Oncorhynchus clarki alvordensis Behnke, 2002
Alvord cut-throat trout
Taxonomy & Nomenclature
Last record: before 1920 (before 1934?)
Alvord cutthroat trout are thought to have been hybridized out of existence starting in the 1930's following the introduction of rainbow trout into both known creeks, with only hybrids now known (Williams & Bond, 1983; Tol & French, 1988). However, trout with the "Alvord" phenotype have been caught in Trout Creek since 2006 when Robert Behnke discovered their presence there. As they were historically found there, the persistence of "Alvord" phenotypes amongst the local trout is indicative of a complex evolutionary scenario in which even though some hybridization has occurred amongst different species, either:
- They can distinguish each other readily enough during breeding season, so that even if some fish breed with members of another taxa, the genetic integrity of each taxa is not diminished too much because of this interspecific hybridizing.
- The "Alvord" phenotype, being native to the creek, is better adapted at surviving in that environment and so there has been a strong enough evolutionary pressure to preserve the "Alvord" phenotype. This has the result that natural selection does not care about the "purity" of each fish but only whether they manifest the phenotype most conducive to survival (on average), regardless of which combination or combinations of genes (the "genotype") can indirectly produce that phenotype via protein-building. Just because a fish is a hybrid does not mean that it cannot exhibit the phenotype of only one of its parents (in this case the Alvords). And in fact we would expect in this case if this scenario (#2) is true.
However, even though only the phenotype of Alvord cutthroat trout has been preserved, that is still a major discovery and could pave the way for a breeding back program, selecting only those fish which exhibit the correct meristic counts as originally identified by (Hubbs and Miller, 1948). However, rainbow trout genes were already present in Alvord cutthroats starting in the 1930's, so the meristic counts of Alvord's in the late 1940's would have been compromised at least somewhat. It is therefore necessary, if the possibility a breeding-back program is seriously considered, to examine the original specimens collected from the pre-rainbow trout creeks, if such still exist, or were ever collected for that matter.
Trout Creek, Oregon and Virgin Creek, Nevada, USA
Biology & Ecology
Original scientific description:
Behnke, Robert J. (2002). Trout and Salmon of North America. New York: Free Press.
Hubbs, C. L. and Miller, R. R. (1948). The zoological evidence: correlation between fish distribution and hydrographic history in the desert basins of western United States, pp. 17-166. In: The Great Basin with emphasis on glacial and postglacial times. Bull. Univ. Utah, Volume 38.
Jelks, Howard L., Walsh, Stephen J., Burkhead, Noel M., Contreras-Balderas, Salvador, Díaz-Pardo, Edmundo, Hendrickson, Dean A., Lyons, J., Mandrak, Nicholas E., McCormick, Frank, Nelson, Joseph F., Platania, Steven P., Porter, Brady A., Renaud, Claude B., Schmitter-Soto, Juan Jacabo, Taylor, Eric B. and Warren, Melvin L. Jr. (2008). Conservation status of imperiled North American freshwater and diadromous fishes. Fisheries 33(8): 372-407.
Miller, R. R., Williams, J. D. and Williams, J. E. (1989). Extinctions of North American fishes during the past century. Fisheries 14(6): 22-38.
Tol, D. and French, J. (1988). Status of a hybridized population of Alvord cutthroat trout from Virgin Creek, Nevada, pp. 116-120. In: Gresswell, R. E. (ed.). Status and management of interior stocks of cutthroat trout. Am. Fish Soc. Symp. 4. Bethesda, MD.
Williams, J. E. and Bond, C. E. (1983). Status and life history notes on the native fishes of the Alvord Basin, Oregon and Nevada. Great Basin Naturalist 43: 409-420.