Swimming Ability and Early Development of an Imperiled Redhorse Species and Other River Fishes

Swimming ability is important in determining patterns of larval and juvenile fish dispersal, distribution, and nursery habitat selection.  The Sicklefin Redhorse Moxostoma sp. is a sucker (family Catostomidae) endemic to the southern Appalachian Mountains and of high conservation concern.  We designed an experiment to determine swimming ability of larval and juvenile Sicklefin Redhorse and other lotic fish species.  Sustained swimming abilities were assessed by subjecting captive-reared Sicklefin Redhorse (N=102) to fixed-velocity swim trials, wherein fish were subjected to a prescribed water velocity until they became exhausted and unable to maintain position.  Fish were subjected to trials approximately 1, 2, 4, 6, and 10 weeks after they exhibited swim-up behavior; mean total lengths were 16.0, 16.1, 20.3, 26.3, and 33.3 mm, respectively.  Development classifications included early- and late-stage mesolarva, metalarva, and juvenile.  Swimming ability increased monotonically among classes; sustained swimming speeds (30-min) increased from 0.099 m/s to 0.166 m/s across the range of sizes observed.  Comparable estimates were also derived for sympatric wild fish larvae that were identified using DNA barcoding.  Information gained from our findings will be used to develop a more thorough understanding of habitat associations observed in concurrent field research and to guide conservation and recovery efforts.