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Federal Register / Vol. 86, No. 156 / Tuesday, August 17, 2021 / Notices
Klamath River, such interbreeding must have also occurred historically at some level, although the rate of interbreeding was not determined and could be lower than is seen now.
In both the OC and the SONCC ESUs, there is therefore strong evidence from GREB1L region markers that interbreeding between spring-run and fall-run Chinook salmon is common, at least for the two watersheds that have been studied to date Rogue River, Siletz River. However, the data do not indicate whether the current levels of interbreeding occurred historically under more pristine conditions. Patterns of random genomic variation indicative of population history indicate that spring-run Chinook salmon in the OC
and SONCC ESUs are, as a group, not substantially reproductively isolated from fall-run Chinook spawning in the OC and SONCC rivers. There is some indication that spring-run Chinook salmon in the Umpqua River may have somewhat reduced gene flow from other OC fall-run and spring-run Chinook salmon populations, but past hatchery practices may have also influenced this result. As a whole, however, the available data indicate that the springrun portions of the OC and SONCC
ESUs are not substantially reproductively isolated from the fall-run populations in the ESUs. Additional genetic sampling of fish throughout the period of migration in multiple populations, especially in the OC ESU, would be very helpful for further evaluating this question.

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Evolutionary Legacy Criterion The early run-timing trait is an important component of diversity within the Chinook salmon species. In particular, the trait allows Chinook salmon to access upstream habitats that are inaccessible to later returning fish in some years. Run time diversity as a whole is also expected to increase viability by broadening the portfolio of traits within a species or an ESU, which leads to increased resilience to environmental variation Quinn et al.
2016. Recent reviews of ESU/DPS
configurations of Chinook salmon Anderson et al. 2018 and steelhead Pearse et al. 2019 support this point, as does a recent expert workshop report Ford et al. 2020 and the original coastwide status review of Chinook salmon Myers et al. 1998. Recovery plans for Chinook salmon ESUs that contain populations with both springrun and fall-run fish also emphasize the importance of recovering populations
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with both life-history strategies Shared Strategy Development Committee 2007;
Dornbush 2013; Pearse et al. 2019.
While recognizing the importance of run-timing variation to species and ESU
viability, Myers et al. 1998 concluded that patterns of genetic variation and patterns of variation for other lifehistory traits indicated that coastal springand fall-run Chinook salmon shared the same recent evolutionary history. Coastal ESUs were identified based on concordant patterns of genetic, life-history, and geographic variation, with run-timing variation considered to be an important element of diversity within ESUs. Subsequent reports of Upper Klamath Trinity River Chinook salmon and Northern California steelhead have reached the same conclusion Williams et al. 2013, Anderson et al. 2018, Pearse et al. 2019.
Recent genetic studies have greatly increased our knowledge of the genetic basis of run-timing variation, but these studies do not change or invalidate the previous conclusion that spring-run and fall-run Chinook salmon in the currently delineated OC and SONCC Chinook salmon ESUs share a recent evolutionary legacy, and they are, on the whole, more genetically similar to each other than to populations in other ESUs.
The two run types display similar characteristics in other life-history traits, and are genetically similar to each other due to a combination of recent common ancestry and ongoing interbreeding. Identifying a spring-runonly Chinook salmon ESU for either the OC or SONCC areas would therefore be inconsistent with our ESU policy, both because of high levels of interbreeding between spring-run and fall-run fish in these ESUs and because spring-run fish, as a group, in these ESUs do not form a distinct evolutionary lineage within the species.
Conclusions on the Evolutionarily Significant Unit Analysis The Panel concluded, and the WCR
concurred, that the best available information indicates that OC and SONCC spring-run Chinook salmon populations do not meet the reproductive isolation and genetic legacy criteria of the ESU Policy. The spring-run phenotype and the springrun variant within the GREB1L
chromosomal region are clearly an important part of the diversity within the Chinook salmon species, but the available data indicate that spring-run Chinook salmon in the OC and SONCC
ESUs regularly interbreed with and
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share a recent evolutionary history throughout the vast majority of their genome with fall-run Chinook salmon in the same rivers.
Final Determination Section 4b1 of the ESA requires that NMFS make listing determinations based solely on the best scientific and commercial data available after conducting a review of the status of the species and taking into account those efforts, if any, being made by any state or foreign nation, or political subdivisions thereof, to protect and conserve the species. We have independently reviewed the best available scientific and commercial information, including the information provided in the petitions and public comments submitted on the 90-day findings 85 FR 20476, April 13, 2020;
86 FR 14407, March 16, 2021, the ESU
configuration review report, and other published and unpublished information, and have consulted with species experts and individuals familiar with the OC and SONCC Chinook salmon ESUs.
Our determination set forth here is based on a synthesis and integration of the foregoing information. Based on our consideration of the best available scientific and commercial information, as summarized here and in the ESU
configuration report, we conclude that OC and SONCC spring-run Chinook salmon populations do not constitute ESUs. Accordingly, OC and SONCC
spring-run Chinook salmon populations do not meet the statutory definition of a species, and thus, OC and SONCC
spring-run Chinook salmon populations do not warrant listing under the ESA.
This is a final action, and, therefore, we are not soliciting public comments.
References A complete list of all references cited herein is available upon request see FOR
FURTHER INFORMATION CONTACT.
Authority The authority for this action is the Endangered Species Act of 1973, as amended 16 U.S.C. 1531 et seq..
Dated: August 6, 2021.
Samuel D. Rauch, III, Deputy Assistant Administrator for Regulatory Programs, National Marine Fisheries Service.
FR Doc. 202117211 Filed 81621; 8:45 am BILLING CODE 351022P

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