Sturgeon swim upstream from Lake Winnebago to spawn in the shallows of the Wolf River. This species has existed since the time of the dinosaurs 100 million years ago and has a viable naturally-reproducing population. They are highly prized for the taste of their flesh as well as for their eggs, caviar, which are said to rival those of the beluga sturgeon of Russia and Ukraine. Female sturgeon deposit their eggs only about every four to six years, starting at age 20 up to their life span of 50 years. Mature sturgeon measure five feet in length.