Summer food habits and gill raker morphology of seven Catostomid species in Iowa rivers

Previous attempts to age Carpiodes spp. have focused on the use of scales or dorsal fin rays. Past studies indicate that obtaining age estimates from these structures in other species is difficult and inconsistent. We examined between reader precision of age estimates of scales and pectoral fin rays for 123 highfin carpsuckers Carpiodes velifer, 174 quillback carpsuckers C. cyprinus and 135 river carpsucker C. carpio. Precision of age estimates was assessed through measures of agreement, the coefficient of variation (CV), and a confidence rating. Exact agreement between readers was higher for fin rays (highfin carpsucker = 82.1%; quillback carpsucker = 75.9%; river carpsucker = 77.0%) than scales (highfin carpsucker = 69.5%, quillback carpsucker = 68.9%; river carpsucker = 71.1%). In addition, CV was lower for fin rays (highfin carpsucker = 2.28; quillback carpsucker = 2.43; river carpsucker = 2.90) than scales (highfin carpsucker = 2.95; quillback carpsucker = 3.00; river carpsucker = 3.46). Fin rays were also assigned a higher confidence rating (i.e., mean readability, 0-3 with 3 being high; highfin carpsucker = 2.22; quillback carpsucker = 1.95; river carpsucker = 1.92) than scales (highfin carpsucker = 1.53; quillback carpsucker = 1.51; river carpsucker = 1.68).