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equipment. Sharber and Carothers (1988) observed vertebral compressions in 43-67% of rainbow trout Oncorhynchus mykiss captured with a WP-15 and Fredenberg (1992) reported spinal injuries in 18-98% of rainbow trout collected with a WP-15. The acute injury rate of Colorado pikeminnow was also much lower than the injury rate of razorback sucker Xyrauchen texanus shocked using similar equipment (WP-15) in laboratory settings. Eight razorback suckers had a 50% rate of injury during a laboratory study of electrofishing effects on gametes (Muth and Ruppert 1996). However, Colorado pikeminnow injury rate was greater than that of wild roundtail chub Gila robusta which showed no evidence of vertebral injury after electrofishing capture from the eolorado River with equipment and techniques similar to ISMP (eowdell and Valdez 1994). All spinal injuries of Colorado pikeminnow in this study were spinal compressions (Class-1 injury) and none of the injured vertebrae were fractured (Class 2) or misaligned (Class 3), suggesting that Colorado pikeminnow were less susceptible to electrofishing injury than trout which typically experience severe elass 2 and Class 3 injuries (Hollender and Carline 1994; Dalbey et al. 1996; Thompson et al. 1997). Because of their protected status, fish in this study were not necropsied to confirm their injury classification. Necropsy would allow examination for spinal hemorrhages often associated with acute vertebral injury and whether injured vertebrae were calcified, indicating healed previous injury. However, a low rate of acute injury for Colorado pikeminnow was supported by the lack of multiple injuries in recaptured fish. In addition, a low rate of acute injury was supported by a relatively low congenital/chronic injury rate (20%) for Colorado pikeminnow. With repeated electrofishing, non-lethal acute injuries should accumulate in the population as chronic 13