HYDROLOGY, HYDRAULICS AND FISH PASSAGE PERFORMANCE OF ARCTIC GRAYLING (THYMALLUS ARCTICUS) AT FISH CREEK, DENALI HIGHWAY NEAR CANTWELL, ALASKA. FINAL REPORT

A two year study of fish passage through the Fish Creek culvert, located at Mile 132.2 of the Denali Highway, was carried out by an interdisciplinary task force. The purposes of this study were: monitor the interaction of the spawning Arctic grayling (Thymallus Arcticus) and the existing culvert, and document variables of watershed hydrology (primarily runoff) and hydraulic behavior of the culvert that may impact fish passage. In summary, Arctic grayling encountered minimal difficulty in passing upstream through the culvert. The major areas of difficulty for the fish were entering the slightly perched culvert and exiting where nonuniform flow rates of movement through the culvert barrel varied from less than a minute to over 80 minutes. Generally, larger fish moved through more rapidly than smaller fish. All fish stayed as close to the boundary of the culvert as possible, and they oriented themselves normal to this boundary; meaning that they were not always swimming in a vertical position.