Texas_hornshell_SSA_Report_July_2016
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Texas_hornshell_SSA_Report_July_2016
Species Status Assessment Report for theTexas HornshellVersion 1.0Adult Texas homshell from the Black River. New Mexico. Photo by Joel Lusk. U.S. Fish Texas_hornshell_SSA_Report_July_2016h and Wildlife Service.42522U.S. Fish and Wildlife Service Region 2 Albuquerque. NMThis document was prepared by Susan Oetker with assistance from Nathan Allan and the U.S. Fish and Wildlife Service’s Texas Hornshell Listing Decision Team (Adam Zerrenner, Amber Miller. Charrish Stevens. Chris Harper Texas_hornshell_SSA_Report_July_2016. David Hath, Dawn Gardiner. Debra Bills. Debra Hill. Ernesto Reyes. George Dennis. Jacob Lewis. Jennifer Smith-Castro. Ty Allen, and Wally Murphy). WTexas_hornshell_SSA_Report_July_2016
e also received assistance from David Smith of the U.S. Geological Survey.Additionally, valuable peer reviews of a draft of this document were provideSpecies Status Assessment Report for theTexas HornshellVersion 1.0Adult Texas homshell from the Black River. New Mexico. Photo by Joel Lusk. U.S. Fish Texas_hornshell_SSA_Report_July_2016ndangered Species Task Force. We appreciate their comments, which resulted in a more robust status assessment and final report.Suggested reference:U.S. Fish and Wildlife Service. 2016. Species status assessment report for the Texas homshell (Popenaiaspopeii). Version 1.0. July 2016. Albuquerque. NM. Texas_hornshell_SSA_Report_July_2016Texas Homshell SSA Reportii42552Species Status Assessment Report For 1’exas homshell (Popenaias popeii) Prepared by TheU.S. Fish and Wildlife ServiceLTexas_hornshell_SSA_Report_July_2016
XLCl riVL SUMMARYThis species status assessment reports the results of the comprehensive status review for the Texas homshcll (Popenaias popeii (Lea 1Species Status Assessment Report for theTexas HornshellVersion 1.0Adult Texas homshell from the Black River. New Mexico. Photo by Joel Lusk. U.S. Fish Texas_hornshell_SSA_Report_July_2016io Grande drainage in Texas and New Mexico as well as south along Mexican gulf coastal river systems. The species occurs in medium to large rivers, generally in crevices, undercut riverbanks, travertine shelves, and under large boulders adjacent to Bins.To evaluate the biological status of the Texas Texas_hornshell_SSA_Report_July_2016 hornshell both currently and into the future, we assessed a range of conditions to allow us to consider the species* resiliency, redundancy, and reprTexas_hornshell_SSA_Report_July_2016
esentation (together, the 3Rs). Texas honishcll needs multiple resilient populations distributed widely across its range to maintain its persistence iSpecies Status Assessment Report for theTexas HornshellVersion 1.0Adult Texas homshell from the Black River. New Mexico. Photo by Joel Lusk. U.S. Fish Texas_hornshell_SSA_Report_July_2016creases the resiliency of a population to stochastic events. These factors are the amount of fine sediments accumulated in the substrate, flowing water, and water quality. As we consider the future viability of the species, more populations with high resiliency distributed across the known range of Texas_hornshell_SSA_Report_July_2016the species are associated with higher overall species viability.Texas homshell historically ranged throughout much of Mexico, but the species has notTexas_hornshell_SSA_Report_July_2016
been recorded alive in any locations in Mexico since the mid-1980s; collection information has been scant. The species is believed to be extirpated fSpecies Status Assessment Report for theTexas HornshellVersion 1.0Adult Texas homshell from the Black River. New Mexico. Photo by Joel Lusk. U.S. Fish Texas_hornshell_SSA_Report_July_2016resentation currently and into the future by ranking the condition of each population. Rankings arc a qualitative assessment of the relative condition of occupied streams based on the knowledge and expertise of Service staff. as well as published reports.Our analysis of the past, current, and future Texas_hornshell_SSA_Report_July_2016 influences on what the Texas homshcll needs for long term viability revealed that there arc three influences that pose the largest risk to future viaTexas_hornshell_SSA_Report_July_2016
bility of the species. These risks are primarily related to habitat changes: the accretion of fine sediments, the loss of flowing water, and impairmenSpecies Status Assessment Report for theTexas HornshellVersion 1.0Adult Texas homshell from the Black River. New Mexico. Photo by Joel Lusk. U.S. Fish Texas_hornshell_SSA_Report_July_2016ich reduce habitat availability and increase fine sediment accumulation in Texas hornshell habitat. Water contamination is a concern for the population in the Black River. New Mexico. Additionally, a low-waler weir lias been proposed for construction al the downstream end of the Rio Grande - Laredo Texas_hornshell_SSA_Report_July_2016population, which would eliminate al least 25% of the habilal for that population.Texas Homshell SSA Reportiii42552The Texas homshell faces a varietyTexas_hornshell_SSA_Report_July_2016
of risks from loss of stream How. contamination, and inundation. These risks play a large role in the future viability of the Texas hornshell. If popuSpecies Status Assessment Report for theTexas HornshellVersion 1.0Adult Texas homshell from the Black River. New Mexico. Photo by Joel Lusk. U.S. Fish Texas_hornshell_SSA_Report_July_2016ing the species' persistence in Mexico and future water quality, flowing water availability and substrate suitability within the populations, we have forecasted what the Texas homshell may have in terms of resiliency, redundancy, and representation under five future plausible scenarios, in which we Texas_hornshell_SSA_Report_July_2016made the following assumptions about stressors to the populations:-1Status Quo:•Black River - There is a small to moderate water flow reduction due toTexas_hornshell_SSA_Report_July_2016
drought and groundwater extraction, the CCA is not enacted and or is not successful, the Delaware River reintroduction is not successful, and the risSpecies Status Assessment Report for theTexas HornshellVersion 1.0Adult Texas homshell from the Black River. New Mexico. Photo by Joel Lusk. U.S. Fish Texas_hornshell_SSA_Report_July_2016limate change and groundwater extraction.•Rio Grande - Lower Canyons - There is a small to moderate water flow reduction due to drought, groundwater extraction, and management of the Rio Conchos.•Rio Grande - Laredo - The low-water weir is not constructed, water quality declines, and there is s a sm Texas_hornshell_SSA_Report_July_2016all water flow decline.•Mexico - 2 small populations are extant1.-2Conservation:•Black River - The Delaware River reintroduction is successful, the CCTexas_hornshell_SSA_Report_July_2016
A is enacted and successful, the risk of a contaminant spill is reduced, and there is no substantial flow reduction due to drought or groundwater extrSpecies Status Assessment Report for theTexas HornshellVersion 1.0Adult Texas homshell from the Black River. New Mexico. Photo by Joel Lusk. U.S. Fish Texas_hornshell_SSA_Report_July_2016 no flow loss due to drought or groundwater extraction.Species Status Assessment Report for theTexas HornshellVersion 1.0Adult Texas homshell from the Black River. New Mexico. Photo by Joel Lusk. U.S. FishGọi ngay
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