Yellowstone cutthroat trout

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Yellowstone cutthroat trout

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Salmoniformes
Family:	Salmonidae
Genus:	Oncorhynchus
Species:	O. clarki
Subspecies:	O. c. bouvieri

Trinomial name

Oncorhynchus clarki bouvieri
(Jordan & Gilbert, 1883)

Main article: Cutthroat Trout

The Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri) is a subspecies of the Cutthroat trout (Oncorhynchus clarki) and is a freshwater fish in the salmon family (family Salmonidae) of order Salmoniformes. Though originally found through a large portion of northwest Wyoming and south-central Montana, they have been extirpated from the majority of their native range and strong populations remain only in the Greater Yellowstone Ecosystem, centered on the Yellowstone River within Yellowstone National Park. Populations have been stocked elsewhere, but these are often contaminated with genes from other populations of cutthroat trout and sometimes rainbow trout. The Yellowstone cutthroat trout is a prized game fish, with fly fishing the most popular angling method, since the subspecies feed primarily on insects as adults, unlike brown trout, a European species introduced into much of the cutthroat's range in the late 1800s and early 1900s.

Yellowstone cutthroat can be identified from other cutthroat subspecies by their typically larger black spots, which are clustered towards the tail, and by their typical gray, gold, or copper hues. Spawning males, especially, typically wear golden brown colors. Like all cutthroats, they can be differentiated from rainbow trout by the red, pink, or orange marking beneath the jaw, which give the species its name. Depending on habitat, Yellowstone cutthroat can range from six to twenty-six inches as adults, with six to ten inches common in high-elevation, high-gradient tributary streams and the largest fish found only in lakes or in spawning tributaries that feed lakes or emerge from them, such as the Yellowstone River in Hayden Valley in Yellowstone National Park. As a general rule, in most streams and small ponds cutthroat typically run from ten to eighteen inches as adults, with a weight of one half to two pounds. Before habitat destruction, the threats presented by introduced species, and overfishing, they could run much larger, with fish to over thirty inches reported, especially in the strain present in Heart Lake, in the southeastern portion of Yellowstone National Park. Regardless of habitat, all Yellowstone cutthroat trout require flowing water to spawn successfully, so ponds and lakes must have inlet or outlet streams (or both) for cutthroat to be present naturally, though some are stocked in otherwise suitable lakes in the Beartooth Mountains and elsewhere to provide angling opportunities that otherwise would not be available.

Though their range was originally reduced due to overfishing and habitat destruction due to mining, grazing, and logging, the more pressing current threats to the subspecies are interbreeding with nonnative rainbow trout stocked in the Greater Yellowstone Ecosystem, the illegal introduction of Lake trout into Yellowstone and Heart Lakes in Yellowstone National Park, which prey upon cutthroat trout to fifteen inches in length, and several outbreaks of whirling disease in major spawning tributaries. The recent drought in the area has also made several spawning tributaries run dry in late summer, preventing cutthroat fry from migrating to Yellowstone Lake and making them easy prey for predators such as gulls, pelicans, and others. These threats have significantly reduced cutthroat populations in some areas, primarily Yellowstone Lake and the Yellowstone River immediately upstream and downstream of it, while smaller effects have been felt lower in the Yellowstone drainage, in these locations primarily due to hybridization with rainbow trout, as lake trout and whirling disease are not known to be found below the Upper Falls of the Yellowstone. Currently, the strongest populations of cutthroat are to be found in the Grand and Black Canyons of the Yellowstone River and in the Yellowstone's major tributary in Yellowstone Park, the Lamar River, and in this river's tributaries. Attempts as recently as 2004 by environmentalists to have the U.S. Fish and Wildlife Service place the subspecies on the list of Endangered Species was not approved by the agency, citing evidence that major efforts are already underway to ensure the continued existence of this subspecies. All Yellowstone Cutthroat trout caught within Yellowstone National Park must be released back into the water. Areas outside the national park have slightly different guidelines depending on the location of the stream or waterway.