Comparative proximate analysis of wild and captive lumpfish (Cyclopterus lumpus) eggs show deficiencies in captive eggs and possible egg quality determinants

Abstract

The production of lumpfish (Cyclopterus lumpus) is increasing rapidly due to their use as a cleaner fish for sea lice infections in Atlantic salmon farming. The sustainable development of captive broodstocks is reliant on good egg quality however this remains unknown. The present study assessed the hatching success and nutritional composition of eggs collected from two wild groups, at the start and end of the Norwegian fishing season (2018–2019), and one captive broodstock population (2019). Eggs from the farmed broodstock, used in this study, showed significantly lower fertilisation rates, eyeing rates and survival to hatching than eggs from wild broodstock. There was significantly less overall lipid content in the captive eggs when compared to the wild group as well as significantly lower levels of lipid fractions such as total N-3 PUFAs, minerals such as sodium and phosphorus and overall egg pigment levels. A principal component analysis of all 139 measured nutritional components within fatty acids, minerals and pigments was conducted to identify those associated with egg quality in lumpfish. A total of 51 components was identified as being positively (31) and negatively (20) correlated with hatching rate including essential fatty acids such as EPA, DHA and ARA, total pigment levels and calcium levels. Overall, this study clearly showed a reduction in egg quality from captive broodstock and suggested nutritional deficiencies in the current broodstock diets. As such, this study provides a foundation for further work into the optimisation of lumpfish broodstock management with a number of nutritional factors to be further investigated.