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<br />Arizona Game and Fish Department <br />Draft EA: Kanab Ambersnail <br /> <br />June 1998 <br />Page 3 <br /> <br />et al. 1997a), They are most abundant under fallen cattail stalks, decadent monkeyflower litter, or <br />young watercress (USFWS 1995), <br /> <br />Biology. KASs have an approximately annuallifecycle, and reportedly live 12-15 months (Clarke <br />1991), They emerge from winter hibernation in early spring with the onset of warm weather, and <br />begin reproducing throughout the late spring and summer months, Peak reproduction typically <br />occurs in the late summer (July-August), when densities of mature KASs are highest. A seasonal,' , <br />decline of KASs occurs in early fall with gradual die-off's of mature individuals, while young KASs <br />go into winter donnancy (Stevens et al, 1997a), KASs are hermaphroditic, possessing both male and <br />female sex organs (Pi1sbry 1948), Young snails develop from gelatinous egg masses attached to wet <br />plant litter, leaves, or stems, Fully mature KASs can have shell lengths up to 20 mm, <br /> <br />Threats to KAS Existence. The Utah population (Three Lakes; 3L) is threatened by habitat loss and <br />possible extirpation by planned commercial development (USFWS 1995), The VP population is <br />threatened by habitat loss and incidental take from high flow water releases from Glen Canyon Dam <br />(USFWS 1995), This population experienced habitat loss and incidental take during an experimental <br />45,000 cfs (\275 m3/s) stage BHBF in March 1996 (Stevens et al, 1997a, 1997b), BHBFs are <br />controlled floods from Glen Canyon Dam designed to redistribute sediments from the channel bottom <br />to the river banks. Natural disturbances to VP may also threaten the KAS population, The talus slope <br />upon which KAS reside at VP was created in the past by an unknown number of debris flows from <br />an ephemeral wash that exits above the VP spring orifices, and future flows could negatively impact <br />the VP KAS population, <br /> <br />Interagency KAS investigators have identified two potential biological threats (both naturally <br />occurring at VP) that may aff'ect KAS, Deer mice (Peromyscus spp,) are suspected to be KASs <br />predators (Stevens et al, 1997b), The parasitic trematode (flatworm) in the genus Leucochloridium <br />may be another biological threat to individual KASs, Neither of these biological threats are <br />detrimental to VP KAS at the population level, based on information gathered to date, The deer <br />mouse population at VP is relatively small, ,and there are numerous other invertebrate prey species <br />available to the mice, The trematode parasite is naturally occurring in succineid snails, it is present <br />in both Utah and Arizona populations ofKAS (pers, comm, V, Meretsky), Based on interagency <br />studies (1995-1997), Leucochloridium is estimated to be present in <10% ofVP KAS (Stevens et <br />al, 1997a, 1997b; IKAMT 1998), <br /> <br />Ecological Studies. The USFWS 1994 Biological Opinion on the operation of Glen Canyon Dam <br />required that the VP KAS population and habitat be quantified, The 1996 Biological Opinion <br />specifically addressed the incidental take of VP KAS and habitat loss from the March 1996 <br />experimental BHBF. An interagency teall;l,of researchers began ecological studies on KAS at VP in <br />1994 and continued monitoring through 1997, Representatives of the following agencies/institutions <br />participated in Kanab Ambersnail Working Group (KAWG) activities: AGFD, Grand Canyon <br />Monitoring and Research Center (GCMRC), National Park Service (NPS), Northern Arizona <br />