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<br />December 2008
<br />
<br />Ll b b4
<br />
<br />Notes
<br />
<br />529
<br />
<br />THE NONNATIVE IOWA DARTER (ETHEOSTOMA EXILE) ESTABLISHED IN
<br />THE YAMPA RIVER, COLORADO, AND GREEN RIVER, UTAH
<br />
<br />CAMERON D, WALFORD* AND KEVIN R. BESTGEN
<br />
<br />Larval Fish Laboratary, DefJa1tment af Fish, V/ildlife, and Canservatian Bialagy, Calarada State University,
<br />Fort Callins, CO 80523
<br />*CorresfJandent: cameran. walfard@calostate,edu
<br />
<br />ABsTRAGr-The Iowa darter (Etheostoma exik) was first captured in Little Yampa Canyon, Yampa River,
<br />Colorado, by electrofishing in autumn 2003, and abundance of this nonnative species increased during
<br />2004-2007. The Iowa darter also expanded downstream 229 river km, based on captures of young fish in
<br />a drift net at the confluence of the Yampa and Green rivers in 2005, and in light traps in the Green River
<br />nearJensen, Utah, in 2005-2007, Likely introduction of the Iowa darter via bait-bucket transfer suggests
<br />that additional legal deterrents might be needed to reduce further illicit introductions of potentially
<br />problematic nonnative fishes in the Colorado River Basin.
<br />
<br />RESUMEN-EI Etheostoma exik fue capturado por primera vez en Little Yarnpa Canyon, rfo Yampa.
<br />Colorado. mediante electropesca durante el otorio del 2003, y la abundancia de esta especie no nativa se
<br />incremento durante 2004-2007. EI E. exik tam bien se expandio rfo abajo 229 km, basado en capturas de
<br />peces juveniles en una red de arrd.stre en la confluenciade los rios Yampa y Green en 2005, y en trampas
<br />de luz en el rio Green cerca de Jensen, Utah, durante 2005-2007. La probable introduccion de E. exik
<br />viatraslado de cebo sugiere que elementos disuasivos legales adicionaJes podr;in ser necesarios para
<br />reducir introducciones ilicitas de peces no nativos potencialmente problematicas en la cuenca del rio
<br />Colorado.
<br />
<br />Native distribution of the Iowa darter (Etheas-
<br />toma e:xile) extends north to central Canada, east
<br />to New York, south to central Illinois, and the
<br />species is particularly common in westem Great
<br />Lakes drainages and Iowa (Scott and Crossman,
<br />1973; Lee and Gilbert, 1978). Western popula-
<br />tions are distributed patchily in Colorado,
<br />Wyoming, Montana, and Alberta, perhaps as
<br />glacial reliels. Native in Colorado only in the
<br />South Platte River drainage, the Iowa darter
<br />occurs primarily in small, cool, and dear streams
<br />or vegetated ponds in the Rocky Mountain
<br />foothills or plains, habitat similar to that
<br />occupied in the center of its range (Ellis, 1914;
<br />Hendricks, 1950; Li, 1968; Baxter and Simon,
<br />1970; Scott and Crossman, 1973; Lee and
<br />Gilbert, 1978; Becker, 1983; Propst and Carlson,
<br />1986; Bestgen, 1989). Native populations of the
<br />Iowa darter in Colorado are listed as a Species of
<br />Special Concern by the Colorado Division of
<br />Wildlife. Iowa darters have been collected in
<br />Shadow Mountain Reservoir in the headwaters of
<br />the Colorado River, Colorado, where they likely
<br />were introduced via bait-bucket transfer (Propst,
<br />
<br />THE SOUTHWESTERN NATURALIST 53(4):529-533
<br />
<br />1982; Woodling, 1985). Other records of the
<br />Iowa darter from the Colorado River Basin in the
<br />Dolores and San Juan rivers (Beckman, 1974;
<br />Lee and Gilbert, 1978; the latter may be the
<br />Etheostoma recorded from the Animas River by
<br />Sublette et aI., 1990) arc not supported by
<br />specimens and it likely is not established there,
<br />based on absence of more recent spec}mens
<br />(Woodling, 1985), Historical and recent sam-
<br />pling in the Yampa River, induding that con-
<br />ducted within our study areas as recently as 2001
<br />and with comparable sampling gear, failed to
<br />detect the Iowa darter (Holden and Stalnaker,
<br />1975; R. Anderson, pel's, comm.)
<br />The Yampa River is a tributary to the Green
<br />River, and the Green River is the largest tributary
<br />of the Colorado River in the Upper Colorado
<br />River Basin, Sampling of the Yampa River
<br />occurred in three areas, The most upstream
<br />reach, Little Yampa Canyon (river Ian 161-200,
<br />just downstream of Craig, Colorado), and the
<br />intermediate reach, Lily Park (river Ian 80-89),
<br />were sampled with an electric seine (10 m long,
<br />2 kW generator). The most downstream site on
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