Shortnose Chasmistes brevirostris and Lost River Suckers Deltistes luxatus endemic to the Klamath River Basin on the California-Oregon border have experienced dramatic population declines in parallel with many other Catostomid species. Captive propagation has become a key element of many endangered fish recovery programs, although there is little evidence of their success in restoring or recovering fish populations. A novel rearing program for Klamath suckers was initiated in 2016 with the goal of developing a husbandry strategy that better balances the ecological, genetic, and demographic risks associated with captive propagation. We collected 4,306 wild-spawned Klamath sucker larvae from a major spawning tributary May-June 2016 and reared them at a geothermal facility established through a partnership with a local landowner and aquaculture expert. Mortality during collection was less than 1%. Larvae were reared in glass aquaria for 17-78 days until reaching approximately 30 mm total length, upon which they were moved to round fiberglass tanks for 14-46 days or until reaching approximately 60 mm total length. Overall survival of larvae to ponding for final growout was 71%. Larval tank rearing survival was 98% for 37 days until an isolated fish health incident affected three aquarium populations, reducing survival to transfer to 75%. Survival after transfer to round fiberglass tanks for 14-46 days was 94%. This study outlines the first successful collection and early life history husbandry of wild-spawned endangered Klamath suckers that we are aware of.

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