There is increased commercial interest in the production of Lumpfish (Cyclopterus lumpus, Linnaeus, 1758) as a biological control for sea lice infections in Atlantic salmon (Salmo salar ). To ensure sustainability, reliable captive broodstock management is required however many aspects are still unknown. A key component in closing the life cycle of any species is improving survival within the egg. Thus determining the components that affect egg quality is a key step in improving the sustainability of any captive breeding program.
The present study attempts to assess the current difference in egg quality between wild and captive broodstocks. Egg samples and quality data have been collected from Norwegian wild (n=40) and Captive Scottish (n=44) stocks. There was a significant difference between wild and captive egg performances at all stages (fertilization, eyeing and hatch rates). There was high variation in hatching success in wild batches (0%-75%), whereas the majority of captive eggs did not reach hatching (6/44), those that did, hatching rates were significantly lower than wild eggs.
There was significant compositional difference between wild and captive stocks at the point of stripping, in lipids, fatty acids, minerals and pigments. The captive eggs were deficient in EFA’s such as EPA and DHA as well as overall lipid levels 1/3rd lower than the wild stocks. The captive eggs were deficient in 8/12 measured minerals and overall pigment levels were 1/3rd of those in the wild stocks. Lumpfish eggs are characterized by a high level of neutral lipid fraction similar to those found in other species which exhibit lipid globules within the egg, and high levels of pigmentation were found within the eggs, with large levels of variation of individual pigments, which appear to reflect the observed natural variation found in wild caught fisheries. A total of 49 nutritional components were identified as having significant positive or negative relationships with hatching rate. EFA’s such as EPA and DHA and Total N- 3 PUFA showed strong significant positive relationships with hatching rate as well as levels of saturated FA’s such as 16:0. High levels of N-6 PUFAS especially ARA were strongly associated with poor egg quality in this species.
The present study is the first to address egg quality in Lumpfish, currently underperforming eggs are a substantial factor in the creation of a commercially viable broodstock. the present study has confirmed significantly poorer egg quality in captive derived broodstock, than the wild caught stocks, displaying significantly lower fertilization, eyeing and hatching rates. Poor egg quality is a major hurdle in successful commercial production of this new species. This work can provide key information to inform the creation of broodstock diets for lumpfish, as well as an important bassline in further egg quality work within the species.