On February 27, 2018, the National Marine Fisheries Service (“Service”) published a 90-day finding on the Karuk Tribe and Salmon River Restoration Council’s (“Petitioners”) petition to list the Upper Klamath-Trinity Rivers Basin (“UKTR”) Chinook salmon (Oncorhynchus tshawtscha) evolutionarily significant unit (“ESU”) as endangered or threatened. Based on the information included in Petitioners’ filing, the Service found that listing the UKTR ESU as endangered or threatened under the Endangered Species Act (“ESA”) may be warranted.

The Service’s determination follows a prior “not warranted” finding made in 2012, and relies heavily on the continued decline of the spring-run spawning population of the UKTR ESU. In determining that listing the UKTR ESU may be warranted, the Service notes that it may only be warranted based on two factors: (1) disease, and (2) the inadequacy of existing regulatory mechanisms. Specifically, the Service cites the high rate of infection of juvenile Chinook salmon by the lethal parasite Ceratonova shasta, and analogizes its potential population level impact to the population impacts observed in the closely related Klamath River Basin coho salmon which are affected by the same parasite. Moreover, although the Klamath Fisheries Management Council indicated in 2003 that it intended to develop management recommendations aimed at conserving spring-run Chinook salmon, the Petitioners presented evidence that harvest management objectives were not set. Finally, the Service concluded that a 2017 genetic study of spring run and fall run Chinook salmon indicates that spring-run premature migration qualifies UKTR ESU as an evolutionarily significant unit under the Service’s evolutionarily significant unit policy.

The Service’s finding indicates that it is accepting additional information related to its “may be warranted” finding until April 30, 2018.