Klamath River Project - Recovery of Fall-run Chinook and Coho Salmon at Iron Gate Hatchery October 8, 2015 to December 3, 2015

A total of 8,176 fall-run Chinook salmon, (Chinook, Oncorhynchus tshawytscha), entered Iron Gate Hatchery (IGH) during the fall 2015 spawning season from October 8, 2015, through November 25, 2015. Klamath River Project (KRP) staff systematically sampled 1 in every 1 O Chinook, as well as all adipose-clipped Chinook during recovery efforts, for a sample size of 2,343. Scale samples and sex and fork length (FL) data were collected from systematically sampled Chinook. Analysis of the length-frequency distribution for systematically sampled Chinook males indicates that the preliminary cutoff point between grilse and adults occurred at <56 cm FL. Systematically sampled male Chinook ranged in size from 44 to 96 cm FL, and systematically sampled female Chinook ranged from 49 to 89 cm FL. Based on scale age analysis, the Klamath River Technical Team estimated that 2.7% (220) of the run were grilse. Females accounted for 57% (4,643) of the run while males accounted for 43% (3,533). The 2015 Chinook return to IGH contributed roughly 9.8% to the total (Klamath basin) in-river run of 83,846 and 19.0% to the total spawner escapement of 43,125. Based on coded wire tag (CWT) expansion, KRP staff estimated that 82% (6,735) of the Chinook entering IGH during the 2015 season were of hatchery origin.