Steamboat Springs Officials with the U.S. Fish and Wildlife Service in Denver announced last week that they will begin euthanizing nonnative smallmouth bass that they remove from the Yampa River in spring rather than transferring them to Elkhead Reservoir east of Craig.
Too many of the relocated bass are escaping over the dam spillway, they say, and returning to the Yampa, where they threaten endangered native fish including the Colorado pikeminnow, razorback sucker, humpback chub and bonytail.
The Upper Colorado River Endangered Fish Recovery Program has removed and relocated an estimated 6,000 bass as well as large numbers of northern pike from stretches of the Yampa downstream from Hayden since increasing those efforts in 2003, recovery program Nonnative Fish Coordinator Pat Martinez said in a news release.
The bass harm the recovery effort by competing for habitat, but they also are opportunistic predators that will eat whatever is available, including juvenile pikeminnows, for example. By doing so, the bass disrupt the entire food chain in the lower stretches of the Yampa, Martinez said.
The program previously has collaborated with water users, reservoir managers and the
Colorado Division of Wildlife to return the bass to the reservoir where they are a sought-after game fish.
Program Director Tom Chart said Friday that after expansion of the reservoir in 2008, it was hoped the new dimensions of the dam along with fish screens added to the spillways would greatly reduced the number of fish returning to the river. But it doesn’t seem to have worked, as fish go over the top of the dam when it spills water in high runoff years.
Individual bass are recognizable by tags attached to their bodies at the time they are captured and relocated to Elkhead.
“We know that 5 to 10 percent of the fish are turning up downstream, but that’s a lowball estimate,” Chart said. “There’s convincing evidence that some of the fish have escaped every year. Smallmouth bass are a fantastic sport fish, and we don’t like to kill these fish. We support fisheries that are compatible with what we’ve been doing to (restore populations of the endangered native fish), but this is too counterproductive.”
Escaped bass have been re-captured as far as 100 miles downstream from the confluence of Elkhead Creek and the Yampa.
DOW spokesman Randy Hampton said his agency continues to view the smallmouth as a valuable game fish for Colorado anglers but also recognizes that it must play a dual role as a state agency that provides angling opportunities for the license holders that fund its operations, as well as one that must play a role in the recovery of the endangered native fish.
“It’s tough. We have an obligation to the sportsmen who pay for our management,” Hampton said. “But part of adaptive management tells us we need to do what’s supported by science.”
Failure to restore the populations of the endangered native species could have broader implications for management of nonnative species on Colorado’s Western Slope, he added.
Chart said the recovery program has contracted fisheries biologists from Colorado State University to assess the effectiveness of euthanizing captured smallmouth in the effort to remove them from the Yampa. And Hampton said it’s his understanding that only after those results are known that the stakeholders will sit down to determine what further action might need to be taken.
Recovery program biologists have routinely used an anesthetic solution in holding tanks to euthanize smallmouth smaller than 10 inches. Now, that practice will be applied to the larger fish that were formerly returned to Elkhead, Chart said.
Hampton said that northern pike removed from the Yampa in and downstream from Hayden will continue to be relocated to the Yampa State Park Headquarters pond to provide angling opportunities for the public. The exceptions are pike that are removed from the river in mid-summer because they are more difficult to keep alive.
“The pond is easily accessible to anglers and we know that it will not reconnect to the river under any conditions,” Hampton said.
Martinez wrote in last week’s news release that the Yampa plays a critical role in the recovery of the four endangered fish species throughout the upper Colorado River Basin.
“This is primarily due to its relatively unaltered patterns of seasonal flows and habitat which are important to the fishes’ life cycle,” he said.
The Yampa also is a positive influence on the Green River, which flows unnaturally cold and clear at its confluence with the Yampa.
“As the largest tributary to the Green, the Yampa provides habitat and delivers flows and sediment downstream to the Green River, helping to maintain a river system with hundreds of miles of habitat consider vital to the recovery of the endangered fishes.”
To reach Tom Ross, call 970-871-4205 or email tross@SteamboatToday.com