Successful Collection and Captive Rearing of Wild-Spawned Larval Klamath Suckers

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. We initiated a novel rearing program for Klamath suckers 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 <1%. We reared larvae in glass aquaria for 17–78 d until they reached approximately 30 mm total length, upon which we moved them to round fiberglass tanks for 14–46 d 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 d 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 d 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.