Age and Growth of the Utah Chub, Gila Atraria (Girard), in Panguitch Lake and Navajo Lake, Utah, from Scales and Opercular Bones

Abstract

Abstract Age and growth were calculated for 222 Utah chubs collected from Panguitch Lake and 212 Utah chubs collected from Navajo Lake, southern Utah, in 1952–1953 from both scales and opercular bones. Scales were measured with the aid of a projector. Opercular bones were measured directly. The center of growth of the opercular bone is posterior to the posterior lip of the fulcrum. Correction for curvature is necessary in opercular bone measurements. Agreement of dominant age classes for successive years, agreement of empirical length-frequency modes of young fish with calculated length-frequency modes of lower age classes, agreement of ages as indicated by scales and opercular bones, agreement of age with sexually immature fish, and an increase in length with an increase in age are accepted as evidence in support of both methods. The opercular-bone method displays no appreciable advantages over the scale method.