Status, Distribution, and Conservation of Native Freshwater Fishes of Western North America

Improved Status of the Endangered Oregon Chub in the Willamette River, Oregon

Paul D. Scheerer

doi: https://doi.org/10.47886/9781888569896.ch9

ABSTRACT Status and trends in the abundance of populations of federally endangered Oregon chub Oregonichthys crameri, small floodplain minnows endemic to the Willamette Valley of western Oregon, were investigated by estimating fish abundance and from extensive fish surveys of 650 off-channel habitats from 1991 through 2004. The recent discovery of previously unknown populations of Oregon chub, some occurring in subbasins where they were presumed extinct, combined with successful reintroductions into suitable habitats have resulted in the improved status of this species. In 1991, eight populations of Oregon chub were known to exist. In 2004, we identified 33 populations of Oregon chub in the Willamette River basin. Ten of these populations, including the two most abundant populations, were introduced. The status of Oregon chub is approaching the recovery plan goal for downlisting the species to threatened. Nonnative fishes, which were found to be widespread in off-channel habitats preferred by Oregon chub, are the largest threat to full recovery and delisting of this species.