Alvord Cutthroat Trout, Not Extinct After All?

Alvord cutthroat trout were a subspecies of cutthroat trout native to the Alvord Basin of southeast Oregon that many believe went extinct in their pure form shortly after they were described. At the time they were discovered in the 1930’s, they were already on their way out due to hybridization with introduced rainbow trout. In the 1980’s a few slightly hybridized fish were found in Virgin Creek of northern Nevada and they were subsequently moved to a barren stream in the Jackson Mountains of Nevada so that they could escape further hybridization but these fish didn’t survive and were never seen again.

About Cutthroat

There are 13 recognized subspecies of cutthroat trout that evolved in distinct basins of western North America. Some of the subspecies evolved in large closed basins like the Bonneville Basin that once contained ancient Lake Bonneville or the Lahontan Basin of Nevada that once contained ancient Lake Lahontan. Both of these were essentially inland seas where the fish grew large and preyed on other fish species. Others evolved in riverine environments where they preyed primarily on insects.

After the ice age, many of the large inland seas receded and the cutthroat in these Great Basin sub-basins were relegated to small streams with harsh environments. Some of these these fish can survive temperatures that can reach 80 degrees during the day.

Most of these subspecies evolved without the presence of rainbow trout and, with the exception of coastal cutthroat and portions of the westslope cutthroat population, they readily hybridize with the more aggressive, and introduced rainbows. Many of the inland subspecies of cutthroat have seen drastic reductions in range due to introduction of rainbows and other trout like brook, or brown trout. Water quality issues or diversions have also caused reductions in cutthroat populations and those populations that survive are often only found in small headwater streams or lakes. Because of this, several cutthroat species are protected under the Endangered Species Act.

Cutthroat trout were able to occupy many of the inland sub-basins through a process known as headwater transfer where a stream changes course to flow from one drainage to another. This could happen if a stream flowing off of a mountain side onto an alluvial fan changes course or if a landslide blocks the flow causing it to flow into a neighboring drainage. There is an example of this phenomena just south of Yellowstone National Park where Two Ocean Creek splits and turns into Pacific Creek and Atlantic Creek. Pacific Creek flows into the Snake River while Atlantic Creek flows into the Yellowstone River.

Alvord Cutthroat

Alvord cutthroat were first described in 1934 by Carl Hubbs who traveled around the west with his family collecting trout. He preserved specimens in formalin and these are held by the University of Michigan Museum of Zoology.

The Alvord Basin is a relatively small closed basin in southeast Oregon that once contained a large lake where the cutthroat presumably fed on Gila chub and attained large size. The trout would spawn in the inflowing streams.

After those rediscovered Alvord cutthroat that were transplanted to the Jackson Mountains disappeared, everyone thought that they were truly extinct, but in 2005, Dr Robert Behnke wrote an article in Trout Magazine titled Ivory-Billed Trout where he noted that there were records of Alvord cutthroat being stocked into an unknown stream of a neighboring basin. This transplant took place in 1928, prior to the introduction of rainbow trout into the Alvord Basin leaving open the possibility that another population might exist.

The next summer Dr. Behnke and Oregon Department of Fish and Wildlife sampled a stream in Hart Mountain National Antelope Refuge where they found what appeared to be Alvord cutthroat. The biggest problem was that the Oregon Department of Fish and Wildlife had been stocking the stream with closely related Lahontan cutthroat trout and redband rainbow trout for many years which might be hybridizing with the fish.

To try to save the remaining phenotypic Alvord cutthroat from further hybridization, the Oregon Department of Fish and Wildlife has devised a plan to capture some specimens and raise their progeny in a hatchery where they will be measured and observed to determine whether they exhibit the phenotypic features of known Alvord cutthroat specimens. Once this is determined they will be stocked into a barren stream on the Sheldon National Wildlife Refuge in Nevada.

Unfortunately, since very few preserved specimens exist from the original population, and because they were preserved in formalin which can break down DNA, there really isn’t a genetic baseline to compare this newly rediscovered population to, making it unlikely that we will ever really know for sure whether these are pure, or hybridized Alvord cutthroat. The only way to measure these fish for comparison to other cutthroat or other trout is to look at phenotypic characteristics such as spotting pattern, number of scales along the lateral line, pyloric caeca, or the number of gill rakers. These features vary between the subspecies and if the counts lie within a certain range then it can be reasonably presumed that the fish are mostly pure Alvord cutthroat.

The rediscovery of a population of Alvord cutthroat has been long sought by native trout enthusiasts but few had any hope that any would be found. This is exciting news to many. Native trout enthusiasts hope for the rediscovery of one other subspecies of cutthroat trout, the yellowfin cutthroat of Twin Lakes, Colorado. These fish lived only in Twin Lakes alongside greenback cutthroat but they disappeared under similar circumstances when rainbow trout were introduced. There are reports of some of these fish being taken to Europe for an exposition in Paris but there are no records for where they might have been stocked.

You can read more about the effort to establish a population of Alvord cutthroat a the Kortum of Discovery blog that is dedicated to this subject and deserves some credit for keeping up pressure to find anew home for these special fish.
Truly Good News We’ve All Been Hoping For, For Many Years | Alvord Cutthroat Trout — Phenotype     Remnant Rescue‎ | ‎Restoration Précis.

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