Wenatchee River Salmon Escapement Estimates Using Video Tape Technology in 1994
Accurate determination of escapement is necessary for analysis of the status of important fish stock. In an effort to evaluate and develop more accurate Pacific salmon escapement estimation technique, a time-lapse video recording system and a computerized counting system were tested. The time-lapse video tape recording system was installed and operated from 11 May 1994 through 29 September 1994 in the fish counting station at Tumwater Dam on the Wenatchee River. This was a continuation of studies conducted annually since 1989. The automated counting system was installed and operated from 22 August 1994 to 14 September 1994.
In 1994, Wenatchee River salmon escapement above Tumwater Dam was estimated to be 7,595 Sockeye Salmon Oncorhynchus nerka and 1,882 for and Chinook Salmon O. tshawytscha. Salmon migratory timing estimates have remained similar from 1989 through 1992. The mean dates of passage for salmon in 1994 were 24 July (SD = 10.3) for Sockeye, and 19 July (SD = 12.5) for Chinook Salmon. Nighttime (2100 to 0500) Sockeye Salmon passage estimates accounted for 10.6% of the run. That percentage is slightly higher than estimates made in previous years at Tumwater Dam and at Bonneville Dam in 1973 and 1974.
Hatch, D.R., D.R Pederson, J.K. Fryer, and M. Schwartzberg. 1995. Wenatchee River salmon escapement estimates using video tape technology in 1994. Columbia River Inter-Tribal Fish Commission Technical Report 95-3. Portland, OR. 38p.