Non-native, invasive or introduced species can outcompete native fish species for food and habitat resulting in a loss of biodiversity, impacts to the food web and loss of economic income. The Willamette River Basin contains 32 non-native or introduced species. Almost half the total list of 67 native and non-native fish in the Willamette River Basin is made up of non-native species.
This indicator measures the ratio of native to non-native fish species in the Willamette River.