DNA extraction methods
Two different DNA extraction methods were used: 1) an organic DNA extraction using a phenol-chloroform based method that avoids pipetting to maximize the integrity of the DNA (Ana Ramón-Laca et al., 2021) and favors the isolation of DNA of high molecular weight; 2) and a mitochondria isolation procedure (see below, Fig 1 and S1) followed by the phenol-chloroform extraction. A chinook salmon (Oncorhynchus tshawytscha ) from the NOAA Northwest Fisheries Science Center hatchery was euthanized and approximately 0.125 cm3 of skeletal muscle (fresh) and liver and heart (frozen at -80ºC) samples were dissected (Table 2). These tissue samples in Longmire buffer were macerated using a TissueRuptor (Qiagen) with disposable probes. DNA was eluted in 100 and 50 µl of TlowE for either extraction method, respectively. Additional methods discarded for the purposes of this study are in File S3. Additional species (Table 2) were also extracted with either one or the two methods and these were eluted in 200 and 100 µl of TlowE, respectively. Wide bore tips were used where required to avoid fragmentation. All DNA extractions were performed in a dedicated genetics laboratory.