Production of Triploid Lake Trout by Means of Pressure Treatment

Abstract To induce triploidy in lake trout Salvelinus namaycush, we treated a production-sized group at Story State Fish Hatchery, Wyoming, with 65,500 kPa at 300 degree-minutes (°C·min) for 5 min and investigated four different pressure treatments (62,053 kPa at 300°C·min for 5 min; 65,500 kPa at 200, 300, or 400°C·min for 5 min) at Saratoga National Fish Hatchery, Wyoming. For the production group, eggs hatched and survived at a higher rate when held in chilled water (10.6°C) than ambient water (11.5°C). For the experimental groups, mean survival of pressure-treated groups to the eyed egg, hatching, and feeding fry stages was at least 15% lower than that of the control group. However, due to high variability, there was no statistical difference in survival among the experimental groups. All fry (n = 178) sampled from the four experimental treatments and the single production group were triploid.