Native and Non-Native Fish Species in the Willamette River Basin, Oregon

The Willamette River Basin, Oregon, supports native fish species and non-native fish species introduced for sport fisheries or accidentally from aquarium releases and other sources. Based on fish surveys completed from 1998 to 2018 by Oregon State University and records from the Oregon State University Ichthyology Collection, the Willamette River Basin has 34 native fish species found upstream of the confluence of the Willamette and Columbia Rivers and 28 non-native fish species. Each native and non-native fish species has its own thermal tolerances and diet, spawning, and vertical preference traits. This means that distributions of native and non-native fishes along the river network are shaped by physical factors (such as water temperature, water depth and velocity, and suitable spawning habitats; Williams, 2014) as well as biological factors (such as available food resources).

This compilation summarizes the: 1) thermal tolerances; 2) diet, spawning, and vertical preference traits; and 3) locations of relative detection frequencies for native and non-native riverine fish species found along the Willamette River network as of 2018. This information is based on fish surveys completed from 1998 to 2018 by Oregon State University, records from the Oregon State University Ichthyology Collection, and thermal tolerances, spawning traits, and diet as adults from the literature (Williams, 2014). Where necessary, USGS added diet and spawning trait information from Frimpong and Angermeier (2013).