Validation of Daily Ring Deposition in the Otoliths of Age-0 Blue Catfish and Flathead Catfish
Peter C. Sakaris, Daniel J. Daugherty, and David L. Buckmeier
Abstract.—We validated methods for estimating daily age of age-0 blue catfish Ictalurus furcatus and flathead catfish Pylodictis olivaris. Larvae of each species were reared in the laboratory and were sampled approximately every 10 d over a 4-month period. Five individuals of each species were randomly selected for daily age estimation from each of nine age-groups, ranging from 40 to 119 d posthatch for blue catfish and 20–121 d posthatch for flathead catfish. Mean daily ring count and known age were related for both species, indicating that daily ring deposition occurred in the otoliths of these fishes. Daily increment counts were accurate through 60 d posthatch for blue catfish and through 72 d posthatch for flathead catfish, with mean deviance of estimated age within 1 d of the known age. For both species, daily increments could be enumerated for older fish; however, accuracy decreased with age. We encourage researchers to utilize our aging technique to estimate hatch dates, the timing and frequency of hatching, and early growth rates of catfishes in wild populations. Such early life history information will be valuable in enhancing the management and conservation of important catfish populations.