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2009-02-04_APPLICATION CORRESPONDENCE - C2008086
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2009-02-04_APPLICATION CORRESPONDENCE - C2008086
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Last modified
8/24/2016 3:43:22 PM
Creation date
2/4/2009 2:15:47 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C2008086
IBM Index Class Name
APPLICATION CORRESPONDENCE
Doc Date
2/4/2009
Doc Name
Response to BLM Letter dated 9/15/08
From
Fish and Wildlife
To
BLM
Email Name
MPB
Media Type
D
Archive
No
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bankfull or much larger floods mobilize coarse sediment to build or reshape <br />cobble bars, and they create side channels that Colorado pikeminnow sometimes <br />use for spawning (Harvey et al. 1993)." <br />"Colorado pikeminnow spawning sites in the Green River subbasin have been well <br />documented. The two principal locations are in Yampa Canyon on the lower <br />Yampa River and in Gray Canyon on the lower Green River (Tyus 1990, 1991). <br />These reaches are 42 and 72 km long, respectively, but most spawning is believed <br />to occur at one or two short segments within each of the two reaches. Another <br />spawning area may occur in Desolation Canyon on the lower Green River (Irving <br />and Modde 2000), but the location and importance of this area has not been <br />verified. Although direct observation of Colorado pikeminnow spawning was not <br />possible because of high turbidity, radio-telemetry indicated spawning occurred <br />over cobble-bottomed riffles (Tyus 1990). High spring flows and subsequent post- <br />peak summer flows are important for construction and maintenance of spawning <br />substrates (Harvey et al. 1993). In contrast with the Green River subbasin, where <br />known spawning sites are in canyon-bound reaches, currently suspected spawning <br />sites in the upper Colorado River subbasin are at six locations in meandering, <br />alluvial reaches (McAda 2003)." <br />"After hatching and emerging from the spawning substrate, Colorado pikeminnow <br />larvae drift downstream to backwaters in sandy, alluvial regions, where they <br />remain through most of their first year of life (Holden 1977; Tyus and Haines <br />1991; Muth and Snyder 1995). Backwaters and the physical factors that create <br />them are vital to successful recruitment of early life stages of Colorado <br />pikeminnow, and age-0 Colorado pikeminnow in backwaters have received much <br />research attention (e.g., Tyus and Karp 1989; Haines and Tyus 1990; Tyus 1991; <br />Tyus and Haines 1991; Bestgen et al. 1997). It is important to note that these <br />backwaters are formed after cessation of spring runoff within the active channel <br />and are not floodplain features. Colorado pikeminnow larvae occupy these <br />in-channel backwaters soon after hatching. They tend to occur in backwaters that <br />are large, warm, deep (average, about 0.3 m in the Green River), and turbid (Tyus <br />and Haines 1991). Recent research (Day et al. 1999a, 1999b; Trammell and Chart <br />1999) has confirmed these preferences and suggested that a particular type of <br />backwater is preferred by Colorado pikeminnow larvae and juveniles. Such <br />backwaters are created when a secondary channel is cut off at the upper end, but <br />remains connected to the river at the downstream end. These chute channels are <br />deep and may persist even when discharge levels change dramatically. An optimal <br />river-reach environment for growth and survival of early life stages of Colorado <br />pikeminnow has warm, relatively stable backwaters, warm river channels, and <br />abundant food (Muth et al. 2000)." <br />Population Dynamics <br />Preliminary population estimates presented in the Recovery Goals (USFWS 2002a) for <br />the three Colorado pikeminnow populations (Green River Subbasin, Upper Colorado <br />River Subbasin, San Juan River Subbasin) ranged from 6,600 to 8,900 wild adults. These <br />numbers provided a general indication of the total wild adult population size at the time <br />12
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