Using pectoral fin rays as a non-lethal aging structure for smallmouth bass: precision with otolith age estimates and the importance of reader experience

Abstract

We evaluated the potential utility of pectoral fin rays as non-lethal aging structures for smallmouth bass (Micropterus dolomieu). We compared age estimates among three reading pairs and against sectioned sagittal otolith age estimates for precision. Reading pair bias was not detected, although the highest rates of age estimate agreement occurred between reading pairs with high and moderate aging experience. Precision of otolith and fin ray age estimates were equivalent based on between-structure comparisons of average percent error and coefficient of variation. However, fin rays underestimated fish age compared to otoliths for older fish, especially when aged by less-experienced readers. Pectoral fin rays may provide a non-lethal alternative to otoliths for aging smallmouth bass, particularly for younger fish (≤age 4) or when experienced readers conduct aging. Additional evaluations of fin rays as smallmouth bass aging structures are needed, including validation using known-age fish and documentation of consistent annulus formation throughout a fish's life.