In Native Trout of North America, Robert Smith relates that the University of California, Davis “turned up strong evidence of Lahontan cutthroat ancestry and a unique allele found only in Alvord Trout. There was also evidence of an ancient rainbow influence dating back thousands of years—strange echoes of the past indeed” (Trout of the Alvord Basin; pg. 48).
He then offered the thought that there may have been a headwater transfer of redbands from pluvial Lake Catlow as an explanation.
Where the Alvord cutthroat trout is concerned, relevant questions may arise from the pluvial past. The prospect of a genetic legacy that originates from more than one source population may add complicating factors for the analysis of and understanding of this rare form of cutthroat trout.
Yet known geological history may help shed some light on the pluvial past of the Alvord Basin, and upon inter-basin connections that could account for unusual genetic findings; as well as show just how unique the Alvord cutthroat trout may be in the historical placement of trout in North America.
In Ellen Bishop’s book In Search of Ancient Oregon, she explains that many uplifts (that have become formidable mountain ranges today) developed after some strains of trout had already experienced (regional) differentiation. The basin and range was at one time flatter, and its waterways very different than we find them today. The isolated basins that we see today were not necessarily isolated basins during these earlier periods (pages 184-185).
In a geological abstract (thanks to Ellen Bishop for the information) that may be found at http://www.wou.edu/las/physci/taylor/g407/carter_etal_2006_macnab.pdf, the author states: “At least one large, late Pleistocene flood traveled into the Owyhee River as a result of a rise and subsequent outburst from pluvial Lake Alvord in southeastern Oregon. Lake Alvord breached Big Sand Gap in its eastern rim after reaching an elevation of 1292 m, releasing 11.3 km of water into the adjacent Coyote Basin as it eroded the Big Sand Gap outlet channel to an elevation of about 1280 m. The outflow filled and then spilled out of Coyote Basin through two outlets at 1278 m and into Crooked Creek drainage, ultimately flowing into the Owyhee and Snake Rivers….”
The author goes on to state: “Well-developed shorelines of Lake Alvord at 1280 m and in Coyote Basin at 1278 m suggest that after the initial flood, post-flood overflow persisted for an extended period, connecting Alvord and Coyote Basins with the Owyhee River of the Columbia River drainage….” (emphasis mine in this paragraph)
A question then is: Could this extended period of overflow allow for genetic influence from trout strains of the Snake and Columbia River Basins to have affected the Alvord Basin?
The ancient scars of that overflow from the Alvord Basin through the Coyote Basin and into Crooked Creek are still visible today via Google Earth. Yet there are also scars to the north, which from a layman’s perspective would indicate potential for an outlet at the north end of the Alvord Basin, near present-day Mickey Basin (which also drained into Crooked Creek, but from the northern channel rather than the southern channel).
So, “once upon a time” the Alvord Basin was not, technically, a closed basin. And there was a prolonged time span connection between the Great Basin and the Columbia Basin. Which could explain the thousands of years old redband genetics found in Robert Smith’s Alvord.
It is true that a headwater transfer is also geologically possible. Yet since there indeed was overflow for an extended period from the Alvord Basin into the Snake River Basin (on into the Columbia Basin) are there other possibilities this prolonged inter-connection time span might indicate?
In Trout and Salmon of North America, on pages 170-171, Robert J. Behnke expounds in remarkable detail regarding remnants of cutthroat trout in the Snake and Columbia River systems and of the probable elimination of Yellowstone cutthroat trout in the lower Snake and Columbia Rivers by rainbow trout; and the eventual replacement in some tributaries by Westslope cutthroat trout.
If remnants of Yellowstone cutthroat trout were salted throughout the lower Columbia and Snake River plateaus, and if remnants of Westslope cutthroat trout also found their way to these basins (as is known that they did), one might wonder what other ‘secrets’ the whole genome of the Alvord cutthroat trout might reveal.
© KOD 5-2011