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McClane Canyon Mine Expansion and Fruita Loadout Facility Biological Assessment
<br />4.3.3 Bonytail
<br />4.3.3.1 Species Account and Critical Habitat
<br />Status. The bonytail is an exceedingly rare minnow originally native to the Colorado River
<br />system of the western United States and northern Mexico (FWS, 2002c). The bonytail was
<br />listed as endangered by the FWS in 1980 because it had been nearly extirpated from its
<br />historical range (FWS, 1980).
<br />Threats. Primary threats to the bonytail are stream flow regulation and habitat modification,
<br />including coldwater dam releases, habitat loss, and blocked migration corridors, as well as
<br />competition from non - native fish species, pesticides, and pollution (FWS, 20029). The bonytail
<br />is endemic to the Colorado River Basin. The species experienced a significant decline in
<br />abundance, starting around 9950, although the decline was poorly documented. At the time it
<br />was listed, threats to the species included physical alterations (impoundments and diversions)
<br />and chemical changes to habitats and introductions of non - native fish (FWS, 1980). There have
<br />been adverse effects to bonytails and other fish native to the Colorado. River Basin by changes
<br />in river flow regimes, migratory barriers, changes in water temperature; competition and
<br />predation by exotic fish species, parasites, and altered food base (FWS, 1987; FWS, 20029).
<br />Life History, Habitat, Distribution. Bonytails_ are considered big river or mainstem river species,
<br />preferring �poois and eddies of warm, often heavily silted, swift moving rivers; however, they do
<br />occur in reservoir habitats as well (FWS, 2008). Bonytails that inhabit riverine habitats have'not
<br />been observed to spawn; however, spawning appears to occur during late June and early July
<br />at water temperatures of about 18 °C (Vanicek and Kramer, 1969). Apparently, spawning ,occu'rs
<br />over gravel bars in moderately deep water where eggs were deposited randomly, and no- effort
<br />to safeguard the eggs was observed (Vanicek and Kramer, 1969).
<br />Females produce between 1,000 and 17,000 eggs. Eggs begin hatching about 9 hours after
<br />ferblizatidn and alevins remain in'the _graVpi for 48 to 120 hours before emerging. Survival rate
<br />of juveniles is 17 to 38`percent (FWS, .20029). Water temperatures between 68 °F and 70 °F
<br />appear to be optimal for reproduction, incubation, and survival of eggs and newly hatched fry
<br />(FWS, 20029). Water temperatures have decreased due to impoundments within the Colorado
<br />River Basin because colder water from the bottom of impoundments-is released downstream
<br />(FWS, 20029). The FWS has suggested that flooded bottomland habitats that are relatively free
<br />of predators may contribute to successful reproduction and recruitment, and support species'
<br />recovery (FWS; 20029). Viable populations are extremely rare within the Green River drainage
<br />in Utah and are not known within the State of Colorado (FWS, 20029; CDOW, 2007b).
<br />Species Recovery. Recovery goals for the bonytall were released by the FWS in 2002 as an
<br />amendment and supplement to the' 1990 recovery plan. There are two recovery units; the upper
<br />Colorado River Basin, including the Green River and upper Colorado River subbasins,* and the
<br />lower basin, including the mainstem and its tributaries from Lake Mead_ downstream to the
<br />southeriy.International Boundary with Mexico (FWS, 20029). The primary threats to bonytail are
<br />streaniflow' regulation, habitat modification,. predation by non - native fish species, hybridization,
<br />and pesticides and pollutants (FWS, 20029).
<br />The following were identified as needed management actions (FWS, 20029):
<br />• Use hatchery- produced fish to reestablish populations.
<br />• Identify genetic variability and maintain a genetic refuge in a lower basin location.
<br />• Provide and legally protect habitat that provides adequate habitat and sufficient range for
<br />all-life stages to support recovered populations.
<br />• Provide passage over barriers within occupied habitat.
<br />• Investigate options for providing appropriate water temperatures in the Gunnison River.
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