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Federal Register / Vol. 86, No. 167 / Wednesday, September 1, 2021 / Proposed Rules
TABLE 2RESERVOIR POPULATION COLLECTIONS BASED ON TVA BENTHIC TRAWLS, 20162019 Continued Reservoir
Population score number collected
Kentucky

I Low 0 I

Age classes
Evidence of reproduction 0

Reproduction score
I No

N/A

Overall resilience Not established.

Age classes based on total length measurements from Hickman and Fritz 1978. Evidence of reproduction is based on capture of juvenile individuals, adults in spawning condition, or multiple age classes Simmons 2019, p. 7.

For the purpose of evaluating the snail darters status, we considered those tributaries that ranked moderate or high as contributing to resiliency.
Because of the limited amount of reservoir sampling that has been completed, we considered those reservoir populations that had evidence of reproduction present as permanent, independent populations Simmons 2019, p. 2 that contribute to resiliency.
We, therefore, considered 7 reservoir populations Fort Loudoun, Watts Bar, Chickamauga, Nickajack, Guntersville, Wheeler, and Pickwick and 10 tributary populations Holston, French Broad, Little, Hiwassee, Ocoee, Sequatchie, Paint Rock, and Elk Rivers, and South Chickamauga and Bear Creeks as contributing to species resiliency. We did not count Wilson Reservoir or Kentucky Reservoir toward resiliency because snail darters had never been collected there despite trawling efforts.
While Watts Bar is only represented by three juveniles, their collection far from any large tributaries is evidence of reproduction within the reservoir. We did not consider Citico Creek, Big Sewee Creek, Flint River, or Shoal Creek as contributing toward resiliency either, because the species had not been collected there within the analysis period, despite multiple efforts Big Sewee Creek, Citico Creek or because a single snail darter had been found on only one occasion Shoal Creek, Flint River and we considered the populations to be not established in those locations see Table 1, above.

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Analysis of Redundancy and Representation With discoveries of new tributary and reservoir populations, the known redundancy and representation of the snail darter has expanded during the analysis period. When we listed the species 40 FR 47505; October 9, 1975, it had very low redundancy and representation because only one population was known from several miles of the Little Tennessee River, in the Ridge and Valley physiographic region. Currently, the species is known across more than 400 miles 640 km of the Tennessee River Valley, with
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moderately to highly resilient populations in 9 tributaries and 7
reservoirs, providing a level of redundancy that helps shield the species from localized stochastic events.
While we do not have population genetic data for the snail darter, we can look at the species ability to adapt to changes in the environment representation by looking at its distribution across a range of habitats and physiographic regions. Resilient populations are currently known from streams ranging in size from mid-sized creeks to the large Tennessee River itself, with collections in depths ranging from less than 3 ft 1 m to 25 ft 7.6 m.
These populations occur in reservoirs and tributaries with these conditions in four different physiographic regions Ridge and Valley, Cumberland Plateau, Highland Rim, and Gulf Coastal Plain.
This wide range of habitat use and geographic distribution helps to demonstrate the snail darters adaptability to changing environmental pressures representation.
Summary of Factors Affecting the Species A recovered species is one that no longer meets the Acts definition of an endangered species or a threatened species. Determining whether the status of a species has improved to the point that it can be delisted or downlisted requires consideration of the same five factors identified above for listing a species. When we initially listed the snail darter as endangered in 1975, the only identified threat influencing its status was the modification and loss of habitat and curtailment of range Factor A caused by the completion of Tellico Dam and the flooding of the entire known range of the species. When we reclassified the species as threatened in 1984, we evaluated a more complete list of factors based on improved knowledge of the snail darters range and life history. These factors included threats to habitat such as shipping activities in the mainstem Tennessee River, impacts from development in some of the tributaries such as South Chickamauga Creek, threats from agricultural runoff and channelization in streams like the
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Elk River, impacts from coal mining in the Sequatchie River watershed, and chemical spills in the Hiwassee and Ocoee watersheds Factor A; excessive collection associated with the notoriety of the species Factor B; and protections afforded the species by State and Federal laws Factor D. The following analysis evaluates these previously identified threats, any other threats currently facing the species that we have identified, as well as any other threats that are reasonably likely to affect the species in the foreseeable future.
To establish the foreseeable future for the purpose of evaluating trends in the threats and the species responses, we analyzed trends from historical data on distribution and abundance, ongoing conservation efforts, factors currently affecting the species, and predictions of future climate change. When combined with our knowledge of factors affecting the species see discussion below, available data allow us to reasonably predict future conditions, albeit with diminishing precision over time. Given our understanding of the best available data, for the purposes of this proposed rule, we consider the foreseeable future for the snail darter to be approximately 30 years. We determined that we can reasonably predict the threats to the species and the species response during this timeframe based on climate vulnerability assessments through 2050, the planning horizon of the reservoir release improvement program RRIP, and enough time for the species to respond based on biology and lifespan.
As noted above, when the species was downlisted 49 FR 27510; July 5, 1984, the reclassification rule identified additional threats to habitat in the additional populations established or discovered since listing 40 FR 47505;
October 9, 1975. These included threats from shipping activities in the mainstem Tennessee River, impacts from development in some of the tributaries such as South Chickamauga Creek, threats from agricultural runoff and channelization in streams like the Elk River, impacts from coal mining in the Sequatchie River watershed, and
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