A case of mistaken identity

 Since I stated my native trout quest the classification of Cutthroat has seen some rather large changes, which have been primarily driven by an increased understanding of genetics. The first major shake up came with a study published by Metcalf et al. in 2012 and the discovery that what we knew as Greenback Cutthroat were actually Cutthroat from the Colorado River basin. Along with this revelation came another key finding that the Colorado River Cutthroat was actually comprised of three distinct lineages the Colorado River Cutthroat (termed the green lineage as they were originally believed to be Greenback Cutthroat), the Green River Cutthroat (Blue lineage) and the San Juan Cutthroat.

A Green River (Blue lineage) Cutthroat 

For me the initial impact of this discovery was that the Greenback Cutthroat I had caught, were not actually Greenbacks meaning I had yet to catch that subspecies and would have to wait to do so until they had recovered sufficiently. However, this also raised the question of what those “Greenbacks” I had caught actually were, Green River or Colorado River Cutthroat. It turned out that this question did not have a simple answer, as the primary broodstock used to recover the former “Greenback Cutthroat” was drawn from two streams Como Creek and Hunter Creek to raise the genetic diversity. And raise the genetic diversity it did, as Como Creek held Colorado River Cutthroat (Green lineage) while Hunter held Green River Cutthroat. The records I have found do suggest that Como Creek and thus Colorado River Cutthroat were the dominant lineage, but these former recovery populations of “Greenbacks” appear to be Green x Colorado River hybrids.

A Greenback Cutthroat? Nope a Colorado River Cutthroat with some Green River influence 

 

One of the other findings of the Metcalf et al. study was that due to past stocking many of the Cutthroat populations in the upper Colorado River that should Colorado River Cutthroat were actually Green River Cutthroat. For a long time I wondered about what the “Colorado River Cutthroat” I had caught in Rocky Mountain National Park in 2006 were, until recently when I found a map showing the genetics of the known populations. As it turned out the “Colorado River Cutthroat” I had caught were actually Green River Cutthroat, likely Trappers Lake strain from the extensive stocking that occurred over the last century. 

--UPDATE-- As if it wasn't challenging enough to ID Green vs Blue lineage, the most recent inventory of Cutthroat in Rocky Mountain National Park shows that indeed the fish I caught ARE green lineage or actual Colorado River Cutthroat. 

Green lineage Colorado River Cutthroat

For now I have updated my website with to account these mistaken fish, but in just over a week I will be heading to Colorado to hopefully find both the true Greenback Cutthroat. With any luck this trip will be successful and and in two weeks time I will have once again caught all of the extant subspecies of Cutthroat Trout.