Status and Structure of Two Populations of the Bluehead Sucker (Catostomus discobolus) in the Weber River, Utah

Abstract

Abstract We compared two populations of the bluehead sucker (Catostomus discobolus) during 2007–2009 in the Weber River, Davis, Summit, and Weber counties, Utah. We estimated 225 and 546 individuals in these populations. Based on recaptured, PIT-tagged fish, annual survival of adults (202–575 mm total length) was high (77%); however, our top model indicated mortality increased with size (i.e., senescence). We documented movements ≤15 km downstream and 5 km upstream and 88% of detections from a stationary antenna occurred at night. Despite high rates of survival of adults, recruitment appeared minimal in one of the populations because it was composed primarily of mature adults. Recruitment potentially was limited by interactions with a high density of brown trout (Salmo trutta) and combined effects of an altered hydrograph (magnitude, duration, and timing) and thermal regime. If conservation of these populations is a priority, recruitment must be increased immediately in one of the populations to avoid ext...