Study design
We domesticated Chinook salmon from Yellow Island Aquaculture Ltd, an organic salmon farm on Quadra Island, BC, Canada to create a nested breeding design with two sires crossed with one dam (2×1) replicated six times. Eggs were fertilized in October 2019 and the eggs were incubated in replicate cells of vertical stack incubation trays. When the offspring reached the first feeding (March 2020) offspring from replicated incubation tray cells were transferred to 200 L tanks with well water flow of 2 L per minute with continuous aeration with a 16:8 h light-dark cycle. Fish were fed ~3% of their body weight three times per day until October 24th, 2020. At that time, 5 fish per family were moved to new 200 L tanks for a total of 72 tanks (12 (families)*2 (replicates)* 3 (treatments – see below)).