Description and Analysis of Spawning Sounds Produced By Lake Sturgeon, Acipenser Fulvescens

This investigation brings to science detailed recordings and spectrographic analyses of previously undocumented lake sturgeon (Acipenser fulvescens) spawning sounds, obtained during wild sturgeon reproduction. Biologists have long known that sturgeon produce low-frequency sounds during spawning bouts; energy from these sounds breaks the surface of the water occasionally and propagates harmonics in the terrestrial atmosphere, creating a faint, mysterious drumming popularly known as “sturgeon thunder”. Understanding the contribution of this sonic behavior in context is essential for obtaining a more comprehensive scientific understanding of the process of sturgeon spawning, and accurate acoustic data should hold prove useful for fisheries managers seeking to monitor sturgeon stocks for reproductive activity. Recordings were made at several locations on the Wolf and Embarrass River during the 2011-2013 spawning seasons. Drumming sounds ranging from 5 to 8 Hz fundamental frequency were evident. Other characteristic noises generated by spawning lake sturgeon, including low-frequency rumbles and hydrodynamic sounds, were identified. Other high frequency sounds were also discovered. All these sounds coalesce into a distinctive acoustic signature of lake sturgeon spawning activity. Knowledge of this sonic signature can be used to accurately document lake sturgeon spawning activity at multiple locations over extended periods using remote recording tools and techniques.