EAGLE POST 8
Introduction: The Forest Service has begun an exciting new research project in Eagles Nest Wilderness. They will inventory the dwindling native cutthroat trout population (it's found in less than two percent of its historic range) in every stream and lake using new, cutting-edge DNA technology, like that used on the famous TV program, CSI. The aim of the project is to discover and document new populations of genetically-pure, native cutthroat trout, with a long term goal of restoring their numbers and range.
Background: Originally, the only trout in Western rivers was the cutthroat, descended from ancient Pacific species (how they crossed the Continental Divide is anybody's guess). Then, in the 1860s, began the relentless introduction of non-native species (e.g., rainbow, brook, brown...), for anglers' sporting pleasure, marking the beginning of the near-end for the native cutthroat. In fact, cutthroats were reckoned to be extinct in 1937, thankfully incorrectly. Recovery efforts began in the 1950s, and the species moved from endangered to threatened status, although today non-native trout, overfishing, and habitat loss continue to hamper cutthroat recovery efforts.
Unfortunately, it gets worse. A new challenge - global warming - has emerged. Why? Well, the final refuge for cutthroats is found in the highest mountain lakes and streams, because the non-natives don't like the cold waters there. But with global warming, the invaders are moving upstream and hybridizing with the native cutthroats. Whether you find that acceptable or not, the hybrids are turning out to be less fit than their parents, thereby threatening the entire future trout population! (see NPR article)
Monitoring cutthroat populations has traditionally relied on visual observations made directly in the field, which are subject to myriad uncertainties. However, in just the last few years, measurements have been put on more scientific ground with the development of environmental DNA, or eDNA, analysis, which brings the wonders of molecular biology into the wonders of the Wilderness. Analysis of eDNA has been successful in detecting a huge range of plants and animals, both extinct and alive, on land and sea, without having to see them at all in the wild.
It turns out that Eagles Nest Wilderness, especially on Meadow Creek, is a key eDNA study site. Read below how USFS Fish Biologist Matt Grove is using eDNA to assess cutthroat populations on every stream and lake in Eagles Nest Wilderness.
Saving the cutthroat trout with eDNA
By Matt Grove
All animals shed their own DNA into the environment as they lose hair, skin, scales... whatever. This makes it possible for fish DNA to be retrieved from any aquatic environment. Working on a project funded by the Fisheries Program of the Holy Cross Ranger District, I collect these pieces of environmental DNA (eDNA) by pumping ten liters of stream water through a fine filter, then saving the filter with its trapped contents. Back in the office, I freeze the filters, which are later delivered to the lab. The eDNA is then identified using a technique known as PCR, which relies on short stretches of DNA sequences that are unique to each species of trout (more about PCR HERE). With PCR, we can distinguish which trout species are present in the stream based on the presence of the individual species' markers. This technology can be used to discover "lost" populations of cutthroat trout and to identify expanded ranges of existing populations. Because eDNA degrades as it moves downstream, I collect samples periodically along the stream. So far, I've sampled 13 of 31 target streams in Eagles Nest Wilderness.
Why is Eagles Nest Wilderness a preferred study site? It's because of the extensive historic database of trout presence, especially on East Meadow Creek, which allows us to compare results using the new eDNA technology with decades of field observations. So far, we find pretty good agreement between the historic and the eDNA data, and we have also determined that eDNA travels intact for about one-half mile in the streams (which determines how often I take samples).
A recently completed status assessment in the White River National Forest suggests that cutthroats occupy only 14% of their former range. Most of these cutthroats, however, are hybrids with non-natives; genetically pure native cutthroats are found in only one percent of their former range. These are the most remote headwater streams and lakes, isolated from lower reaches by impassable barriers to upstream fish movement. This isolation, though protective in the short term, decreases the probability that native cutthroat populations will persist over longer time periods.
Results of our inventory so far are preliminary, but encouraging. We documented cutthroat trout in three new streams of the 13 that we have sampled in Eagles Nest Wilderness. Naturally, we are hopeful that more populations will be identified in the remaining 18 streams to be sampled.
How will these results be used? They will be a big help guiding our management decisions over the next decade, and beyond. We hope to create a new system of classification of watersheds, one that relies on genetic lineage of the native fish that reside in them. This will guide us to watersheds and even to individual streams that have the potential for native cutthroat restoration, not just in Eagles Nest Wilderness, but across the entire Upper Colorado River Headwaters.
About Matt Grove : In 1998, after being awarded a BS in Zoology from Southern Illinois University, Matt joined the National Park Service, where he worked for seven years on a variety of biological monitoring projects. In 2006, he moved to a new position - lead fisheries technician - with the Eagle/Holy Cross USFS Ranger District. Since then, he has been promoted to Fisheries Biologist. His full title is East Zone Fish Biologist, Eagle/Holy Cross and Dillon Ranger Districts, White River National Forest.
Does Matt enjoy fishing for cutthroats in his spare time? "I pretty much only fish at work with electrofishers.... Other than that I only fish in Florida when I am visiting my family. However, I do enjoy floating down a river and sipping on a cold beer," he says.
Make a difference!
2016 Trail projects:
We spent two long weekends - one at Upper Cataract Lake, and one on Slate Creek - improving trails and campsites. We obliterated a total of 54 illegal rock-ringed campfire pits at lakes.
Day Projects Saturdays: June 4, June 18, July 9
Pack-in weekends (Fri-Sun): July 15-17 and August 12-14. Details
Interested in becoming a Volunteer Wilderness Ranger? Details
We also need volunteers
Details: contact Bill Reed (email@example.com).
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