Data was uploaded in .xlsx format. Table 1: Size data for sires used in Exp 1: sire effects, Exp 2: strain effects, and Exp 3: transgenotype. River of origin for each male is given along with a unique identifier and fork length (cm). Note that while the same males were used in Exp 2 and Exp 3, SireID is different as the sire is associated with a different family. SireID can be used to match males with offspring in other tables from this dataset. Table 2: Offspring weights (g) and lengths (cm) from Exp 1: sire effects collected on 3 sampling dates. There are two replicates (Group A or B) for each sire. All sires originated from the Chehalis River, BC, Canada. Table 3: Size data for Exp 2: strain effects. Offspring weights (g) and lengths (cm) were collected over 7 sample dates. River of sire origin is given along with the sire ID for each family. Table 4: Size data for Exp 3: transgenotype. Offspring weights (g) and lengths (cm) were collected on 2 sample dates. River of sire origin is given along with the sire ID for each family. Genotype indicates if offspring were transgenic (T) or non-transgenic (NT). Table 5: Density of fish in tanks held as part of Exp 2: strain effects. Density refers to the number of fish in each tank prior to PIT tagging in July 2015 (max 50). SireID corresponds to individual families held together in one tank.