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<br />Part I <br /> <br />INTRODUCTION <br /> <br />! <br /> <br />l <br />I <br />l <br />I <br />! <br />i <br />I <br />! <br />! <br /> <br />Historv: <br /> <br />-Pallid sturgeon (Scaphirhynchus a7bus) evolved from an ancient group of bony <br />fishes, the subclass Pa1eopterygii, which was dominant during the Paleozoic <br />Era. This group continued to flourish through the late Paleozoic Era and <br />early Mesozoic Era. Most species in this subclass became extinct. sometime in <br />the Mesozoic Era. The living descendants of this group in North America <br />include padd1efish (Po1yodontidae), and eight species of sturgeon <br />(Acipenseridae). <br /> <br />The.North American species of sturgeon, in addition to pallid sturgeon, are <br />the shovel nose sturgeon (Scaphi rhynchus p7 atorynchusRafinesque): white. <br />sturgeon (Acipenser transmontanus Richardson); green sturgeon (Acipenser <br />medirostris Ayres); Atlantic sturgeon (Acipenser oxyrhynchus Mitchi11); <br />shortnose sturgeon (Acipenser brevi rostrum LeSueur); and lake sturgeon. <br />(Acipenser fu7vescens Rafinesque). An eighth species, the Alabama sturgeon <br />(Scaphirhynchus suttkus Williams), was recently described from the Mobile <br />Basin in Alabama and Mississippi (Williams and Clemmer 1991). This location <br />is outside the range of pallid sturgeon and is not included in further <br />discussions of Scaphirhynchus species in this plan. <br /> <br />The pallid sturgeon was first described by S.A. Forbes and R.E. Richardson in <br />1905 from nine specimens collected from the Mississippi River near Grafton, <br />Illinois, in June 1904 (Forbes and Richardson 1905). Known locally as the <br />white sturgeon, they named itParascaphirhynchus a7bus and suggested it be <br />considered as its own genus. Later classifications, however, placed it in the <br />genus Scaphirhynchus where it has remained (Bailey and Cross 1954). <br /> <br />Electrophoretic analysis of the two species of Scaphirhynchus have suggested a <br />very close genetic relationship. Phelps and Allendorf (1983), using <br />electrophoretic techniques, were unable to distinguish the species by looking <br />at 37 enzyme systems. Pallid sturgeon from the Missouri River in Missouri and <br />shovel nose sturgeon from the Missouri, Yellowstone, and Mississippi Rivers <br />were analyzed. The authors co~cluded th~t tbec1~se.genetic similarity of <br />pallid sturgeon and shovel nose sturgeon )'Ias due to recent or incomplete <br />reproduct ive 15o]at i on. . .. .. <br /> <br />General Description: <br /> <br />Pallid sturgeon have a flattened, shovel-shaped snout: long, slender, and <br />completely armored caudal peduncle; and lack a spiracle (Smith 1979). As with <br />other sturgeon, the mouth is toothless, protrusible, and ventrally positioned <br />under the snout. The skeletal structure is primari1y.carti1aginous (Gi1braith <br />et a1. 1988). Pallid sturgeon are similar in appearance to the more common, <br />darker shovel nose sturgeon. Pflieger (1975) reports the principal features <br />distinguishing pallid sturgeon from shovel nose sturgeon are the paucity of <br />dermal ossifications on the belly, 24 or more anal fin rays, and 37. or more <br />dorsal fin rays. <br /> <br />1 <br />