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Interior Department Eyes Removal Of Non-Native Trout From Colorado River in Grand Canyon National Park


Non-native trout, while prized by anglers who fish the Colorado River below Glen Canyon Dam, threaten to wipe out native species in the river that can't compete with them. While Interior Department officials have a plan to remove the trout, it's effectiveness is being questioned.

With an estimated 1 million trout in the Colorado River within Grand Canyon National Park, Interior's plan to live-trap the fish to dent the population is nothing but a "Band-aid" fix, says Nikolai Lash of the Grand Canyon Trust.

“Obviously, mechanically removing fish, they’re only going to be able to, practically speaking, get tens of thousands of fish, and there are a million," said Mr. Lash when reached Wednesday for his reaction to Interior's plan. "If you remove 30,000, that means you’ll have 970,000 trout left. And maybe it will go over a million, 1.2 million the next time we look at it.

".... The problem is so out of hand now. You can’t mechanically remove trout and think it’s gonna fix the problem."

Anne Castle, Interior's assistant secretary for water and science, announced the fish removal plan on Wednesday when she and Interior Secretary Ken Salazar said high-flow releases would resume from Glen Canyon Dam. She said the efforts would involve live-trapping of trout in different locations of the canyon. Live-trapping is being used instead of lethal means to honor Native American concerns for all living things, the assistant secretary added.

How much the live-trapping effort will cost, or how successful it might be, she did not say. For more than a decade crews in Yellowstone National Park have been trying to rid Yellowstone Lake -- a largely closed system, unlike the Colorado River -- of non-native lake trout with very limited success.

At the Grand Canyon Trust, Mr. Lash said the Colorado River plan, as a means of helping the endangered humpback chub recover, had several problems. Along with only removing a fraction of trout, the live-trapping likely will lead to the deaths of native fish, he said.

Live trapping typically is accomplished by using electro-shock to stun fish, which then float to the surface, said Mr. Lash. While native fish that are stunned are to be thrown back into the river, some will die from the shock, he maintained.

Rather than trapping, Mr. Lash said he'd rather see the river managed for humpback chub; using the flushes proposed by Interior Secretary Salazar would benefit the chub over the trout, he said.

“I think there’s a lot of room still to experiment fundamentally with flows and mix up the interplay between natives and non-natives," he said.

At the Grand Canyon Monitoring and Research Center, a U.S. Geological Survey facility in Flagstaff, Ariz., Scott Vanderkooi said Colorado River researchers have been using electro-shock for years and the fish, both native and non-native, endure it fairly well.

“If it’s done properly it can stun fish, but it generally does not harm fish," said Mr. Vanderkooi, the center's biology program manager. "There certainly are exceptions to that. But by and large natives and non-natives seem to do well when they are handled.”

According to Mr. Vanderkooi, it will be a while before any live-trapping with a goal of denting the trout population is done. A number of "triggers" need to be reached before fish removal begins, he said. They range from the overall population of humpback chub, the trout population, and even water temperatures.

Trout prefer cooler waters than humpback chub, he explained, and so live-trapping would not occur until and unless the water temperature falls below a certain point. Humpback chub, meanwhile, prefer warmer waters and likely would be in the Little Colorado River.

Currently, the USGS biologist said, humpback chub in the Colorado River drainage within the Grand Canyon seem to be on the upswing, number-wise. A decade ago estimates put the population around 5,000, and the latest estimate, made in 2008, raised that number of 7,650, said Mr. Vanderkooi.

According to the USGS official, the bulk of the non-native trout population within the canyon is found just downstream of Lee's Ferry.

"Most appear to be in that reach down to Lee’s Ferry, and the upper parts of Marble Canyon," he said. "The surveys that we’ve done, the catches of trout fall off as you go down river.”

So when live trapping does begin, it will likely be focused on that upper stretch of the river. Captured trout then will most likely be taken by boat to Lee's Ferry and transferred to their final location, said Mr. Vanderkooi.

More troublesome would be removing trout near the confluence of the Colorado River and Little Colorado River, which is the main habitat for humpback chub because its waters are warmer than the main Colorado. As the confluence is roughly 60 miles downstream of Lee's Ferry, said Mr. Vanderkooi, any captured trout most likely would have to be floated down the Colorado River and out of the park.

“The exact method has not been finalized. Likely it would have to be on some sort of raft," he said.

With the vast number of non-native trout in the canyon's waters, trying to tamp down their numbers through live trapping would be difficult, acknowledged Mr. Vanderkooi.

“With the abundance that there is, it would be very challenging," the USGS official said.


There's more evidence of agenda in Interior Dept. plans here, I believe.

