age class structure
英[eidʒ klɑ:s ˈstrʌktʃə]美[edʒ klæs ˈstrʌktʃɚ]
Age class structure in fisheries and wildlife management is a part of population assessment. Age can be determined by counting growth rings in fish scales, otoliths, cross-sections of fin spines for species with thick spines such as triggerfish, or teeth for a few species.