Voglio sapere a riguardo di…

Federal Register / Vol. 86, No. 171 / Wednesday, September 8, 2021 / Rules and Regulations Short and Town Creek watersheds Bearden et al. 2017, p. 31.

jbell on DSKJLSW7X2PROD with RULES

Low Abundance The number of slenderclaw crayfish is currently low, with only two populations and few individuals within each population, which is reflected in the species low resiliency, redundancy, and representation. The current estimated low abundance n=32 and genetic drift may negatively affect populations of the slenderclaw crayfish.
In general, the fewer populations a species has or the smaller the sizes of those populations, the greater the likelihood of extinction by chance alone Shaffer and Stein 2000, p. 307. Genetic drift occurs in all species but is more likely to negatively affect populations that have a smaller effective population size Caughley 1994, pp. 219220; Huey et al. 2013, p. 10. There are only two populations of the slenderclaw crayfish with limited connectivity between those populations, which may have reduced genetic diversity. However, no testing for genetic drift has been conducted for the slenderclaw crayfish.
Synergistic Effects In addition to impacting the species individually, it is likely that several of the risk factors are acting synergistically or additively on the species. The combined impact of multiple stressors is likely more harmful than a single stressor acting alone. For example, in the Town Creek watershed, Town Creek was previously listed as an impaired stream due to ammonia and organic enrichment/dissolved oxygen impairments, and recent surveys documented eutrophic conditions of elevated nutrients and low dissolved oxygen. In addition, hydrologic variation and alteration has occurred within the Town Creek watershed as discussed further in the SSA report.
Low-water conditions naturally occur in streams where the slenderclaw crayfish occurs, and alteration causing prolonged low-water periods could have a negative impact on the reproductive success of the slenderclaw crayfish. Further, connectivity between Town Creek and Short Creek watersheds is likely low due to Guntersville Lake. The combination of all of these stressors on the sensitive aquatic species in this habitat has probably impacted slenderclaw crayfish, in that only four individuals have been recorded there since 2009.
Conservation Actions TMDLs have been developed in Scarham Creek for siltation, ammonia, pathogens, organic enrichment/low
VerDate Sep<11>2014

16:25 Sep 07, 2021

Jkt 253001

dissolved oxygen, and pesticides ADEM 2002, p. 5. Town Creek is currently on the 303d list for mercury contamination due to atmospheric deposition ADEM 2016a, appendix C.
However, a TMDL for organic enrichment/dissolved oxygen has been developed for Town Creek ADEM 1996, entire. Through the 303d program, ADEM provides funding derived under section 319 of the Clean Water Act to improve water quality in the watersheds. In 2014, the Upper Scarham Creek Watershed was selected as a priority by ADEM for the development of a watershed management plan. In Fiscal Year 2016, the DeKalb County Soil and Water Conservation District contracted with ADEM to implement the Upper Scarham Creek Watershed Project using section 319 funding ADEM 2016b, p. 39.
The U.S. Department of Agricultures Natural Resources Conservation Service NRCS National Water Quality Initiative program identified the Guntersville Lake/Upper Scarham Creek in DeKalb County as an Alabama Priority Watershed in 2015 NRCS 2017, unpaginated. This watershed is within the historical range of the slenderclaw crayfish. It is recognized as in need of conservation practices, as it was listed on the Alabama 303d list as impaired due to organic enrichment/low dissolved oxygen and ammonia as nitrogen ADEM 2002, p. 4. The National Water Quality Initiative helps farmers, ranchers, and forest landowners improve water quality and aquatic habitats in impaired streams through conservation and management practices. Such practices include controlling and trapping nutrient and manure runoff, and installation of cover crops, filter strips, and terraces.
Future Condition of the Slenderclaw Crayfish For the purpose of this assessment, we define viability as the ability of the species to sustain populations in the wild over time. As part of the SSA, to help address uncertainty associated with the degree and extent of potential future stressors and their impacts on the needs of the species, the concepts of resiliency, redundancy, and representation were applied using three plausible future scenarios. We devised these scenarios by identifying information on the following primary stressors that are anticipated to affect the species in the future: Nonnative virile crayfish, hydrological variation precipitation and water quantity, landuse change, and water quality. However, having determined that the current condition of the slenderclaw crayfish is
PO 00000

Frm 00057

Fmt 4700

Sfmt 4700

50269

consistent with that of an endangered species see Determination of Slenderclaw Crayfish Status, below, the results of the future scenarios are not material to our decision, and therefore, we are not presenting the results in this final rule. Please refer to the proposed listing and designation of critical habitat rule for the slenderclaw crayfish 83 FR
50582; October 9, 2018 and the SSA
report Service 2018, entire for the full analysis of future conditions and descriptions of the associated scenarios.
Determination of Slenderclaw Crayfish Status We have carefully assessed the best scientific and commercial information available regarding the past, present, and future threats to the slenderclaw crayfish. Section 4 of the Act 16 U.S.C.
1533 and its implementing regulations 50 CFR part 424 set forth the procedures for determining whether a species meets the definition of an endangered species or a threatened species. The Act defines an endangered species as a species in danger of extinction throughout all or a significant portion of its range, and a threatened species as a species likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. The Act requires that we determine whether a species meets the definition of endangered species or threatened species because of any of the following factors: A The present or threatened destruction, modification, or curtailment of its habitat or range; B
Overutilization for commercial, recreational, scientific, or educational purposes; C Disease or predation; D
The inadequacy of existing regulatory mechanisms; or E Other natural or manmade factors affecting its continued existence.
Status Throughout All of Its Range After evaluating threats to the species and assessing the cumulative effect of the threats under the section 4a1
factors, we have determined the slenderclaw crayfish to be endangered throughout all of its range. Our review of the best available information indicates that there are currently two populations of slenderclaw crayfish in low condition occurring across the species historical range in Alabama.
Despite the species being identified at three new sites as reflected by recent increased survey efforts, there is substantial evidence of reduced abundance current estimate of n=32
and presumed extirpation at four historical sites. In the Short Creek population, 28 slenderclaw crayfish
E:FRFM08SER1.SGM

08SER1