Research into lumpfish (Cyclopterus lumpus) broodstock management and gamete quality

Abstract

The lumpfish (Cyclopterus lumpus) has been proposed as a sustainable solution to sea lice infestations in Atlantic salmon (Salmo salar) aquaculture. Current production is reliant on wild caught broodstock and closed life cycle management is essential to improve sustainability and allow for stock improvement. This thesis aimed to address knowledge gaps in the broodstock management of the species. Holding temperature for broodstock during the spawning season should be kept below 10° C to improve egg quality and spawning performance. In order to extend the spawning season, temperatures can be safely lowered to 6° C without impeding egg quality. Oocyte histology and distribution data suggests that lumpfish are a batch spawning species and provided the first histological oocyte development scale for the species. Subsequent research, aimed to address challenges associated with gamete management to improve artificial fertilisation protocols. Ex vivo egg ageing suggested that the window of overripening for lumpfish is 24 hours before significant reduction in egg quality. Sperm concentration was also affected by high broodstock holding temperature for this species. Research into milt quantification and storage identified two extender solutions and two rapid methods for assessing sperm concentration to aid milt management. Research into egg quality determinants identified several candidates within egg composition which strongly associated with hatching success within lumpfish. Increased levels of essential fatty acids such as EPA and DHA as well as minerals such as calcium and total levels of pigment within eggs correlated with high hatching success. Analysis of the lumpfish ovarian fluid proteome also identified several protein biomarkers for egg quality through analysis of wild, captive “good” and “bad quality eggs, it also Identified several potential biomarkers for overripe eggs in lumpfish. Overall, this research provides important baseline data on the management of broodstock and the optimisation of hatchery protocols to close the life cycle of the species.