Jesse D. Jones College of Science, Engineering and Technology
Many structures are used to age Silver Carp Hypophthalmichthys molitrix, but no consensus had been obtained concerning which structure is best. Previous studies have used sections from the pectoral spine, but some of those studies have used transmitted light to illuminate the annuli of the sectioned pectoral spine. We used reflected light to enhance the contrast of annuli in sectioned pectoral spines and compared the aging precision obtained from this method among 6 readers who varied in their aging experience. Overall precision as measure by the mean coefficient of variation (CV) was 5.23 ± 0.76SE, which compares well with other structures for which the CV has been reported. Exact agreement among all 6 readers was 63.3%, 88.8% were within 1 year, and 100% were within 2 years. However, mean CV and percent agreement varied between those readers who had several years of experience aging Silver Carp with this structure (mean CV = 1.15 ± 0.39SE, 91.8% exact agreement between 2 readers, 100% agreement within 1 year) and readers who had experience aging fish, but less experience with Silver Carp spines (mean CV = 4.94 ± 0.77SE, 67.3% exact agreement among 4 readers, 93.8% agreement within 1 year, 100% agreement within 2 years). Silver Carp were also aged by reading digital images presented as on online quiz. Precision for the online quiz was similar to fish aged by looking at the spine section directly (mean CV = 5.67 ± 1.24SE, 66.0% exact agreement among 4 readers, 96.0% agreement within 1 year, 100% agreement within 2 years). We suggest that pectoral spine sections read with reflected light are a viable method for estimating ages from Silver Carp.
Spier, Timothy; Morris, Jessica; and Tompkins, Josh, "Aging Precision using Sectioned Pectoral Fin Rays from Silver Carp Hypophthalmichthys molitrix" (2022). Faculty & Staff Research and Creative Activity. 195.