The annual world sturgeon catch has ranged from 20,000 to 40,000 metric tons during the past fifty years and, as such, has been less significant than the catch of many other commercial fisheries. Although the history of sturgeon culture is over a century old, its husbandry level is far behind that of the trout, common carp and channel catfish. The sturgeon species are acipenserid chondrosteans, a primitive stock of teleost fish that diverged 200 million years ago. Sturgeon inhabit the inland and coastal waters of the northern hemisphere, from the Arctic circle to the subtropics. Longevity is a characteristic of most sturgeon species. Sturgeon spend their adult lives in both freshwater and saltwater environments: rivers, lakes, estuarine lagoons and coastal waters of the ocean. All sturgeon require a much longer time to reach sexual maturity and to complete the gametogenic cycle than do modern teleost fish.