Identification of a nonlethal method for aging tautog (Tautoga onitis)

Abstract

Abstract-Aging of tautog (Tautoga onitis) has historically required sacrificing fish to obtain opercula and otoliths. Use of these structures for age determination has hindered researchers from obtaining samples from fish that were to be released alive, as well as from commercially collected fish that are commonly sold whole. In this study we evaluated the use of scales, dorsal-fin spines, pelvic-fin spines, opercula, whole sagittal otoliths, and sectioned sagittal otoliths as structures for age determination of tautog. Our results indicate that pelvic-fin spines provide high-precision age estimates without bias. Dorsal-fin spines had well-defined annuli, but vascularization near the core prevented consistent identification of the first annulus and led to biased ages. Scales were difficult to read and provided highly biased ages in older (>age 7) fish. The precision of age estimations derived from pelvic-fin spines was better than the precision of age estimations derived from the other structures. Pelvic-fin spines provide suitable age estimates for tautog, and these structures can be collected easily from a wider variety of sample sources than can the structures currently being collected for age determination of this species.