Comparison of age estimates from otoliths, vertebrae, and pectoral spines in African sharptooth catfish, Clarias gariepinus (Burchell)

Abstract

Otoliths, vertebrae, and pectoral fin spine sections were compared to ascertain the best ageing structure in Clarias gariepinus. Standard procedures were followed to prepare and study the age structures. All ageing structures showed alternating opaque and translucent bands that were interpreted as annuli. Age estimates were evaluated for comparison between readers and among structures. Among all structures otoliths showed highest (95.6%) agreement between readers, followed by vertebrae (91.2%) and pectoral spine sections (79.7%). Due to the highest values of percent agreement and lowest average percent error and coefficient of variation values between two readers, otoliths were considered to be the most suitable structure for ageing C. gariepinus. When otoliths' ages were compared with other bony structures, viz. vertebrae and pectoral spine sections, the highest percent agreement and lowest average percent error and coefficient of variation values were found between otoliths and vertebrae age estimates (90.7%). Mean age estimates from otoliths were comparable (P > 0.05) to the values obtained from vertebrae but significantly (P < 0.05) different to those from pectoral fin spine sections.