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Characteristics of the first blastomeres in fish have been evaluated in previous studies as a tool for predicting egg and larva quality. Nevertheless, there are still few studies of the presence of inclusions in fish blastodiscs or blastomeres. The object of the present study was to describe the relationship between cellular inclusions and some embryo quality parameters (symmetry, fertility rate, survival rate) in farmed coho salmon. Eggs from 261 females were fertilized with 400 × 103 spermatozoa/egg and incubated in the dark in separated flow-through incubators. Embryos at the four-cell stage were fixed in Stockard's solution and the blastodiscs were classified as: i) unfertilized, ii) fertilized with inclusion, and iii) without inclusion. The blastomere symmetry was also recorded. Embryos from 30 females (15 with and 15 without inclusions) were incubated until pigmented eye embryo stage to determine the survival rate. Cell inclusions were detected in 8.81 % of the females evaluated, with 24.1 ± 24.2 of the eggs from each of those females presenting inclusions. Egg samples with this abnormality showed significantly lower fertility, blastomere symmetry, and survival rate when compared with eggs without inclusions. • The term 'inclusion' is used to denote one or more holes of varying size and depth. • Inclusions can be found in the intracellular space of both blastomeres and blastodiscs. • Eggs with inclusions had low blastomere symmetry and survival rates. • As the percentage of inclusions increases, the fertility percentage decreases. [ABSTRACT FROM AUTHOR]

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. [Copyright &y& Elsevier]