Temporal patterns in environmental DNA align with lake sturgeon (Acipenser fulvescens) spawning activity

Monitoring the use of spawning grounds by lake sturgeon (Acipenser fulvescens) is essential to support population recovery from historical overfishing and habitat degradation. However, conventional monitoring methods, such as adult capture and egg sampling, are invasive and labour-intensive, which hampers conservation efforts. The analysis of environmental DNA (eDNA), that is, genetic material shed by fish in the water, offers a promising, non-invasive and time-effective alternative. We evaluated the use of eDNA as a tool to monitor temporal variation in lake sturgeon presence at spawning grounds. From 2022 to 2024, we collected water samples from a known spawning site and quantified lake sturgeon eDNA using quantitative polymerase chain reaction (qPCR). In 2024, eDNA sampling was complemented by aerial drone surveys to visually detect individuals in a section of the spawning ground. Temporal trends in lake sturgeon eDNA concentrations matched the known timing and progression of spawning in this species and were consistent with drone observations. The results suggest that eDNA provides an indirect indicator of lake sturgeon reproductive activity, supporting its integration into monitoring frameworks. By offering a scalable and less invasive tool, eDNA can enhance the effectiveness of conservation strategies and inform the management of critical spawning habitats.