Each year, Colorado Parks and Wildlife aquatic biologists conduct fishery surveys of many of our rivers and reservoirs. Periodic monitoring allows CPW to collect and record the biological data needed to guide fishery management in Colorado. CPW biologists can choose from a wide variety of techniques to survey the different types of waters across the state. For the Gold Medal stretch of the South Platte River just below Cheesman Reservoir dam, however, the survey method of choice is electrofishing.
Colorado’s Gold Medal Waters
Gold Medal Waters are the highest quality cold-water habitats and have the capability to produce many quality-size (14 inches or longer) trout. For a complete list of Colorado Gold Medal waters, see the Colorado Fishing brochure (page 5).
Electrofishing uses electricity to stun fish, allowing them to be caught alive using dip nets. This common scientific survey method provides insight into fish abundance, density, and species composition. When performed correctly, electrofishing results in no permanent harm to fish, who return to their natural state just seconds after being stunned. Soon after the team records important biological data, the fish are safely released back into the water. It sounds easy enough, but electrofishing surveys take a well-coordinated team to get the job done.
“It’s kind of like underwater lacrosse. It could be an Olympic sport,” Tyler Swarr, CPW’s Upper South Platte Basin Aquatic Biologist says half-jokingly.
Capturing fish is only the first challenge that the teams face. They need to collect necessary data quickly to make sure they can return a healthy population of fish back into the water.
“We’re trying to get length and weights of all of the fish and assess the fish health,“ says Swarr. “We’re also looking for any sort of stream disease issues.”
Known for quality fishing for large rainbow trout and brown trout, the Gold Medal stretch of the stream can intimidate even the best anglers. This tailwater fishery remains ice-free for most of the winter and anglers target fish in deep runs or pools during this time of year. With heavy year-round fishing pressure, anglers can experience days where not a single fish bites. But, on the day of the survey, a team of electrofishers worked through a 300-foot long section of water and collected an estimated 600-700 fish – including a number of trophy size rainbow and brown trout with the largest being approximately 21 inches. This was a shocking revelation for even the most successful Colorado Gold Medal Water anglers.
CPW will provide a finalized report on the Fishing Survey Summaries page on the Colorado Parks and Wildlife website. To learn more about fishery management and the different ways that CPW surveys Colorado’s waters, please visit the Colorado Parks and Wildlife website.