Evaluation of First Feeds for Larval Lost River Suckers

Abstract

AbstractThe Lost River Sucker Deltistes luxatus is endemic to the Klamath Basin in southern Oregon and northern California. Population declines led to listing this species as endangered in 1988. Its native habitat has been greatly reduced and degraded putting their future in question. If this species is to be reared in captivity to prevent extinction, the development of culture methodologies is necessary. Successful initial feeding methods are one of the first areas of culture that need to be developed. Lost River Suckers begin feeding during the larval life stage. Larval fish often require live prey at the onset of feeding; however, it may be possible to start larvae on formulated microdiets. We investigated the use of live Artemia and two commercial microdiets (Hikari and Otohime brands) as first feeds over the course of a 41‐d feeding trial. Starting on day 21 of the trial, feed sizes were increased, and the Artemia‐fed fish were offered a commercial microdiet (Otohime) while being co‐fed Artemia through day 26 of the trial (6 d cofeeding). After day 26 the Artemia‐fed fish were only offered the microdiet. The response variables of total length, weight, survival, whole‐body lipid content, and whole‐body fatty acid profile were measured during and at termination of the trial. Fish grew significantly faster when started on Artemia and also displayed significantly higher survival compared with fish fed only commercial microdiets. Fish started on Artemia transitioned well to Otohime B1, and maintained 95.2% (SD, 2.2) survival over the 41‐d feeding trial. The fatty acid profiles of the fish generally reflected the profiles of the diets they were fed. This study demonstrated that live Artemia followed by a transition to Otohime commercial feed is an effective feeding regimen for the duration of the larval phase of this species.