There is increased commercial interest in the production of Lumpfish (Cyclopterus lumpus ) as a biological control for sea lice infections in Atlantic salmon farming. In the early stages of domestication for new species, ambiguity in the spawning windows can have detrimental effects on egg quality. A Lack of clarity in the lumpfish’s spawning season can lead to a-synchronous development and long spawning windows. Under these conditions, eggs can be left in the body cavity for long periods of time and result in over-ripening of eggs and a reduction in egg quality.
The present study aimed to investigate the length of the overripening widow, through documenting the effect of post ovulatory aging for lumpfish. It also aimed to characterise the protein composition of the ovarian fluid and identify potential biomarkers for egg quality. Eggs were stripped from wild and captive broodstock and maintained in their ovarian fluid at 4 °C until fertilised. Batches of eggs were fertilised at 4, 12, 24, 48, 72, 96 and 120 hours post stripping.
Ovarian fluid was collected at the point of stripping and analysed using TMT isobaric tagging to identify proteins present.
All three measured quality parameters decreased significantly with increased ageing. The quality of captive eggs decreased faster than the wild eggs. Hatching success was significantly reduced (> 50 %) after just 24 hours post ovulatory aging for both groups. The data suggests a short overripening window for this species.
A total of 304 proteins were identified as being present in the lumpfish ovarian fluid, with no proteins unique to either wild of captive ovarian fluid. 21 proteins were identified as potential biomarkers associated with egg quality which warrant further investigation, with 1 protein (VPS33B late endosome and lysosome associated) being significant marker of quality for this species.
Poor egg quality is a major hurdle in successful production of any new marine species and there appeared to be a significant difference in the performance of the wild and captive eggs. The findings of this study suggest that even if egg composition improves within the species, there is a small window that these benefits can be lost because of mismanagement of ovulation and stripping in the species. This study clearly shows that intensive management of broodstock is required in order to identify ovulating individuals for stripping. With a short window (24hr) post ovulation until a significant reduction in quality.
Future work needs to clarify the role of many of the proteins identified in this study. It would also aim to build on the data in the current study to develop individual biomarkers for poor quality within the species. Development of such can allow rapid on farm testing of ovarian fluid to improve broodstock management, identify good quality individuals and reduce hatchery effort in poor quality eggs.