The Effect of Electric Lights Upon the Upstream Passage of Sockeye Salmon Through the University of Washington Fishladder.


P E. Fields




adult, Columbia River, fish ladder, illumination, laboratory study, light conditions, night, salmon, screens, sockeye salmon, steelhead, trout, University of Washington, upstream, upstream passage


A 64 foot approach to the University of Washington fishladder was wired so that electric lights underneath the screen could be turned on and off on alternate nights during the adult salmon runs. The number of salmon ascending the ladder was recorded daily. For sockeye, 42 fish ascended the ladder; none of these came in during the daytime; one came in on the 14 nights when the lamps underneath the screen were burning; and 41 came in on 8 of the 14 nights when the lights were out. These results confirm the findings obtained in six previous studies with all species of downstream migrant Pacific salmon and steelhead trout, i.e. fish avoid areas of high illumination and seek those which are dark. These findings apply to the Columbia River conditions in that the procedures involving the use of lights at the major fishladders there have been found effective in blocking and diverting all species of Pacific salmon in the present series of laboratory studies. It will be difficult to determine what, if any, effect this 'blocking' has upon the Columbia River salmon until experimentation validating laboratory findings is permitted in the major fishladders.

This document is currently not available here.