Assessing the quality of Atlantic salmon (Salmo salar) eggs

Atlantic salmon disappeared from our rivers in the 1930s due to pollution, dam construction and overfishing. Therefore, the reintroduction of the natural life cycle of this species in the Meuse system has a high ecological value. Furthermore, salmonid and salmonid egg consumption are of nutritional interest as they provide us with health-promoting omega-3 highly unsaturated fatty acids (n-3 HUFA) (EPA and DHA). The present work was designed to evaluate the way to (1) optimise the Atlantic salmon reintroduction in our region and (2) introduce their eggs in our diet. Regarding the first objective, we worked in association with the CoSMos centre where salmonids are artificially reproduced to restock the rivers of the Meuse basin. For this purpose, we assessed the egg quality to ensure a better spawning success and hence a higher survival rate of salmonids. The second objective was to assess the egg nutritional quality in order to evaluate the interest for a Walloon Atlantic salmon egg production. In addition, a sensory test gave us a better insight into the way potential consumers could appreciate the eggs. The egg n-3 HUFA content could have a direct impact on their survival rate. Survival rate of salmonids registered at CoSMos were higher among semi-wild fish, as compared with captive counterparts. The life type difference between captive and semi-wild salmonids appeared to have a direct impact on the n-3 HUFA content of the eggs, which was higher in the migrating semi-wild fish eggs. Besides, the results of the environment impact between the eggs of salmons, which spent two years at sea, either caught in the Meuse system or in their own Loire-Allier system, suggested that they both shared an identical feeding ground at sea. The Allier returners, compared with their Meuse counterparts, may however migrate to a more northern feeding ground. The study of the species impact between the eggs of the semi-wild sea trouts, which spent one year at sea, and the semi-wild Atlantic salmons of Loire-Allier strain, which spent two years at sea, both caught in the Meuse river in Lixhe (Belgium), suggested a more “marine-type” pattern for the Atlantic salmons, compared with the sea trouts. However, the results showed that our semi-wild sea trouts were effectively going at sea for feeding and growing. If the n-3 HUFA egg content could be related to the latitude of the fish feeding area, with higher n-3 HUFA content in fish travelling to more northern feeding areas, needs further studies to be clarified. Atlantic salmon eggs could be a good additional source of n-3 HUFA in human nutrition. Their n-3 HUFA content was lower but in the same range as the commercial Pacific salmon eggs. Moreover, the sensory test revealed that the salmonid egg samples were globally well appreciated. The colour, brightness, saltiness and aftertaste were the more variable features between the four egg samples tested. Atlantic salmon eggs may further be improved in nutritional and sensory terms, but could definitively become a valid opportunity to give an added value to the Atlantic salmon farming. More extensive research needs to be performed in order to find out the relative implication of the fish metabolism and diet in the derived egg composition, as well as the possible impact of other compounds, present in the fish eggs, on the egg quality.