Kill fish to save fish: Behind Colorado’s effort to revive the Rio Grande cutthroat trout – The Colorado Sun

On a beautiful early September day, Ken Gierhart hiked a trail familiar since boyhood to Music Pass in the Sangre de Cristo mountains above Westcliffe. As he dropped off the saddle toward the Sand Creek lakes, he noticed people heading the opposite direction with fishing poles.

Hows the fishing? he asked one woman.

Theyre all dead, she replied, saying nothing more as she passed.

Puzzled, Gierhart came upon another woman heading away from the lakes and tried his question again.

There is no fishing, she said. Theyre all dead.

This time, the angler paused to explain that Colorado Parks and Wildlife, according to signs posted in the area, had used a chemical called rotenone to kill all the fish in the lakes and Sand Creek, which meanders south down the mountain before veering west to eventually disappear, after 13 miles, into the depths of the Great Sand Dunes.

The project is part of a long-planned strategy to restore the native Rio Grande cutthroat trout to waters where its numbers have dwindled toward the edge of extinction.

Increasingly scarce in a dwindling native range and hybridized with other species like non-native cutthroats, which had been stocked alongside it many years ago, the Rio Grande cutthroat eventually will be reintroduced to the mountain lakes and streams where it once thrived. But the process can be disconcerting especially to an unsuspecting hiker like Gierhart.

It wasnt until he got closer to Lower Sand Creek Lake that he saw the informational signs for himself. Then he headed toward the upper lake, following the trail that crosses the creek several times along the way. He said piles of dead earthworms filled seemingly every crevice in the rocks. And then it got worse.

It was horrifying at that level to see what had been done to the lake, Gierhart said. When I got to the lake I saw fish belly-up, carcasses on the bank where animals or birds had pulled them out.

Gierhart, a 54-year-old wholesale tree grower, hadnt heard anything about the fish management plan, and he stewed all the way back to his home in Westcliffe. There, he fired up his Facebook account and vented in a post that estimated thousands of dead fish and that attracted nearly 100 comments, most expressing concern over an undertaking they, too, seemed unaware of.

Ive always been preservation conscious, Gierhart said, still steamed a couple weeks later, but to see aquatic life dead like that, I started thinking about the watershed, the lasting effects, side effects.

The rant and its response caught the attention of CPW officials, who expressed frustration over response to a broad regional project that has been years in the making and which framed its intent in a compact signed in 2003 and renewed in 2013 by six federal entities, state agencies in Colorado and New Mexico and three American Indian tribal agencies. The agreement also received non-signatory support from two Trout Unlimited groups.

The Sand Creek drainage was officially listed in a 2013 strategy document.

In 2019, meetings on both the Westcliffe and Alamosa sides of the mountain yielded no opposition other than concern over the temporary loss of fishing and little public comment. The project moved ahead, though a year later than originally scheduled due to a late fish spawn.

Its something we need to do, said John Alves, the Durango-based senior aquatic biologist for CPWs Southwest Region. With only 11% of its historic range left, the Rio Grande cutthroat trout is always susceptible to petitions to list it as endangered, and also to extrication if there are events like fire. Its a constant process for us.

Joe Lewandowski, spokesman for CPWs Southwest Region, which includes the Sand Creek drainage, notes that the state agency has done similar projects before and will do more of them throughout Colorado.

We dont get a great deal of pleasure having to poison a stream, but it is necessary to restore native species, he said in an email to The Colorado Sun. This has been done in waters to restore the Rio Grande, greenback and the Colorado River cutthroat; and these projects will continue.

We know people are not happy to see dead fish, and it is confusing. Its very difficult often impossible to explain to the general public why we have to do these projects.

The intersection of history, science and politics of wildlife management can be complex. And while in this case the ultimate goal to restore the Rio Grande cutthroat to its native range is mostly a shared interest, the path to achieving it can be challenging.

After the 2003 conservation agreement, federal and state authorities started doing reconnaissance in 2004 to determine if the drainage could be restored. Geography that essentially isolated water flow, and therefore fish migration, proved fortuitous.

Its an ideal situation in a lot of regards, because its a closed system, said Fred Bunch, chief of resources management for the Great Sand Dunes National Park and Preserve, which takes in the Sand Creek drainage. The creeks have their headwaters high in the Sangres, they flow into those lakes and the lakes flow out to the dunes. Thirty-four square miles of sand is a pretty substantial fish barrier.

Bunch points to several reasons why reintroduction of the Rio Grande cutthroat looms important. First, theres federal policy that favors native species in national parks and preserves. Another has to do with the essential characteristics of a wilderness area. A third is for preservation of the species.

This is an ideal opportunity to restore 13 miles of habitat for the Rio Grande cutthroat trout, he said.

The stakeholders who signed the conservation agreement meet annually to discuss the status of its efforts. The key thing, Bunch said, is to prevent the listing of the Rio Grande cutthroat as an endangered species and ensure it has robust habitat.

And thats where politics can come in.

The Center for Biological Diversity, a nonprofit organization that claims roots in the fear that government authority alone will not always protect flora and fauna when powerful business interests can exert political leverage. (The timber industry was its founders nemesis.) Now, it contests threats to biodiversity on a range of levels, from climate change to encroachment of off-road vehicles.

