Fryingpan census nets results
The bare cottonwoods shine silver in the sunlight, but it’s cold in the shade of the canyon walls, down near the freezing point.
The Fryingpan River runs clear against its dark, rocky bed as a Colorado Division of Wildlife crew, clad in chest waders, moves slowly against the current, dispersed across the river.
The crew is electrofishing. They are conducting an annual census of the trout in the river, keeping tabs on one of Colorado’s premier trout fisheries.
Barry Nehring, a fish researcher for the DOW, says in addition to the census, the division is also getting information for a study on the effects of whirling disease on the river’s fish populations. That disease, which affects the development of cartilage in young rainbow trout, has affected the lower seven or eight miles of the Fryingpan.
Each of five men on the front line carries an electrode mounted on an eight-foot pole in one hand and a long-handled landing net in the other. Others follow behind with more nets and two aluminum boxes, about 18 by 30 inches, lined with nets. The boxes, known as “live cars,” hold the captured fish.
The electrodes are all connected to a big roll of electrical cord that Nehring pays out as he wades upstream. They are powered by a generator that drones on a pickup truck parked by the river. Nehring explains that the fish are initially attracted to the field of electricity near the electrodes, and then stunned momentarily.
The workers try to net them before they recover, as they drift downstream. A negative electrode near the truck completes the circuit, Nehring says, but the electrical current is so diffused everywhere except near the positive “trodes” that neither fish nor humans can feel it.
“Toby, right here, little guy!” Nehring shouts, as he points out a tiny fish to the electrode-wielding technician ahead of him. The fish is netted and passed to a net held by a woman following the front line. She transfers the little fellow to the nearest live car.
The division surveys four, 1,000-foot stretches of the river each year, Nehring says. When the crew reaches the end of the 1,000-foot cord, the fish are measured and counted and returned to the river.
A mathematical formula has been established to determine the number of fish per acre with a fair degree of accuracy. It has been done every year since 1970, with the exception of about two years, Nehring says.
The river is in good shape, Nehring declares, but the division won’t know if the survey has turned up any unusual news until the biologists enter the information into a computer database.
“We’re seeing about what we anticipated,” he says.
“There’s been a real shift in species composition in the last 10 years,” he added. Brown trout populations are expanding as rainbows decline due to whirling disease.
“We’ve seen about a 90 percent drop in the survivorship of two- to five-inch rainbows in the last five years,” he continued. But he’s not seeing any other health problems in the Fryingpan trout population.
“Between you!” Nehring shouts. Nets stab the water, and someone comes up with a nice 16-inch brown.
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