A study of inadvertent domestication selection during start‐feeding of brown trout families

A study was undertaken to compare first‐feeding mortality among 10 brown trout families fed high (100%) and low (25%) rations in replicate mixed family tanks. Microsatellite DNA profiling was used to assign individual brown trout to family of origin. At the end of the 35 day experimental period, highly significant differences in overall mortality were observed between the two treatments, and within the treatments there were highly significant differences in family mortality. Both replicates displayed similar patterns of family mortality. Notably, the distribution of mortality among families differed significantly between the two ration treatments, although this was more distinct for some families than others. No correlation between mean family egg diameter and family mortality were observed within either feeding treatment, although a significant positive correlation between mean family egg diameter and timing of family mortality was observed. It is suggested that these data indicate the existence of a genotype x environment interaction relating to feeding level during the critical start‐feeding period.