Acoustic camera, a non-invasive approach to monitor whitefish spawning phenology in the shallow water areas of peri-alpine lakes
Résumé
Due to variations in water temperature, climate change impacts the phenology of lake fish population, especially their reproduction. In peri-alpine lakes, whitefish (Coregonus spp.) spawn in very shallow waters in late December and early January when surface water temperature reaches 7 - 8° C. To study spawning phenology, traditional sampling methods such as gill-netting are invasive and difficult to implement, specially during under unfavorable weather conditions of winter. Non-invasive alternatives such as visual observations and environmental DNA have been proposed, but have limitations in terms of observer bias and sampling frequency. Acoustic cameras (high frequency multi-beam sonars) provide an innovative and non-intrusive approach to monitor fish populations, including their migration or breeding phenology. This study explores the phenology of whitefish reproduction in the littoral zone of Lake of Geneva, over several seasons using an acoustic camera ARIS (Sound Metrics Corp.). The results show that acoustic cameras allow to monitor the phenology of whitefish spawning in shallow waters in a non-invasive way. Furthermore, the semi-automated processing using Sonar5-pro facilitates rapid data analysis, allowing a high frequency description of the reproduction rhythms with long time series.