White sturgeon (Acipenser transmontanus) is a species of sturgeon in the family Acipenseridae of the order Acipenseriformes. They are an anadromous fish species ranging in the Eastern Pacific; from the Gulf of Alaska to Monterey, California. However, some are landlocked in the Columbia River Drainage, Montana, and Lake Shasta in California, with reported sightings in northern Baja California, Mexico. Description A. transmontanus is distinguished by the two rows of four to eight ganoid bony plates between the anus and anal fin, with about 45 rays present in the dorsal fin. Coloring can range from gray to brownish on the dorsal side, paler on the ventral side, and gray fins. Barbels are situated anterior to the mouth, closer to the snout than the mouth. At sexual maturity, A. transmontanus can reach in length, while the maximum length recorded of any age class is , with common lengths around . While age at maturity is uncertain, possible age ranges of known A. transmontanus specimens range from 11–34 years old. The most authentic record of the maximum weight of this species is reported to be , while other unauthenticated records show a higher weight estimate, as with the estimate for an individual with a reported age of 104 years. In one 1995 study, a sample of adults weighed from . A specimen, considered the largest in the state in recent years, of at a length of was recorded relatively recently in California. Taxonomy Alternate common names include: Pacific Sturgeon, Oregon Sturgeon, Columbia Sturgeon, Snake River Sturgeon and Sacramento Sturgeon. The specific name is derived from the Latin words acipenser (sturgeon), trans (beyond), and montanus (mountain). The white sturgeon is part of a Pacific clade of species including Kaluga (Huso dauricus), Sakhalin (Acipenser mikadoi), Green (Acipenser medirostris), Chinese (Acipenser sinensis) and Amur (Acipenser schrenkii) Sturgeon. Recent genetic analysis supports a close relationship between (A. transmontanus) and (A. schrenckii), which is only found in Asia, showing a common ancestor between the two around 45.8 million years ago. Using microsatellites, genetic differentiation between different river systems in the Pacific Northwest and California is high enough to be able to distinguish between white sturgeon populations and validate a structure in which watershed (A. transmontanus) resides in. Extant sturgeon species are polyploid, containing more than two paired sets of chromosomes, derived from an extinct ancestor containing 60 chromosomes. Genome duplication during sturgeon evolution has led to three different