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Federal Register / Vol. 86, No. 109 / Wednesday, June 9, 2021 / Rules and Regulations
storms and flooding, and exacerbated drought conditions IPCC 2013, p. 7.
Based on the results of the SLEUTH
slope, land use, exclusion, urban, transportation, and hillshade BAU
model Terando et al. 2014, entire, urbanization in the relevant watersheds could expand to triple the amount of developed area, resulting in large increases of impervious surface cover and, potentially, consumptive water use. Increased urbanization and climate change effects are likely to result in increased impacts to water quality, water flow, and habitat connectivity, and we predict that there is limited capacity for species restoration under this scenario.
In the third scenario, labeled the Optimistic scenario, factors that influence population and habitat conditions of the Neuse River waterdog and the Carolina madtom are expected to be somewhat improved. Reflecting Climate Model RCP 2.6 Wayne 2013, p.
11, climate change effects are predicted to be minimal under this scenario and would not include increased temperatures, and storms or droughts are as set forth in the Status Quo and Pessimistic scenario predictions.
Urbanization is also predicted to have less impact in this scenario, as reflected by effects that are slightly lower than BAU model predictions Terando et al.
2014, table 51. Because water quality, water flow, and habitat impacts are predicted to be less severe in this scenario as compared to others, it is expected that the species would have slightly positive responses. Targeted permanent protection of riparian areas is a potential conservation activity that could benefit these species, and current efforts are considered successful as part of the Optimistic scenario.
In the fourth scenario, the Opportunistic scenario, those landscape-level factors e.g., development and climate change that are influencing populations of the Neuse River waterdog and the Carolina madtom get moderately worse, reflecting Climate Change Model RCP
4.5 Wayne 2013, p. 11 and SLEUTH
BAU Terando et al. 2014, table 51.
Effects of climate change are expected to be moderate, resulting in some increased impacts from heat, storms, and droughts IPCC 2013, p. 7.
Urbanization in this scenario reflects the moderate SLEUTH BAU levels, indicating approximately double the amount of developed area compared to current levels. Overall, it is expected that the synergistic impacts of changes in water quality, water flow, and habitat connectivity will negatively affect both species, although current land
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conservation efforts will benefit the species in some watersheds.
Future Conditions of the Carolina Madtom and Neuse River Waterdog For details regarding the predicted future under each scenario, see chapter 6 of the SSA reports for each species Service 2021ab.
Estimates of future resiliency for the Carolina madtom are low, as are estimates for representation and redundancy. Similarly, estimates of future resiliency for the Neuse River waterdog are moderate to low, as are estimates for representation and redundancy. Both species face a variety of risks from declines in water quality, loss of stream flow, riparian and instream fragmentation, and deterioration of instream habitats, and the madtom is particularly susceptible to predation from the invasive flathead catfish. These risks, which are expected to be exacerbated by urbanization and climate change, were important factors in our assessment of the future viability of the Carolina madtom and Neuse River waterdog. Given losses of resiliency, populations become more vulnerable to extirpation, resulting in concurrent losses in representation and redundancy. Predictions of Carolina madtom habitat conditions and population factors suggest possible extirpation in one of two currently extant populations. The one population predicted to remain extant Tar is expected to be characterized by low occupancy and abundance. Predictions of Neuse River waterdog habitat conditions and population factors suggest possible extirpation in two of three currently extant populations.
Similar to the madtom, the one waterdog population predicted to remain extant Tar-Pamlico is expected to be characterized by low occupancy and abundance in the future.
Determinations of Carolina Madtom and Neuse River Waterdog Status 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 endangered species or threatened species. The Act defines an endangered species as a species that is in danger of extinction throughout all or a significant portion of its range, and a threatened species as a species that is 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
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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.
Carolina Madtom: Status Throughout All of Its Range The historical range of the Carolina madtom included third and fourth order streams and rivers in the Tar, Neuse, and Trent drainages, with documented historical distribution in 11 MUs within 3 former populations, the Tar, Neuse, and Trent. The Carolina madtom is presumed extirpated from 55 percent 6
of the historically occupied MUs. Of the five MUs that remain occupied, one is estimated to have high resiliency, one with moderate resiliency, two with low resiliency, and one with very low resiliency. Scaling up from the MU to the population level, the Tar population is estimated to have moderate resiliency, the Neuse population is characterized by very low resiliency, and the Trent population is presumed to be extirpated. Of streams that were once part of the species range, 82 percent are estimated to be in low condition or likely extirpated. Once known to occupy streams in two physiographic regions, the species has also lost substantial physiographic representation with an estimated 44
percent loss in Piedmont watersheds and an estimated 86 percent loss in Coastal Plain watersheds.
Estimates of current resiliency for Carolina madtom are low, as are estimates for representation and redundancy. The Carolina madtom faces a variety of ongoing threats from declines in water quality, loss of stream flow, riparian and instream fragmentation, and deterioration of instream habitats Factor A. This species also faces the threat of predation from the invasive flathead catfish Factor C. These threats are expected to be exacerbated by continued urbanization Factor A and climate change Factor E. Given current rates of resiliency, populations are vulnerable to extirpation from stochastic events, in turn, resulting in concurrent losses in representation and redundancy.
The current conditions as assessed in the Carolina madtom SSA report show that 55 percent of the management units over three populations river systems are presumed extirpated. The Carolina madtom currently has two of three
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