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 tr out are not established. The purpose of this study was to determine whether variability in the survival of rainbow trout embryos could be attributed t o either the female or male parent. Gametes from individual female and male rainbow trout were used in single pair matings to produce families whose s urvival was followed from fertilization to the time of swim-up (i.e., simil ar to 7 weeks post-fertilization). Survival was assessed at 0.5, 9, 19, 33, and 48 days post-fertilization, corresponding to second cleavage, embryoni c keel formation, retinal pigmentation, hatch, and swim-up, respectively. T he variability of survival at all times was significantly (P<0.01) influenc ed by the female parent, whereas the influence of the male parent was negli gible (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 fe rtilization, was the earliest time at which a highly significant positive c orrelation (r = 0.889, P < 0.001) was demonstrated. (C) 2000 Elsevier Scien ce B.V. All rights reserved.