Use of Ultrasound Imaging to Determine Sex of Shovelnose Sturgeon

—During November 2002, 51 shovelnose sturgeon Scaphirhynchus platorynchus were sexed by ultrasound imaging using a portable ultrasonograph. We identified males with 96% accuracy (N 5 25) and females with 80% accuracy (N 5 25); one hermaphroditic individual was misidentified as a male. Overall, ultrasound imaging was 86% accurate. Sex in postspawned females was difficult to determine, 60% being misidentified as males (N 5 5). Ultrasonography is an effective noninvasive method for sex determination that can be applied to other species of Acipenseriformes. Modern portable equipment expands its utility to field studies. The shovelnose sturgeon Scaphirhynchus platorynchus is commercially exploited in 7 of 24 states where it occurs in the Mississippi River basin (Keenlyne 1997). Throughout much of its range, its status is unknown or has declined (Keenlyne 1997). Various species of sturgeon have been harvested in the USA since the 1800s primarily to harvest roe for caviar production (Boreman 1997). The reduction of historical sturgeon fisheries in the Caspian Sea and Volga River (Khodorevskaya et al. 1997) and the restrictions on importation of caviar into the USA (Gnam 1998) will undoubtedly lead to increased exploitation and possibly poaching of domestic sturgeons (Secor et al.