Early embryonic cleavage pattern, hatching success, and egg-lipid fatty acid composition: comparison between two cod (Gadus morhua) stocks
1997
Pickova, J | Dutta, P C | Larsson, P -O | Kiessling, A
Baltic cod (Gadus morhua), from a brackish environment, were compared with oceanic (Skagerrak) cod in terms of early embryonic cleavage pattern, hatching success, and egg-lipid fatty acid composition. The influence of diet on these variables was investigated by analysing eggs from the Baltic stock, caught during three successive years and given controlled food for 24, 7, and 2 months, respectively, before the experiment commenced. Skagerrak cod eggs contained twice as much arachidonic acid (AA) in the phospholipid (PL) fraction as eggs from the Baltic cod, regardless of the length of time the Baltic cod had been kept in captivity and fed a control diet. Correlation between hatching rate and docosahexaenoic (DHA; 22:6n-3)/ eicosapentaenoic acid (EPA; 20:5n-3) ratio was significant (r² = 0.56) as well as hatching rate and AA content of the PL fraction (r² = 0.61). Symmetry during development, which was correlated to egg viability, was higher for eggs from Skagerrak than those from the Baltic stock. We suggest that AA content and DHA/EPA ratio of the PL fraction are important factors influencing egg viability and possibly also egg symmetry.\b Further, it appears that the factor(s) influencing the composition of the PL fraction is mostly related to stock rather than to diet.
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