There are 23 species of sturgeons, all found in the northern hemisphere. They are mostly found in large, freshwater lakes and rivers but some species also travel to the ocean and return to rivers and lakes to breed. Sturgeons can grow to be very large, up to 4.2 meters. Sturgeons have rows of large, bony scutes on their bodies. Their mouths are positioned ventrally and have 4 barbels. All sturgeon species have been extensively used by humans for their meat and their roe. As a result, all sturgeon species are either threatened or endangered.