What if genetic is just the dam component?
I am not very familiar with fish experiments but I understand that sometimes families are raised in different tubs. Since in this case, families are represented by sires, if these families were raised in different tubs, then the sire variance is tub variance (in the sire dam model), and the dam variance is primarily genetic. Under this scenario, sire is analgous to ‘maternal environment’ effects in animal experiments. I have therefore fitted sire + dam (allowing for 6 outliers and on the log scale with the model, see below) log(wt) ~ mu age out(53) out(301) out(302) out(342) out(1004) out(631) !r sire dam This gives Source Model terms Gamma Component Comp/SE % C dam 13 13 0.747327 0.104939 1.09 0 P sire 26 26 1.40185 0.196846 2.50 0 P Variance 1300 1292 1.00000 0.140419 25.18 0 P The dam variance is still too large to provide a plausible heritability though.
