Precision of age assignment from four structures of smallmouth buffalo [Ictiobus bubalus, (Rafinesque, 1818)] in the Southeastern United States

Abstract

Accurate and precise age determination is essential for estimating key life-history parameters in fishes. Recent studies suggest that some fisheries management metrics, such as mortality, may be robust to biased age estimates. Thus, it can be more important to identify the most precise structure for age assignment. However, precision can vary geographically, highlighting the need for location-specific evaluations. Smallmouth buffalo [ Ictiobus bubalus , (Rafinesque, 1818)] have received little attention in this regard, particularly outside their native range. We compared the precision of four structures, scales, opercles, otoliths, and anal fin rays, for assigning ages to smallmouth buffalo from a large river in the Southeastern United States. Anal fin rays showed the highest between-reader agreement, with the lowest coefficient of variation (CV) and average percent error (APE), followed by otoliths, opercles, and scales. Ages assigned from scales, opercles, and anal rays were generally consistent with otolith ages up to age 12. Variability in age assignments had little effect on von Bertalanffy growth parameters or mortality estimates between otoliths and anal rays, and these models were generally consistent across readers. Overall, our results indicate that anal fin rays provided the most precise age estimates for smallmouth buffalo in this system. Although bias was not assessed, the close agreement between anal fin ray and otolith ages suggests that anal fin rays are a reliable, non-lethal option for aging individuals less than 12 years old.

Bibliographic Information