The National Marine Fisheries Service (NMFS) recently concluded that listing of the Chinook salmon (Oncorhynchus tshawytscha) in the Upper Klamath and Trinity Rivers Basin as threatened or endangered is not warranted. The agency made the 12-month finding following receipt of a petition to list the species in January 2011 from the Center for Biological Diversity, Oregon Wild, Environmental Protection Information Center, and The Larch Company.
In its 12-month finding, NMFS included both spring-run and fall-run Chinook salmon populations in the Klamath River Basin upstream from the confluence of the Klamath and Trinity rivers in the population (referred to by NMFS as the evolutionarily significant unit or ESU) that it evaluated for the purpose of its regulatory determination. NMFS rejected petitioners' contention that spring-run and fall-run Chinook salmon qualify as separate ESUs based on significant and persistent genetic and reproductive isolation resulting from their different run timing.
NMFS also considered hatchery stocks of Chinook salmon to be part of the ESU, finding that "each stock is no more than moderately divergent from other local, natural populations." According to the agency, the decision to include hatchery stocks is consistent with its hatchery listing policy. John Bowman reports that petitioners are reviewing the 12-month finding and evaluating whether the challenge it. (Siskiyou Daily, April 6, 2012).