Triploid induction in cultured burbot (Lota lota) using thermal and hydrostatic shock

The feasibility of triploid induction for burbot (Lota Iota) was determined following a series of hydrostatic (pressure) and thermal (heat) shock treatments. Hydrostatic shock treatments were designed to test a range of variables including 1) duration of shock; 2) timing of shock (post-fertilization); and 3) shock pressure. Shock times post-fertilization and shock duration were varied by degree minutes CC minutes). A hydrostatic shock of 8,500psi at 180 degrees C minutes post-fertilization for 10 degrees C minutes yielded the highest percent triploid induction (100%) and survival (95%) relative to the controls. Duration of pressure-shock longer than 10 degrees C min at 8,500psi and higher, resulted in 100% pre-hatch mortality. A reduced shock pressure (7,500psi) resulted in a high percent triploidy (100%), but pre-hatch larval survival was 65.5% at a shock duration of 30 degrees C minutes. Thermal shock treatments included: duration of shock, timing of shock, and shock temperature. Triploid induction and survival were greatest following a thermal shock of 16 degrees C at 120 degrees C minutes post-fertilization for 500 degrees C minutes. This resulted in 96.6% triploidy and 57.4% survival relative to control groups. Shock temperatures above 16 degrees C generally resulted in a higher percent triploid induction but lower survival. Results presented here confirm that triploid induction in burbot is possible. Further work is needed to confirm scale up potential, survival dynamics, sterility of triploid burbot, and changes in growth performance. Production of sterile burbot may increase opportunities for culturing burbot in areas where escapement may be a concern or when growth is inhibited due to reproductive maturation.