Chinook salmon age, sex, and length analysis from selected escapement projects on the Yukon River

Anecdotal information from fishers along the Yukon River suggests that the length of chinook salmon harvested and the proportion of female Chinook salmon in the run have decreased over time. To determine whether sex composition, size, age, and size-at-age of chinook salmon in spawning escapements have experienced a basin-wide decline over time, we examined escapement data from the Andreafsky, Anvik, Gisasa, Salcha, Chena, and Big Salmon Rivers. The scope of the analysis is limited to a relatively small number of spawning tributaries over a relatively short time period during which both fisheries and environmental changes have occurred confounding the ability to establish the sources of the decreasing size trend in Yukon River Chinook salmon.