LIFE-HISTORY AND STATUS OF THE SHOVELNOSE STURGEON, SCAPHIRHYNCHUS-PLATORYNCHUS

The shovelnose sturgeon, Scaphirhynchus platorynchus, is a freshwater sturgeon of the Mississippi and Missouri rivers and their tributaries. It is one of the smaller North American sturgeons, seldom weighing mo re than 2.5 kg over most of its range except in the upper Missouri Riv er, where individuals of over 7 kg have been found. Spawning occurs in spring at temperatures between 17 and 21 degrees C over rock or grave l substrate downstream from dams, near rock structures, or in tributar ies. most males reach sexual maturity at 5 years, most females at 7 ye ars. Adults do not spawn every year. Shovelnose sturgeon are found in large, turbid rivers and frequently concentrate in areas downstream fr om dams or at the mouths of tributaries. Population densities range up to 2500 fish per km. They are commonly found in areas of current over sandy bottoms or near rocky points or bars, where they feed primarily on aquatic invertebrates. The shovelnose sturgeon is classified as a sport species in 12 of 24 states where it occurs. Commercial harvest i s allowed in seven states, where fresh shovelnose sturgeon sell for 55 to 88 cents per kg, smoked shovelnose for about $5.75 per kg, and roe from 33 to 110 dollars per kg. About 25 tons of shovelnose sturgeon a re harvested commercially each year. Shovelnose sturgeon are considere d extirpated in three states, fully protected in four states, and rare , threatened, or of special concern in eight states. Populations are c onsidered stable throughout most of the upper Mississippi, lower Misso uri, Red, and Atchafalaya rivers. Three states, Wyoming, West Virginia , and New Mexico, have developed plans to reintroduce the species into rivers where it has been extirpated.