The waters between Glen Canyon Dam and Lee's Ferry are the coldest of any areas on the Colorado due to the water that's released from very deep in Lake Powell. 49 degrees, I believe, is the release temp which warms a bit the farther (not much) as it flows toward Lake Mead aboce Hoover Dam. The Little Colorado with it's warmer water and not effected by the Dam seems to be the best place for the suckers and chubs to survive. The effects of yearly flushing in the LC naturally would seem to put some of them into the Colorado proper. I do not know if they find their way back into the LC or in what numbers. There has been electro shocking, fish trapping and traditional fishing with killing all trout the goal in Bright Angel Creek that's been going on for years, some 80 River miles below the Little Colorado. The many recreational fisherman that I've spoke with are very saddened by this especially when there can be such dubious results. Seeing trout pulled out of a weir in the 20-30 inch range only seems to thrill the government employee tending the weir. It's science, I know but the the reality of the conditions on the River provided by the Glen Canyon Dam with it's present state of operation just don't favor suckers and chubs to any degree outside the Little Colorado. Could there be a way of engineering the dam operations where the water closer to the surface could drawn into the generators at the bottom allowing much warmer water to be sent downriver, I don't know. Taking out the dam, I know, is a popular theme by many but the multi billion (trillion?) dollar impacts would turn Arizona, it's economy and residents/visitors (scientists) dire impacts.

I believe the goal should be to manage both trout and the suckers/chubs in the best way possible. The trout are much more adaptive to present conditions to the point that they could be considered "native" since the construction of Glen Canyon Dam and provide a trophy sport fishery giving untold outdoor experiences to many thousands of adventurers every year.

I guess to restore the natural order of things, one must remove a very large dam. That sounds very unlikely. I would be curious what the avg water temps would be when the Colorado was wild. Very fluctuant I am sure. Diversion further down stream and the impact on marine species in the Gulf would seem to me 1000x more important.

Like to make a correction. Bright Angel Creek where active trout eradication has been going on is about 26 river miles below the confluence of the Little Colorado with it's warmer waters and not 80 River miles as I stated.

We cannot fix the infastructures collapsing in the parks, but we can catch a few fish to eliminate a million... OPEN fishing regs to catch all you can of these buggers and even hire fisherman that were thrown off the beaches of cape hatteras to catch them and fry them up...

The first sentence above is the only thing one needs to consider in this debate. Trying to simulate the conditions for the native species under the current circumstances is a joke - either blow up the dam or let the trout live. At least that way people can have some fun fishing as consequence of the giant atrocity committed on the Colorado by the Glen Canyon Dam.

The current non native fish removal plan unfortunately deals, ineffectively, with the symptom rather than the root source of the problem which is chronically high population levels of rainbow trout in the Lees Ferry reach along with concomitant high reproduction rates. The current dam operations are very conducive to this condition. Taking rainbow trout out anywhere downstream of this nursery area is likely a waste of time and money since trout will quickly reestablish themselves in these downstream areas by juveniles migrating downstream from this very productive source area where they are being forced out by lack of avaialble habitat.

So why has Interior chosen to spend millions on a doomed process rather than bite the bullet and put into place new management policies designed to reduce the number of fish in the Lees Ferry reach to a level that would greatly reduce or eliminate downstream movement? Politics clear and simple. The Lees Ferry trout fishery is managed by the Arizona Game and Fish Department within Glen Canyon National Recreation Area. AGFD is happy with the fishery as it stands and is reluctant to entertain any changes to the current policies that are seen as successful with the angling public (especially the fishing guides) even though such changes are likely the permanent solution to the hbc predation problem downstream near the LCR confluence. The National Park Service (and Interior) wants no part of a public squabble with AGFD over wildlife management in the state of Arizona so it looks the other way.

By ignoring the clear evidence that the source of rainbow trout is from the Lees Ferry reach and that a change in fish management policies there could reduce that population, Interior has delayed effective protection of hbc which it claims to seek. It has also thumbed its nose at the adaptive management process which it is supposed to be promoting. As established by Babbitt in 1996, the Glen Canyon Dam Adaptive Management program was supposed to use the best available science to make management policy changes to address known problems and then test those changes through actual full implementation. Interior now uses adaptive management differently. It uses the best available science to develop studies of possible policy changes which it usually studies indirectly or minimally seeking %100 certainty in results. As any scientist will tell you, %100 certainty is all but impossible, thus interior is off the hook about making any changes to current management policies.

The current set of EAs are mostly stalling maneuvers designed to ensure that no meaningful changes are made to current management policies related to dam operations and Colorado River management policies. Interior may dispute my assessment but history speaks for itself. Since the completion of the 1996 EIS and 1997 ROD that made changes to dam operations as well as well as implemeting a comprehensive adaptive management program for the operation of Glen Canyon Dam to make further changes within the confines of the operational parameters, not a single change in policy has occurred. In fact, if you read the two EAs carefully you will find that the existing policies under MLFF are fully and explicitly protected.

Let me see if I understand this.... we have turned the Colorado river system into a long, putrid lake system - altering it beyond belief and now we're worried about non-native fish?

Wouldn't exactly call it a "putrid lake system" but I get your drift. There does seem to be bigger problems facing the country, if anyone cares to notice.

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