Klamath Falls Field Station
Shortnose sucker (Chasmistes brevirostris)
Shortnose suckers are long-lived catostomids endemic to the Upper Klamath River Basin in Oregon and 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 suckers is now restricted to the lower Williamson River and the Sprague River. The majority of spawning activity occurs in April. 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.