A Field Guide to White Sturgeon

Covered with bony armor plates and capable of growing to 20 feet and over 1,500 pounds, the white sturgeon (Acipenser transmontanus) is North America's largest and most primitive freshwater fish. Dating to the Jurassic period and prized for its immense size and spectacular aerial fighting ability, the white sturgeon is known as the poor man's marlin.

SKELETON/NOTOCHORD The sturgeon has a primitive, cartilaginous skeleton and a notochord, the precursor to the backbone, which is common to only the equally evolutionarily primitive lamprey.

AIR BLADDER A gelatin called isinglass was historically prepared from the lining of the sturgeon's air bladder and used as a clarifying agent and glue.

SKIN Covered not with scales but microscopic teeth called denticles, the sturgeon's sandpaper-like skin resembles that of another family of ancient fish--the sharks.

MOUTH The sturgeon uses its tubular, extendable, toothless mouth to suck food up off the bottom. Favored foods include aquatic insects and plants, small fish, leeches, clams, and crayfish.

SCUTES Running the length of the sturgeon are five rows of bony plates called scutes. The scutes are very sharp in juvenile fish to deter predators but smooth out as the fish matures and predation becomes less likely.

ROE Sturgeon roe, which is pickled to make caviar, is a prized delicacy. A mature, spawning female may contain 200 pounds of roe.

EYES & NOSE Adapted to murky environments, the white sturgeon relies heavily on its sense of smell. Thus its eyes are rudimentary and dull.

BARBELS Sensitive barbels allow the sturgeon to identify food on the river floor or seabed as it hunts.