We compared marking success for larval and juvenile fishes immersed in alizarin red S (ARS) to that of fish immersed in alizarin complexone (AC). Postlarval and juvenile central stonerollers Campostoma anomalum and southern redbelly dace Phoxinus erythrogaster and larval white suckers Catostomus commersoni were immersed in ARS or AC at concentrations of 50-400 mg/L for 6-24 h. Both chemicals imparted a violetred mark, visible in the whole otoliths under a brightfield light source. Immersion in ARS at 200-300 mg/L for 12 or 24 h resulted in optimal marking success (100%) and minimal mortalities (0-3%). Marking success and mortalities were similar for ARS and AC in comparable treatments. Alizarin red S marks were retained for at least 160 d.

Calcein is a fluorescent compound that can bind with alkaline earth metals, such as calcium. Upon binding, an increase in fluorescence under ultraviolet light results. Therefore, calcein was evaluated as potentially useful for creating a fluorescent mark in the otoliths of larval and juvenile fish. Such a mark was produced in the sagittae of larvae and juveniles of three species of estuarine fishes after a 2‐h immersion in a solution of 125 mg/L in seawater. The mark was easily distinguished under ultraviolet epifluorescent microscopy. This technique provides an alternative to the use of tetracycline in age and growth studies.

White suckers Catostomus commersoni were collected by electroshocking from Lake Taneycomo, a coldwater reservoir in southwest Missouri, to validate the use of otoliths as a yearly estimator of age. Otoliths (lapillae) were sectioned through the transverse plane for age estimation. Age validation was by edge analysis, whereby the formation of an annulus at the growing edge of the otolith was tracked throughout the year. Results indicated that only one annulus was formed per year. It was determined that otoliths are a reliable estimator of yearly age for white suckers age 2–18 in Lake Taneycomo.

Morphometric measurements and otoliths (sagittae) were collected from black drums Pogonias cromis caught in estuarine and coastal waters off Louisiana. Transverse sections of otoliths had distinct opaque zones that were validated as annual for age determination. One annulus was formed per year during winter and early spring months in all age‐classes during each of four years of sampling. There was low variability in age estimates made independently by three readers. Maximum age observed was 43 years. Von Bertalanffy growth models did not describe growth well for all age‐classes, perhaps due to an extreme decrease in growth rate at about 4 years of age and continuous, nonasymptotic growth thereafter.

No abstract