Comparison of Counting Tower Estimates and Digital Video Counts of Coho Salmon Escapement in the Ugashik Lakes. Alaska Fisheries Technical Report Number 81

摘要

In 2001, the U.S. Fish and Wildlife Service King Salmon Fish and Wildlife Field Office began a counting tower project to estimate coho salmon Oncorhynchus kisutch escapement into the Ugashik lakes using standard protocols developed for sockeye salmon O. nerka. Because the coho salmon run size was much smaller than the sockeye salmon run, there was concern that the standard protocols may be biased for coho salmon. In 2002, we compared escapement estimates of coho salmon obtained from the counting tower using standard protocols to counts obtained from a video camera that recorded images of all fish that passed the site. Over the 152 hours that we sampled using both methods, we counted 478 coho salmon from the video files while the counting tower estimated 426 coho salmon. A sign test indicated a significant difference in the frequency of positive and negative differences between the two methods (Z = 3.53, P