This report provides data from the biological tests conducted in December 2004 and January 2005 by Battelle Pacific Northwest Division for the Washington State Department of Transportation at the Culvert Test Bed located at the Washington Department of Fish and Wildlife Skookumchuck Hatchery near Tenino, Washington. The work reported here aimed to determine the leaping ability of juvenile hatchery coho salmon as the fish entered a perched culvert.
Results of the trials showed that entry rate and passage success decreased as outfall drop increased. The dominant behavior used to accomplish entry varied with outfall drop. When overcoming the 0-cm and 12-cm outfall-drop configurations, juvenile coho predominantly used swim-in behavior. For the greater outfall drops of 20 and 26 cm, juvenile coho used leaping behavior for culvert entry. Juvenile coho were not able to successfully overcome the 32-cm outfall drop, which was equivalent to approximately 3 body lengths for the 100-mm coho tested in this study.