Old fish a good sign for Eagle River
Aspen, CO Colorado
EDWARDS ” Senior citizens are a good thing to find flopping in the Eagle River.
That’s why biologist John Woodling was excited to pull from the water an eight-year-old trout, which is sort of an ancient oddity in the fish world. He knows this because of the small tag he found embedded in its head. Someone put it there five years ago when the fish was probably three, and here he is, still swimming.
“We’re seeing lots of ages today, which is a good thing for the river,” Woodling said.
That trout was one of hundreds of fish “shocked” in the Eagle River Thursday and Friday by several volunteers along with members of the Colorado Division of Wildlife, the U.S. Forest Service and the Eagle River Watershed Council conservation group.
The process is called “fish shocking” because literally, the fish are stunned with electric probes and collected by quick people with nets and waders. The dazed fish are then counted, measured and weighed by a team of biologists to determine the river’s health.
Mainly, they’re concerned about the high levels of metal that have spilled over the years from the Eagle Mine south of Minturn and hurt the fish population. There was a major cleanup around the mine site, and overall, things are looking better than they did 17 years ago, Woodling said.
The biologists are looking for a few things. Finding a lot of fish is good, but it’s also important to find a wide variety of species and ages. Brown trout, for instance, are pretty tolerant of zinc in the water, while a fish called a sculpin can barely stand it.
The fish shockers were happy to actually find some sculpin in the river the past couple days, which shows progress.
“Certainly there’s been dramatic improvement,” said Wendy Naugle, a hydrologist with the Colorado Department of Public Health and Environment. “We have good and bad years, but it’s still much better than it was before the mine cleanup.”
Delicate species like sculpin haven’t been found in areas closer to the mine though, but brown trout are thriving in those more polluted areas, which means the river is getting better, Woodling said.
The Division of Wildlife has been doing this for the past 17 years. They count fish at four mine sites and three reference sites that weren’t as polluted.
While the numbers of trout have steadily increased since the mid 1990s, the numbers have leveled off and even dropped in some years even though the amounts of metal in the water didn’t have a corresponding increase. That’s one of the mysteries everyone’s trying to solve by collecting the data.
“The objective here is to use the data to determine when the river is healthy enough,” Woodling said.
As for this year’s shocking project, the numbers have to be crunched and analyzed to get a true picture of how the river is shaping up this year, Naugle said.
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