Movement and Growth of Juvenile Colorado Pikeminnows in the San Juan River, Colorado, New Mexico, and Utah

AbstractUnderstanding patterns of animal distribution and abundance based on their movements is important to identify the habitats and factors that maximize growth and reproductive success. Despite stocking age-0 hatchery-reared Colorado Pikeminnow Ptychocheilus lucius for over 10 years in the San Juan River of Colorado, New Mexico, and Utah, the population consists primarily of stocked juveniles; adults remain rare. We investigated seasonal movement and growth of juvenile Colorado Pikeminnows in the San Juan River from 2009 to 2012 to inform recovery efforts throughout the Colorado River basin. Our results indicated fish made long-distance upstream movements from spring to summer while moving back downstream over winter. Seasonal movements may be associated with maximizing growth along longitudinal and seasonal temperature regimes. Length-at-age relationships reveal Colorado Pikeminnows in the San Juan River were larger than individuals of the same age in other populations in the upper Colorado River bas...