Ruedi Reservoir anglers are catching lots of yellow perch this year, and it’s not a good thing.
The species is considered invasive to waters of the Western Slope. As for the reservoir, 15 miles east of Basalt, the fish — meaty and tasty if it reaches its maximum size — is upsetting the dynamics of the Ruedi habitat. But members of the species rarely grow beyond 10 inches in length.
“I’ve been coming to Ruedi with my kids a few times each summer to catch rainbow trout for the last several years,” said James Thompson, a part-time resident of Summit County who was fishing near the dam on the reservoir’s western end about two weeks ago.
“The last few times we were here we didn’t catch a single trout. It’s all yellow perch, and they are too small to eat and not much fun to catch,” he said.
Colorado Parks and Wildlife aquatic biologist Kendall Bakich said the fish likely was illegally introduced to Ruedi between 2003 and 2007. Yellow perch have populated the reservoir very quickly and compete with other species for Ruedi’s limited food supply.
“The introduction of yellow perch at Ruedi Reservoir was totally illegal,” said Sherman Hebein, senior aquatic biologist for the Northwest Region of Colorado Parks and Wildlife. Both Hebein and Bakich are based out of Grand Junction.
“We don’t know who did it,” Hebein said of the stocking. “We would like to meet them, talk with them and perhaps give them a ticket for their introduction.”
Illegal stocking of Colorado waters can result in a fine of as much as $5,000 plus other penalties. Perpetrators, sometimes referred to disparagingly as “bucket biologists,” also can be held accountable for returning a habitat back to its normal state, which could be a cost of hundreds of thousands of dollars.
But it’s extremely difficult to catch someone in the act, especially at reservoirs and streams located in rural, mountainous areas.
“As you can imagine, reclaiming Ruedi Reservoir could be a rather expensive task,” Hebein said. “As far as I’m concerned, introducing yellow perch to Ruedi was an act of malice. I don’t know if people are adding more of them to the mix or not, but the perch population there continues to expand, the result of natural reproduction.”
The major questions surrounding the prolific panfish species, which can live in both cold and warm-water fisheries, are twofold, Hebein said: Will they contribute anything meaningful to the fishery, and will they impact anything downstream?
Though some yellow perch find their way past the dam and into the Fryingpan River, Hebein said the species doesn’t do well in Western Slope streams, and the impact on the Fryingpan and other downstream fisheries is slight.
“On the other hand, they will have an impact on the reservoir fishery,” he said. “You can’t extend the food chain and expect there to be no other consequence. They will eat the same things that juvenile trout will eat. They are all in the same place, hugging the shoreline.”
Yellow perch also will compete with Kokanee salmon for food as well. “We have a hard enough time getting Kokanee to thrive at Ruedi,” Hebein said.
In the United States, the species is native to Ohio, Illinois, the Northeast and the Southern Atlantic states. Their introduction to Colorado was the combined result of people who stock them for use as bait or those who enjoy their taste.
Why a person wanted to stock yellow perch in Ruedi is a bit of a mystery, though, according to state wildlife officials. Colorado Parks and Wildlife stocks many thousands of Kokanee salmon and rainbow trout each year. The reservoir also holds a sizable number of lake trout, which also are a native species.
Bakich said she’s not sure that there are more yellow perch in Ruedi this year compared to the past few years, but it’s likely that they are spreading out to areas where they haven’t ventured before.
“It seems to me that we’re catching more small perch, which means they are reproducing more,” she said, referring to regular fish surveys at Ruedi by the state wildlife department.
The only positive aspect of the yellow perch is that lake trout feed on them and get bigger as a result, according to Hebein and Bakich.
While the yellow perch issue is important to Ruedi Reservoir, Hebein stressed that illicit stocking is a common problem at many Colorado reservoirs and fisheries. It’s also an issue across the nation and the world.
Anyone with information about illegal stocking activity is asked to call the state’s Operation Game Thief hotline at 877-265-6648.