Comparison of Browned and Standard Otolith Preparation Methods for Estimating Age of Catfish in Oklahoma

Catfish are highly regarded by recreational anglers as sportfish in some areas of North America and are intensively managed by fisheries biologists. Accurate population metrics (e.g., growth, mortality, recruitment, age, and size at maturity) are essential to manage these fisheries, which relies on accurate age estimates for fish in these populations. When otoliths are used for age estimation, they are typically sectioned or ground in a transverse plane, but otolith preparation prior to sectioning may differ. Browning otoliths prior to sectioning to help distinguish annuli has been used by some biologists, but there is a need to determine if this technique results in increased precision. Browning otoliths substantially increases otolith processing time; thus, it should only be done if it demonstrably increases aging precision. The objective of this study was, therefore, to compare precision of age estimates between browned and standard otoliths for black bullhead (Ameiurus melas), blue catfish (Ictalurus furcatus), channel catfish (I. punctatus), flathead catfish (Pylodictis olivaris), and yellow bullhead (A. natalis). Paired t-tests were used to compare consensus ages and CV of reader age estimates between aging techniques. Consensus age estimates were lower in browned otoliths compared to standard otoliths only for black bullhead and yellow bullhead. Reader CV was lower for standard otoliths for black bullhead and higher for yellow bullhead but was similar between techniques for the other species. The results of this study suggested that only otoliths from yellow bullhead need to be browned, and managers may be able to forego this lengthy process while still achieving precise age estimations for most catfish species.

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