Threatened fishes of the world: Deltistes luxatus (Cope 1879) (Catostomidae)

Abstract

Common name: Lost River sucker, mullet, c’waam. Conservation status: Endangered: (USFWS 1988; Gimenez Dixon 1996). Identification: D 10–12, LL 82–113, gill rakers 23–37 in adults >200 mm, 44–48 post-Weberian vertebrae. Elongate body with long, narrow head, long snout, small eyes. Upper lip thin (two to five rows of large papillae). Lower lip (one to three rows of papillae) deeply notched. Adults up to 1 m TL and 4.5 kg. Maximum recorded age: 43 years. Illustration by Joe Tomelleri. Distribution: Historically widely distributed in upper Klamath and Lost River basins (Oregon/California). Limited to the following lakes/rivers and their tributaries: Upper Klamath Lake, Clear Lake, Lost River, Tule Lake, and Klamath River to Copco Reservoir. Abundance: Historically very abundant; sufficiently abundant to support a fishery. Long-term abundance data limited, but dramatic decline evident (NRC 2004). Current population size estimated in the tens of thousands (USFWS 2007). Low recruitment and low adult survival may indicate future declines (USFWS 2007). Habitat and ecology: Lakes: shallow depths, cool water (16–24°C), moderate alkalinity (pH 7.2– 9.2), DO levels of 6–10 mg/L (Moyle 2002). Feeds benthically on detritus and invertebrates. Reproduction: Spawns at shoreline lake springs and in tributaries from February–May in shallow riffle/run habitat with gravel substrate and moderate current. Matures between 5– 9 years (Scoppettone and Vinyard 1991); most mature by age 9. Iteroparous. Threats: Current threats include hyper-eutrophication of Upper Klamath Lake and mass mortality of adults; loss of aquatic marsh habitat from drainage of wetlands for agriculture; conflicting water management goals; and predation of larvae by nonnative species. Some measures addressing limited access to spawning areas by dams and entrainment by water control structures are underway. Conservation action: ESA listing prompted wetland/riparian restoration, dam removal, and fish screening/passage programs. Remarks: Recovery is complicated by the long life span, episodic recruitment, and multiple demands on water management of the upper Klamath Basin. Environ Biol Fish (2009) 86:401–402 DOI 10.1007/s10641-009-9530-3