In response to a 2007 petition from the Cowlitz Indian Tribe, the National Oceanic and Atmospheric Administration (NOAA) listed the southern distinct population segment (DPS) of eulachon (Thaleichthys pacificus) as "threatened" under the Endangered Species Act of 1973 (ESA). NOAA's Northwest Fishery Science Center's summary report of eulachon noted: ". . . there is a largely untapped store of knowledge on eulachon residing in the culture and traditions of Native American Indian Tribes and First Nations in Canada. . . ." We interviewed Cowlitz Tribal elders and recorded oral histories of eulachon fishing along tributaries and the mainstem of the lower Columbia River. We also recorded oral histories of non-tribal elders who experienced community traditions of eulachon fishing in the same region. Traditional Ecological Knowledge (TEK) can augment strict biological data and create more holistic and better-integrated understanding of ecological relationships. In this inquiry, tribal oral histories identify timing and distribution of spawning eulachon runs. They do not identify habitat features associated with spawning areas but do reveal physical and behavioral characteristics of returning eulachon. This information may inform or generate new ideas for species- or habitat-related research. This information also supports NOAA and the Cowlitz Indian Tribe's continuing efforts to identify and protect critical habitat, increase abundance of the species, and achieve species recovery. [ABSTRACT FROM AUTHOR]