Atlantic sturgeon

The Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) is a member of the family Acipenseridae, and, along with other sturgeon, it is sometimes considered a living fossil. The Atlantic sturgeon is one of two subspecies of A. oxyrinchus, the other being the Gulf sturgeon (A. o. desotoi). The main range of the Atlantic sturgeon is in eastern North America, extending from New Brunswick, Canada, to the eastern coast of Florida, United States. A disjunct population occurs in the Baltic region of Europe (today only through a reintroduction project). The Atlantic sturgeon was in great abundance when the first European settlers came to North America, but has since declined due to overfishing, water pollution, and habitat impediments such as dams. It is considered threatened, endangered, and even locally extinct in many of its original habitats. The fish can reach 60 years of age, in length and over in weight. Rather than having true scales, the Atlantic sturgeon has five rows of bony plates known as scutes. Specimens weighing over 800 lb and nearly 15 ft in length have been recorded, but they typically grow to be and no more than . Its coloration ranges from bluish-black and olive green on its back to white on its underside. It has a longer snout than other sturgeons and has four barbels at the side of its mouth. Atlantic sturgeon under six years of age stay in the brackish water where they were born before moving into the ocean. They may be long at this stage. In areas where shortnose sturgeon are also present, the adults of that species can be, and historically were for centuries, confused with immature Atlantic sturgeon. When mature, they travel upstream to spawn. The females may lay 800,000 to 3.75 million eggs in a single year, doing so every two to six years. After laying their eggs, females travel back downstream, but males may remain upstream after spawning until forced to return downstream by the increasingly cold water. They may even return to the ocean, where they stay near the coastline.