Improved fertilization of halibut eggs
The main bottlenecks in sea fish farming are the early stages of development and the supply of quality eggs, larvae and juveniles. The egg quality of fish varies greatly and is mainly assessed by the fertilization rate and performance of eggs and larvae, but is controlled by various factors. It is very important for the management and performance of companies to be able to assess roe quality as soon as possible. The aim of this project was to define factors that affect the fertilization rate of halibut eggs and that can possibly be controlled. At the same time, experiments were carried out with different methods of fertilization where the amount of seaweed was changed or substances were added to the environment during fertilization. Fish in two spawning groups were followed up and extensive research was carried out on the characteristics and bacterial flora of roe doses. The results show that there is not much variability in the measures examined and there is no significant correlation with the fertilization rate, which indicates that they are unlikely to have a decisive effect on egg quality. However, the results indicate that the composition of the total bacterial flora and the composition of essential fatty acids are different in eggs with a higher fertilization rate and can therefore affect the quality of eggs. The main results of fertilization experiments indicate that the addition of glucose at a certain concentration in the roe environment can lead to a 10% increase in the fertilization rate of roe, which offers the possibility of a large increase in income for aquaculture companies. Extensive research is planned on the further effects of glucose admixture on roe performance as well as larval performance and quality.
The main bottle necks in intensive marine aquaculture are the first stages and the supply of high quality eggs, larvae and juveniles. Egg quality is highly variable and has been defined in many ways mainly the fertilization rate and the viability of fertilized eggs and larvae. Multiple factors affect egg quality and an early assessment of egg quality is of great importance for hatchery management. The objective of this work was to define indicators for halibut egg quality that could possibly be regulated. Furthermore, the effects of variable fertilization methods have been tested, that is, variable amounts of seawater and addition of various chemicals during fertilization. Batches of eggs were collected from two spawning groups and extensive examination carried out on their characteristics and bacterial composition. The results show very little variability in the factors examined and no correlation with the fertilization rate that indicates insignificant importance for egg quality. However, the bacterial composition and the fatty acid composition were different in the batches of eggs with higher fertilization rate compared to lower indicating its importance for egg quality. The fertilization experiments indicate that the use of a certain concentration of glucose during fertilization could result in 10% increase in the fertilization rate which could bring about an increased operation success for the aquaculture companies. Comprehensive studies are scheduled to further investigate the effect of additional glucose on egg viability and larval survival as well as quality.