Considerable efforts have been undertaken to characterize population dynamics of the Alligator Gar Atractosteus spatula. Accomplishing this task required identification of suitable structures to estimate age. Buckmeier et al. (2012) validated sagittal otoliths to 31 years—the oldest fish in their study. However, they noted that interpreting annuli became increasingly difficult with age and cautioned that difficulties may result in underestimates of age for older fish. In recent years, sampling efforts have resulted in the collection of otoliths from a number of large (>1,800 mm TL) individuals. Age estimates of these fish ranged to 68 years; however, the accuracy of these ages was unknown. Therefore, we used bomb radiocarbon dating to assess accuracy. The technique measures the time‐specific increase in the radioactive carbon isotope (¹⁴C) in calcified aging structures resulting from the testing of thermonuclear devices in the 1950s and 1960s. An abrupt, worldwide increase in environmental radiocarbon occurred in approximately 1958 and acts as a time stamp, providing a reliable means of corroborating the age estimates of long‐lived fishes. Core material (i.e., hatch year), along with a subsample from early growth years, was extracted from the otoliths of 24 Alligator Gar (1,805 to 2,540 mm TL) and analyzed for Δ¹⁴C. Estimated age from growth zone counting ranged from 26 to 68 years, corresponding to hatch years spanning from 1946 to 1989. Otolith Δ¹⁴C was then plotted against the corresponding hatch years and compared to reference curves for environmental ¹⁴C levels across time. Despite evidence of regionally specific trends attributed to differences in groundwater and surface inflows, Δ¹⁴C levels in the otoliths were highly correlated with reference data, indicating that age estimates were accurate to within a few years. Thus, our results extend the utility of methods developed by Buckmeier et al. (2012) for Alligator Gar in excess of 60 years and provide greater insight on longevity.

中文翻译：

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基于炸弹放射性碳年代估计超过60年的鳄鱼Gar的基于耳石的年龄估计

相当多的努力已经进行表征鳄雀鳝的种群动态Atractosteus锅铲。完成此任务需要确定合适的结构以估计年龄。Buckmeier等。（2012年）验证了矢状耳石至31年-他们研究中最古老的鱼类。但是，他们指出，随着年龄的增长，解释环空变得越来越困难，并警告说，困难可能会导致年龄较大的鱼类年龄被低估。近年来，采样工作已导致从许多大型（> 1,800 mm TL）个体收集耳石。这些鱼的年龄估计为68岁。然而，这些年龄的准确性尚不清楚。因此，我们使用炸弹放射性碳测年来评估准确性。该技术测量放射性碳同位素随时间的增加（¹⁴C）是在1950年代和1960年代对热核装置进行测试后产生的钙化老化结构。1958年左右，全球环境放射性碳突然增加，这是一个时间戳，为证实长寿鱼类的年龄估计提供了可靠的手段。芯材料（即，舱口年）中，用从早期生长年的子样本一起从24鳄鱼碣（1805至2540毫米TL）的耳石提取和分析为Δ ¹⁴ C.估计年龄从生长区计数从26范围到68岁，对应于舱口年跨越从1946年至1989年耳石Δ ¹⁴ ℃下再对相应的舱口年绘制，并且与环境的参考曲线¹⁴跨时间的C水平。尽管归因于地下水和地表流入差异区域的具体趋势的证据，Δ ¹⁴在耳石C水平与基准数据高度相关，表明年龄估计是准确的几年内。因此，我们的结果扩展了Buckmeier等人开发的方法的实用性。（2012年）对短吻鳄Gar已有60多年的历史，并提供了更长寿的见解。