Graduation date: 2007Larval transport and retention of two endangered suckers were studied in a highly altered lacustrine/riverine complex. The endangered populations of Lost River sucker, Deltistes luxatus, and shortnose sucker, Chasmistes brevirostris, in Upper Klamath Lake (UKL), Oregon are the largest remnant populations of these suckers. Downstream of UKL, the Keno Impoundment is a seasonally lethal, anoxic habitat. We investigated species densities and hatch date differences between larvae retained in Upper Klamath Lake and those transported below the Link River Dam into the Keno Impoundment. In 2004, larval and juvenile Lost River suckers were captured in greater densities below the dam. Larval shortnose suckers were captured in greater densities in UKL while juveniles were captured in equal densities above and below the dam. Lost River suckers had earlier hatch dates than shortnose suckers and individuals below the dam had earlier average hatch dates for both species. These patterns suggest that, in 2004, early spawned fish, especially Lost River suckers, were more likely to be transported from Upper Klamath Lake while shortnose suckers were more likely to be retained.