A giant among Wisconsin’s inland freshwater fishes, the bottom dwelling lake sturgeon is a living fossil – a relic from the Middle Ages of fish evolution. This ancient species made its first appearance about 100 million years ago in the Upper Cretaceous period of the Mesozoic era, just about the time that the dinosaurs made their abrupt exit from Earth’s ever-changing stage. Today the lake sturgeon retains many primitive characteristics that have been lost or modified in other modern-day fishes. Research into the mysterious sounds that lake sturgeon produce resumes in April, or whenever the water warms to a temperature conducive for fish spawning, which is the best time to experience sturgeon thunder. In spring, Ron Bruch, a biologist with the Wisconsin Department of Natural Resources, and Chris Bocast, an acoustic ecologist with the UW Sea Grant Institute, will conduct additional biological examinations and collect detailed field recordings of the infrasonic sounds of this ancient fish.