Evaluation of egg quality parameters as predictors of hatching success and early larval survival in hapuku (Polyprion oxygeneios)

Abstract

This study investigates the efficacy of using different quality parameters to predict hatching percentage of fertilized eggs and early larval survival in a newly farmed species Polyprion oxygeneios (called ‘hapuku’ and ‘groper’ in New Zealand). Blastomere morphology was assessed for individual fertilized eggs, which were then incubated and monitored until hatch. Additionally, blastomere morphology, percentage of floating eggs, fertilization percentage and egg and lipid vesicle diameter were measured for multiple batches incubated during two consecutive captive hapuku spawning seasons in 2008 and 2009. The blastomere morphology score of individual fertilized eggs was significantly correlated with the percentage of individual fertilized eggs that hatched (R²=0.89, p<0.001). Furthermore, blastomere morphology score showed a significant correlation with the combined hatching percentage data from egg batches incubated in 2008 and 2009 (R²=0.32, p<0.001) and was also significantly correlated with larval survival to the post-yolk sac stage (R²=0.34, p=0.005). The percentage of floating eggs and fertilization percentage also significantly correlated with hatching success (R²=0.18 and 0.21 respectively, p<0.05) and with larval survival (R²=0.22 and 0.16 respectively, p<0.05). By comparison, egg diameter and lipid vesicle diameter showed no correlation with percentage hatch or with larval survival. We conclude that of all the egg quality parameters tested, the blastomere morphology score is the most useful and is an effective tool for assessing the quality of egg batches during hapuku hatchery management.