Evaluation of Initial Feeds for Larval Lost River Suckers

The Lost River sucker (LRS, Deltistes luxatus) is endemic to the Klamath Basin. Population declines resulted in the listing of LRS as an endangered species in 1988 and establishment of a controlled propagation program is one of the recovery actions listed in the LRS recovery plan. However, there is no published information on nutritional requirements of this species.

Thus, we conducted a study to compare growth responses and survival of LRS fed live Artemia or one of two commercial microdiets as first feeds. Three replicate tanks of first-feeding larvae were assigned to each of the three dietary treatments. Starting on day 21 of the trial, feed sizes were increased and larvae fed Artemia were offered a microdiet while being co-fed Artemia through day 26 of the trial (6 days co-feeding).

Fish started on Artemia had significantly higher growth rates and survival compared to fish fed only the microdiets. Further, fish started on Artemia transitioned well to Otohime B1 and maintained 95% survival during the 41 day feeding trial. These results indicate first feeding with live Artemia followed by a transition to an appropriate microdiet is an effective feeding regimen for the duration of the larval phase in LRS.