Precision and Relative Accuracy of Striped Bass Age Estimates from Otoliths, Scales, and Anal Fin Rays and Spines

Abstract

We counted annuli on otoliths, scales, anal fin rays, and anal fin spines of striped bass Morone saxatilis to determine precision of age estimates from several readers and relative accuracy of the estimates from the different structures. Our principal objective was to determine if estimates from scales, spines, and rays, which can be removed without harming the fish, were similar to those from otoliths. Among-reader variation was similar for spines, scales, and rays, and lowest for otoliths. Variation increased with fish total length (TL) for otoliths and scales. Age estimates from scales, spines, and rays were usually within 1 year of the otolith age estimate for striped bass shorter than 900 mm TL. However, for striped bass longer than 900 mm TL, estimates from spines and scales were lower than estimates from otoliths by averages of 1.6 and 3.0 years, respectively. Scales, spines, and rays can provide relatively accurate and precise age estimates for striped bass up to about 900 mm TL (age 10 from our samples). For longer fish, the choice of a structure for age determinations should depend on whether the improved accuracy and precision expected from otoliths is worth killing the fish.