Shortnose Sucker (Chasmistes brevirostris) - KFFS

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Species Studied

Shortnose Sucker (Chasmistes brevirostris)

Adult shortnose sucker

Adult shortnose sucker. Credit: USGS, Western Fisheries Research Center. (Public domain.)

Shortnose suckers (Chasmistes brevirostris) are long-lived catostomids endemic to the Upper Klamath River Basin in Oregon and the Lost River Basin in California. Individuals have been aged to over 30 years and the largest adult females can grow to 600 mm fork length. Shortnose suckers were listed as endangered under the U.S. endangered Species Act in 1988 because of range contractions, declines in abundance, and a lack of evidence of recent recruitment to adult populations. Numerous threats common to imperiled fishes in the western United States also affect the recovery of shortnose suckers (e.g., habitat alteration and degradation, nonnative species). Shortnose suckers, like other western lakesuckers (genus Chasmistes), migrate relatively short distances up tributaries to spawn in the spring. Although spawning may have occurred in other tributaries in the past, nearly all riverine spawning activity for the Upper Klamath River Basin suckers is now restricted to the lower Williamson River and the Sprague River. The majority of spawning activity occurs in April. Another population of apparently Shortnose Suckers is present in Clear Lake Reservoir, CA. Although there has been an on going debate on whether these fish are Shortnose or Klamath largescale suckers. Shortnose suckers share a complex evolutionary genetic heritage with the Klamath largescale sucker. Although most adults are morphologically distinct from Klamath largescale sucker adults, hybrids do occur and genetic techniques indicate broad overlap in genotypes between these two species.

The USGS runs a long-term monitoring program for this species that tracks abundance, survival and recruitment to spawning aggregations. Passive integrated transponder (PIT) technology allows staff to track adult suckers through multiple years. These data are used in populations models to estimate demographic parameters.  PIT tag data are also used to understand the timing of spawning migrations into rivers and to shoreline springs. The Klamath Falls Field Station staff uses PIT technology to investigate how lake management effects spawning behavior and survival of adult suckers.  Survival of juvenile suckers is monitored in a long-term monitoring program and in-lake mesocosoms. Mesocosms allow fish to experience ambient conditions and to be closely observed for development of disease.  Sucker research is used to help guide water management in the Upper Klamath Basin and to help plan sucker recovery actions.