9527938 MAYDEN The sturgeon family of bony fish (Acipenseridae) includes several species of commercial value, long sought after by humans of many cultures. Nearly all of these species are in need of immediate conservation measures. Among the most imperiled are sturgeon species in the subfamily Scaphirhynchinae, genera Scaphirhynchus and Pseudoscaphirhynchus. The subfamily is endemic to North America and Central Asia. Conservation efforts are hampered by an inadequate knowledge of the taxonomy, systematics and ecology of these fish, in particular by the uncertainty of species boundaries and the likelihood that undescribed species are present. This proposal is an international partnership among scientists of the United States, Russia and Uzbekistan. Principal investigators Mayden and Birstein, with their colleagues, will examine morphological characteristics of sturgeon in the subfamily Scaphirhynchinae, and use these characters to evaluate, and revise where necessary, the taxonomy and systematics of these fish. The revised taxonomy will then more effectively inform conservation activities.