs to Upper Klamath Lake. Fencing portions of streams to reduce cattle-caused erosion, replanting streambanks with native vegetation, improving forestry and agricultural practices, and ensuring adequate water levels in lakes and reservoirs also promote recovery of this species. Coordination among land use agencies and private landowners is necessary to constrain further degradation of sucker habitat improve current conditions.

    By minimizing the impacts of future modifications to spawning habitat, restoring waters to a more natural state, and augmenting the population through assisted rearing program, recovery of shortnose 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. Lost River (Deltistes luxatus) and Shortnose (Chasmistes brevirostris) Sucker Recovery Plan. Portland, Oregon 108pp.

    USFWS. 2012. Endangered and threatened wildlife and plants: designation of critical habitat for Lost River sucker and shortnose sucker. Federal Register 77:73740–73768.

    USFWS. 2013. Revised recovery plan for the Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris). U.S. Fish and Wildlife Service, Pacific Southwest Region, Sacramento, California.

    Childress, E., J. Rasmussen, D. Blake, S. Doose, B. Erickson, R. Fogerty, D. Higgins, M. Shaffer, M. Schwemm, E. Willy. (2019). Species Status Assessment for the Endangered Lost River Sucker and Shortnose Sucker.

    Perkins, D. L., G. G. Scoppettone, and M. Buettner. 2000b. Reproductive biology and demographics of endangered Lost River and shortnose suckers in Upper Klamath Lake, Oregon. U.S. Geological Survey, Reno, Nevada.

     


    Last updated: November 2019

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