Single pair mating indicates maternal effects on embryo survival in rainbow trout, Oncorhynchus mykiss

The maternal and paternal influences on early embryo survival in rainbow trout are not established. The purpose of this study was to determine whether variability in the survival of rainbow trout embryos could be attributed to either the female or male parent. Gametes from individual female and male rainbow trout were used in single pair matings to produce families whose survival was followed from fertilization to the time of swim-up (i.e., similar to 7 weeks post-fertilization). Survival was assessed at 0.5, 9, 19, 33, and 48 days post-fertilization, corresponding to second cleavage, embryonic keel formation, retinal pigmentation, hatch, and swim-up, respectively. The variability of survival at all times was significantly (P<0.01) influenced by the female parent, whereas the influence of the male parent was negligible (P>0.05). Therefore, in rainbow trout embryo survival can be equated with the quality of the egg. To predict survival at swim-up (i.e., after 48 days) it was found that embryonic keel formation, measured 9 days after fertilization, was the earliest time at which a highly significant positive correlation (r = 0.889, P < 0.001) was demonstrated. (C) 2000 Elsevier Science B.V. All rights reserved.