7858

• UCREFRP Catalog Number: 7858
• Author: U.S. Fish and Wildlife Service.
• Title: Draft Greenback Cutthroat Trout Recovery Plan.
• USFW Year: 1995.
• USFW - Doc Type: \
• Copyright Material: NO

publications, Cope stated that the "type locality" of S. etiomias is the Kansas '
River at Fort Riley, Kansas. The Kaneae River, however, has no native trout.
The confusion originated with an Army expedition under the ,command of Lt. F.
T. Bryant, traveling from Fort Ri-ley, Kansas, to Fort Bridgier, Wyoming, and '
back again in 1856. A surgeon, Dr. W. R. Hammond, accompanied the expedition
and made natural history collections; among his collectionsiwere two specimens
of cutthroat trout. The expedition traversed parts of the ~Cansas, North
Platte, South Platte, and Green River drainages in Kansas, Nebraska, Wyoming
and Colorado. Cutthroat trout could have been collected on~1y in the Green
River or South Platte drainages. The problem is that all of the specimens
collected on the expedition were simply labeled 'Fort Riley, Kansas' (the
terminus of the expedition) and shipped to the Philadelphia Academy of '
Sciences, where Cope later saw the cutthroat trout specimens and named Salmo
etomias."
Jordan (1891) redefined etomias and limited its use to the cutthroat trout
native to the South Platte and Arkansas River drainages. Jordan also appears '
to be the first person to use the common name "greenback" for this trout in
the literature. All cutthroat trout are currently placed in the genus
Oncorhvnchus, with the current scientific name of the greenback being
Oncorhvnchua clarki etomias. '
Taxonomy
The cutthroat trout, Oncorhvnchus clarki (formerly Salmo clarki), is a prime '
example of a polytypic species. Trout referred to as O. clarki are found in
both coastal and inland streams from Alaska to New Mexico, and within this
range the species has evolved into numerous subspecies or geographic races. '
Many subspecies undoubtedly are polyphyletic, having evolved directly from
other subspecies rather than (monophyletically) from a centrally localized
stem group. This evolutionary pattern, coupled with the declining abundance
of "pure" inland trout, and extensive hybridization with introduced species '
(e.g. rainbow trout O. mvkiss), has made it difficult to unravel the myriad
systematic problems within inland O. clarki (Gold 1977).
The taxonomy of the greenback cutthroat trout (O. c. etomias) has been ,
described by Wernaman (1973), Behnke (1973, 1979), and Behnke and Zarn (1976).
The following-description of the subspecies is from Behnke and Zarn (1976):
but much overlap occurs in these characters.
Salmo clarki etomias undoubtedly derived via an ancient headwater
"Taxonomic criteria for S, clarki etomias remain tentative due to the '
extreme rareness of pure populations and to the scarcity of ancient
museum specimens. Even so, scale counts (180-230) made from available
specimens consistently exhibit the highest values of any cutthroat trout,
or any trout in the genus Salmo. It may be assumed that extremely high '
scale counts are characteristic of pure populations of S. c. etomias,
with some suggestion that those populations native to the South Platte
Basin may show slightly higher counts than those native to the Arkansas
drainage. The greenback cutthroat trout displays typically lower numbers '
of pyloric caeca and vertebrae than most other subspecies of S. clarki,
transfer of the Colorado River basin to the South Platte River drainage
(and then to the Arkansas River drainage) and for this reason shares many
similarities with the Colorado River cutthroat, S. c. Aleuriticus.
The striking spotting pattern and intense coloration which can develop in '
mature fish are the most diagnostic field characteristics of the
greenback trout. S. c. etomias typically displays the largest and most
pronounced spots of any cutthroat trout. Round to oblong in shape, the
spots appear concentrated posteriorly on the caudal peduncle area. '
Coloration is similar to that found in S. c. pleuriticus and tends toward