Once as rare as prehistoric dinosaurs in Michigan waters, lake sturgeon have rebounded thanks to years of conservation. Michigan's Lake Sturgeon ConservationGetty Images Getty ImagesBefore 1850, lake sturgeon were so abundant they were considered a nuisance in the Great Lakes. Getty Images Getty ImagesFishermen soon discovered the value of lake sturgeon meat and caviar, triggering a commercial fishing boom. Getty Images Getty ImagesIt wasn't until 1994 that Michigan listed lake sturgeon as a threatened species. Read More: DNR Investigates 6-Foot Michigan Lake Sturgeon KillingResearches who have compiled tons of data on lake sturgeon and once believed some of the fish live more than 100 years, are now saying they may live over 400 years.