Determination of Age and Growth of Populations of the White Sucker (Catostomus commersoni) Exhibiting a Wide Range in Size at Maturity

Abstract

The use of the scale method to determine age of mature white suckers should be avoided. Sections of pectoral fin rays can provide accurate age determinations for most populations once the position of the first annulus has been identified. The age of immature white suckers can be estimated by both methods. It is suggested that, for identification of the first fin ray annulus and facility in the determination of the age of immature white suckers, both pectoral fins and scales should be sampled in all age and growth studies of this species.White suckers (Catostomus commersoni) from populations examined in this study attained ages of up to 17 years although little or no growth occurred in the latter years. Considerable variation in size at sexual maturity was found throughout the range for this species and, thus, the validity of a subspecies designation for a dwarf white sucker (C. c. utawana) based primarily on size differences should be reexamined.