Investigation of Fertilization, Hatching and Survival Rates of Eggs from Crossbreeding Diploid and Tetraploid in Trout (Oncorhynchus mykiss)

The aim of this study was to compare the sperm size and reproductive performance of tetraploid and diploid rainbow trout (Oncorhynchus mykiss) and to investigate the effects of polyploidy on reproductive success. The effects of different ploidy levels on sperm morphology, fertilization rates, embryo development and survival rates were evaluated. Tetraploid and diploid rainbow trout individuals were used in the study. Four different crossover combinations were tested: (i) Diploid male× Diploid female, (ii) Tetraploid male× Tetraploid female, (iii) Diploid male × Tetraploid female, (iv) Diploid female × Tetraploid male. Sperm sizes were measured by microscopic analysis and fertilization rates and survival of offspring were compared. Statistical analyses were performed using ANOVA and correlation tests. Sperm size from tetraploid males was found to be significantly larger than diploid individuals (p < 0.05). In terms of fertilization rates, diploid × tetraploid crossovers showed significant fertilization success. When looking at embryo hatching rates, tetraploid individuals were lower; however, when looking at survival rates, there was no significant difference between the groups. In conclusion, tetraploidization may affect sperm size reproductive success. Improving reproductive results by crossing diploid and tetraploid individuals is considered a viable method. However, genetic and environmental factors need to be further investigated to fully understand how this process works.