Steamboat Springs Big fish are fond of eating smaller fish, and that's why more than 25 people turned out at the Routt County Courthouse on Tuesday night. They were there to learn about a series of experiments that will be carried out this year in area rivers including the Yampa.
Angela Kantola told the group the experiments are intended to increase biologists' and wildlife managers' understanding of the impact aggressive predator fish are having on endangered native fishes.
Kantola is the assistant director of the Upper Colorado River Endangered Fish Recovery Program. Her agency is attempting to determine whether a reduction in the numbers of non-native predators such as northern pike and smallmouth bass will result in a corresponding increase in the numbers of four threatened native species. They include the Colorado pike minnow, razorback sucker, humpback chub and bonytail.
"Our goal is to recover the endangered fish while allowing water development to continue," Kantola said.
Water development is the incentive that has bound together a consortium of area governments and agencies represented by the Recovery Program. The federal government has tied future development of water projects in the Yampa and upper Colorado basins to the ability of cooperating government agencies to bolster the populations of the endangered fish.
Kantola said there are a variety of reasons why the native fish are struggling to survive.
They include levees that eliminate flooding of their traditional spawning grounds and water projects that prevent their traditional migration patterns.
Increasingly, wildlife managers believe predation and competition from pike, bass and channel catfish are the major reasons for the decline of native species.
Pat Nelson, non-native fish coordinator for the Recovery Program, said he intends to begin testing that hypothesis this spring and summer in the Green, Colorado, White and Yampa rivers.
The closest experiments to Steamboat Springs will be conducted between Hayden and Craig.
In portions of the rivers designated as control stretches, Nelson and his colleagues will collect and tag fish, then release them back into the river. In "treatment" stretches of the river, fish will be tagged and transferred to landlocked ponds. The ponds are on state-owned land near Hayden, and fishing for the transferred pike is encouraged.
Over a period of years, Nelson will compare populations of native fish in control and treatment stretches of the rivers. That will allow him to test whether populations of endangered native species rebound or fail to respond to removal of the predators.
The data could become the basis for future management of fish populations.
Gene Kite of Steamboat asked Nelson how the greater ecosystem would benefit from restoration of the native fish.
Nelson said that 120 years ago, there were reports of exceptionally large pike minnow in the Yampa River farther downstream in Moffat County.
"They were the top carnivore in the river," Nelson said. "They were the T-Rex of the upper Colorado Basin. They grew to be 6 feet long and weigh 80 pounds."
The combined effects of water projects and competing predators such as the northern pike have turned the pyramid upside down, Nelson said.
Where once the pike minnow resided alone at the top of the food chain, there are now several carnivores competing with each other for food.
The native fish seem to be losing out.
Richard Abate expressed concerns that once large pike minnow regain their stature in the Yampa, they will prove to be as voracious predators as the northern pike. He asked if in the future, big pike minnow wouldn't become as big a threat to other endangered fishes as northern pike seem to be today.
John Hawkins, a fisheries biologist from Colorado State University, said the natural history of the pike minnow tends to negate that situation.
He explained that, historically, pike minnow have migrated many miles from several rivers to spawn in the deep canyons of the Yampa River in Moffat County.
The young fish, or fry, tend to drift downstream while the adults swim back upstream to their home waters.
The youngsters will run into some hungry mature pike minnow downstream that will attempt to gobble them up, but in general, the younger fish are separated from their cannibalistic elders.
Nelson told the group that he realizes that for sport fishermen, angling for big pike in small ponds on state property isn't a substitute for catching them from a free-flowing river.
"If this works, fishing may not be as good as it has been," Nelson said. "For those folks who like to fish rivers, I realize, it's not the same. I like to fish rivers. I hope we find out we can sustain native fish without reducing non-natives."
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