The yellowfin cutthroat trout (''Oncorhynchus clarkii macdonaldi'') is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

or variety of the

cutthroat trout The cutthroat trout (''Oncorhynchus clarkii'' clade) is a clade of four fish species of the Family (biology), family Salmonidae native to cold-water Tributary, tributaries of the Pacific Ocean, Rocky Mountains, and Great Basin in North America. ...

, a North American freshwater fish.

Natural history

At the end of the last ice-age boulders and clay moraine blocked off a tributary of the headwaters of the

Arkansas River The Arkansas River is a major tributary of the Mississippi River. It generally flows to the east and southeast as it traverses the U.S. states of Colorado, Kansas, Oklahoma, and Arkansas. The river's source basin lies in Colorado, specifically ...

in what is now the state of

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

. The two

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s which formed were named the " Twin Lakes" by the area's settlers. Both lakes held small greenback cutthroat trout from the early days of the Wild West, but in the mid-1880s reports circulated of much larger trout, up to in weight, with bright yellow fins. Recent research has speculated that the yellowfin cutthroat may have been native to the entire Arkansas River basin, not just Twin Lakes.

Discovery and naming

In July 1889, Professor

David Starr Jordan David Starr Jordan (January 19, 1851 – September 19, 1931) was the founding president of Stanford University, serving from 1891 to 1913. He was an ichthyologist during his research career. Prior to serving as president of Stanford Universi ...

and G. R. Fisher visited Twin Lakes and published their discoveries in the 1891 Bulletin of the

United States Fish Commission The United States Fish Commission, formally known as the United States Commission of Fish and Fisheries, was an agency of the United States government created in 1871 to investigate, promote, and preserve the Fishery, fisheries of the United St ...

. They found both the greenback and what they proclaimed to be a new species the "yellowfin cutthroat". In the species description, published in the 1890 edition of the Proceedings of the United States National Museum, Jordan and Evermann described the fish as follows:

''Color, silvery olive; a broad lemon yellow shade along the sides, lower fins bright golden yellow in life, no red anywhere except the deep red dash on each side of the throat.''

The subspecies was scientifically named ''macdonaldi'' after the US Fish Commissioner, Marshall McDonald. Jordan's specimens were re-examined by the fisheries biologist Robert J. Behnke, who commented, "I have no doubt that Jordan was correct; the yellowfin trout and the greenback trout from Twin Lakes were two distinct groups of cutthroat trout".

Extinction

Until about 1903, greenback and yellowfin cutthroats survived together in Twin Lakes, the populations remaining isolated as both breeders and feeders. The end for the yellowfin cutthroat came soon after the introduction of the

rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributary, tributaries of the Pacific Ocean in North America and Asia. The steelhead (sometimes called steelhead trout) is an Fish migration#Classification, ...

to Twin Lakes. The greenback population interbred with the rainbows, resulting in

cutbow The cutbow (''Oncorhynchus'' sp. × ''mykiss'') is an hybrid (biology)#Interspecific hybrids, interspecific fertile hybrid between rainbow trout (''Oncorhynchus mykiss'') and cutthroat trout (''Oncorhynchus'' sp.). Based on currently accepted tax ...

s, but the yellowfin disappeared completely. The yellowfin is now extinct.

Natural history

Discovery and naming

Extinction

References

Further reading