The American Eel Anguilla rostrata has experienced a marked population decline due to a multitude of threats, including pollution, overfishing, and damming. Government agencies responsible for American Eel management have identified gaps in survey coverage and understanding of habitat needs as critical obstacles to recovery. However, efforts to expand American Eel monitoring are hindered by this species’ resistance to capture, the wide variety of habitats in which they occur, and their extensive natural range, which would be cost prohibitive to survey using established techniques. Surveys based on analysis of environmental DNA (eDNA) may offer an affordable and efficient means of closing these gaps. While eDNA methods are increasingly used as a rapid, minimally invasive means of detecting species presence, attempts to use them to produce quantitative estimates of abundance have yielded mixed results. In order to evaluate the viability of eDNA as a quantitative American Eel monitoring tool, we compared the concentration of American Eel DNA in water samples to estimates of numerical and biomass density measured by electrofishing in the Bronx River, New York. Our results revealed a strong, positive association between DNA concentration and numerical density but no relationship with biomass density. Mass-specific eDNA production rates were found to decline with mean American Eel weight. While further study will be required to determine whether the observed relationship between DNA concentration and numerical abundance is consistent across sites and whether it can be generalized to other systems, our findings suggest that eDNA will likely be a feasible and cost-effective option for surveying American Eel abundance throughout their range.

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美国鳗鱼丰度与布朗克斯河环境 DNA 浓度的关系

美国鳗鲡Rostrata由于污染、过度捕捞和筑坝等多种威胁，该地区的人口数量显着下降。负责美国鳗鱼管理的政府机构已将调查覆盖范围和对栖息地需求的理解方面的差距确定为恢复的关键障碍。然而，扩大美国鳗鱼监测的努力受到该物种对捕获的抵抗力、它们栖息地的广泛多样性以及它们广泛的自然范围的阻碍，使用既定技术进行调查成本高昂。基于环境 DNA (eDNA) 分析的调查可能会提供一种经济实惠且有效的方法来缩小这些差距。虽然 eDNA 方法越来越多地用作检测物种存在的快速、微创手段，试图用它们来对丰度进行定量估计，结果喜忧参半。为了评估 eDNA 作为定量美国鳗鱼监测工具的可行性，我们将水样中美国鳗鱼 DNA 的浓度与纽约布朗克斯河电捕鱼测量的数值和生物量密度估计值进行了比较。我们的结果显示 DNA 浓度与数值密度之间存在很强的正相关，但与生物量密度无关。发现质量特异性 eDNA 生产率随着美国鳗鱼的平均重量而下降。虽然需要进一步研究来确定观察到的 DNA 浓度和数值丰度之间的关系是否在不同地点一致，以及是否可以推广到其他系统，