Comparison of Diploid and Triploid Atlantic Salmon (Salmo salar) Physiological Embryonic Development

SIMPLE SUMMARY: This study looked at the development rate from the moment of fertilisation to hatching in both diploid and triploid Atlantic salmon. These two types of salmon have distinct physical and biological characteristics, including differences in their hearts, brains, digestive systems, their ability to handle different temperatures as eggs and after hatching, and their nutritional needs. The study did not find a significant difference in the rate at which the two types of embryos developed their physical characteristics. However, there were two notable differences between the two types of salmon. Triploid salmon hatched earlier than diploid salmon and reached the halfway point of hatching significantly sooner. Unfortunately, triploid salmon also experienced a higher rate of mortality. These findings provide valuable insights for future research involving Atlantic salmon aquaculture. ABSTRACT: Diploid and triploid Atlantic salmon show distinct physiological differences including heart, brain, and digestive system morphology, propensity for certain deformities, temperature tolerance as eggs and once hatched, and different nutritional requirements. Whilst several studies have looked in detail at the rate of embryogenesis in diploid salmon, no study has compared the rate of embryogenesis between ploidies from fertilisation to hatch. This study based its assessment on a seminal paper by Gorodilov (1996) and used the same techniques to compare the rate at which triploid and diploid embryos developed morphological characteristics. Whilst no significant difference was found, this study provides well-needed justification for the assumption that both ploidies develop at the same rate and gives scientific weight to studies which involve manipulation at these stages of development. Two factors that did differ, however, were the timing of hatch, and mortality. Triploids hatched more quickly than diploids and reached 50% hatch at a significantly earlier point. Triploids also suffered from a significantly higher rate of mortality.