Although environmental DNA shed from an organism is now widely used for species detection in a wide variety of contexts, mobilizing environmental DNA for management requires estimation of population size and trends in addition to assessing presence or absence. However, the efficacy of environmental-DNA-based indices of abundance for long-term population monitoring have not yet been assessed. Here we report on the relationship between six years of mark-recapture population estimates for eulachon (Thaleichthys pacificus) and "eDNA rates" which are calculated from the product of stream flow and DNA concentration. Eulachon are a culturally and biologically important anadromous fish that have significantly declined in the southern part of their range but were historically rendered into oil and traded. Both the peak eDNA rate and the area under the curve of the daily eDNA rate were highly predictive of the mark-recapture population estimate, explaining 84.96% and 92.53% of the deviance, respectively. Even in the absence of flow correction, the peak of the daily eDNA concentration explained an astonishing 89.53% while the area under the curve explained 90.74% of the deviance. These results support the use of eDNA to monitor eulachon population trends and represent a >80% cost savings over mark-recapture, which could be further increased with automated water sampling, reduced replication, and focused temporal sampling. Due to its logistical ease and affordability, eDNA sampling can facilitate monitoring a larger number of rivers and in remote locations where mark-recapture is infeasible.

中文翻译：

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环境DNA有助于对数百万条无鳍鱼类进行准确，廉价和多年的种群估计。

尽管从生物体中获取的环境DNA现在已在多种情况下广泛用于物种检测，但动员环境DNA进行管理除了评估是否存在外，还需要估计种群规模和趋势。但是，尚未评估基于环境DNA的丰度指标对长期人口监测的功效。在这里，我们报告了关于斑马鱼（Thaleichthys pacificus）的6年标记夺回种群估计与“ eDNA比率”之间的关系，该比率是根据河流流量和DNA浓度的乘积计算得出的。Eulachon是一种具有文化和生物学意义的重要an鱼，在其范围的南部已经大大减少，但历史上被变成石油并进行了贸易。eDNA的峰值速率和日eDNA速率曲线下的面积都可以很好地预测标记夺回的种群估计，分别解释了84.96％和92.53％的偏差。即使没有进行流量校正，每日eDNA浓度的峰值也可以解释为惊人的89.53％，而曲线下方的面积可以解释为偏差的90.74％。这些结果支持使用eDNA监测欧拉克种群的趋势，并且比标记夺回节省了80％以上的成本，这可以通过自动水采样，减少复制和集中时间采样来进一步提高。由于其后勤的便利性和可负担性，eDNA采样可以促进监测大量河流以及无法进行标记回收的偏远地区。