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

Spiegel, Jason
Major Professor
Joseph E. Morris
Committee Member
Journal Title
Journal ISSN
Volume Title
Research Projects
Organizational Units
Journal Issue
Natural Resource Ecology and Management

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).

Food habits, diet overlap and gill raker morphology of highfin carpsucker Carpiodes velifer, quillback carpsucker C. velifer, river carpsucker C. carpio, golden redhorse Moxostoma erythrurum, shorthead redhorse M. macrolepidotum, silver redhorse M. anisurum, and northern hogsucker Hypentelium nigricans in four Iowa rivers. Diet overlap of invertebrates among all species was calculated with Morista's index (C). Food habit niche width was quantified with Levin's index (B) and similarity of gill raker morphology was compared with analysis of covariance. Values from Morista's index suggested significant overlap in the diets of highfin carpsucker and river carpsucker (C = 0.81), quillback and river carpsucker (C = 0.66), and shorthead redhorse and silver redhorse (C = 0.67). Levin's index showed that golden redhorse, quillback carpsucker, and river carpsucker had the most generalized feeding strategies as their food niche widths were substantially wider than other species (golden redhorse B = 0.32; quillback carpsucker B = 0.53; river carpsucker B = 0.41). Gill raker length and spacing were positively correlated with the standard length of the fish for all species (length: r2 = 0.67-0.88, P ≤ 0.01; spacing: r2 = 0.63-0.73, P ≤ 0.01). Comparisons of the slope of the regression of gill raker spacing to standard lengths were not significantly different for highfin carpsucker and quillback carpsucker (P = 0.37), highfin carpsucker and river carpsucker (P = 0.08), quillback carpsucker and river carpsucker (P = 0.10) shorthead redhorse and golden redhorse (P = 0.76), golden redhorse and silver redhorse (P = 0.07). Differences in gill raker morphology allow the sampled catostomid species to utilize different aquatic invertebrate species and reduce competition.