The group has petitioned multiple times to place the Rio Grande cutthroat trout on the endangered species list, including one case thats still pending an appeal.

From the standpoint of state wildlife managers like Alves, who shares the groups desire to see the native species rebound, the fishs presence on the list represents another potential layer of bureaucracy that state workers on the ground would have to contend with.

Once a species is listed by the U.S. Fish and Wildlife Service, local agencies dont make decisions, he said. Theyre made by the federal government. For years, since the late 90s, there have been petitions to list the Rio Grande cutthroat trout. (The Center for Biological Diversity) sees listing as a way to get timber and mining off public lands.

That is true, said Noah Greenwald, the centers Portland, Oregon-based endangered species director.

Those things present a real threat to their habitat and to the species, so we want to make sure those things are done in a careful way or theres avoidance of trout habitat or, to the extent that theres damage, theres mitigation which is what the Endangered Species Act requires.

Aside from territorial concerns stemming from listing the species, both the center and the state agree on some key issues. The center supports and applauds the effort to repopulate the Sand Creek drainage with the native fish. But Greenwald also claims that his organizations petitions to list the Rio Grande trout spurred the state to take action to conserve them more than they were before.

We havent succeeded in putting them on the protected list, but weve pressured the state to do more for them, which is a benefit for the species, he said. Theyve done a tremendous amount of surveys and used staffing resources in an effort to avoid listing them. We dont think thats the right tradeoff. It makes more sense to list them and work for recovery.

The center doesnt even have problems with the kill-to-restock method, or the rotenone compound used to achieve it.

Greenwald calls the CPW a credible messenger with regard to the safety of rotenone.

We dont love having to use poisons, he said. But theres been a lot of work done on this issue, and there are not other effective means. As chemicals go, rotenone is pretty specific to fish. We definitely think it needs to be done carefully and we dont relish the thought of poison being used. But its the only way.

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Although the battle over listing the fish persists, all sides celebrate the ideas that in the case of the Sand Creek drainage, the area could become a refugium for the species, where the fish could naturally multiply and be used as a source for future stocking or restoration if some other habitat experiences problems say, from wildfire.

So were doing it for many things, Bunch said. One is the philosophy of land managers, but theres also the species itself. Also theres a recreational piece. Its a great situation where a hiker can backpack in and catch native fish. Thats a pretty great situation to have, and thats what were shooting for.

From the start, the effort to restore the species has been a multipartner project, including federal, state and county agencies and even private groups like Trout Unlimited. Some of the early upfront money came from the National Park Service but functionally, the reintroduction process is a CPW project done in a national preserve. Cost of a helicopter, boats and other equipment is covered mostly by the state.

This year, phase one of the process got underway. But before fish and wildlife authorities took any action, they needed to know exactly how many different species they were dealing with in those waters that stretch from the Sand Creek lakes to the sand dunes.

And thats where science played a big role.

John Wood founded Pisces Molecular more than 20 years ago, just a few years before efforts began in earnest to restore the Rio Grande cutthroat trout.

Though it has just four people on staff, the Boulder-based biotech lab has clients all over the world, not to mention right in its backyard. Woods lab has worked with Colorado Parks and Wildlife on multiple different fish projects, including when in 2007, in conjunction with University of Colorado post-doc Jessica Metcalf, it discovered that CPWs stock of supposed greenback cutthroat trout which happens to be Colorados state fish were actually Colorado River cutthroat trout.

How do scientists figure out what species are in a waterway? One method is simply catching a sample of fish, clipping off the tiniest bits of their fins, and sending the material to a lab for DNA sequencing. Wood notes that can be laborious and difficult to get an accurate representation of the species makeup of a waterway.

The other option is environmental DNA testing. Just as humans regularly shed skin, hair, saliva and other sources of DNA, so do fish. Field researchers can collect a sample of water, filter out all the bits from the water, and send the gunked-up, DNA-laden filter to the lab for testing. These results will indicate the presence of species upstream of where the sample was taken.

Regardless of the type of sample, once it gets to the lab, Woods team uses polymerase chain reactions, also known as PCR, to check for species-specific genetic markers. For reference, this is the same kind of procedure used in the SARS-CoV-2 coronavirus test; Wood says its become a very sexy technique since the patent on PCR expired in the 2000s. And its remarkably precise; if one-tenth of a drop of a fishs DNA solution were mixed into an Olympic-sized swimming pool, Wood said, we would pick it up.

The only technical field that is changing as fast as computers is molecular genetics, so the sort of techniques that we use now are incredibly more sophisticated than when I was in graduate school, and I find that really fun, Wood said.

Theoretically, this could happen all in the field, but Wood says that it requires a lot of coordination, because you dont keep wild fish outside of their water body for very long. More often, its an iterative process between the lab and the wildlife managers testing the waterway, analyzing the results for the percent purity for individual fish or the population at large, then removing or restocking fish as needed, and doing it all over again.

