Data from: Environmental DNA for the enumeration and management of Pacific salmon

Pacific salmon are a keystone resource in Alaska, generating annual
revenues of well over ~US$500 million/yr. Due to their anadromous life
history, adult spawners distribute amongst thousands of streams, posing a
huge management challenge. Currently, spawners are enumerated at just a
few streams because of reliance on human counters and, rarely, sonar. The
ability to detect organisms by shed tissue (environmental DNA, eDNA)
promises a more efficient counting method. However, although eDNA
correlates generally with local fish abundances, we do not know if eDNA
can accurately enumerate salmon. Here we show that daily, and near-daily,
flow-corrected eDNA rate closely tracks daily numbers of returning sockeye
and coho spawners and outmigrating sockeye smolts. eDNA thus promises
accurate and efficient enumeration, but to deliver the most robust numbers
will need higher-resolution stream-flow data, at-least-daily sampling, and
a focus on species with simple life histories, since shedding rate varies
amongst jacks, juveniles, and adults.

太平洋鲑鱼（Pacific salmon）是阿拉斯加的关键资源，年营收远超5亿美元。由于其溯河洄游的生活史，成年产卵亲鱼会分布于数千条溪流之中，这给种群管理带来了极大挑战。当前，由于依赖人工计数，仅极少数场景会使用声呐设备，因此仅能在少数溪流中对产卵亲鱼进行计数。通过生物脱落组织提取环境DNA（environmental DNA，eDNA）以检测生物的技术，有望成为更高效的种群计数手段。不过，尽管eDNA通常与当地鱼类的种群丰度存在相关性，但我们仍不清楚eDNA能否精准计数鲑鱼种群。本研究证实，经流量校正后的每日（近乎每日）eDNA检出率，与当日回归产卵的红大麻哈鱼（sockeye salmon）、银大麻哈鱼（coho salmon）亲鱼数量，以及降海洄游的红大麻哈鱼幼鲑（smolt）数量高度吻合。因此，eDNA有望实现精准且高效的种群计数，但要获得最可靠的计数结果，还需要更高分辨率的溪流流量数据、至少每日一次的采样策略，以及优先选取生活史较为简单的物种——因为雄早熟鲑（jacks）、幼体和成体的DNA脱落率存在显著差异。