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Last modified
1/26/2010 12:49:26 PM
Creation date
10/11/2006 11:37:38 PM
Metadata
Fields
Template:
Water Supply Protection
File Number
8220.101.09
Description
Glen Canyon Dam/Lake Powell
State
AZ
Basin
Colorado Mainstem
Date
2/16/1996
Title
Biological Opinion Summary
Water Supply Pro - Doc Type
Biological Opinion
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<br />~~ID <br /> <br />'~ <br />. ",j,--' <br /> <br />STATUS OF THE SPECIES <br /> <br />,~ i <br />;1 <br />~: ' <br /> <br />Humpback Chub <br /> <br />'t,- <br />~ <br /> <br />The species description, life history, population dynamics, status and distribution are presented <br />in the January 1995 biological opinion and November 1995 biological assessment. Seven <br />reaches of the Colorado River system were designated as critical habitat for humpback chub, for <br />A total river length of 610 kilometers (lem). This represents approximately 28 percent of the <br />historical habitat for the species (U.S. Fish and Wildlife Service 1994a). ,Critical habitat <br />primary constituent elements for the humpback chub were discussed in the 1995 biological <br />opinion. <br /> <br />:';' <br /> <br />t': <br /> <br />"". <br /> <br />Kanab Ambersnail <br /> <br />t," <br />" <br />" <br />:..: <br />,'" <br />:'..l <br />(.: <br />" <br />., <br /> <br />;" <br /> <br />The Kanab ambersnail is a terrestrial snail in the family Succineidae. The shell is dextral (right <br />handed), thin-walled, and a light amber color sometimes with grayish mottling. Mature <br />individuals are between 14 and 19 millimeters (mm) (Pilsbry 1948, Clarke 1991). The Kanab <br />ambersnail is known from three locations of the Colorado Plateau, two areas near Kanab, Utah. <br />and one in Grand Canyon National Park. One of the two Utah populations is believed extirpated" <br />after its habitat was dewatered within the past 10 years. The other Utah population has suffered <br />losses due to flooding, wetland destruction, and livestock trampling (U.S. Fish and Wildlife <br />Service 1995a). The Grand Canyon population is the only one known in a wilderness Setting. <br /> <br />~ <br />~ <br />~ <br />, <br />'..' <br />i)' <br />g:,; <br /> <br />f;;~ <br />!X <br />','. <br /> <br />The Kanab ambersnail was listed under emergency rule in August 1991, and the fmal rule to list <br />the species as endangered was published in April 1992 (U.S. Fish and Wildlife Service 1991. <br />1992). Critical habitat was proposed but not finalized for the larger population in Utah. <br /> <br />~;- <br /> <br />In Arizona, the Kanab ambersnail is found in a single spring-fed wetland habitat named Vasey~ <br />Paradise in the gorge of the Grand Canyon. Dominant vegetation includes the native cardinal <br />monkey-flower (Mimulus cardinalis) (snapdragon family), and nonnative watercress (Naslunium <br />officinaIe). Other common plants in the area are Polygonum (knotweed or smartWeed family I. <br />Carex (sedge family), and poison ivy (Toxicodendron rydbergir). The Kanab ambersnail is vc:ry <br />rarely found on rock surfaces and even then within a short distance from primary vegetation <br />(Stevens et aI. 1995a). Wildlife other than the Kanab ambersnail is limited at this locatio" <br />Canyon wren (Catherpes mexicanus) and Says phoebe (Sayomis saya) have been documc:nlc:d <br />at the Arizona location, but it is not known if they feed on the ambersnail. Ravens (Con 1/.1 <br /> <br />:'i~" <br />,:.-1 <br />1"t1 <br />~;~ <br />~ <br />~~ <br />I <br />y.", <br />~, <br />i~~ <br />~ <br />-Ii <br />~. <br />;~~; <br /> <br />In Utah, the Kanab ambersnail is associated with cattail (Typha sp.) marshes and sedge meadows <br />dominated by Juncus spp. (Clarice 1991, U.S. Fish and Wildlife Service 1995a). Cattails and <br />dense sedge and grass meadows may provide crucial vegetative cover and food resources for the <br />snails. The American robin (Turdus migratorius) has .been observed to feed on the Kanab <br />ambersruill in Utah and may be the largest natural predator in the area (Clarke 1991, U.S. Fish <br />and Wildlife Service 1995a). . <br /> <br />Biological and Conference Opinions Glen Canyon Beach/Habuat.Building Flows 2/16196 <br /> <br />II <br />
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