Supporting material Figures Fig. S1. BT hybrids (brown trout mother) suffered significantly higher mortality during the initial 100 days of juvenile rearing than did other groups (p < 0.001), including (left to right) brown trout, AS hybrids (salmon mother), and Atlantic salmon. Error bars represent one standard deviation 1 Tables Table S1. Parental sources of gametes used in experimental crosses. Source Family 1 2 3 4 5 6 Cross Trout Trout Trout Trout Trout Trout Paternal Trout 7 Trout 8 Trout 9 Trout 1 Trout12 Trout10 Maternal Trout13 Trout14 Trout15 Trout 16 Trout 17 Trout 18 7 8 AS Hybrid AS Hybrid Trout 4 Trout 12 9 10 11 12 BT Hybrid BT Hybrid BT Hybrid BT Hybrid Salmon 1 (transgenic) Salmon 2 (transgenic) Salmon 3 (transgenic) Salmon 4 (transgenic) Trout 19 Trout 20 Trout 21 Trout 22 13 14 15 16 17 18 19 Salmon Salmon Salmon Salmon Salmon Salmon Salmon Wild salmon 6 Wild salmon 9 Salmon 5 (transgenic) Salmon 6 (transgenic) Wild salmon 3 Wild salmon 8 Wild salmon 2 Salmon 8 (transgenic) Salmon 9 (transgenic) Wild salmon 11 Wild salmon 10 Salmon 7 (transgenic) Salmon 10 (transgenic) Salmon 11 (transgenic) Salmon 7 (transgenic) Salmon 8 (transgenic) 2 1 Table S2. Mass (g) and length (mm) of groups at the start and end of 100 days rearing in common laboratory conditions. Note 2 differences in initial size among groups. Cross Trout (n=6) AS hybrids (n=2) BT hybrids (n=4) Salmon (n=7) Initial length (mm) Wild-type Transgenic 22.38 NA 25.24 25.00 21.33 21.26 24.47 24.08 Initial mass (g) Wild-type Transgenic 0.091 NA 0.139 0.137 0.087 0.082 0.144 0.138 Final length (mm) Wild-type Transgenic 43.134 NA 46.290 55.159 39.799 51.671 43.675 51.991 Final mass (g) Wild-type Transgenic 0.976 NA 1.296 1.977 0.810 1.536 1.040 1.535 3 4 Table S3. Comparisons of size-standardized growth rate in length (mm) and mass (g) during 100 days rearing in common laboratory 5 conditions compared to growth rate not considering size-effects. -1 Cross Trout (n=6) AS hybrids (n=2) BT hybrids (n=4) Salmon (n=7) Growth (mm day ) Wild-type Transgenic 0.00659 NA 0.00572 0.00746 0.00584 0.00834 0.00565 0.00752 -1 Growth (g day ) Wild-type Transgenic 0.0240 NA 0.0210 0.0252 0.0209 0.0277 0.0193 0.0236 Standardized Growth (% change mm-1) Wild-type Transgenic 1.92 NA 1.71 2.29 1.66 2.48 1.67 2.28 Standardized Growth (% change g-1) Wild-type Transgenic 1.68 NA 1.64 2.11 1.41 2.07 1.46 1.89 6 3 Table S4. Initial and final mass (g) and length (mm) and of wild-type and transgenic Atlantic salmon reared in allopatry or sympatry with transgenic AS and BT hybrids. Treatment Initial mass (g) Allopatry- Control (n=92) Sympatry- AS hybrids (n=61) Sympatry- BT hybrids (n=45) Initial length (mm) Final mass (g) Final length (mm) Wild-type Transgenic Wild-type Transgenic Wild-type Transgenic Wild-type Transgenic 1.081 1.045 0.9569 1.484 1.572 1.644 43.86 43.93 42.36 51.55 52.38 53.05 1.454 1.246 1.136 1.766 1.606 1.693 48.23 46.13 44.52 54.43 54.09 54.42 Table S5. Growth rate (size-standardized) and condition factor (103 x Weight/Length3) of wild-type and transgenic Atlantic salmon reared in allopatry or sympatry with transgenic AS and BT hybrids. Treatment Allopatry- Control (n=92) Sympatry- AS hybrids (n=61) Sympatry- BT hybrids (n=45) Standardized growth (% mm day-1) Wild-type Transgenic 0.00973 0.00579 0.00491 0.00340 0.00485 0.00273 Standardized growth Δ Condition factor -1 (% g day ) (Final CF-Initial CF) Wild-type Transgenic Wild-type Transgenic 0.0100 0.0063 1.72E-05 9.37E-06 0.0056 0.0006 2.50E-05 -8.53E-05 0.0051 0.0011 1.86E-05 -4.65E-05 4