9444

• UCREFRP Catalog Number: 9444
• Author: Hawkins, J. A.
• Title: X-ray Assessment of Electrofishing Injury of Colorado Pikeminnow.
• USFW Year: 2002.
• USFW - Doc Type: Recovery Program Project 64,
• Copyright Material: NO

similar to adult Colorado pikeminnow. Technique was refined by consulting x-ray

technicians about the quality of field exposed radiographs. The technique chart

specified the current (mA) and time (s) in milliampere-seconds (mAs) of each exposure

based on thickness of the fish. Thicker fish had longer exposures. At 74 to 76 cm

focal film distance, exposure was 12 mA @ 65 kVp and exposure time ranged from

0.25 to 0.5 seconds (s) for lateral views. For ventro-dorsal views, exposure was 11 mA

@ 70 kVp for 0.45 to 0.9 s.

Each fish received an estimated exposure of 2.9 ,uRoentgen per x-ray as

measured by a Qualified State Inspector by x-raying a dead, surrogate fish (walleye)

with length, thickness, and mass similar to an adult Colorado pikeminnow. Estimated

exposure to the operator was less than 0.6 ,uRoentgen per x-ray at a distance of 3 m.

Both operator and assistant wore lead aprons during all exposures and each wore an

exposure badge monitored by CSU Environmental Health Services.

Fish were immobilized by the anesthetic Tricaine to prevent movement during

each x-ray procedure and restrained in the ventro-dorsal position by gently wedging

them between adjustable, soft, styrofoam blocks2. Each radiograph was labeled with

species, sample number, and date on lead-impregnated tape. Exposed film was

removed and fresh film loaded into the cassettes inside a light-proof, photographer's,

film-change bag. Exposed films were stored in light-proof film bags in a dry cooler and

developed 1-3 days after exposure, either at local hospitals near each sampling site or

at CSU Veterinary Teaching Hospital in Fort Collins.

2Styrofoam blocks used to position fish were floats known as "pull buoys" used by swimmers for
training and were obtained from a sporting-goods store.

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