ABSTRACT-Spawninagn d movementso f the razorbacks ucker,X yrauchent exanus,w ere evaluated by radiotelemetry( n = 17 fish) and captureo f 230 adults (105 recaptures)i n the Green and Yampa rivers, 1987 to 1989. Ripe fish (n = 194) were captured in riffles with cobble, gravel, and sand substratesf romm id-Aprilt o early June. Recapturedm alesw ere ripe from2 to 28 days and recaptured females from 2 to 15 days. Razorback suckers spawned during ascending and highest spring flows at water temperatureso f about 14'C (range of 9 to 17?C).S pawning migrationso f 30 to 106 km were detectedi n 17 razorbacks uckers,b ut movementsw ere more limitedo r undetectedi n other individuals. Floodedl owlandsa nd lower portionso f tributarys treamsp resumablys [...]