Though Pisces was not directly involved with last months rotenone treatment, it has generally worked on identifying species in the Upper Sand Creek Lake drainage. In 2015, Woods team found evidence that the drainage had native Rio Grande cutthroat trout that were hybridizing with other subspecies, including Yellowstone cutthroat, greenback cutthroat and Colorado River cutthroat.

Wood called CPWs attitude on restoring native species enlightened, especially when compared to previous practices. Much of the 20th century was spent stocking the states waterways with outside fish such as rainbow trout, which are especially susceptible to whirling disease; when that struck the state in the 1990s, the rainbow trout population quickly spread it to other fish species, including native cutthroats. And this wasnt just in one or two rivers; in the process of moving fish around from waterway to waterway, stocking and other efforts inadvertently introduced the disease to 15 of the 17 hydrographic drainages in the state.

Along Sand Creek, the CPW found ponds on private property that harbored the parasites that transmit whirling disease. But the ponds were removed with stimulus funds during the Great Recession. Since they qualified as gravel pits, they could be remediated as abandoned mines. The whirling disease went away and the reintroduction plans moved forward.

Humans, when we mess with ecology, we generally make a mess, Wood said. So its probably philosophically better to do less interventions and strive to maintain whats there than presume that were smarter than Mother Nature.

That said, its not like leaving the river to rebound on its own would work. Part of it has to do with the different life cycles of fish species: brook trout, for example, spawn in the fall, giving them a full six months head start to grow before cutthroats spawn in the spring. And while rainbow trout spawn in the spring, like cutthroats, Wood notes that the jurys still out as to the impact of the two species interbreeding freely.

In other words: humans made this mess, and only humans can clean it up.

We now know more about genetics, we can discern finer level details, we have a longer history of how our attempts to alter ecologies tend not to work very well, so lets see if we can remediate some of the damage that weve done, Wood said.

In June, weeks before implementation of the first phase of the Rio Grande cutthroat project began, the CPW declared a fish emergency public salvage in the Sand Creek drainage. That tactic, which allows anglers to catch an unlimited number of fish from the waterways, has been used more times this summer, for a variety of reasons, than in the past 10 years.

On this occasion, the CPW wanted to let anglers help make best use of the fish before the chemical rotenone was administered to kill any that remained.

Alves, of the CPWs Southwest Region, noted that removing the bag limit seemed to be a particularly effective strategy in the lakes.

Get enough anglers out there, he said, they do a pretty good job.

The rest is left to rotenone, a plant-based compound effective only on gill-breathing organisms primarily fish and insects. The CPW workers secured the necessary permissions and trained to use it. During the first week of September, they began the process in the two high mountain lakes and the creeks below up to a point where waterfalls along Sand Creek provide a natural barrier to fish migration. Phase 2 of the operation will involve clearing Sand Creek from below the waterfalls to the Great Sand Dunes.

A helicopter from the Colorado Division of Fire Protection and Control had been busy fighting wildfires, but eventually was freed up to transport boats, motors, pumps and the 5-gallon buckets of rotenone itself to the lakes. Workers mixed the chemical with water. It was administered from a boat throughout the lake, in volumes dictated by the waters depth. The mixture shaded the water slightly white, a change that diminishes within several hours.

To apply rotenone to streams, workers spread out drips that added the rotenone/water solution to the flow every 15 seconds. A four-hour drip produced the desired solution throughout the streams.

The chemical works quickly. At one of the drip stations, Alves noticed that as soon as the organic green dye marker reached him from a drip point upstream, fish started dying. Workers also sprayed backwaters where fish might be lurking.

Rotenone, though extremely toxic to fish and some insects, is harmless to man and all warmblooded vertebrates, according to the journal Nature. Alves notes that it breaks down quickly in streams, but in lakes, at a water temperature of 50 degrees, takes about 28 days to decompose.

Then, the waiting begins. The dead fish decompose and, if all goes perfectly, the waterways will be clear for stocking. First, the water is tested environmental DNA sampling comes in handy here to make sure no fish survived that could taint the reintroduction of the native Rio Grande.

Youve got to wait and see,Alves said. Well do a lot of sampling, electrofishing in the streams, gill netting in the lakes, probably use environmental DNA, and test to see if there are genetic markers. We use that as a confirming tool.

If any fish remain, CPW will come back and repeat the process.

If theres zero live fish, Alves said, well start to restock in the fall.

Typically, CPW uses airplanes to stock the high mountain lakes. Workers on foot or on horseback, and sometimes by helicopter, stock the streams. By stocking fish in a variety of age groups, managers can hasten the turnaround.

The Sand Creek drainage, with its hiking trails and beautiful vistas, is a highly used area, Alves said. Though remote, its only about an hour-and-a-half hike in from the trail head. What he wants people to understand is that what the CPW is doing is definitely the right thing. Yes, the fish are all gone but thats only temporary.

As soon as we can, well put in Rio Grande cutthroat trout, really a pretty fish, growing to the same size theyre used to catching, a 15- or 16-inch fish, he said. So theyre temporarily losing their opportunity, but itll come back. I predict within five years, theyll see really good cutthroat trout in the lakes.

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Kill fish to save fish: Behind Colorado's effort to revive the Rio Grande cutthroat trout - The Colorado Sun