Chena River Chinook Salmon Escapement – Phase 5

From 2019 through 2021, this project estimated Chinook and chum salmon by visually counting fish as they pass over a continuous band of white fabric panels strung across the river bottom on the upstream side of the Moose Creek Dam. A DIDSON sonar unit and an ARIS sonar unit were also deployed upstream of the tower site on both sides of the river to insonify the river at all times and record the number of migrating salmon throughout the run. A mixture model was used when necessary to estimate Chinook and chum salmon during extended periods of high water when tower counts cannot be completed. In addition to enumeration, carcasses of spawned-out Chinook and chum salmon were collected during the last week of July through the first two weeks of August to estimate the age, sex, and length (ASL) composition of the escapement.

Escapement monitoring provides the foundation for salmon management in Alaska and this project will provide three additional annual estimates of Chinook salmon escapement and composition for one of the largest spawning systems in the Yukon River drainage. Chinook salmon bound for the Chena River to spawn will be harvested by subsistence users from Alakanuk to Tanana within the mainstem Yukon River and from Tanana to Nenana on the Tanana River tributary. This project will provide inseason information regarding run strength that can be used to make management decisions regarding subsistence harvest opportunities. Furthermore, a continuous series of escapement estimates such as these are critical for evaluating the efficacy of management systems throughout the Yukon River drainage and for refining escapement goals by examining Chinook salmon productivity associated with different levels of escapement and environmental conditions.