Much emphasis has been placed on challenges related to estimating ages of old fish, yet accurately estimating age for young individuals has proved equally challenging for some species. Indices of recruitment are often based on assigning ages to young fish to estimate the strength of a given year class. Similarly, growth is most commonly estimated using age-based methods and has been proposed as a metric for evaluating the quality of nursery habitats. Unfortunately, there is a paucity of information on the validity of age estimates for many fishes, and thus the accuracy of age-based metrics used to guide management of these species is unknown. To address such needs, we conducted a validation study of age and growth estimation methods for juvenile tarpon (Megalops atlanticus), using oxytetracycline to chemically mark otoliths and scales. Oxytetracycline marks were observed on all the otoliths of recaptured tarpon (n = 23), prior to a newly formed annulus, validating true age and that one annulus is deposited yearly. Marginal increment analysis indicated that annuli form in tarpon otoliths and scales during March–April. Annuli in scales were more easily identified by readers leading to more accurate and precise estimates of age from scales (100 % accuracy of age estimates for age-1 fish) compared to otoliths (88 % accuracy). Although annual age estimates were accurate, we observed substantial error and low accuracy for daily age estimates based on otoliths (10 % accuracy). Additionally, there was a poor relationship between otolith radius and tarpon length (R² = 0.46), which resulted in inaccurate estimates of back-calculated length-at-age and growth rates. Our results indicate that scales can be used to differentiate between age-0 and age-1 tarpon, which will aid in conservation efforts by allowing for more accurate evaluation of the age structure within nursery habitats and the quality of these habitats. Further research is needed to better understand factors influencing daily age and growth estimates from otoliths.

人们非常重视与估计老鱼年龄相关的挑战，但事实证明，对某些物种而言，准确估计幼鱼的年龄同样具有挑战性。招募指数通常基于为幼鱼分配年龄以估计给定年级的强度。同样，生长最常使用基于年龄的方法进行估计，并已被提议作为评估苗圃栖息地质量的指标。不幸的是，关于许多鱼类年龄估计的有效性的信息很少，因此用于指导这些物种管理的基于年龄的指标的准确性是未知的。为了满足这些需求，我们对幼年海鲢（Megalops atlanticus）的年龄和生长估计方法进行了验证研究。)，使用土霉素对耳石和鳞片进行化学标记。在新形成的环之前，在重新捕获的海蜇 ( n = 23) 的所有耳石上观察到土霉素标记，验证了真实年龄，并且每年沉积一个环。边际增量分析表明，3-4 月期间在海鲢耳石和鳞片中形成环。与耳石（88% 的准确度）相比，读者更容易识别鳞片中的环带，从而通过鳞片更准确地估计年龄（1 岁鱼的年龄估计准确度为 100%）。尽管年年龄估计是准确的，但我们观察到基于耳石的日年龄估计存在大量误差和低准确度（准确度为 10%）。此外，耳石半径和鲢鱼长度之间的关系很差（R² = 0.46)，这导致对反向计算的年龄长度和增长率的估计不准确。我们的结果表明，尺度可用于区分 0 岁和 1 岁的海鲢，这将有助于更准确地评估苗圃栖息地内的年龄结构和这些栖息地的质量，从而有助于保护工作。需要进一步研究以更好地了解影响耳石每日年龄和生长估计的因素。