In the high alpine streams and creeks of the South Platte Basin, the Greenback Cutthroat Trout (Oncorhynchus clarki stomias) once thrived.

Evolving over two million years from other Oncorhynchus species that migrated through the Columbia and Snake River basins to the Green and Yellowstone River basins, the Greenback Cutthroat emerged as a small but resilient subspecies.

However, the past 20,000 years have marked a crucial chapter in its history, as a population survives the changing conditions of the Continental Divide during the recent ice age, which gave rise to the greenback cutthroat we know today.

Evolutionary Journey and Controversies:

The cutthroat trout's evolutionary journey spans millions of years, with migrations shaping its genetic diversity.

A pivotal moment in its evolutionary trajectory occurred approximately 20,000 years ago, during the final chapters of the last ice age. It was then that a resilient population survived the challenging terrain, and changing landscape of the Continental Divide giving rise to the unique genetic lineage we now recognize as the Greenback Cutthroat Trout.

Over the millennia, the process of adaptation and survival, finely tuned through natural selection, sculpted a species intricately connected to the alpine streams of the South Platte Basin.

However, controversies surrounding the native range of the greenback cutthroat have added complexity to its conservation story. While long believed to be native to the South Platte and Arkansas River basins, recent research speculates that the greenback cutthroat may have been exclusively native to the South Platte River basin, with the yellowfin cutthroat trout inhabiting the Arkansas River basin

As we discuss the controversies surrounding its native range, I can’t help but think how we are peeling back layers of the species' evolution, uncovering a story in adaptation, and survival, against the changing landscapes and shifting habitats of today’s world.

Historical Decline and Human Impact:

In the late 19th century, the Greenback Cutthroat Trout, once thriving and very common in the South Platte basin, faced the arrival of miners and settlers, which quickly led to a massive decline in their population.

As the settlers ventured into the region, the balance between this species and its environment was severely disrupted, initiating a chapter of challenges that would shape its conservation narrative today.

The mining activities that were done in those times have cast a long shadow over the alpine streams of the South Platte Basin. Sediment and toxic runoff from mining operations tainted the pristine waters that the Greenback Cutthroat had called home for centuries.

The consequences of this man-made environmental upheaval were profound, as the trout have struggled against the effects ever since.

Simultaneously, water diversion for agricultural purposes compounded the challenges faced by the Greenback Cutthroat. The redirection of water flows, initially intended to support crop cultivation, unwittingly led to alterations in the natural course of streams and rivers.

Drying many waterways completely with 100% fish kills in those systems. These changes disrupted the balance of the ecosystems, changing the environment forever and further diminishing the available habitats for the Greenback to thrive.

Overfishing added another layer, as settlers sought to capitalize on the abundance of the fish in the river systems, and indiscriminate fishing practices depleted populations that had once flourished.

The convergence of mining, water diversion, and overfishing created a perfect storm of pressures that pushed the Greenback Cutthroat to the brink of extinction. The human impact on this once-abundant species serves as a reminder of the balance between human activities and ecosystems.

Non-Native Intruders and Hybridization

The Greenback faced a significant challenge with the introduction of non-native species. The arrival of brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and rainbow trout (Oncorhynchus mykiss) initiated a complex interplay of interactions, further complicating the survival of the Greenback Cutthroat.

Among the introduced species, brook and brown trout emerged as fierce competitors, consuming the resources within the same ecosystems as the greenback This competition added strain to the native trout, disrupting established hierarchies and altering the dynamics of the fish in the streams.

The challenges didn't end there. Rainbow trout, in particular, posed a unique threat through hybridization. The genetic intermingling of rainbow trout with the Greenback Cutthroat gave rise to hybrid offspring known as cutbows.

To exacerbate matters, additional subspecies of cutthroat trout were introduced into the habitats of the Greenback. This influx of diverse genetic material through hybridization not only diluted the distinct characteristics of the Greenback Cutthroat but also contributed to the overall decline in populations.

The introduction of non-native species has proven to be a significant hurdle in the conservation initiatives aimed at restoring the Greenback Cutthroat Trout to its once-prominent native status.

Advancing the Recovery Effort:

The journey toward the restoration of the Greenback Cutthroat Trout has been both intricate and demanding. A pivotal moment in this journey was in 2013 when a group of geneticists from the University of Colorado achieved a groundbreaking discovery.

They pinpointed a small population of cutthroat trout residing in Bear Creek, near Colorado Springs, as the authentic and unaltered "true" lineage of the Greenbacks.

Armed with this newfound clarity, the Greenback Recovery Group partners embarked on a resolute mission. Their efforts focused on establishing a resilient broodstock comprised of the genuine Greenback Cutthroat, meticulously ensuring the preservation of its unique genetic identity.

Beyond this step, the Greenback Recovery Group initiated a strategy for the identification and restoration of suitable streams. The resilience of the Greenback Cutthroat Trout and the dedication of those involved in its recovery efforts stand as beacons of hope in the landscape of conservation science.

Navigating Conservation Amidst Complexity:

Undertaking the conservation effort of the Greenback Cutthroat Trout unfolds as a confusing endeavor set against its evolutionary history and the multifaceted challenges it faces. The mission requires an approach that extends beyond traditional conservation measures, acknowledging the intricate web of factors influencing the species.

Conservation initiatives must figure out the complexities posed by habitat degradation, overfishing, and the introduction of non-native species, recognizing the interconnected nature of these challenges. Strategic interventions aim not only to restore the habitat but also to address the delicate balance disrupted by human activities.

The conservation unfolds as a dynamic process that will involve habitat enhancement, removal of non-native species, and restoration of streams to ensure a suitable environment for the greenback cutthroat to thrive.

The collaborative efforts of the Greenback Recovery Group, state and federal agencies, NGOs, and local communities stand as a testament to the collective commitment to preserving this unique subspecies.

Closing the Conservation Chapter:

The conservation saga of the Greenback Cutthroat Trout unfolds with the threads of evolution and human influence.

In preserving this living legacy, we encounter not merely a quest to save a species but a commitment to honoring our natural heritage. As we confront the challenges inherent in this conservation journey, the Greenback Cutthroat Trout emerges as more than a trout It stands as a symbol of resilience in the face of adversity,

The ongoing conservation endeavors dedicated to this species strive not just for its survival but for the perpetuation of its presence in the alpine streams of Colorado, for generations to come.

For more info on the Greenback Cutthroat go check the links below

Western native trout:

https://westernnativetrout.org/what-are-western-native-trout-and-char/greenback-cutthroat-trout/

Colorado Parks and Wildlife:

https://cpw.state.co.us/learn/Pages/ResearchGreenbackCutthroatTrout.aspx

Colorado Outdoors Magazine :

https://coloradooutdoorsmag.com/2022/09/26/greenback-cutthroat-trout-naturally-reproducing/

Greenback Recovery Group:

https://coloradotu.org/greenback-cutthroat-recovery-efforts