Optimization of Thermal Shock for Poliplody Induction in Rainbow Trout (Oncorhynchus mykiss) under Photoperiodic Control of Spawning

摘要

Natural fish stocks could be at risk due to interbreeding or competition with farmed fish, which often differ genetically from their counterparts in wild. Farming of sterile or all-female triploids could be a powerfull preventative measure for preservation of natural gene resources or biodiversity of native species. Although, techniques for ploidy are well described in many fish species, there is no report whether the previous techniques applicable in out-off-season production induced by artificial photoperiod that is widely used in salmonid aquaculture. In order to optimize and refund ploidization protocol for off-season production of diploid gynogenomes and triploids three experiments were conducted to determine the optimal UV inactivation of sperm and heat shock treatment of eggs in rainbow trout (Oncorhynchus mykiss). High survival at yolk sac absorption stage (82.3–84.5%) and high yields (approx. 100%) were achieved from the range of treatments applied. There were significant differences in survival rates among treatments and the best optimisation was defined as the shock timing at 20 minutes post-fertilisation for 10 min duration at the shock temperature of 26 °C.