Probable causes of the rapid growth and high fecundity of walleye, Stizostedion vitreum vitreum , in the mid-Columbia River

The introduction of walleye, Stizostedion vitreum vitreum , into the Pacific Northwest of the United States is not documented; however, they are now found throughout the mid-Columbia River and downstream of Bonneville Dam (Durbin). The construction of dams has transformed the Columbia River from a free-flowing river into a series of low water-velocity impoundments with physical characteristics that closely match the model for ideal walleye habitat proposed by Kitchell et al. (1977). The authors studied basic life history factors of mid-Columbia River walleye for 2 yr to determine how well these exotic predators have adapted to their new environment. They found that the walleye grew at a rate approaching the highest previously reported, that they were highly fecund, and that they matured at an early age. They evaluated these high growth and reproductive rates against environmental and genetic variables. They believe these data will help to identify the ever increasing role of walleye in the aquatic ecosystem of the Columbia River and similar river-reservoir systems.